Chlorophyll anomalies along the critical latitude at 30°N in the NE Pacific

Cara Wilson

Geophysical Research Letters, 38, L15603, doi:10.1029/2011GL048210, 2011

Abstract

The dissipation of surface tidal energy into internal tides plays a critical role in ocean mixing. However, quantifying the spatial distribution of this energy flux, which is required for ocean and climate modeling, has been largely based on modeling efforts and there is a need for validating observations. The summer development of large blooms of chlorophyll a along 30°N in the E. Pacific is presented as evidence of enhanced tidal mixing. The region near 30° is a "double" critical latitude, with a transformation of internal waves occurring at both diurnal and semidiurnal frequencies. The breakdown at the critical latitude of internal waves generated at Hawaii could provide the physical mechanism to explain these blooms. The blooms develop in a region characterized by a weak summer surface stratification, which is therefore more susceptible to mixing.

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