Kirstin Krüger

Publikasjon

Fagfellevurderte publikasjoner:

• Brenna, H.; Kutterolf, S.; Mills, Michael; Niemeier, M., Timmreck, C., U., & Krüger, K. (2021). Decadal Disruption of the QBO by Tropical Volcanic Supereruptions. Geophysical Research Letters. ISSN 0094-8276. 48(5), p. 1–13. doi: 10.1029/2020GL089687
• Brenna, H., Kutterolf, S., Mills, M. J. & Krüger, K. (2020). The potential impacts of a sulfur- and halogen-rich supereruption such as Los Chocoyos on the atmosphere and climate, Atmos. Chem. Phys., 20, 6521–6539, https://doi.org/10.5194/acp-20-6521-2020
• Brenna, H., Kutterolf, S., & Krüger, K. (2019). Global ozone depletion and increase of UV radiation caused by pre-industrial tropical volcanic eruptions. Sci Rep 9, 9435, https://doi.org/10.1038/s41598-019-45630-0.
• Toohey, M., Krüger, K., Schmidt, H. et al. (2019). Disproportionately strong climate forcing from extratropical explosive volcanic eruptions. Nature Geosci 12, 100–107, https://doi.org/10.1038/s41561-018-0286-2
• Ziska, F., Quack, B., Tegtmeier, S., Stemmler, I., & Krüger, K. (2017). Future emissions of marine halogenated very-short lived substances under climate change, J Atmos Chem 74, 245–260, https://doi.org/10.1007/s10874-016-9355-3
• Toohey, M., K. Krüger, M. Sigl, F. Stordal, & H. Svensen, H. (2016). Climatic and societal impacts of a volcanic double event at the dawn of the Middle Ages, Climatic Change, 136, 401–412, https://doi.org/10.1007/s10584-016-1648-7
• Krüger, K., Kutterolf, S., T.H., Hansteen, (2015). Chapter 16: Halogen release from Plinian eruptions and depletion of stratospheric Ozone, Volcanism and global environmental change, Cambridge University Press, ISBN: 9781107058378, Ed. A. Schmidt et al., PP. 244-259.
• Sigl, M., J.R. McConnell, M. Toohey, M. Curran, S.B. Das, R. Edwards, E. Isaksson, K. Kawamura, S. Kipfstuhl, K. Krüger, L. Layman, O. Maselli, Y. Motizuki, H. Motoyama, D. Pasteris, & M. Severi, (2014)  Insights from Antarctica on volcanic forcing during the Common Era. Nature Clim Change 4, 693–697, https://doi.org/10.1038/nclimate2293
• Ziska, F., Quack, B., Abrahamsson, K., Archer, S. D., Atlas, E., Bell, T., Butler, J. H., Carpenter, L. J., Jones, C. E., Harris, N. R. P., Hepach, H., Heumann, K. G., Hughes, C., Kuss, J., Krüger, K., Liss, P., Moore, R. M., Orlikowska, A., Raimund, S., Reeves, C. E., Reifenhäuser, W., Robinson, A. D., Schall, C., Tanhua, T., Tegtmeier, S., Turner, S., Wang, L., Wallace, D., Williams, J., Yamamoto, H., Yvon-Lewis, S., & Yokouchi, Y. (2013). Global sea-to-air flux climatology for bromoform, dibromomethane and methyl iodide, Atmos. Chem. Phys., 13, 8915–8934, https://doi.org/10.5194/acp-13-8915-2013
• Montzka, S., S. Reimann, S. O'Doherty, A. Engel, K. Krüger & W.T., Sturges, (2011). Chapter 1: Ozone-Depleting Substances and Related Chemicals, Scientific Assessment of Ozone Depletion: 2010, PP 112.
• Butchart, N, A. Charlton-Perez, I., Cionni, S.C., Hardiman, Krüger, K. et al. (2010). Chapter 4: Stratospheric Dynamics, SPARC CCMVal Report on the Evaluation of Chemistry-Climate Models, SPARC No. 5, WCRP-132, WMO/TD-No. 1526, PP 109-148.

• Zhuo, Zhihong; Fuglestvedt, Herman Fæhn; Toohey, Matthew & Krüger, Kirstin (2024). Initial atmospheric conditions control transport of volcanic volatiles, forcing and impacts. Atmospheric Chemistry and Physics (ACP). ISSN 1680-7316. 24(10), s. 6233–6249. doi: 10.5194/acp-24-6233-2024.
• van Dijk, Evelien J. C.; Jungclaus, Johann; Sigl, Michael; Timmreck, Claudia & Krüger, Kirstin (2024). High-frequency climate forcing causes prolonged cold periods in the Holocene. Communications Earth & Environment. ISSN 2662-4435. 5(1). doi: 10.1038/s43247-024-01380-0.
• Fuglestvedt, Herman Fæhn; Zhuo, Zhihong; Toohey, Matthew & Krüger, Kirstin (2024). Volcanic forcing of high-latitude Northern Hemisphere eruptions. npj Climate and Atmospheric Science. ISSN 2397-3722. 7(1), s. 1–12. doi: 10.1038/s41612-023-00539-4.
• Zhuo, Zhihong; Fuglestvedt, Herman Fæhn; Toohey, Matthey & Krüger, Kirstin (2023). Initial conditions control transport of volcanic volatiles, forcing and impacts. Atmospheric Chemistry and Physics Discussions (ACPD). ISSN 1680-7367. doi: 10.5194/egusphere-2023-2374.
• Ridderseth, Hilde; Daltveit , Dagrun Slettebø; Hollund, Bjørg Eli; Kirkeleit, Jorunn; Kromhout, Hans & Krüger, Kirstin [Vis alle 8 forfattere av denne artikkelen] (2023). Validation of a full-shift benzene exposure empirical model developed for work on offshore petroleum installations on the Norwegian continental shelf. Journal of Occupational and Environmental Hygiene. ISSN 1545-9624. 20(10). doi: 10.1080/15459624.2023.2242416.
• Van Dijk, Evelien; Gundersen, Ingar Mørkestøl; de Bode, Anna; Høeg, Helge Irgens; Loftsgarden, Kjetil & Iversen, Frode [Vis alle 9 forfattere av denne artikkelen] (2023). Climate and societal impacts in Scandinavia following the 536 and 540 CE volcanic double event. Climate of the Past. ISSN 1814-9324. 19(2), s. 357–398. doi: 10.5194/cp-19-357-2023. Fulltekst i vitenarkiv Vis sammendrag

  In the Northern Hemisphere, the mid-6th century was one of the coldest periods of the last 2000 years, as indicated by both proxy records and Earth System Model (ESM) simulations. This cold period was initiated by volcanic eruptions in 536 CE and 540 CE. Evidence from historical sources, archaeological findings, and proxy records suggests that the extent and severity of this volcanic induced cooling was spatially heterogeneous and that the effect on society resulted in adaptation and resilience at some locations, whereas social crisis has been indicated at others. Here, we study the effect of the volcanic double event in 536 CE and 540 CE on the climate and society in Scandinavia with a special focus on Southern Norway. Using an ensemble of Max Planck Institute ESM transient simulations for 521–680 CE, the temperature, precipitation and atmospheric circulation patterns are studied. The simulated cooling magnitude is then used as input for the growing degree day (GDD) model set-up for Southern Norway. This GDD model indicates the possible effects on agriculture for three different study areas in Southern Norway, representative of typical meteorological and landscape conditions. Pollen from bogs and archaeological records inside the study area are then analysed at high resolution (1–3 cm sample intervals) to give insights into the validity of the GDD model set-up with regard to the volcanic climate impact on the regional scale, and to link the different types of data sets. After the 536/540 CE double event, a maximum surface air cooling of up to 3.5 °C during the mean growing season is simulated regionally in Southern Norway. With a worst-case scenario cooling of 3 °C, the GDD model indicates crop failures were likely in our northernmost and western study areas, while crops were more likely to mature in the southeastern study area. These results are in agreement with the pollen records from the respective areas. During the sixth century, excavations show an abandonment of farms, severe social impact but also a continuation of occupation or a mix of those. In addition, archaeological findings from one of the excavation sites suggest wetter conditions for the mid-sixth century in Scandinavia, as simulated by individual ensemble members. Finally, we discuss the likely climate and societal impacts of the 536/540 CE volcanic double event by synthesising the new and available data sets for the whole Scandinavia.

• Fang, Shih-Wei; Timmreck, Claudia; Jungclaus, Johann; Krüger, Kirstin & Schmidt, Hauke (2022). On the additivity of climate responses to the volcanic and solar forcing in the early 19th century. Earth System Dynamics (ESD). ISSN 2190-4979. 13(4), s. 1535–1555. doi: 10.5194/esd-13-1535-2022. Fulltekst i vitenarkiv
• Van Dijk, Evelien; Jungclaus, Johann; Lorenz, Stephan; Timmreck, Claudia & Krüger, Kirstin (2022). Was there a volcanic-induced long-lasting cooling over the Northern Hemisphere in the mid-6th-7th century? Climate of the Past. ISSN 1814-9324. 18(7), s. 1601–1623. doi: 10.5194/cp-18-1601-2022. Fulltekst i vitenarkiv
• Liu, Guangyu; Hirooka, Toshihiko; Eguchi, Nawo & Krüger, Kirstin (2022). Dynamical evolution of a minor sudden stratospheric warming in the Southern Hemisphere in 2019. Atmospheric Chemistry and Physics (ACP). ISSN 1680-7316. 22(5), s. 3493–3505. doi: 10.5194/acp-22-3493-2022. Fulltekst i vitenarkiv
• Bajard, Manon Juliette Andree; Ballo, Eirik Gottschalk; Høeg, Helge Irgens; Bakke, Jostein; Støren, Eivind Wilhelm Nagel & Loftsgarden, Kjetil [Vis alle 11 forfattere av denne artikkelen] (2022). Climate adaptation of pre-Viking societies. Quaternary Science Reviews. ISSN 0277-3791. 278. doi: 10.1016/j.quascirev.2022.107374. Fulltekst i vitenarkiv Vis sammendrag

  Understanding how the Viking societies were impacted by past climate variability and how they adapted to it has hardly been investigated. Here, we have carried out a new multi-proxy investigation of lake sediments, including geochemical and palynological analyses, to reconstruct past changes in temperature and agricultural practices of pre-Viking and Viking societies in Southeastern Norway during the period between 200 and 1300 CE. The periods 200–300 and 800–1300 CE were warmer than the 300–800 CE period, which is known as the “Dark Ages Cold Period”. This cold period was punctuated by century-scale more temperate intervals, which were dominated by the cultivation of cereals and hemp (before 280 CE, 420–480 CE, 580–700 CE, and after 800 CE). In between, cold intervals were dominated by livestock farming. Our results demonstrate that the pre-Viking societies changed their agricultural strategy in response to climate variability during the Late Antiquity.

