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.

Ocean Color Products

Standard

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 aerosol Ångström exponent products are also described.
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
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 at the ocean surface
Instantaneous Photosynthetically Available Radiation (iPAR; Einstein m-2 s-1)
PAR at the ocean surface at the time of the satellite observation
Normalized Fluorescence Line Height (nFLH; mW cm-2 µm-1 sr-1)
Relative measure of water-leaving radiance associated with chlorophyll fluorescence

Provisional

Inherent Optical Properties from GIOP Algorithm (IOP, m-1)
Spectral marine absorption and backscattering coefficients of water column constituents

Special

Inherent Optical Properties from GSM Algorithm (GSM; m-1)
Spectral marine absorption and backscattering coefficients of water column constituents
Inherent Optical Properties from QAA Algorithm (QAA; m-1)
Spectral marine absorption and backscattering coefficients of water column constituents
Euphotic Depth from Lee Algorigthm (ZLEE; m-1)
Depth of the euphotic zone
Land Reflectance from NDVI algorithm (LAND)
Land reflectance generated from the Normalized Difference Vegetation Index (NDVI) algorithm

Test

Net Primary Productivity (NPP) from VGPM algorithm
coming soon
Net Primary Productivity (NPP) from VGPM/Eppley algorithm
coming soon
Calcite (ci2)
Calcite concentration derived from particulate inorganic carbon

Sea Surface Temperature Products

Standard

11 µm Sea Surface Temperature (SST; °C)
Sea surface temperature derived from long-wave (11-12 µm) thermal radiation
4 µm Sea Surface Temperature (SST4; °C)
Sea surface temperature derived from short-wave (3-4 µm) thermal radiation

Developmental

Aerosol correction for VIIRS SST
Aerosol correction for sea surface temperature