P2.9
Synoptic disturbances in the east Pacific ITCZ and their effect on the boundary layer
Yolande Serra, JISAO/Univ. of Washington, Seattle, WA; and M. Cronin and M. McPhaden
The east Pacific ITCZ appears as a band of persistent cloudiness between roughly 10°S and 10°N, depending on the season. The annual cycle in solar insolation tends to dominate the annual variability in the east Pacific convection, with a dominant amplitude in the northern hemisphere. The atmosphere in this region is comprised largely of convectively coupled westward propagating synoptic waves. It has been suggested that these waves play a role in determining the preferred latitude of the ITCZ. It has also been pointed out that the seasonality of these disturbances is similar to that of the ITCZ in the east Pacific. Additionally, these waves are a primary source of hurricanes in the Caribbean and east Pacific, and typhoons in the west Pacific. Thus, these waves are significant for understanding both ITCZ dynamics, and the factors contributing to active or suppressed hurricane years, a present concern in the face of global climate warming.
Here, we present some preliminary results from our investigation of synoptic disturbances on annual and interannual time scales in the surface wind fields, surface fluxes, and upper ocean currents, temperature and salinity fields. Primary data used in the analysis are from ATLAS buoys within the TAO-TRITON array and Eastern Pacific Investigation of Climate Processes (EPIC) enhanced 95°W TAO moorings. In addition, NCEP 850 mb winds are used to determine the presence of synoptic waves in the east Pacific, as these waves have their strongest signature at this level. Preliminary results showing the strength and seasonality of synoptic activity in the boundary layer and sea surface temperature data, as well as upper ocean response to this forcing, are presented and compared with synoptically active periods in the NCEP 850 mb winds.
Poster Session 2, Atmospheric Oscillations and Boundary Layer Processes (Hall 4AB)
Wednesday, 14 January 2004, 2:30 PM-4:00 PM, Hall 4AB
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