38CVC Validating Hydroclimate Signals Around Sudden Stratospheric Warmings

Sudden stratospheric warmings (SSWs), easterly wind reversals in the arctic stratosphere accompanied by polar vortex breakdown and rapid warming aloft, can have significant impacts on surface weather in the Northern Hemisphere for several weeks. SSWs have been investigated as a source of subseasonal predictability, including previous work on precipitation anomalies which indicate a wet/dry dipole signal over Western Europe after SSWs. This ongoing work aims to investigate the consistency and robustness of precipitation anomalies across different reanalyses (MERRA-2, ERA-5, JRA-55, and JRA-3Q) and time periods (20-year periods within 1940–2020) before and after SSWs. Broad agreement exists across the reanalyses for precipitation composites (average anomalies) around SSWs, with a stronger agreement in the composites than in the climatological (mean) precipitation. Additionally, inter-decadal variability in the precipitation composites is present, such as a weak La Niña-like precipitation anomaly in the 1980–1999 period. A more in-depth comparison of the differences in the reanalyzed precipitation as the sum of the mean and anomalous precipitation is ongoing. Future work will extend the analysis to additional hydroclimatological variables such as soil moisture and snowpack. The results of this study will help in better understanding of the reliable and uncertain aspects of hydroclimate signals.