Phytoplankton pigment concentrations in the Middle Atlantic Bight: comparison of ship determinations and CZCS estimates

Abstract

The processing algorithms used for relating the apparent color of the ocean observed with the Coastal-Zone Color Scanner on Nimbus-7 to the concentration of phytoplankton pigments (principally the pigment responsible for photosynthesis, chlorophyll a) are developed and discussed in detail. These algorithms are applied to the shelf and slope waters of the Middle Atlantic Bight and also to Sargasso Sea waters. In all, four images are examined, and the resulting pigment concentrations are compared to continuous measurements made along ship tracks. The results suggest that over the 0.08-1.5-mg/m3 range the error in the retrieved pigment concentration is of the order of 30-40% for a variety of atmospheric turbidities. In three direct comparisons between ship-measured and satellite-retrieved values of the water-leaving radiance the atmospheric correction algorithm retrieved the water-leaving radiance with an average error of approximately 10%. This atmospheric correction algorithm does not require any surface measurements for its application.

Calculation of UV attenuation and colored dissolved organic matter absorption spectra from measurements of ocean color

“…The wavelength ratio approach is also applied to the prediction of chlorophyll concentration in surface waters [Gordon et al, 1983;Aiken et al, 1992], and images of global ocean chlorophyll concentrations and K(490) are now produced routinely from SeaWiFS data (SeaWiFS Project, http://seawifs.gsfc.nasa.gov/SEAWIFS. html (verified 12 May 2000)).…”

“…where H o (l) is the mean extraterrestrial solar irradiance (Wm À2 nm À1 ), and e is the eccentricity of the Earth's orbit (0.0167) [Gordon et al, 1983]. Gregg and Carder [1990] give the following values for H o (l):…”

Chlorophyll enhancement and mixing associated with meanders of the shelf break front in the Mid‐Atlantic Bight

“…Ancillary data were daily ozone maps from the total ozone mapping spectrometer and meteorological variables from the National Centers for Environmental Prediction [McClain et al, 1994]. A singlescattering algorithm was used for atmospheric correction [Gordon et al, 1983], and a three-band chlorophyll algorithm [Saitoh et al, 1997] was used for calculating chlorophyll a (hereafter OCTS-Chl). Sea surface temperature (SST) imagery from advanced very high resolution radiometer (AVHRR) satellite instruments was acquired from the Graduate School of Oceanography, University of Rhode Island.…”

Bio‐optical properties of the southwestern Ross Sea

“…Semianalytical algorithms that convert L w or Rrs to pigment concentration require specification of biooptical properties such as absorption, backscattering, and diffuse attenuation by both particulate and dissolved phases [Carder et al, 1991]. Empirical pigment algorithms, which simply predict pigment concentrations from the ratios of Lw or Rrs at two or more wavelengths, implicitly assume that light attenuation by solutes or non-chlorophyll a (Chl a )-containing particles is proportional to phytoplankton absorption [Gordon et al, 1983]. The extent to which these assumptions may or may not be valid must be determined in order to assess algorithm performance.…”