讲座简介

Enhanced poleward atmospheric moisture transport (AMT) into the Arctic can change atmospheric moisture and cloud formation and distribution, and accordingly surface energy budgets, and sea ice production and melt. In this study, a consistently enhanced poleward AMT across 60°N has been observed since 1959 based on the NCAR NCEP reanalysis. Regional analysis demonstrates that the poleward AMT predominantly occurs over the North Atlantic and North Pacific regions,contributing about 57% and 32%, respectively, to the total transport. To better understand the driving force for the enhanced poleward AMT, we explore the role that extratropical cyclone activity may play. Climatologically about 207 extratropical cyclones move across 60°N into the Arctic each year, among which about 66 (32% of the total) and 47 (23%) originate from the North Atlantic and North Pacific regions, respectively. When analyzing the time series trends constructed by using a 20-year running window, we found a positive correlation of 0.70 between poleward yearly AMT and the cyclone activity across 60°N, which is measured by an integrated cyclone activity index (CAI, total measurement of cyclone intensity, number, and duration). The consistent multidecadal changes between poleward AMT and CAI across 60°N suggest that enhanced cyclone activity is a driving force in the enhanced poleward AMT. Furthermore, a composite analysis of sea level pressure associated with enhanced AMT indicates that intensification and poleward extension of Icelandic low and accompanied strengthened cyclone activity play an important role in enhancing poleward AMT over the North Atlantic region.

主讲人简介

JING ZHANG is Associate Professor of Atmospheric Sciences at the Department of Physics and Department of Energy and Environmental Systems at North Carolina A&T State University. Jing Zhang’s research interests lie in regional climate and weather studies by the means of numerical modeling and data analysis. Specifically, her recent and ongoing research studies include: mesoscale wind field study over complex topography in the Arctic marginal ice zone; data assimilation and its application for regional reanalysis; regional climate downscaling; modeling studies of Arctic storms; surface mass balance modeling for the Antarctic Peninsula. Through these activities, Zhang wishes to gain a better understanding of regional changes in the polar regions.