Special Colloquium: Land-atmosphere coupling and summertime temperature variability in the western United States
The leading pattern of year-to-year variability in summertime (JJA) temperature in the western US spans the entire domain and explains over half the total variance in temperature and in total forest area burned in the western US. In observations, this pattern is linked to springtime (MAM) soil moisture anomalies in the southwest (SW) US that are, in turn, linked to wintertime (DJF) precipitation anomalies; as an example, negative precipitation anomalies in DJF are followed by soil moisture deficits in MAM the SW US that give rise to warmer-than-normal JJA temperatures throughout the western US. We show that climate models (with and without interactive oceans) reproduce the observed relationships between DJF precipitation, MAM soil moisture and JJA temperature. We present analyses of existing (GLACE) climate model experiments and new experiments that show two-thirds of the variance in summertime temperature throughout the western US is causally linked to springtime soil moisture anomalies in the southwest US. Our results suggest that 40 % of the observed warming trend across the western United States since 1981 is due to the trend in wintertime precipitation trend in the southwest US.
Datum
26.09.2024
Uhrzeit
15:15 h
Ort
- Bundesstr. 53, room 022/023
- Seminar Room 022/023, Ground Floor, Bundesstrasse 53, 20146 Hamburg, Hamburg