Covariability of chlorophyll and temperature in the sea

Series of chlorophyll a and temperature obtained from multiple-depth horizontal tows have been treated by spectral analysis. Composite power or variance spectra show the chlorophyll spectra to be similar but not identical in shape to the temperature spectra. Temperature and chlorophyll at the same depth usually were significantly coherent at wavelengths greater than 100 m. Parameters measured 4 to 5 m apart in depth showed no significant coherence.

In general, for runs with low chlorophyll variance and high coherence with temperature, most of the observed variance in the chlorophyll is attributed to internal wave and vertical mixing effects. However, in several runs with high chlorophyll variance, the observed variance is more than 10 times that which could be accounted for by internal wave effects. Such ‘patchy’ observations are believed to indicate regimes of greater biological activity, as characterized by higher growth rates.