Tuesday, 11 February 2003
Ocean Colour Monitor (OCM) on India's Oceansat-1 satellite: applications for ocean, atmosphere, and land
While much attention has been focused on NASA's MODIS (Moderate Resolution Imaging Spectrometer) now flying on both the Terra and Aqua missions, a highly complementary sensor called the Ocean Color Monitor (OCM) is also available from the India Space Research Organization's Oceansat-1 satellite. Oceansat-1 was launched in May 1999, about seven months prior to Terra, into an exact 2-day repeat, local noon sun-synchronous near polar orbit, approximately mid-way between the Terra (10:45AM) and Aqua (1:30PM) overpass times. Its OCM sensor includes eight spectral channels in the visible and near-infrared, exactly matching those of the well-known SeaWiFS. Like SeaWiFS, the OCM also includes a sensor tilt mechanism to avoid sunglint, something that is not available with MODIS. Also, the spatial resolution of OCM is approximately 300 m and does not vary across its 1400 km swath. In comparison the SeaWiFS (and corresponding MODIS) ocean color channels have approximately 1000 m resolution at subpoint, degrading significantly toward the swath edges.
OCM data is downlinked at several locations around the globe, by some of the 15+ TeraScan X-band ground stations that SeaSpace has established in the Americas, Europe, Asia and Australia. Examples of OCM data products (atmospheric smoke and dust; vegetation patterns; ocean color) demonstrate that OCM capabilities extend well beyond the ocean-only applications implied by its name.