Research Seminar: Chuxuan Li

A research seminar from UNC Marine Sciences graduate student, Chuxuan Li. Presented by the UNC at Chapel Hill Department of Marine Sciences. The location of this event will be in seminar room G201 on the ground floor of Murray Hall on UNC-CH campus in Chapel Hill, NC and online via Zoom (Meeting ID: 679 445 871). This event will be held on Monday, October 21st at 12:30 pm.

Seminar Title: Variability and predictability of North Atlantic cold-season atmospheric river activity in high-resolution atmospheric simulations

Abstract: Atmospheric rivers (ARs) are conduits of enhanced water vapor transport in the lower troposphere and can cause extreme precipitation and flooding events in many regions around the world. Previous studies of North Atlantic (NA) ARs focused on regional features and impacts (primarily the western Europe) and an understanding of their variability from a basin-wide perspective and in other regions of the basin (e.g., the southeastern U.S.) is still lacking. Here, we employed an ensemble of 30 simulations with a 60-km-resolution atmospheric general circulation model forced by observed sea surface temperatures (SSTs) to examine the variability and predictability of cold-season (i.e., December–March) AR occurrence in the NA during 1951–2011 and their connections to large-scale climate variations. Specifically, we applied an empirical orthogonal function (EOF) analysis to the ensemble mean of the simulations to determine the SST-forced interannual-decadal variability of the AR occurrence. The results reveal that variations in NA AR occurrence exhibit three distinct modes, which can be linked to ENSO, the North Atlantic Oscillation (NAO) and/or the Scandinavian pattern. We then quantified the internal variability in AR occurrence using the differences across the 30-member simulations. We found that ARs over the central and eastern U.S. show relatively low internal variability because of the forcing imposed by ENSO, whereas the stochastic variations associated with the NAO introduces a high level of internal variability to ARs over the western Europe. Future work includes (1) exploring the diversity and variations of NA AR tracks via a cluster analysis and the contributions of different track groups to extreme precipitation and winds along the NA coastlines, and (2) studying changes in AR occurrence and tracks in a warming climate and their linkages to SST warming patterns.