Abstract: Public perceptions of the risk posed by natural hazards and climate change are typically associated with extreme events. There were studies focused on the detailed synergy of processes that lead to the event's occurrence. Past literature on long-term variations of global weather and climate extremes often studies the derived extreme indices and applies further extreme value analysis to data sampled from a station, fixed grid point, or specifically defined area. Our study proposes an alternative framework to track and analyze extremes from an event perspective, including their individual attributes (e.g., frequency, intensity, duration, areal extent, and total accumulated rainfall volume). It should facilitate better communication with the general public on the climate risk, provide more complete different attributes of the extreme events, and do not need to be limited to a pre-defined location.
Heatwaves account for more than 85% of fatalities associated with natural disasters and catastrophes in European Economic Area member countries in the period 1980-2020. Using long-term ERA5 temperature analysis data from 1940, we investigate how the different attributes of the most intensive heatwave events change over time in European regions. We first identify all the extreme heatwave events with an event tracking algorithm using daily heatwave intensity with a selected intensity threshold for heatwave occurrence and the size of spatiotemporal connected heatwave occurrence. After archiving all the extreme heatwave events, it is possible to rank all the historical events by total integrated severity of heatwave events in Europe and also in subregions, like northern Europe. The long-term trends and variations of all different attributes of extreme heatwave events can also be studied. With the information on the spatial and temporal evolution of extreme events, it's also possible to further study the associated weather system and environmental conditions that fueled the heatwave extremes or make assessments on potential impact with exposure and vulnerability information. Similarly, using daily temperature from CMIP6 models, we will discuss how the frequency, intensity, duration, areal extent, and total integrated effect of extreme heatwave events change over Northern Europe in the present climate. The ability of climate models to reproduce the observed heatwave events and model projected future changes will also be examined.
Cheng-Ta Chen1 and Shih-How Lo2,
1National Taiwan Normal University, Department of Earth Sciences
2Research Center for Environmental Change, Academia Sinica
What is the Joint Oslo Seminar (JOS):
- Atmospheric and climate sciences have a stronghold in Oslo among the four institutions University of Oslo, the Meteorological Institute, CICERO and NILU.
- This joint seminar invites renowned international experts to contribute to an informal series of lectures, meant to create interaction with the Oslo atmospheric and climate science community on recent highlights and analysis in the field.
- Normally seminars will be held on Thursdays (12:15 pm -1pm).