Characteristics of Cyclone Development in the Arctic and Their Hydrologic Impacts

University Of Colorado At Boulder, Boulder CO

Investigators

Abstract

ABSTRACT OPP-0240984 Serreze Barry This study will improve our understanding of the development and decay of extra-tropical cyclones in northern high latitudes and their hydrologic impacts. The study will focus on two key regions: 1) the northern North Atlantic, in particular the area around the Icelandic Low and the marginal ice zones of the Greenland and Barents seas; and 2) a domain comprising northeast Eurasia extending to the central Arctic Ocean. The first region, representing the terminus of the North Atlantic cyclone track, has first order impacts on heat and moisture transports into the Arctic basin and the circulation of the sea ice cover, in particular, the flux of sea ice through Fram Strait. Variability in this ice flux has potentially strong influences on the ocean's thermohaline circulation. Past studies have shown that cyclone variability in this region is closely tied to the phase of the Arctic Oscillation /North Atlantic Oscillation (AO/NAO), but relatively little attention has been paid to the role of local development processes. Synoptic activity in this region during the winter season appears to be strongly influenced by vorticity production in the lee of southeast Greenland and enhanced baroclinicity along the sea ice margins. The hypothesis is that, 1) such local development processes are important in modulating the Fram Strait ice flux; and 2) the intensity of these local development processes is associated with differences in the general synoptic environment associated with the positive/negative phases of the AO/NAO. Studies for the second domain will focus on summer. Summer is characterized by development of a pronounced baroclinic region along the shores of northeast Eurasia. It is interpreted to arise from strong differential heating between the cold Arctic Ocean and snow free land. Development of the baroclinic region over northeast Eurasia is attended by frequent cyclogenesis in the same region where a particularly large fraction of annual precipitation falls during the summer months. Cyclones generated over northeast Eurasia often migrate into the central Arctic Ocean. The hypothesis is that the cyclogenesis maximum can be explained through interactions between coastal baroclinicity and orographic development processes. A second hypothesis is that cyclones forming in this region significantly impact on the wind driven sea ice circulation in the central Arctic Ocean and are primary drivers of the summer maximum in precipitation over the central Arctic Ocean and coastal zone. These studies will use the suite of atmospheric fields from the National Center for Environmental Protection (NCEP) and ERA-40 reanalysis systems, along with generated data sets. These include six hourly time series of cyclone activity, frontal location and intensity, and Q vector fields. Use will also be made of daily satellite derived fields of sea ice motion and concentration together with daily precipitation over both land and the Arctic Ocean.