• Hamer, Paul David; Marécal, Virginie; Hossaini, Ryan; Pirre, Michel; Krysztofiak, Gisele & Ziska, Franziska [Vis alle 19 forfattere av denne artikkelen] (2021). Cloud-scale modelling of the impact of deep convection on the fate of oceanic bromoform in the troposphere: a case study over the west coast of Borneo. Atmospheric Chemistry and Physics (ACP). ISSN 1680-7316. 21(22), s. 16955–16984. doi: 10.5194/acp-21-16955-2021. Fulltekst i vitenarkiv Vis sammendrag

  This paper presents a modelling study on the fate of CHBr3 and its product gases in the troposphere within the context of tropical deep convection. A cloud-scale case study was conducted along the west coast of Borneo, where several deep convective systems were triggered on the afternoon and early evening of 19 November 2011. These systems were sampled by the Falcon aircraft during the field campaign of the SHIVA project and analysed using a simulation with the cloud-resolving meteorological model C-CATT-BRAMS at 2×2 km resolution that represents the emissions, transport by large-scale flow, convection, photochemistry, and washout of CHBr3 and its product gases (PGs). We find that simulated CHBr3 mixing ratios and the observed values in the boundary layer and the outflow of the convective systems agree. However, the model underestimates the background CHBr3 mixing ratios in the upper troposphere, which suggests a missing source at the regional scale. An analysis of the simulated chemical speciation of bromine within and around each simulated convective system during the mature convective stage reveals that >85 % of the bromine derived from CHBr3 and its PGs is transported vertically to the point of convective detrainment in the form of CHBr3 and that the remaining small fraction is in the form of organic PGs, principally insoluble brominated carbonyls produced from the photo-oxidation of CHBr3. The model simulates that within the boundary layer and free troposphere, the inorganic PGs are only present in soluble forms, i.e. HBr, HOBr, and BrONO2, and, consequently, within the convective clouds, the inorganic PGs are almost entirely removed by wet scavenging. We find that HBr is the most abundant PG in background lower-tropospheric air and that this prevalence of HBr is a result of the relatively low background tropospheric ozone levels at the regional scale. Contrary to a previous study in a different environment, for the conditions in the simulation, the insoluble Br2 species is hardly formed within the convective systems and therefore plays no significant role in the vertical transport of bromine. This likely results from the relatively small quantities of simulated inorganic bromine involved, the presence of HBr in large excess compared to HOBr and BrO, and the relatively efficient removal of soluble compounds within the convective column.

• ter Schure, Anneke Theresia Maria; Bajard, Manon Juliette Andree; Loftsgarden, Kjetil; Høeg, Helge Irgens; Ballo, Eirik Gottschalk & Bakke, Jostein [Vis alle 12 forfattere av denne artikkelen] (2021). Anthropogenic and environmental drivers of vegetation change in southeastern Norway during the Holocene. Quaternary Science Reviews. ISSN 0277-3791. 270. doi: 10.1016/j.quascirev.2021.107175. Fulltekst i vitenarkiv Vis sammendrag

  Uncovering anthropogenic and environmental drivers behind past biological change requires integrated analyses of long-term records from a diversity of disciplines. We applied an interdisciplinary approach exploring effects of human land-use and environmental changes on vegetation dynamics at Lake Ljøgottjern in southeastern Norway during the Holocene. Combined analysis of pollen and sedimentary ancient DNA (sedaDNA) metabarcoding of the sedimentary sequence of the lake describes the vegetation dynamics at different scales, and establishes a timeline for pastoral farming activities. We integrate this reconstruction with geochemical analysis of the sediments, climate data, archaeological evidence of local human settlement and regional human population dynamics. Our data covering the last 10,000 years reveals consistent vegetation signals from pollen and sedaDNA indicating periods of deforestation connected to cultivation, matching the archaeological evidence. Multivariate analysis integrating the environmental data from geochemical and archaeological reconstructions with the vegetation composition indicates that the vegetation dynamics at Lake Ljøgottjern were primarily related to natural processes from the base of the core (in ca. 8000 BCE, Mesolithic) up to the Early Iron Age (ca. 500 BCE–550 CE), when agricultural activities in the region intensified. The pollen signal reflects the establishment of a Bronze Age (ca. 1800–500 BCE) farm in the area, while subsequent intensification of pollen concentrations of cultivated plants combined with the first sedaDNA signals of cultivation and pastoralism are consistent with evidence of the establishment of farming closer to the lake at around 300 BCE. These signals also correspond to the intensification of agriculture in southeastern Norway in the first centuries of the Early Iron Age. Applying an interdisciplinary approach allows us to reconstruct anthropogenic and environmental dynamics, and untangle effects of human land-use and environmental changes on vegetation dynamics in southeastern Norway during the Holocene.

• Brenna, Hans; Kutterolf, Steffen; Mills, Michael; Niemeier, Ulrike; Timmreck, Claudia & Krüger, Kirstin (2021). Decadal Disruption of the QBO by Tropical Volcanic Supereruptions. Geophysical Research Letters. ISSN 0094-8276. 48(5), s. 1–13. doi: 10.1029/2020GL089687. Vis sammendrag

  The Los Chocoyos (14.6°N, 91.2°W) supereruption happened ∼75,000 years ago in Guatemala and was one of the largest eruptions of the past 100,000 years. It emitted enormous amounts of sulfur, chlorine, and bromine, with multi‐decadal consequences for the global climate and environment. Here, we simulate the impact of a Los Chocoyos‐like eruption on the quasi‐biennial oscillation (QBO), an oscillation of zonal winds in the tropical stratosphere, with a comprehensive aerosol chemistry Earth System Model. We find a ∼10‐year disruption of the QBO starting 4 months post eruption, with anomalous easterly winds lasting ∼5 years, followed by westerlies, before returning to QBO conditions with a slightly prolonged periodicity. Volcanic aerosol heating and ozone depletion cooling leads to the QBO disruption and anomalous wind regimes through radiative changes and wave‐mean flow interactions. Different model ensembles, volcanic forcing scenarios and results of a second model back up the robustness of our results.

• Tegtmeier, Susann; Anstey, James; Davis, Sean; Dragani, Rossana; Harada, Yayoi & Ivanciu, Ioana [Vis alle 13 forfattere av denne artikkelen] (2020). Temperature and tropopause characteristics from reanalyses data in the tropical tropopause layer. Atmospheric Chemistry and Physics (ACP). ISSN 1680-7316. 20(2), s. 753–770. doi: 10.5194/acp-20-753-2020. Fulltekst i vitenarkiv
• Tegtmeier, Susann; Atlas, Elliot; Quack, Birgit; Ziska, Franziska & Krüger, Kirstin (2020). Variability and past long-term changes of brominated very short-lived substances at the tropical tropopause. Atmospheric Chemistry and Physics (ACP). ISSN 1680-7316. 20, s. 7103–7123. doi: 10.5194/acp-20-7103-2020. Fulltekst i vitenarkiv
• Wright, Jonathon S.; Sun, Xiaoyan; Konopka, Paul; Krüger, Kirstin; Legras, Bernard & Molod, Andrea [Vis alle 9 forfattere av denne artikkelen] (2020). Differences in tropical high clouds among reanalyses:origins and radiative impacts. Atmospheric Chemistry and Physics (ACP). ISSN 1680-7316. 20, s. 8989–9030. doi: 10.5194/acp-20-8989-2020. Fulltekst i vitenarkiv
• Brenna, Hans; Kutterolf, Steffen; Mills, Michael J. & Krüger, Kirstin (2020). The potential impacts of a sulfur- And halogen-rich supereruption such as Los Chocoyos on the atmosphere and climate. Atmospheric Chemistry and Physics (ACP). ISSN 1680-7316. 20(11), s. 6521–6539. doi: 10.5194/acp-20-6521-2020. Fulltekst i vitenarkiv
• Niemeier, Ulrike; Timmreck, Claudia & Krüger, Kirstin (2019). Revisiting the Agung 1963 volcanic forcing - Impact of one or two eruptions. Atmospheric Chemistry and Physics (ACP). ISSN 1680-7316. 19(15), s. 10379–10390. doi: 10.5194/acp-19-10379-2019. Fulltekst i vitenarkiv
• Brenna, Hans; Kutterolf, Steffen & Krüger, Kirstin (2019). Global ozone depletion and increase of UV radiation caused by pre-industrial tropical volcanic eruptions. Scientific Reports. ISSN 2045-2322. 9. doi: 10.1038/s41598-019-45630-0. Fulltekst i vitenarkiv
• Toohey, Matthew; Krüger, Kirstin; Schmidt, Hauke; Timmreck, Claudia; Sigl, Michael & Stoffel, Markus [Vis alle 7 forfattere av denne artikkelen] (2019). Disproportionately strong climate forcing from extratropical explosive volcanic eruptions. Nature Geoscience. ISSN 1752-0894. 12, s. 100–107. doi: 10.1038/s41561-018-0286-2. Vis sammendrag

  Extratropical volcanic eruptions are commonly thought to be less effective at driving large-scale surface cooling than tropical eruptions. However, recent minor extratropical eruptions have produced a measurable climate impact, and proxy records suggest that the most extreme Northern Hemisphere cold period of the Common Era was initiated by an extratropical eruption in 536 ce. Using ice-core-derived volcanic stratospheric sulfur injections and Northern Hemisphere summer temperature reconstructions from tree rings, we show here that in proportion to their estimated stratospheric sulfur injection, extratropical explosive eruptions since 750 ce have produced stronger hemispheric cooling than tropical eruptions. Stratospheric aerosol simulations demonstrate that for eruptions with a sulfur injection magnitude and height equal to that of the 1991 Mount Pinatubo eruption, extratropical eruptions produce time-integrated radiative forcing anomalies over the Northern Hemisphere extratropics up to 80% greater than tropical eruptions, as decreases in aerosol lifetime are overwhelmed by the enhanced radiative impact associated with the relative confinement of aerosol to a single hemisphere. The model results are consistent with the temperature reconstructions, and elucidate how the radiative forcing produced by extratropical eruptions is strongly dependent on the eruption season and sulfur injection height within the stratosphere.

