A ten-year time series from Monterey Bay, California: Seasonal, interannual and long-term patterns

R E S U L T S : Seasonal cycle, Interannual variabilities, Long-term trends

Results are taken from a ten-year time series of ship occupations of five major stations in Monterey Bay that began in 1989 and includes data from the 1992-93 and 1997-98 El Niño’s. The ship observations are supplemented by moored observations of currents and winds. Satellite observations of temperature and ocean color provide spatial coverage. Our primary focus is phytoplankton, the organisms that form the base of the oceanic ecosystem. We report the seasonal mean fields and use these fields to quantitatively assess the consequences of El Niño as well as long term trends.

SUMMARY

There is clear physical-biological coupling in the time series, starting with the seasonal cycle. There appears a maximum in nutrients, centric diatoms, chlorophyll and primary production associated with the upwelling season. The so-called oceanic and winter seasons also have characteristic physics and biology. During the warmer El Niño years chlorophyll levels dropped (-19% in 1992 and -21% in 1997), and during colder years levels have risen (+19% in 1991 and +11% in 1994). Results indicate sea surface temperature has gradually risen over the course of the ten-year study, while chlorophyll, primary production and subsurface nitrate levels are decreasing.

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