A Climatology of Rossby Wave Breaking-Induced Moisture Transport in the Arctic and Its Possible Connection to Tropical Sea Surface Temperatures

Abstract:

The Arctic climate system is sensitive to temperature and moisture changes, where intrusions of warm, moist air can significantly alter the surface energy budget and consequently contribute to melting of sea ice and the Greenland ice sheet. Past research has shown that greater moisture is transported into the Arctic via Rossby wave breaking (RWB), which can be associated with blocking anticyclones. We identify daily instances of RWB on the Dynamic Tropopause and calculate integrated vapor transport (IVT) on these dates using a state-of-the-art reanalysis product for the period of 1979-2018. We further classify RWB as cyclonic and anticyclonic to quantify the role of wave breaking type on both the spatial and temporal distributions of IVT. Emphasis is placed on the seasonality of the relationship between RWB and IVT, with considerable focus on summer events. Preliminary results through compositing indicate an importance of cyclonic wave breaking in distributing extreme IVT in the North Atlantic, despite more frequent wave breaking activity in the North Pacific. Lead-lag composites of IVT and RWB suggest a connection between the quantity of IVT and persistence of a wave break-induced blocking event. Moreover, a possible link of these events and tropical sea surface temperature variability in the Pacific, is discussed.