• Vogel, Andreas; Durant, Adam; Cassiani, Massimo; Clarkson, Rory J.; Slaby, Michal & Diplas, Spyridon [Vis alle 8 forfattere av denne artikkelen] (2019). Simulation of volcanic ash ingestion into a large aero engine: particle–fan interactions. Journal of turbomachinery. ISSN 0889-504X. 141(1). doi: 10.1115/1.4041464. Vis sammendrag

  Volcanic ash (VA) clouds in flight corridors present a significant threat to aircraft operations as VA particles can cause damage to gas turbine engine components that lead to a reduction of engine performance and compromise flight safety. In the last decade, research has mainly focused on processes such as erosion of compressor blades and static components caused by impinging ash particles as well as clogging and/or corrosion effects of soft or molten ash particles on hot section turbine airfoils and components. However, there is a lack of information on how the fan separates ingested VA particles from the core stream flow into the bypass flow and therefore influences the mass concentration inside the engine core section, which is most vulnerable and critical for safety. In this numerical simulation study, we investigated the VA particle–fan interactions and resulting reductions in particle mass concentrations entering the engine core section as a function of particle size, fan rotation rate, and for two different flight altitudes. For this, we used a high-bypass gas-turbine engine design, with representative intake, fan, spinner, and splitter geometries for numerical computational fluid dynamics (CFD) simulations including a Lagrangian particle-tracking algorithm. Our results reveal that particle–fan interactions redirect particles from the core stream flow into the bypass stream tube, which leads to a significant particle mass concentration reduction inside the engine core section. The results also show that the particle–fan interactions increase with increasing fan rotation rates and VA particle size. Depending on ingested VA size distributions, the particle mass inside the engine core flow can be up to 30% reduced compared to the incoming particle mass flow. The presented results enable future calculations of effective core flow exposure or dosages based on simulated or observed atmospheric VA particle size distribution, which is required to quantify engine failure mechanisms after exposure to VA. As an example, we applied our methodology to a recent aircraft encounter during the Mt. Kelud 2014 eruption. Based on ambient VA concentrations simulated with an atmospheric particle dispersion model (FLEXPART), we calculated the effective particle mass concentration inside the core stream flow along the actual flight track and compared it with the whole engine exposure.

• Fiehn, Alina; Quack, Birgit; Stemmler, Irene; Ziska, Franziska & Krüger, Kirstin (2018). Importance of seasonally resolved oceanic emissions for bromoform delivery from the tropical Indian Ocean and west Pacific to the stratosphere. Atmospheric Chemistry and Physics (ACP). ISSN 1680-7316. 18(16), s. 11973–11990. doi: 10.5194/acp-18-11973-2018. Fulltekst i vitenarkiv Vis sammendrag

  Oceanic very short-lived substances (VSLSs), such as bromoform (CHBr3), contribute to stratospheric halogen loading and, thus, to ozone depletion. However, the amount, timing, and region of bromine delivery to the stratosphere through one of the main entrance gates, the Indian summer monsoon circulation, are still uncertain. In this study, we created two bromoform emission inventories with monthly resolution for the tropical Indian Ocean and west Pacific based on new in situ bromoform measurements and novel ocean biogeochemistry modeling. The mass transport and atmospheric mixing ratios of bromoform were modeled for the year 2014 with the particle dispersion model FLEXPART driven by ERA-Interim reanalysis.We compare results between two emission scenarios: (1) monthly averaged and (2) annually averaged emissions. Both simulations reproduce the atmospheric distribution of bromoform from ship- and aircraft-based observations in the boundary layer and upper troposphere above the Indian Ocean reasonably well. Using monthly resolved emissions, the main oceanic source regions for the stratosphere include the Arabian Sea and Bay of Bengal in boreal summer and the tropical west Pacific Ocean in boreal winter. The main stratospheric injection in boreal summer occurs over the southern tip of India associated with the high local oceanic sources and strong convection of the summer monsoon. In boreal winter more bromoform is entrained over the west Pacific than over the Indian Ocean. The annually averaged stratospheric injection of bromoform is in the same range whether using monthly averaged or annually averaged emissions in our Lagrangian calculations. However, monthly averaged emissions result in the highest mixing ratios within the Asian monsoon anticyclone in boreal summer and above the central Indian Ocean in boreal winter, while annually averaged emissions display a maximum above the west Indian Ocean in boreal spring. In the Asian summer monsoon anticyclone bromoform atmospheric mixing ratios vary by up to 50% between using monthly averaged and annually averaged oceanic emissions. Our results underline that the seasonal and regional stratospheric bromine injection from the tropical Indian Ocean and west Pacific critically depend on the seasonality and spatial distribution of the VSLS emissions.

• Fiehn, Alina; Quack, Birgit; Marandino, Christa A. & Krüger, Kirstin (2018). Transport Variability of Very Short Lived Substances From the West Indian Ocean to the Stratosphere. Journal of Geophysical Research (JGR): Space Physics. ISSN 2169-9380. 123(10), s. 5720–5738. doi: 10.1029/2017JD027563. Fulltekst i vitenarkiv Vis sammendrag

  Halogen- and sulfur-containing compounds are supersaturated in the surface ocean, which results in their emission to the atmosphere. These compounds can be transported to the stratosphere, where they impact ozone, the background aerosol layer, and climate. In this study we calculate the seasonal and interannual variability of transport from the West Indian Ocean (WIO) surface to the stratosphere for 2000–2016 with the Lagrangian transport model FLEXPART using ERA-Interim meteorological fields. We investigate the transport relevant for very short lived substances (VSLS) with tropospheric lifetimes corresponding to dimethylsulfide (1 day), methyl iodide (CH3I, 3.5 days), bromoform (CHBr3, 17 days), and dibromomethane (CH2Br2, 150 days). The stratospheric source gas injection of VSLS tracers from the WIO shows a distinct annual cycle associated with the Asian monsoon. Over the 16-year time series, a slight increase in source gas injection from the WIO to the stratosphere is found for all VSLS tracers and during all seasons. The interannual variability shows a relationship with sea surface temperatures in the WIO as well as the El Niño–Southern Oscillation. During boreal spring of El Niño, enhanced stratospheric injection of VSLS from the tropical WIO is caused by positive sea surface temperature anomalies and enhanced vertical uplift above the WIO. During boreal fall of La Niña, strong injection is related to enhanced atmospheric upward motion over the East Indian Ocean and a prolonged Indian summer monsoon season. Related physical mechanisms and uncertainties are discussed in this study. 1.

• Zavarsky, Alex; Booge, Dennis; Fiehn, Alina; Krüger, Kirstin; Atlas, Elliot & Marandino, Christa (2018). The influence of air-sea fluxes on atmospheric aerosols during the summer monsoon over the Indian Ocean. Geophysical Research Letters. ISSN 0094-8276. 45(1), s. 418–426. doi: 10.1002/2017GL076410.
• Schlundt, Cathleen; Tegtmeier, Susann; Lennartz, Sinikka T.; Bracher, Astrid; Cheah, Wee & Krüger, Kirstin [Vis alle 8 forfattere av denne artikkelen] (2017). Oxygenated volatile organic carbon in the western Pacific convective center: Ocean cycling, air-sea gas exchange and atmospheric transport. Atmospheric Chemistry and Physics (ACP). ISSN 1680-7316. 17(17), s. 10837–10854. doi: 10.5194/acp-17-10837-2017. Fulltekst i vitenarkiv
• Vogel, Andreas; Diplas, Spyridon; Durant, Adam; S. Azar, Amin; Sunding, Martin Fleissner & Rose, William I. [Vis alle 10 forfattere av denne artikkelen] (2017). Reference data set of volcanic ash physicochemical and optical properties. Journal of Geophysical Research (JGR): Atmospheres. ISSN 2169-897X. 122(17), s. 9485–9514. doi: 10.1002/2016JD026328. Fulltekst i vitenarkiv
• Fiehn, Alina; Quack, Birgit; Hepach, Helmke; Fuhlbrugge, Steffen; Tegtmeier, Susann & Toohey, Matthew [Vis alle 8 forfattere av denne artikkelen] (2017). Delivery of halogenated very short-lived substances from the west Indian Ocean to the stratosphere during the Asian summer monsoon. Atmospheric Chemistry and Physics (ACP). ISSN 1680-7316. 17, s. 6723–6741. doi: 10.5194/acp-17-6723-2017. Fulltekst i vitenarkiv Vis sammendrag

  Halogenated very short-lived substances (VSLS) are naturally produced in the ocean and emitted to the atmosphere. When transported to the stratosphere, these compounds can have a significant influence on the ozone layer and climate. During a research cruise on RV Sonne in the subtropical and tropical West Indian Ocean in July and August 2014, we measured the VSLS, methyl iodide (CH3I) and for the first time bromoform (CHBr3) and dibromomethane (CH2Br2), in surface seawater and the marine atmosphere to derive their emission strengths. Using the Lagrangian transport model Flexpart with ERA-Interim meteorological fields, we calculated the direct contribution of observed VSLS emissions to the stratospheric halogen burden during Asian summer monsoon. Furthermore, we compare the in situ calculations with the interannual variability of transport from a larger area of the West Indian Ocean surface to the stratosphere for July 2000-2015. We found that the West Indian Ocean is a strong source region for CHBr3 (910 pmol m 2 h 1), very strong for CH2Br2 (930 pmol m 2 h 1), and average for CH3I (460 pmol m 2 h 1). The atmospheric transport from the tropical West Indian Ocean surface to the stratosphere experiences two main pathways. On very short timescales, especially relevant for the shortest-lived compound CH3I (3.5 days lifetime), convection above the Indian Ocean lifts oceanic air masses and VSLS towards the tropopause. On a longer timescale, the Asian summer monsoon circulation transports oceanic VSLS towards India and Bay of Bengal, where they are lifted with the monsoon convection and reach stratospheric levels in the southeastern part of the Asian monsoon anticyclone. This transport pathway is more important for the longer-lived brominated compounds (17 and 150 days lifetime for CHBr3 and CH2Br2). The entrainment of CHBr3 and CH3I from the West Indian Ocean to the stratosphere during Asian summer monsoon is less than from previous cruises in the tropical West Pacific Ocean during boreal autumn/early winter, but higher than from the tropical Atlantic during boreal summer. In contrast, the projected CH2Br2 entrainment was very high because of the high emissions during the West Indian Ocean cruise. The 16-year July time series shows highest interannual variability for the short-lived CH3I and lowest for the long lived CH2Br2. During this time period, a small increase of VSLS entrainment from the West Indian Ocean through the Asian monsoon to the stratosphere is found. Overall, this study confirms that the subtropical and tropical West Indian Ocean is an important source region of halogenated VSLS, especially CH2Br2, to the troposphere and stratosphere during the Asian summer monsoon.

