An eight-band camera on Oceansat-1 and Oceansat-2 that measures the colour of the sea to estimate chlorophyll, plankton blooms and sediment.
Seawater changes colour with what floats in it. Water rich in tiny plants (phytoplankton) looks greener, and muddy water looks brown. OCM measures this colour in eight narrow bands. From it scientists estimate chlorophyll, spot plankton blooms, and track suspended sediment and haze in the air.
OCM is a solid-state camera with one lens for each band. It looks down on a very wide strip, so it covers a large part of the ocean in each pass. On Oceansat-2 the improved OCM-2 has a resolution of about 360 m along the track and 236 m across it, over a strip about 1,420 km wide. Oceansat-2 returns over the same area every two days.
The first OCM flew on Oceansat-1 (IRS-P4), launched by PSLV-C2 from Sriharikota in May 1999. It was India's first satellite built mainly for the oceans. OCM-2 followed on Oceansat-2, launched by PSLV-C14 in September 2009, to keep the data flowing for existing users. The next version, OCM-3, flies on EOS-06.