Algorithm Descriptions

The Ocean Biology Processing Group (OBPG) produces and distributes a standard suite of ocean color products for all compatible sensors at Level-2 and Level-3, plus sea surface temperature (SST) products from MODIS and VIIRS. The OBPG also produces a suite of Level-3 evaluation products. The descriptions and references for these standard and evaluation products (provided below) are intended to satisfy the Algorithm Theoretical Basis Document (ATBD) requirement as defined by the NASA Earth Observing System Project Science Office.

Standard Ocean Color Products

Chlorophyll a (chlor_a; mg m-3)

The concentration of the photosynthetic pigment chlorophyll a.

Diffuse attenuation coefficient for downwelling irradiance at 490 nm (Kd_490; m-1)

The diffuse attenuation coefficient for downwelling irradiance over the first optical attenuation layer.

Inherent Optical Properties (IOPs; m-1)

The spectral marine absorption and backscattering coefficients of water column constituents.

Particulate Organic Carbon (POC; mg m-3)

The concentration of particulate organic carbon.

Particulate Inorganic Carbon (PIC; mol m-3)

The concentration of particulate inorganic carbon.

Photosynthetically Available Radiation (PAR; Einstein m-2 d-1)

Daily mean photosynthetically available radiation (PAR) at the ocean surface.

Instantaneous Photosynthetically Available Radiation (iPAR; Einstein m-2 s-1)

PAR the ocean surface at the time of the satellite observation.  (MODIS only)

Normalized Fluorescence Line Height (nFLH; mW cm-2 µm-1 sr-1)

Relative measure of water-leaving radiance associated with chlorophyll fluorescence.  (MODIS only)

Remote Sensing Reflectance (Rrs; sr-1)

The at-surface spectral remote-sensing reflectances observed by the satellite instrument after atmospheric correction. The aerosol optical thickness and Ångström data products are also described.

Standard Sea Surface Temperature Products

11 µm Sea Surface Temperature (SST; °C)

Sea surface temperature derived from long-wave (11-12 µm) thermal radiation.  (MODIS & VIIRS)

4 µm Sea Surface Temperature (SST4; °C)

Sea surface temperature derived from short-wave (3-4 µm) thermal radiation.  (MODIS only)

Evaluation Products

GSM IOPs (Garver-Siegel-Maritorena algorithm)

QAA IOPs (Quasi-Analytical Algorithm)

Lee spectral diffuse attenuation & euphotic depth products

Morel spectral diffuse attenuation & euphotic depth products

Proposed Products

Aerosol correction for VIIRS SST

Product Flags

Level-2 Flags

Sea Surface Temperature Flags