• Lennartz, Sinikka T.; Marandino, Christa A.; von Hobe, Marc; Cortes, Pau; Quack, Birgit & Simo, Rafel [Vis alle 14 forfattere av denne artikkelen] (2017). Direct oceanic emissions unlikely to account for the missing source of atmospheric carbonyl sulfide. Atmospheric Chemistry and Physics (ACP). ISSN 1680-7316. 17, s. 385–402. doi: 10.5194/acp-17-385-2017. Fulltekst i vitenarkiv
• Fujiwara, Masatomo; Wright, Jonathon S.; Manney, Gloria L.; Gray, Lesley J.; Anstey, James & Birner, Thomas [Vis alle 36 forfattere av denne artikkelen] (2017). Introduction to the SPARC Reanalysis Intercomparison Project (S-RIP) and overview of the reanalysis systems. Atmospheric Chemistry and Physics (ACP). ISSN 1680-7316. 17(2), s. 1417–1452. doi: 10.5194/acp-17-1417-2017. Fulltekst i vitenarkiv
• Ziska, Franziska; Quack, Birgit; Tegtmeier, Susann; Stemmler, Irene & Krüger, Kirstin (2016). Future emissions of marine halogenated very-short lived substances under climate change. Journal of Atmospheric Chemistry. ISSN 0167-7764. doi: 10.1007/s10874-016-9355-3.
• Fuhlbrugge, Steffen; Quack, Birgit; Tegtmeier, Susann; Atlas, Elliot; Hepach, Helmke & Shi, Qiang [Vis alle 8 forfattere av denne artikkelen] (2016). The contribution of oceanic halocarbons to marine and free tropospheric air over the tropical West Pacific. Atmospheric Chemistry and Physics (ACP). ISSN 1680-7316. 16(12), s. 7569–7585. doi: 10.5194/acp-16-7569-2016.
• Fuhlbrugge, Steffen; Quack, Birgit; Atlas, Elliot; Fiehn, Alina; Hepach, Helmke & Krüger, Kirstin (2016). Meteorological constraints on oceanic halocarbons above the Peruvian upwelling. Atmospheric Chemistry and Physics (ACP). ISSN 1680-7316. 16(18), s. 12205–12217. doi: 10.5194/acp-16-12205-2016.
• Hepach, Helmke; Quack, Birgit; Tegtmeier, Susann; Engel, Anja; Bracher, Astrid & Fuhlbrugge, Steffen [Vis alle 11 forfattere av denne artikkelen] (2016). Biogenic halocarbons from the Peruvian upwelling region as tropospheric halogen source. Atmospheric Chemistry and Physics (ACP). ISSN 1680-7316. 16(18), s. 12219–12237. doi: 10.5194/acp-16-12219-2016.
• Hossaini, R*; Patra, P.K.; Leeson, AA; Krysztofiak, G.; Abraham, NL & Andrews, SJ [Vis alle 44 forfattere av denne artikkelen] (2016). A multi-model intercomparison of halogenated very short-lived substances (TransCom-VSLS): Linking oceanic emissions and tropospheric transport for a reconciled estimate of the stratospheric source gas injection of bromine. Atmospheric Chemistry and Physics (ACP). ISSN 1680-7316. 16(14), s. 9163–9187. doi: 10.5194/acp-16-9163-2016.
• Bittner, Matthias; Timmreck, Claudia; Schmidt, Hauke; Toohey, Matthew & Krüger, Kirstin (2016). The impact of wave-mean flow interaction on the Northern Hemisphere polar vortex after tropical volcanic eruptions. Journal of Geophysical Research (JGR): Atmospheres. ISSN 2169-897X. 121(10), s. 5281–5297. doi: 10.1002/2015JD024603.
• Toohey, Matthew; Krüger, Kirstin; Sigl, Michael; Stordal, Frode & Svensen, Henrik (2016). Climatic and societal impacts of a volcanic double event at the dawn of the Middle Ages. Climatic Change. ISSN 0165-0009. 136(3), s. 401–412. doi: 10.1007/s10584-016-1648-7.

Se alle arbeider i Cristin

• Booge, Dennis; Tjiputra, Jerry; Olivie, Dirk Jan Leo; Birgit, Quack & Krüger, Kirstin (2023). Global and regional marine bromoform emissions in a fully coupled ocean-atmosphere-model. Vis sammendrag

  Bromoform (CHBr3) is one of the most important precursors of atmospheric reactive bromine with an atmospheric lifetime of ~20 days. Natural production, being the main source of oceanic CHBr3, is high at the coasts and in open ocean upwelling regions due to production by macroalgae and phytoplankton. Although highly relevant for the future halogen burden and ozone layer in the stratosphere, the global bromoform production in the ocean and their emissions are still poorly constrained in observations and are mostly neglected in Earth System Model (ESM) climate projections. Here, we show first model results of fully coupled ocean-atmosphere bromoform interactions in the Norwegian ESM (NorESM) with the ocean model BLOM and the ocean biogeochemistry component iHAMOCC for the CMIP6 historical period from 1850 to 2014. Our results are validated using oceanic and atmospheric measurements listed in the HalOcAt (Halocarbons in the Ocean and Atmosphere) data base and show an overall good agreement with those observations in open ocean regions. The NorESM open ocean emissions of CHBr3 are higher than previously published emission estimates from bottom-up approaches. Moreover, the emissions are mainly positive (sea-to-air fluxes) driven by the oceanic production, sea surface temperature and wind speed, dependent on season and location. However, during low-productive winter seasons, model results also show local negative fluxes (air-to-sea fluxes) in high latitudes, suggesting some oceanic regions to be a sink of atmospheric bromoform. Driving factors will be shown for different case studies, e.g. the tropical West Pacific, which is a hot spot for oceanic bromine delivery to the stratosphere. How to cite: Booge, D., Tjiputra, J., Olivié, D., Quack, B., Schulz, M., and Krüger, K.: Global and regional marine bromoform emissions in a fully coupled ocean-atmosphere-model, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-12225, https://doi.org/10.5194/egusphere-egu23-12225, 2023.

• Oliviè, Dirk Jan Leo; Seland, Øyvind; Krüger, Kirstin & Schulz, Michael (2023). Analysis of NorESM2 full-chemistry simulation of the historical period (1850–2014).
• Krüger, Kirstin (2023). Volcanic eruptions and viking society. [Internett]. https://www.sigma2.no/volcanic-eruptions-and-viking-society. Vis sammendrag

  How did volcanic eruptions and their climate impact shape the early history and society of Scandinavia? .... Article is to be read at this link: https://www.sigma2.no/volcanic-eruptions-and-viking-society

• Krüger, Kirstin; Booge, Dennis; Quack, Birgit; Tjiputra, Jerry & Olivie, Dirk (2022). Future stratospheric halogen loading and ozone cycle: Modelling biogenic halocarbons in the ocean and their impact on the atmosphere. Vis sammendrag

  Halogenated very short-lived substances (VSLSs) contribute to the tropospheric and stratospheric halogen burden, take part in ozone depletion, and, thus, impact climate. The contribution of oceanic VSLSs is estimated to be 10–40 % of the current total stratospheric bromine. Among them, is bromoform (CHBr3) one the most important precursor of atmospheric reactive bromine with a lifetime of ~20 days in the atmosphere. Oceanic sources of bromoform are highest at the coasts and in the open ocean in upwelling regions due to macroalgae and phytoplankton production. Although highly relevant for the future halogen burden and ozone layer in the stratosphere, the global bromoform production in the ocean and their emissions are still poorly constrained in observations and are mostly neglected in chemistry climate and Earth System Models (ESMs). Here, we show first model results following Stemmler et al (2015) but adding the full coupling of the oceanic bromoform production with the atmosphere through air-sea gas exchange and atmospheric chemistry in the Norwegian ESM (NorESM) with the ocean model BLOM and the biogeochemistry component iHAMOCC. We run NorESM for the CMIP6 historic scenario from 1850 to 2014. Our results reveal higher global bromoform emissions to the atmosphere than previously reported from bottom up approaches. Comparing our modelled bromoform results with HalOcAt observations reveal an overall good agreement for the open ocean and the seasonal cycle. Case studies for the tropical Indian Ocean and Pacific will be shown, which are hot spots in the ocean and for the stratospheric bromine delivery.

• Krüger, Kirstin; Brenna, Hans; Fuglestvedt, Herman; Zhuo, Zhihong; Mills, Mike & Niemeier, Ulrike [Vis alle 7 forfattere av denne artikkelen] (2022). How large has a volcanic eruption to be to disrupt the QBO? Vis sammendrag

  The dominating circulation phenomenon in the tropical stratosphere is the quasi-biennial oscillation (QBO), an approximately 28 months oscillation of alternating easterly or westerly winds centered at the equator. Volcanic aerosols may have an impact on the QBO phase as was observed for the Pinatubo eruption, which showed a “remarkably” prolonged Easterly wind regime. In contrast, geo-engineering studies model a prolonged Westerly phase or a shut-down of the QBO due to the artificial injection of sulfate aerosols. Extremely large volcanic eruptions which inject several 10s to 100s Tg SO2 might therefore have the potential to disturb the QBO. In addition, recent observations revealed two anomalous disruptions of the QBO in the 2010s with anomalous westerly winds probably due to Rossby wave propagating from the extratropics. We use an Earth System Model taking volcanic aerosol chemistry climate interactions into account to study the QBO response to violent volcanic eruptions. Simulating a tropical supereruption with 1000 Tg SO2 and halogens injection into the stratosphere reveals a disruption of the QBO for up to 10 years first with anomalous Easterlies followed by anomalous Westerlies before returning to a QBO regime with slightly longer period. Volcanic aerosol heating and ozone depletion cooling lead to the QBO disruption and anomalous wind regimes through radiation and wave-mean flow interactions. Here, we present a new set of sulfur- and halogen-rich volcanic eruptions experiments with 17 and 200 Tg SO2 injections into the tropical and Northern Hemisphere extratropics during January and July season to answer the above raised question.

