HR: 17:24h
AN: A24A-08    [Abstracts]
TI: Seasonal Evolution of Aleutian Low-Pressure Systems: Implications for the North Pacific Sub- Polar Circulation
AU: * Pickart, R
EM: rpickart@whoi.edu
AF: Woods Hole Oceanographic Institution, Clark 355B, Woods Hole, MA 02540, United States
AU: Moore, K
EM: gwk.moore@utoronto.ca
AF: University of Toronto, 60 St. George Street, Toronto, Ont M5S 1A7, United States
AU: Macdonald, A
EM: amacdonald@whoi.edu
AF: Woods Hole Oceanographic Institution, Clark 355B, Woods Hole, MA 02540, United States
AU: Walsh, J
EM: jwalsh@iarc.uaf.edu
AF: International Arctic Research Center, P.O. Box 757340, Fairbanks, AK 99709, United States
AU: Kessler, W
EM: william.s.kessler@noaa.gov
AF: Pacific Marine Environmental Laboratory, 7600 Sand Point Way NE, Seattle, WA 98115, United States
AB: The development of Aleutian lows and how they evolve from early fall to early winter is analyzed using a combination of meteorological fields and sea surface temperature (SST) and wind data. The time period of the study is from September to December 2002, although results are shown to be representative of the longterm climatology. Characteristics of the storms were documented as they propagated across the North Pacific, including path, central pressure, deepening rate and speed of translation. Clear pattern emerged. Storms tended to spin up in two distinct geographical regions: the Gulf of Alaska in the early fall and the western North Pacific in late fall, seemingly related to the seasonal distribution of the SST field in both regions. In the Gulf of Alaska, a notch in the SST field seems to be of primary importance by optimizing differential heating in the storm and allowing air-sea fluxes to energize the storm more effectively. As winter approaches and the Sea of Okhotsk becomes partially ice covered and cold, the air emanating from the Asian continent leads to cyclogenesis in the region near Kamchatka. The impact of the oceanic circulation of the windstress curl pattern resulting from these two regions of storm development is investigated using historical hydrography data. It is argued that the seasonal bimodal input of cyclonic vorticity from the wind may be partly responsible for the two distinct North Pacific sub-Arctic gyres.
DE: 3307 Boundary layer processes
DE: 3339 Ocean/atmosphere interactions (0312, 4504)
DE: 3364 Synoptic-scale meteorology
DE: 4504 Air/sea interactions (0312, 3339)
SC: Atmospheric Sciences [A]
MN: 2007 Fall Meeting