Interactions among physical and biological variables during the upwel- ling period in Monterey Bay, CA

We used data from moorings deployed in central California to examine the physical variables wind, PAR (photosynthetically available radiation) and temperature and the biological variable fluorescence during coastal upwelling. Variations of the multivariate techniques of principal components analysis and canonical correlation were used to extract the major modes of variability of these variables and to examine relationships among the variables. Data from both 1993 and 1994 indicate a consistent pattern of relationships among the physical variables, with NW winds and sunnier than average days leading lower than average temperatures at the mooring by 2-3 days. The relationship among the physical and biological variables was stronger in 1993 than in 1994. Higher than average fluores-cence was found to lag lower than average temperatures, higher than average PAR and wind from the NW by 4, 6 and 7 days, respectively. The form of the relationship that produced maximal correlation between fluorescence and temperature was that several days of colder than average temperatures, followed by a trend to increased temperatures, was correlated with higher than average fluorescence. Higher than average fluorescence in 1993 showed maximal correlation with wind after several days of NW winds, followed by lighter winds from the SE. Relationships among physical variables and fluorescence are not as strong in 1994 as in 1993, and we hypothesize these differences to be related to differences in the strength and duration of upwelling in the two years.