• Oliviè, Dirk Jan Leo; Seland, Øyvind; Krüger, Kirstin & Schulz, Michael (2022). Implementation of gas-phase chemistry in NorESM2.
• Zhuo, Zhihong; Fuglestvedt, Herman Fæhn; Toohey, Matthew; Mills, Michael J. & Krüger, Kirstin (2022). Impacts of tropical versus extratropical volcanic eruptions co-injecting sulphur and halogen to the stratosphere.
• Sigl, Michael; Gabriel, Imogen & Krüger, Kirstin (2022). Timing of Holocene volcanic eruptions and their radiative aerosol forcing.
• Krüger, Kirstin (2022). VIKINGS - Volcanic Eruptions and their Impacts on Climate, Environment, and Viking Society in 500-1250 CE. [Internett]. YouTube. Vis sammendrag

  Welcome to the Geo-Wednesday in March! This month Kirstin Krüger, Professor at Meteorology and Oceanography, will give a talk about VIKINGS. VIKINGS is a multi-disciplinary project that aims to understand the role of volcanic eruptions and climate change in shaping the early history of Scandinavia. The period 500-1250 Common Era is characterized by societal unrest, Viking expansion, emerging kingship - and large volcanic eruptions evidenced by geochemical markers in natural archives. The climate variations in Europe, and especially in Scandinavia during this period, are however poorly resolved even on a timescale of centuries. Moreover, available dating of archeological findings from the time period have hardly been interpreted within a framework of climatic and environmental change. The VIKINGS project seeks to unravel the climate of this intriguing historic period and to address the role of volcanic eruptions impacting environmental and societal changes with a special focus on Southern Norway. Kirstin Krüger is a Professor in Meteorology at the UiO Department of Geosciences and the leader of the VIKINGS project – a Norwegian TOPPFORSK project. Her research focuses on stratospheric dynamics and the role of transport from climate relevant gases from the surface to the middle atmosphere. In the past 15 years, she has worked on large explosive volcanic eruptions and their impacts on climate, environment and society during present day and paleo time scales.

• Krüger, Kirstin (2022). VIKINGS: Volcanic Eruptions and their Impacts on Climate, Environment, and Viking Society in 500-1250 Common Era. Vis sammendrag

  Welcome to the Geo-Wednesday in March! This month Kirstin Krüger, Professor at Meteorology and Oceanography, will give a talk about VIKINGS. VIKINGS is a multi-disciplinary project that aims to understand the role of volcanic eruptions and climate change in shaping the early history of Scandinavia. The period 500-1250 Common Era is characterized by societal unrest, Viking expansion, emerging kingship - and large volcanic eruptions evidenced by geochemical markers in natural archives. The climate variations in Europe, and especially in Scandinavia during this period, are however poorly resolved even on a timescale of centuries. Moreover, available dating of archeological findings from the time period have hardly been interpreted within a framework of climatic and environmental change. The VIKINGS project seeks to unravel the climate of this intriguing historic period and to address the role of volcanic eruptions impacting environmental and societal changes with a special focus on Southern Norway. Kirstin Krüger is a Professor in Meteorology at the UiO Department of Geosciences and the leader of the VIKINGS project – a Norwegian TOPPFORSK project. Her research focuses on stratospheric dynamics and the role of transport from climate relevant gases from the surface to the middle atmosphere. In the past 15 years, she has worked on large explosive volcanic eruptions and their impacts on climate, environment and society during present day and paleo time scales.

• Krüger, Kirstin (2022). 536 “the worst year to be alive”? .
• Krüger, Kirstin; Fuglestvedt, Herman Fæhn; Van Dijk, Evelien; Zhuo, Zhihong; Sigl, Michael & Toohey, Matthew (2022). Modelling volcanic climate and environmental impacts and their signals in ice cores.
• Krüger, Kirstin; Fuglestvedt, Herman Fæhn; Zhuo, Zhihong; Mills, Mike & Sigl, Michael (2022). Volcanic sulfate deposition to Greenland and Antarctica: A modeling sensitivity study with CESM(WACCM). Vis sammendrag

  Reconstructions of the atmospheric sulfate aerosol burdens resulting from past volcanic eruptions are based on ice core-derived estimates of volcanic sulfate deposition and the assumption that the two quantities are directly proportional. Toohey et al (2013) modelled that the Antarctic and Greenland volcanic sulfate deposition is nonlinear for very large sulfur rich tropical eruptions (Tambora magnitude and larger), with significantly less sulfate deposition to Antarctica than to Greenland using the MAECHAM5-HAM aerosol-climate model. Here we test the relationship for simulations of explosive tropical and extratropical Northern Hemisphere volcanic eruptions by co-injecting sulfur and halogens into the stratosphere with the CESM2(WACCM) model including aerosol, chemistry, climate, and earth system processes. We consider different eruption parameters varying composition, latitude, season, injection height and magnitude. We run the model injecting 17 Tg and 200 Tg of SO2, together with scaled halogens, at 24 km altitude 15° N and 64° N during January and July pre industrial 1850 conditions. We will analyse the modelled sulphate deposition signals over Greenland and Antarctica and compare them to the volcanic ice core records of known eruptions of comparable strength during the Common Era and the Holocene. The analysis will focus on the deposition fluxes and their Greenland/Antarctica efficiencies in relation to the eruption parameters, sulphate aerosol transport, and the atmospheric circulation and deposition. With the help of the model data we will learn more about the volcanic sources to the sink processes, which will be helpful to better interpret volcanic signals in bipolar ice core records.

• Zhuo, Zhihong; Fuglestvedt, Herman Fæhn; Toohey, Matthew; Mills, Michael J & Krüger, Kirstin (2022). Impacts of tropical versus extratropical volcanic eruptions co-injecting sulphur and halogen to the stratosphere.
• Zhuo, Zhihong; Fuglestvedt, Herman Fæhn & Krüger, Kirstin (2022). Impacts of tropical versus extratropical volcanic eruptions co-injecting sulfur and halogen to the stratosphere.
• Zhuo, Zhihong; Fuglestvedt, Herman Fæhn; Toohey, Matthew & Krüger, Kirstin (2022). Impacts of tropical versus extratropical volcanic eruptions with sulphur and halogen injections to the stratosphere.
• Tjiputra, Jerry; Booge, Dennis; Oliviè, Dirk Jan Leo; Quack, Birgit & Krüger, Kirstin (2022). Modeling bromoform in Norwegian Earth system model.
• Zhuo, Zhihong; Fuglestvedt, Herman Fæhn & Krüger, Kirstin (2021). Impacts of tropical versus extratropical volcanic eruptions (including volcanic sulphur and halogen injections).
• Fuglestvedt, Herman Fæhn; Zhuo, Zhihong; Mills, Michael J. & Krüger, Kirstin (2021). Modelling the atmospheric impacts of high-latitude explosive volcanic eruptions.
• Fuglestvedt, Herman Fæhn; Zhuo, Zhihong; Michael, Mills & Krüger, Kirstin (2021). Modelling the atmospheric impacts of high-latitude explosive volcanic eruptions.
• Zhuo, Zhihong; Fuglestvedt, Herman Fæhn; Toohey, Matthew; Mills, Michael J. & Krüger, Kirstin (2021). Model comparison of stratospheric aerosol forcing of tropical and extratropi-cal volcanic eruptions. Vis sammendrag

  Major volcanic eruptions, as one of the natural forcing, increase sulfate aerosols in the stratosphere. The stratospheric aerosol forcing differs from tropical and extratropical eruptions, and depends on the eruption season and height, and volcanic volatile injections. In order to study different aerosol forcing and their impact, we perform simulations based on the fully coupled Community Earth System Model version 2 (CESM2) with the Whole Atmosphere Community Climate Model version 6 (WACCM6) with prognostic stratospheric aerosol and chemistry. Explosive eruptions at 14.6 N and 63.6 N in January and July injecting 17 Tg and 200 Tg SO2 at 24 km with and without halogens are simulated, in line with Central American Volcanic Arc and Icelandic volcanic eruptions. Simulated changes in the stratospheric sulfate and halogen burdens, and impacts on aerosol optical depth and ozone are analyzed.

