You are here:
CHLOROPHYLL A DISTRIBUTION IN NARRAGANSETT BAY, RI: USING A SPECTRAL CURVATURE ALGORITHM
Citation:
Keith, D J., J. A. Yoder, L. W. Harding, J S. Latimer, S. A. Freeman, AND C. Mouw. CHLOROPHYLL A DISTRIBUTION IN NARRAGANSETT BAY, RI: USING A SPECTRAL CURVATURE ALGORITHM. ASLO/AGU Ocean Sciences 2002, Eos. Trans. AGU, 83(4) Ocean Sciences Meeting Supplement Abstract # OS31T-09, Honolulu, HI, February 11-15, 2002.
Description:
Chlorophyll a, a primary indicator of eutrophication in estuarine waters, varies enough in time and space to create spatial problems when monitored by satellite, and temporal problems when measured with in situ field programs. Using aircraft to sense ocean color of local waters, some of these problems can be resolved from the spectral characteristics. Spectral curvature algorithms have been developed and used to estimate chlorophyll a concentrations for the NY Bight, Nantucket Shoals, and the Chesapeake Bay, and incorporated in monitoring programs such as the Chesapeake Bay Program. The objective of this study is to develop an algorithm for Narragansett Bay, Rhode Island, from the biooptical properties of its West Passage. In its basic form, the algorithm calculates chlorophyll a as log10[chl] = a + b(-Log10 G), where G = [R1/R2 R3)], a and b are constants empirically derived from in situ concentrations of chlorophyll, and R is radiance from three spectral wavelengths. The constants for this study will be empirically determined, from in situ concentrations of chlorophyll a already collected during 32 weekly and biweekly cruises between May 1999 and June 2000. G will be determined from remotely sensed reflectances at 443,490, and 555 nm measured during the same period. During this period, measurements were also made of light absorption due to colored dissolved organic matter (CDOM). The data indicated that CDOM is the dominant absorber at 443 nm and a major competitor at 490 nm. Consequently, a CDOM absorption term will be added to the algorithm.