87th AMS Annual Meeting

Wednesday, 17 January 2007
Relationship between climate variability and strong low level wind in the Gulf of Alaska
Exhibit Hall C (Henry B. Gonzalez Convention Center)
Haibo Liu, University of Alaska, Anchorage, AK; and P. Olsson and K. Volz
El Nino-Southern Oscillation (ENSO) and Arctic Oscillation (AO) time series are used to correlate with the relative occurrence and strength of numerically simulated low-level wind jets. These jets were simulated for three consecutive winters in the Gulf of Alaska (GOA) and show an interannual variability in their climatology. Due to the paucity of observations in the GOA, the simulated winds represent a good proxy for physical measurements of these terrain-dominated events.

The GOA is a wind prone region. A high frequency of synoptic pressure systems interact with rugged coastal terrain to produce a variety of strong low level winds. There are considerable monthly and annual variability in these strong low level winds in the throughout Alaska's Cook Inlet due to the variation of the location relative to the coastal region and strength of these pressure systems.

In the region of interest El Nino typically features a zonally-extended Pacific jet stream situated to the south of its climatological mean position Also the midlatitude low pressure systems tend to be more vigorous than normal over the eastern North Pacific. Also there are reduced cold air outbreaks from polar and sub-polar regions. Therefore, the strong westerly low level winds occur less with less fluctuation from month to month in Cook Inlet.

During ENSO-neutral conditions, the Pacific jet stream is near its climatological mean position. Active polar and subtropical branches of the jet stream result in increased month to month variability of occurrence of the strong westerly low level wind events in Cook Inlet. AO is almost perfectly aligned with the fluctuation of the strong westerly low level wind in Cook Inlet.

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