• Zhuo, Zhihong; Fuglestvedt, Herman Fæhn; Toohey, Matthew; Mills, Michael J. & Krüger, Kirstin (2021). Model comparison of aerosol forcing and impactof tropicaland extratropical eruptions.
• Krüger, Kirstin & Et al, More authors (2021). Modeling sulfur- and halogen-rich supereruptions impacts on the atmosphere, climate and environment .
• Krüger, Kirstin & Et al, More authors (2021). Modeling sulfur- and halogen-rich eruptions impacts on the atmosphere, climate and environment .
• Sigl, Michael; Krüger, Kirstin & Et al, More authors (2021). Insights on the timing, global sulfate lifecycle an􀀀 climate impact of Earth's largest (pre-) historic volcanic eruptions. EGU General Assembly. EGU21-946. doi: 10.5194/egusphere-egu21-946,%202021. Vis sammendrag

  Extratropical volcanic eruptions are commonly thought to be less effective at driving large-scale surface cooling than tropical eruptions, and only the latter are commonly thought to be able to distribute sulfate globally. Here, we test both of these assumptions using a network of ice cores from the polar regions of Antarctica and Greenland covering the past 15’000 years and climate-aerosol modeling. We employ state-of-the-art analyses of trace elements, cryptoptephra and sulphur isotopes (Burke et al., 2019) to gain new insights into the timing of past eruptions, their stratospheric sulphur mass injections and subsequent sulphate aerosol lifecycle. We use this information to estimate the climate impact potential due to negative radiative forcing caused by Earth’s largest volcanic eruptions since the last Glacial. Our analysis encompasses over 1’000 eruptions and include the caldera-forming eruptions of Okmok II (Alaska, 43 BCE, VEI=6, 53°N; McConnell et al., 2020), Aniakchak II (Alaska, 1600s BCE, VEI=6, 57°N), Crater Lake (Mazama, Oregon, 5600s BCE, VEI=7, 43°N) and Laacher See (Germany, c. 13 ka BP, VEI=6, 50°N). We use our reconstructed radiative forcing and the coupled earth system models MPI-ESM1.2 and CESM (version 1.2.2) to analyze the climatic impact caused by these eruptions and compare the simulated temperature response with temperature reconstructions based on ultra-long tree-ring chronologies. Finally, based on these comparisons, we propose a number of stratigraphic age tie-points to anchor ice-core chronologies from Greenland (GICC05) and Antarctica (WD2014) to the absolute dated tree-ring chronology. We thereby aim to improve proxy synchronization throughout the Holocene -- a prerequisite for detection and attribution studies -- and invite the paleo-climate community to update climate proxy records based on ice cores to the latest chronologies. The European Research Council Grant 820047 under the European Union’s Horizon 2020 research and innovation program funded the research project THERA - Timing of Holocene Volcanic eruptions and their radiative aerosol forcing.

• Van Dijk, Evelien; Gundersen, Ingar Mørkestøl; Loftsgarden, Kjetil; Ballo, Eirik Gottschalk; Krüger, Kirstin & Iversen, Frode (2021). Can we link volcanic impacts on the climate to a change in society?
• Van Dijk, Evelien; Gundersen, Ingar Mørkestøl; Loftsgarden, Kjetil; Krüger, Kirstin & Iversen, Frode (2021). Can we link volcanic impacts on the climate to a change in society in Norway?
• Van Dijk, Evelien & Krüger, Kirstin (2021). Large volcanic eruptions as a natural hazard: The impact of the 536/540 CE double event on the atmospheric circulation, surface climate, vegetation and society in Scandinavia.
• Van Dijk, Evelien & Krüger, Kirstin (2021). Impact of large volcanic eruptions on the 6th-7th century climate.
• Tjoflot, Gunn Kristin; Brenna, Hans & Krüger, Kirstin (2021). Supervolcano eruption can change the periodic wind system in the tropical stratosphere. [Internett]. www.phys.org.
• Tjoflot, Gunn Kristin; Krüger, Kirstin & Brenna, Hans (2021). Supervulkan kan endre vindsystemet i den tropiske stratosfæren. [Internett]. www.forskning.no. Vis sammendrag

  Da Los Chocoyos i Guatemala hadde utbrudd for 84.000 år siden, kan utslipp av svovel og klor ha påvirket klimaet i lang tid, viser ny forskning.

• ter Schure, Anneke; Bajard, Manon Julietto Andree; Loftsgarden, Kjetil; Høeg, Helge Irgens; Ballo, Eirik Magnus Gottschalk & Bakke, Jostein [Vis alle 12 forfattere av denne artikkelen] (2021). Disentangling anthropogenic and environmental drivers of biological change in southeastern Norway during the Holocene.
• ter Schure, Anneke; Bajard, Manon Julietto Andree; Loftsgarden, Kjetil; Høeg, Helge Irgens; Ballo, Eirik Magnus Gottschalk & Bakke, Jostein [Vis alle 12 forfattere av denne artikkelen] (2021). Anthropogenic and environmental drivers of biological change in southeastern Norway during the Holocene.
• Fuglestvedt, Herman; Krüger, Kirstin; Zhuo, Zhihong; Sigl, Michael; Toohey, Matthew & Mills, Michael J. (2021). Modelling high-latitude explosive eruptions and their atmospheric and environmental impacts .
• Zhuo, Zhihong; Fuglestvedt, Herman; Toohey, Matthew; Mills, Michael J. & Krüger, Kirstin (2021). Model comparison of volcanic aerosol forcing and climate impact of tropical and extratropical eruptions.
• Bajard, Manon Julietto Andree; Ballo, Eirik Magnus Gottschalk; Høeg, Helge I.; Bakke, Jostein; Støren, Eivind N. & Loftsgarden, Kjetil [Vis alle 11 forfattere av denne artikkelen] (2021). Instability or adaptation of the pre-Viking society to the climate variability of the Late Antiquity? Vis sammendrag

  Understanding how agricultural societies were impacted and adapted to past climate variations is critical to adapt to contemporary climate change and guaranty the food security. However, linking climate and change in the behaviour of a population are difficult to evidence. Here, we studied the climate variations of the period between 200 and 1300 CE and its impact on the pre-Viking and Viking societies in south Norway. We used a retrospective approach combining a multi-proxy analysis of lake sediments, including geochemical and palynological analyses, to reconstruct past changes in temperature and agricultural practices during the period 200-1300 CE. We associated variations in Ca/Ti ratio as a result of change in lake productivity with the temperature. The periods 200-300 and 800-1300 CE were warmer than the period between 300 and 800 CE, which is known as the “Dark Ages Cold Period” in the Northern Hemisphere. During this colder period, phases dominated by grazing activities (280-420 CE, 480-580 CE, 700-780 CE) alternated with phases dominated by the cultivation of cereals and hemp (before 280 CE, 420-480 CE, 580-700 CE, and after 800 CE). The alternation of these phases is synchronous of temperature changes. Cold periods are associated to livestock farming, and warmer periods to crop farming. This result suggests that when temperature no longer allowed crop farming, the food production specialized in animal breeding. The development of activities reached a maximum between 400 and 550 CE and a minimum between 680 and 800 CE, in agreement with archaeological findings. The Viking Age (800-1000 CE) started with an increase in temperature and corresponds to the warmest period between 200 and 1300 CE, allowing a larger development of the agriculture practices and society. Our results prove that the pre-Viking society adapted their agricultural practices to the climate variability of the Late Antiquity and that the Vikings expanded with climate warming.

• Van Dijk, Evelien & Krüger, Kirstin (2020). Was there a volcanic induced long lasting cooling in the mid 6th-7th century?
• Van Dijk, Evelien Jacoba Cornelia & Krüger, Kirstin (2020). The impact of the 536/540 CE double volcanic eruption event on the climate.
• Van Dijk, Evelien Jacoba Cornelia & Krüger, Kirstin (2020). Impact of the 536/540 CE double volcanic eruption event on the 6th-7th century climate using model and proxy data.
• Van Dijk, Evelien Jacoba Cornelia & Krüger, Kirstin (2020). Impact of the 536/540 CE double eruption event on the 6th -7th century climate using model and proxy data.
• Krüger, Kirstin (2020). Volcanic Eruptins and their Impacts on Climate, Environment, and Viking Society in 500-1250 CE . Vis sammendrag

  This multi-disciplinary project aims to understand the role of volcanic eruptions and climate change in shaping the early history of Europe. The period 500-1250 CE is characterized by natural disasters, societal unrest, Viking expansion, emerging kingship – and large volcanic eruptions evidenced by geochemical markers in natural archives. Contemporary reports of a mysterious cloud which dimmed the light of the sun for at least a year were written at the dawn of the Middle Ages which marked the beginning of an unusual cold period in the mid of the 6th century due to the double volcanic eruption event in 536/540 CE. The social structure of Scandinavian society was radically changed between 500 and 750 CE. Population levels were reduced by plague and agriculture had to be adapted to a colder climate. Tree ring and climate model data from Scandinavia identify a prolonged period of cooling which may have lasted over a century. Following is a period of volcanic activity which was thought to be more quiescent in a global sense and is marked by the onset of the medieval warm period (c. 950 -1250 CE). However, volcanic eruptions in Iceland were frequently active during 700 to 1100 CE and must have had severe impacts on climate, environment and society in Northern Europe, which is not supported by available records. This presentation aims to shed more light into the background of this early Common Era period based on revised volcanic forcing, complex earth system climate model, proxy, and archaeology data.

• Bajard, Manon Julietto Andree; Ballo, Eirik Magnus Gottschalk; Støren, Eivind Wilhelm Nagel; Bakke, Jostein; Høeg, Helge Irgens & Loftsgarden, Kjetil [Vis alle 8 forfattere av denne artikkelen] (2020). Volcanic Eruptions and their Impacts on Climate, Environment, and Viking Society in 500-1250 CE .
• Bajard, Manon Julietto Andree; Ballo, Eirik Magnus Gottschalk; Støren, Eivind Wilhelm Nagel; Bakke, Jostein; Høeg, Helge Irgens & Loftsgarden, Kjetil [Vis alle 9 forfattere av denne artikkelen] (2020). Record of climate and environmental changes in a dead-ice lake close to Gardermoen told by a 10 000 years old freshwater fish and a Viking King. Vis sammendrag

