Long-term Changes in Atmospheric Teleconnection Affecting Hydroclimate Conditions Over the Western U.S.

다국어 초록 (Multilingual Abstract)

In the recent 20 years, extreme droughts have occurred more widespread over the western U.S. causing billions dollar worth of damages and enormous in 2021. Particularly, extreme water cycle in California such as the 2013-2014 drought and 2016-2017 flood are accompanied by persistent anomalous upper-level atmospheric circulation patterns over North America. The structure of this circulation pattern is anomalous ridge near the west coast and the trough over the eastern seaboard and the location and polarity is distinctly matched with the winter stationary wave over North America which is called North America Winter Dipole (NAWD). On the other hand, its relationship to the Pacific-North American (PNA) pattern and North Atlantic oscillation (NAO) are the traditionally well-recognized patterns across North America remains unresolved. Here we report the linkage between three dominant winter atmospheric teleconnection patterns in the last 70 years. and they have remarkable relationship in recent decades and these relationship are revealed with winter hydroclimate variables over western U.S. Possible mechanisms for this phenomenon include the long-term change of the upper-level Jetstream under global warming.