Title: The sensitivity of the surface water and energy balance estimates in the WRF model to lower surface boundary representations; a South-Norway case study
Speaker: Helene Birkelund Erlandsen, Department of Geosciences - UiO / NVE / MET Norway
Abstract
Vegetation, snow, and the sea surface are natural, transient compounds of the lower surface boundary to the atmosphere. In numerical weather and climate prediction models these compounds are parametrized with varying complexity. This paper investigates how (1) a heightening of the boreal forest line to 1250 m [Veg], (2) an increase in the snow covered area caused by altering the snowfall ratio [T_S/R], and (3) a uniform 0.4ºC sea surface temperature increase [SST] affect the modeled surface water and energy balance in South Norway. High resolution (3.7 km) runs are conducted for a dry (2009/-10) and a wet year (2010/-11), using the WRF model with the Noah land surface model. Annual surface temperature changed with +0.1°C [Veg], -0.2ºC [T_S/R], and +0.2ºC [SST], averaged over the study area. The T_S/R experiment had little effect on precipitation.
Both the Veg and SST experiment induced similar, significant increases in annual mean precipitation both years, 5.1% and 5.6%, respectively, in about one fourth of the study area. For the SST experiment most of the additional precipitation led to extra runoff. While the Veg and T_S/R experiments influenced runoff timing and amplitude, they had little effect on annual runoff, due to evaporation and precipitation changes balancing out.
The sensitivity reflects on the effect of model biases, initialization and parameterizations, and, to some extent, on what information may be lost in land surface modeling disregarding atmospheric feedback, in the region.
About the seminar:
This seminar is offered by the research environments geography and hydrology at the Department of Geosciences.
The seminar is in cooperation with LATICE - Land-ATmosphere Interactions in Cold Environments - A strategic research initiatives at the Faculty of Mathematics and Natural Sciences, University of Oslo.
The seminar is open for all interested in the topic of the seminar.
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