  We studied a six-meter long sediment sequence retrieved from the kettle lake Ljøgottjern, close to Oslo-Gardermoen Airport, to reconstruct environmental and climate changes during the last millennia. The lake is 18 m depth and located at 185 m a.s.l., under the maximum postglacial sea level. The largest burial mound of Northern Europe was built in the mid-6th century on the shore of this lake allegedly for King Rakni and makes this place ideal to study human-environment interactions in a paleo-perspective approach. Using a multi-proxy sedimentological analysis of this record, including 14C dating, paleo-secular variations, XRF and CT scans, and pollen, this study highlights different climate patterns throughout the Holocene. At the bottom of the core, a carbonated sandy-clayey layer with centimetric twigs overlays an organic rich black peaty-type layer, suggesting a continental environment. On top of that, a disturbed clay layer containing fish bones from a freshwater Carpinidae species was found. The fish could have been buried by the massive (70 cm) sandy carbonated deposit covering it. A sharp transition separates a clay cap on top of the deposit and the start of a finely laminated lacustrine sedimentation dated 9.3 ka cal. BP. The massive deposit could be associated to the outburst flood from the glacial lake Nedre Glomsjø dated 10-10.4 ka cal BP (Longva, 1984; Høgaas and Longva, 2016). A major change in the sedimentation occurred around 8 ka cal. BP, with darker sediments and a lower sedimentation rate. This change could be related to a warming climate and stabilization of the catchment by soil and forest development around the lake in the mid-Holocene. The sedimentation rate increased again between 2000 and 3000 years cal. BP as a result of the development of first human activities and major change in the vegetation (Høeg, 1997). We reconstructed temperature changes during the first millennia and compared it to societal dynamics. The period between 300 and 800 years cal. CE is colder than the period 800-1300 years cal. CE. After 1600 years cal. CE, an increase in erosion could be associated to the extension of the population and agriculture in Scandinavia and revealed a chronicle of the major floods in this area. The presence of freshwater fish older than 9,3 ka attests of their early and natural colonization of Scandinavian lakes. The comparison of this record with archaeological data will allow us to discuss socio-environmental dynamics following the deglaciation in the area. References: Smith, A.A. 2010. CO2 stor¬age. Journal of Sciences 32, 10-20. Høeg, H.I., 1997. Pollenanalytiske undersøkelser på Øvre Romerike : Ullensaker og Nannestad, Akershus fylke : Gardermoprosjektet, Varia (Universitetets oldsaksamling : trykt utg.). Universitetets oldsaksamling, Oslo. Høgaas, F., Longva, O., 2016. Mega deposits and erosive features related to the glacial lake Nedre Glomsjø outburst flood, southeastern Norway. Quat. Sci. Rev. 151, 273–291. https://doi.org/10.1016/j.quascirev.2016.09.015 Longva, O., 1984. Romeriksmjelen danna ved ein storflaum på Austlandet for vel 9000 år siden. Norges geologiske undersøkelse, Årsmelding 1984 8–11.

• Bajard, Manon Julietto Andree; Ballo, Eirik Magnus Gottschalk; Støren, Eivind Wilhelm Nagel; Bakke, Jostein; Høeg, Helge Irgens & Loftsgarden, Kjetil [Vis alle 9 forfattere av denne artikkelen] (2020). Tracing socio-environmental dynamics and climate changes in the period 300-1300 CE in Scandinavia from lake sediments. Vis sammendrag

  Understanding large volcanic eruptions impacts on environments and societies is necessary to consider future climate and socio-environmental interactions. Lake sediments can record these dynamics on a continuous long time scale and include at the same time footprints from volcanic eruptions, climate changes and human activities. We analysed the sediments of Lake Ljøgottjern, located southeastern Norway. The largest burial mound of Northern Europe was built in the mid-6th century on the shore of this lake and makes this place an ideal site to study human-environmental interactions throughout the last millennia. Using a multi-proxy analysis of this sedimentary record, including 14C dating, geochemistry, as well as palynological data, we reconstructed temperature and socio-environmental changes in this area between 300 and 1300 CE (Common Era). We associated changes in Ca/Ti ratio with changes in temperature. The period between 300 and 800 CE was colder than the periods 200-300 and 800-1300 CE. Five abrupt cooling events seem to be linked to weakened positive NAO (North Atlantic Oscillation) phases, and two of them can also be linked to the two largest volcanic events of the period (i.e. the 536/540 CE double event, and 1257 CE eruption of Samalas). Palynological data indicate a decrease of the human activities and reforestation of the area in the 6th century. This abandonment is consistent with archaeological findings and could be related to the 536/540 cooling event. Very little activities are then recorded between 700 and 850 CE. Agricultural activities start again strongly in the Viking age with increase in temperature.

• Krüger, Kirstin (2019). The sulfur- and halogen-rich super eruption Los Chocoyos and its impacts on climate, environment, and circulation. Vis sammendrag

  The Los Chocoyos super eruption happened ~81 kyrs ago in Guatemala, and was one of the largest eruptions of the past 100,000 years. The eruption emitted enormous amounts of sulfur, chlorine and bromine with consequences for the global climate, environment and atmospheric circulation. Using the Earth System Model CESM2(WACCM6) we simulate the impacts of this super eruption on the pre-industrial Earth System. Our model results show that the ozone layer nearly collapses, with large impacts on UV and the biosphere, and the surface climate cools globally with >6 K. Recovery to pre-eruption ozone levels and climate takes 15 and 30 years respectively. The quasi-biennial oscillation (QBO), an oscillation of the zonal winds in the tropical stratosphere with ~28 month periodicity, reveals a 10 year disruption before returning to QBO conditions with a slightly prolonged periodicity. Different model ensembles, volcanic forcing scenarios and comparison with other models are used to test the robustness of our results.

• Brenna, Hans; Kutterolf, Steffen; Mills, Michael; Niemeier, Ulrike; Timmreck, Claudia & Krüger, Kirstin (2019). The Los Chocoyos super volcanic eruption disrupts the Quasi-Biennial Oscillation . Vis sammendrag

  The Los Chocoyos super eruption happened ~81 kyrs ago in Guatemala, and was one of the largest eruptions of the past 100,000 years. The eruption emitted enormous amounts of sulfur, chlorine and bromine, with multi-decadal consequences for the global climate and environment (Brenna et al 2019 ACPD). In this paper, we simulate the impact of this sulfur- and halogen-rich super-eruption on the quasi-biennial oscillation (QBO), an oscillation of the zonal winds in the tropical stratosphere, with the comprehensive aerosol chemistry Earth System Model CESM2(WACCM6). We find a ~10 year disruption of the QBO before returning to QBO conditions with a slightly prolonged periodicity. Volcanic induced aerosol heating and ozone depletion cooling leads through radiative changes and wave-mean flow interactions to the QBO disruption and anomalous wind regimes. Different model ensembles, volcanic forcing scenarios and one other model backs up the robustness of our results.

• Krüger, Kirstin (2019). Working Group Overview. Vis sammendrag

  VIKINGS/NFR TACCO INES KeyCLIM

• Krüger, Kirstin (2019). Volcanic Eruptions and their Impacts on Climate, Environment, and Viking Society in 500-1250 CE .
• Krüger, Kirstin; Sigl, Michael; Toohey, Matthey & Iversen, Frode (2019). Volcanic Eruptions and their Impacts on Climate, Environment, and Viking Society in 500-1250 CE .
• Fouilloux, Anne Claire; Krüger, Kirstin & Iaquinta, Jean (2019). Climate Analysis with Galaxy. Vis sammendrag

  Advance in the development of climate models and associated data viewers and processing tools has achieved unprecedented maturity in the environmental scientific community. This progress was accompanied by the standardization of model output formats (conventions for Climate and Forecast metadata), the availability of open databases (i.e., the Earth System Grid Federation), and of the climate model codes themselves. However, scientific communities are not fully realizing the benefits of such advances because of the complexity for both running and analysing climate models. Using Galaxy makes it possible to share tools and easily (re-)run climate model runs or analyse climate data thus opening new opportunities for multidisciplinary research for instance ecology, social and human sciences. In this presentation, we will show how climate models can be run out-of-the-box, without much effort, using Galaxy platform. We will show how climate model outputs can be visualized using the same web portal.

• Fouilloux, Anne Claire; Iaquinta, Jean & Krüger, Kirstin (2019). Towards an infrastructure for Earth system modelling in Norway.
• Krüger, Kirstin & Bajard, Manon Julietto Andree (2019). Volcanic Eruptions and their Impacts on Climate, Environment, and Viking Society in 500-1250 CE . Vis sammendrag

  VIKINGS(NFR) TACCO(Notur/NorStore)

• Krüger, Kirstin (2018). Does the ocean impact the ozone layer? . Vis sammendrag

  Natural, halogenated very short-lived substances (VSLS) with an atmospheric lifetime τ<0.5 yr play an important role in the stratospheric ozone budget besides the anthropogenic long-lived chlorine- and brominefluorocarbons. The tropical oceans are a known source of reactive iodine and bromine to the atmosphere such as the VSLS methyl iodide (CH3I), bromoform (CHBr3), and dibromomethane (CH2Br2). They contribute to the halogen loading of the stratosphere if they are transported fast enough within, i.e., deep tropical convection. The tropical West Pacific and Indian Ocean are of special interest since the oceanic compounds of the VSLS are projected to have hot spots for both their emissions and transport pathways to the stratosphere. This study will give an overview of 10 years of research work on VSLS sources in the tropical oceans and their transport pathways and contribution to the stratospheric halogen level to answer the question.

• Fiehn, Alina; Krüger, Kirstin; Stemmler, Irene; Quack, Birgit & Ziska, Franziska (2018). Importance of seasonally resolved oceanic emissions for bromoform delivery to the stratosphere through the Asian monsoon. Vis sammendrag

  Very short-lived substances (VSLS) of marine origin, such as bromoform (CHBr3), contribute to stratospheric bromine loading and, thus, to ozone depletion. However, amount, timing, and region of bromine delivery to the stratosphere through one of the main entrance gates, the Asian monsoon circulation, are still uncertain. The atmospheric distribution of bromoform and its delivery to the stratosphere have been the topic of several chemistry transport and chemistry climate modeling studies, but only few studies considered seasonally varying surface water concentrations or emissions in their model simulations. In this study, we create two bromoform emission inventories with monthly resolution for the tropical Indian Ocean and West Pacific based on new in situ bromoform measurements in the tropical West Indian Ocean (Fiehn et al., 2017) incorporated into the observation based climatology (Ziska et al., 2013), and the ocean biogeochemistry modeling (Stemmler et al., 2015) of bromoform. Mass transport and atmospheric mixing ratios of bromoform are simulated for the year 2014 with the particle dispersion model FLEXPART driven by ERA-Interim reanalysis. Model experiments are performed with two emission scenarios: (1) monthly varying emissions and (2) constant emissions over the whole year. We compare these model results with ship- and aircraft-based observations in the boundary layer and upper troposphere lower stratosphere. Using monthly emissions, main oceanic source regions for the stratosphere include the Arabian Sea and Bay of Bengal in boreal summer and the tropical west Pacific Ocean in boreal winter. The corresponding main stratospheric injection occurs over the southern tip of India in boreal summer associated with the high local oceanic sources and strong convection of the summer monsoon. The annually averaged stratospheric injection of bromoform is in the same range independent of temporal resolution of the emissions. However, monthly emissions result in highest mixing ratios within the Asian monsoon anticyclone in boreal summer and above the central Indian Ocean in boreal winter, while constant emissions show a maximum above the West Indian Ocean in boreal spring. Our results for the Asian monsoon circulation underline that the seasonal and regional stratospheric bromine injection from the tropical Indian Ocean and west Pacific critically depends on the seasonality and spatial distribution of the VSLS emissions next to the variability in the atmospheric transport. Finally, we discuss our results with respect to circulation changes of the Asian monsoon which shows an increase in bromoform delivery between 2000 and 2015.

