A COMPARISON OF THE SEAWIFS CHLOROPHYLL AND CZCS PIGMENT ALGORITHMS USING OPTICAL-DATA FROM THE 1992 JGOFS EQUATORIAL PACIFIC TIME-SERIES

Optical data were collected during two U.S. JGOFS EqPac Time Series cr uises aboard the U.S. Research Vessel Thomas G. Thompson, at a station at 140 degrees W on the equator, during the time of both the first eq uinox and the second equinox of 1992. This data set represents the ran ge of conditions expected in this region, and was used to compare the SeaWiFS chlorophyll a algorithm with the CZCS pigment algorithm, as we ll as test the validity of using ocean color remote sensing to track t he biological response to physical phenomena such as Kelvin Waves and Tropical Instability Waves (TIW). Time Series I (23 March to 9 April) took place during the maximum expression of the 1991-92 El Nino event, and coincided with the peak of a passing Kelvin wave. Time Series II (2-21 October) occurred during La Nina conditions and encompassed the passage of a TIW. The SeaWiFS pigment compared favorably with the earl ier CZCS pigment algorithm and indicate that the SeaWiFS algorithm is capable of determining both quantitative and qualitative changes in su rface chlorophyll a from remotely sensed optical data in high nutrient , low chlorophyll regions such as the Equatorial Pacific. Our results show that, although Kelvin waves can not be currently tracked using oc ean color sensors alone, when a Kelvin wave is detected by other metho ds, satellite ocean color data can be used to characterize the biologi cal response to the Kelvin wave. However, since TIWs have a much short er period and can enhance near-surface phytoplankton growth rates quic kly, they can be tracked using remotely sensed ocean color data using either the CZCS pigment or the SeaWiFS chlorophyll algorithm. (C) 1998 Elsevier Science Ltd. All rights reserved.