Relationship between physical and biological variables during the upwelling period in Monterey Bay, CA

Abstract

Data from moorings deployed in central California waters were used to examine physical variables (wind, photosynthetically available radiation, and temperature) and a biological variable (fluorescence) during coastal upwelling. Modifications of the multivariate techniques of principal component analysis and canonical correlation were used to extract the major modes of variability and to examine relationships among the variables. Data from 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. Higher than average fluorescence was found to lag lower than average temperatures, higher than average PAR and wind from the NW by 4, 6 and 7 days, respectively. Several days of colder than average temperatures, followed by a trend to warmer 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.