• Brenna, Hans; Kutterolf, Steffen; Mills, Michael J & Krüger, Kirstin (2018). Are we ready for the next big sulfur-and-halogen-rich eruption in the tropics? Vis sammendrag

  Large Plinian volcanic eruptions inject large amounts of gases (e.g. S, Cl, Br) and solid particles into the stratosphere. If the eruption occurs in the tropics, it can have a global impact due to the dispersal through the large scale meridional overturning circulation. Previous modeling studies mainly concentrate on the sulfate aerosol effects on climate and ozone. In contrast, the role of volcanic halogens from tropical eruptions is believed to play an insignificant role for the global atmosphere, based on observations from the 1982 El Chichón and 1991 Pinatubo eruptions. New measurements regarding the halogen release by paleo Plinian eruptions (Kutterolf et al. 2015), as well as recent volcanic plume observations and model simulations facilitate our investigation into what effect the combined sulfur, chlorine and bromine emissions from large tropical eruptions have on ozone and the atmosphere in general. The post-Pinatubo period has been volcanically relatively quiet. This means that there are few well-observed large eruptions that can be used as input to modeling studies. Using the large and almost complete eruptive data set from the Central American Volcanic Arc (CAVA) of the last 200 ka, we can construct well constrained input-values to chemistry-climate model simulations. This past record suggests that a future Plinian CAVA eruption will release large amounts of sulfur and halogen. As the chlorine content of the atmosphere decreases during the 21th century future sulfur-and-halogen-rich eruptions will have a large impact on stratospheric ozone and climate. We will present results from the coupled chemistry climate model CESM(WACCM) of different CAVA eruption strength containing sulfur, chlorine and bromine and their impact on stratospheric ozone. We argue that if humanity wants to be prepared for the next big tropical eruption we need also take volcanic halogens into account due to their potentially large impact on stratospheric composition and chemistry.

• Brenna, Hans; Kutterolf, Steffen; Mills, Michael J & Krüger, Kirstin (2018). Atmospheric, climatic and environmental effects of the super-size Los Chocoyos eruption 84 kyrs ago. Vis sammendrag

  The Los Chocoyos eruption (Magnitude ~8, dated to 84 kyrs before present) was one of the largest volcanic eruptions during the past 100,000 years. Originating from present-day Guatemala, the eruption formed the current stage of the large Atitlán caldera. Los Chocoyos released more than ~1100 km3 of tephra and the eruption is used as a widespread stratigraphic key marker during that time. The ash layers can be found in marine deposits from offshore Ecuador to Florida over an area of more than 107 km2. Using the new erupted magma mass from Kutterolf et al (2016) and recent volatile measurements (Metzner et al 2014, Krüger et al 2015, Kutterolf et al 2015) we estimate that the Los Chocoyos eruption released >1045 Mt SO2, ~1200 megatons of chlorine, and ~2 megatons of bromine, which classifies it as a super-size eruption. Considering these volatile emissions, the eruption must have caused massive effects on the atmosphere, climate and environment at that time, e.g. pronounced and long lasting ozone depletion with impacts on surface ultraviolet radiation. We will present results of the impact of volatile injections from the super-size Los Chocoyos eruption on atmospheric composition, chemistry and radiation. We will use the newly developed coupled chemistry climate model CESM2(WACCM) taking the combined effect of both sulfur and halogen interactively into account. The model results will be compared with a sulfur-rich only volcanic eruption. The analysis will focus in particular on halogen and ozone chemistry, radiation, atmospheric circulation and surface climate changes.

• Brenna, Hans; Kutterolf, Steffen & Krüger, Kirstin (2018). Global ozone depletion and increase of UV radiation caused by pre-industrial tropical volcanic eruptions. Vis sammendrag

  Abstract Large explosive tropical volcanic eruptions inject significant amounts of gases into the stratosphere, where they disperse globally through the large-scale meridional circulation. Halogens from tropical eruptions have been thought to be negligible based on observations of the largest eruptions of the satellite era, and thus most studies focus on sulfuric acid aerosols. More recent observations and plume modeling indicate that explosive volcanism can be a big source of halogens to the stratosphere. Here, we present the first study, based on observations, of sulfur, chlorine and bromine releases from tropical volcanic eruptions from the Central American Volcanic Arc over the last 200 ka combined with state-of-the-art coupled chemistry climate model simulations using CESM1(WACCM). The simulations reveal global, long-lasting impact on the ozone layer affecting atmospheric composition and circulation for a decade. Column ozone drops below 220 DU (ozone hole conditions) in the tropics, Arctic and Antarctica, increasing biologically active UV by 80 to 400%. Given the current decline in anthropogenic chlorine, halogen and sulfur rich explosive tropical eruptions may become the major threat to the future ozone layer.

• Fiehn, Alina; Gjermo, Sarah; Fuhlbrugge, Steffen; Quack, Birgit; Marandino, Christa A. & Atlas, Elliot L [Vis alle 7 forfattere av denne artikkelen] (2017). SO243 ASTRA-OMZ: Does ENSO influence the transport of halogenated very short-lived substances above the tropical East Pacific?
• Fiehn, Alina; Quack, Birgit; Stemmler, Irene & Krüger, Kirstin (2017). What drives the seasonal cycle of stratospheric entrainment of oceanic halogenated VSLS through the Asian monsoon?
• Brenna, Hans; Krüger, Kirstin & Kutterolf, Steffen (2017). A new threat to the future ozone layer? Halogen and sulfur rich explosive eruptions in the tropics. Vis sammendrag

  Large Plinian volcanic eruptions inject large amounts of atmosphere-relevant gases (e.g. S, Cl, Br) and solid particles into the stratosphere. If the eruption occurs in the tropics, it can have a global impact due to the dispersal through the large scale meridional overturning circulation. Previous modelling studies mainly concentrate on the sulfate aerosol effects on climate and ozone. In contrast, the role of volcanic halogens from tropical eruptions is believed to play an insignificant role for the global atmosphere, based on observations from the recent El Chichon and Pinatubo eruptions. New results regarding the halogen release by paleo Plinian eruptions, as well as recent volcanic plume observations and model simulations facilitate our investigation into what effect the combined chlorine and bromine emissions from large tropical eruptions have on ozone and the atmosphere in general. Here, we present the first study of combined chlorine, bromine from a tropical halogen and sulfur rich volcanic eruption using a state-of-the-art coupled chemistry climate model. A complete halogen and sulfur data set for the last 200ka (Metzner et al, 2013; Kutterolf et al., 2013, 2015), derived by the petrological method from paleo-eruptions of the Central American Volcanic Arc (CAVA), are used to force simulations with WACCM (Whole Atmosphere Community Climate Model). Using the petrological data we simulated 3 forcing scenarios: Sulfur, halogen and combined injections. The goal is to quantify the impact of volcanic halogen and sulfur on the preindustrial atmosphere when the background chlorine levels were low compared to the present day with the main focus on stratospheric ozone. We carried out 5 model simulations of each of the 3 forcing scenarios assuming that 10% of the Cl and Br emitted from the average CAVA eruption is injected into the tropical stratosphere during January. The model response reveals a global impact on the ozone layer affecting, through radiation, atmospheric circulation as well for more than 7 years. Total ozone drops below 220 DU, the present-day ozone hole threshold, in the tropics, Arctic and Antarctica. The increase in biologically active UV caused by the global ozone depletion is found to be more than 80% over much of the northern hemisphere during the first two years post eruption. Given the current decline in anthropogenic chlorine, halogen and sulfur rich explosive tropical eruption will become a major threat for the future ozone layer.

• Fiehn, Alina; Hepach, Helmke; Atlas, Elliot L; Quack, Birgit; Tegtmeier, Susann & Krüger, Kirstin (2016). Transport of halogenated very short-lived substances from the Indian Ocean to the stratosphere through the Asian monsoon circulation.
• Auganæs, Sigrid Marie & Krüger, Kirstin (2023). Ozone Above the Tropical Atlantic Ocean. Universitetet i Oslo. Vis sammendrag

  Ozone (O3) plays a crucial role in the Earth’s atmosphere, both in the stratosphere and the troposphere. This thesis investigates tropospheric ozone above the tropical Atlantic Ocean using observations, trajectories and the Norwegian Earth system model (NorESM). The research questions addressed include the presence of a minimum in tropospheric ozone over the tropical Atlantic, the comparison of ozone profiles between ship campaigns and land-based stations, the variability of ozone above the Atlantic compared to other ocean basins, and the performance of NorESM in representing observed ozone features. Observations from the SO287 CONNECT ship campaign crossing the tropical Atlantic Ocean reveal no ozone minimum similar to that previously observed in the tropical West Pacific. Ozone concentrations over the tropical Atlantic ranged from 25 to 80 parts per billion (ppb), with an average of 45 ppb throughout the troposphere. The sampled air masses exhibited characteristics from different regions, indicating biomass burning and stratospheric influences. Comparisons with nearby SHADOZ stations confirmed the successful sampling of the same air mass by the ship campaign and the Paramaribo SHADOZ station. Furthermore, the ozone concentrations from ship campaigns in different tropical ocean basins, revealed higher ozone concentrations above the tropical Atlantic compared to other tropical ocean basins. The NorESM model, newly including the MOZART-TS1 chemistry scheme, captures the expected patterns of surface ozone and wave-one distributions, with some deviations. However, the model simulates the abrupt increase to stratospheric ozone at lower altitudes than observed, likely due to coarse resolution in the upper troposphere and stratosphere.

• Fiehn, Alina & Krüger, Kirstin (2017). Transport of very short-lived substances from the Indian Ocean to the stratosphere through the Asian monsoon. Universitetet i Oslo.
• Krüger, Kirstin & Gjermo, Sarah (2017). Transport of very short lived halogenated substances from the tropical East Pacific to the stratosphere and the influence of El Niño 2015/16. Universitetet i Oslo.

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