A new subseasonal atmospheric teleconnection bridging tropical deep convection over the western North Pacific and Antarctic weather

Abstract

Previous studies indicate that convective heating variability of the western North Pacific summer monsoon (WNPSM) influences strongly weather and climate over East Asia. Based on daily reanalysis data and interpolated outgoing longwave radiation (OLR) data, this study demonstrates that the WNPSM convection can also cause severe weather events remotely over the Antarctic through the exciting of the Australia-South Pacific-Atlantic wave train (ASPA pattern). Surface air temperature (SAT) rises over the Ross Sea-Mawson-Dumont d'Urville Seas sector and over the Weddell Sea, while the SAT drops over the Amundsen–Bellingshausen Seas. Concurrently, sea ice concentration (SIC) is reduced over the Ross Sea and enhanced over the Amundsen–Bellingshausen Seas. The result suggests that the newly found ASPA pattern may serve as an important bridge linking the WNPSM convection and the weather over the Antarctic region.

The dynamics of ASPA's formation and propagation are also investigated comprehensively. Day-to-day energy budget analysis suggests that after its initiation by WNPSM convection, the ASPA pattern is driven by the baroclinic energy conversion from the climatological flow and nonlinear term. The barotropic energy conversion from the climatological flow contributes to positive KE tendency before day +1 and negative KE tendency after day +1. It is therefore extremely important to improve the representations of the climatological-mean sea ice and jet stream, wave-mean flow interaction and wave-wave interaction in the mid- and high-latitudes of the Southern Hemisphere, as well as the convection over the WNPSM region of the Northern Hemisphere in numerical model for a better weather prediction for the Antarctic.