Oceanic Thermal and Biological Responses to Santa Ana Winds

Abstract:
Ocean surface wind vectors with improved spatial resolutions were derived from the National Aeronautics and Space Administration's (NASA's) Quick Scatterometer (QuikSCAT) satellite. They allow us to examine the details and extent of oceanic influence of a Santa Ana event - a strong offshore and downslope wind in southern California that may spread wide fires, damage properties, and endanger aviation. The oceanic thermal and biological responses to the surface wind jets were observed with other spaceborne sensors. It is found that surface wind jets reduce sea surface temperatures and increase biological productivities. Spacebased measurements demonstrate the inadequacy of current operational numerical weather prediction (NWP) models to accurately and consistently predict the characteristics of Santa Ana winds over the coastal ocean.

Figure 1. Ocean surface winds measured by QuikSCAT at 13:25UT, February 10, 2002. Data are at 12.5-km resolutions. Observations within 15 km of coastlines were not used in this study. The color scale indicates the magnitude of wind speed. The location of the weather station FMC is labeled on the plot.

Figure 2. Sea surface temperatures measured at 20:38 UT on February 10, 2002 from AVHRR at 1.1-km resolutions. Black areas over the ocean represent missing data due to clouds or data not available from NOAA CoastWatch regions.

Figure 3. Ocean color chlorophyll data at 1-km resolutions from SeaWiFS HRPT HUSC station. The data were obtained at 20:00UT on February 12, 2002, a dust-free and normal wind condition. Black areas over the ocean indicate missing data due to clouds. The size of the plotted region is the same as in Figure 2.

Reference:
Hu, H., and W.T. Liu, 2003: Oceanic thermal and biological responses in Santa Ana Winds, Geophy. Res. Lett., 30(11), 1596, doi:10.1029/2003GL017159.