Tuesday, 13 January 2009: 9:30 AM
On the relationship between the surface and 850mb storm tracks
Room 128B (Phoenix Convention Center)
Time filtering analysis is applied to 7 years of QuikSCAT winds to isolate baroclinic wave activity at the surface in the Northern Hemisphere Atlantic and Pacific Oceans. A 2-6 day bandpass is used to derive maps of eddy kinetic energy and meridional wind variance. In addition, Empirical Orthogonal Functions (EOFs) and Principle Components of the filtered surface winds are compared with their analog in the winds at 850mb and the sea level pressure field. Regression statistics show that the time variability of the band pass filtered surface winds correlates significantly with the winds aloft. However, the spatial patterns of the mean variance in the filtered surface wind differ from the filtered 850mb and SLP variance fields. These differences can be explained by the influence of the sea surface temperature (SST) fronts and boundary layer stability. It is shown that the SST fronts enhance the 2-6 day variance in winds blowing from cold to warm waters. At the same time, wind variance is enhanced in regions in which the boundary layer is unstable and suppressed when the boundary layer is stable. In light of these results, we discuss the verity of the using the time-filtering analysis of the surface winds as a proxy for extratropical cyclone (ETC) variability in the context of studying ocean forcing on ETCs.