| The time-series of remote-sensed surface chlorophyll concentration measured by SeaWiFS radiometer from September 1997 to December 2001 and the relevant hydrological and meteorological factors (remote-sensed sea surface temperature, atmospheric precipitation, air temperature and wind stress) in Santa Monica Bay and adjacent waters off southern California were analyzed using wavelet and cross-correlation statistical methods. All parameters exhibited evident seasonal patterns of variation. The seasonal cycles of air temperature, sea surface temperature, upwelling index and chlorophyll concentration were approximated by sine-function with annual periods. Upwelling index was closely related to solar cycles with the minimum and maximum coinciding with winter and summer solar solstices, respectively. The seasonal cycles of air temperature and sea surface temperature lagged behind the wind cycle about 2 and 2.5 months, respectively. Wavelet analysis revealed short-period (<100 days) variations of remote-sensed chlorophyll biomass during spring seasons; these variations were not evident from time-series data. The long-term variations were evident in air temperature during El Niño 1997¡|998 and in wind stress during La Niña 1998¡|999. Chlorophyll biomass was significantly correlated with sea surface temperature, air temperature and wind stress; no correlation with precipitation was observed. The variations of chlorophyll biomass and sea surface temperature lagged 5¡| and 5¡|5 days behind the variations of wind stress; the latter being accompanied by a coherent variations of air temperature. The mechanism of these variations was an intensification of phytoplankton growth resulting from mixing of water column by wind stress and entrainment of cold rich in nutrients sub-thermocline water into the euphotic layer. |
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