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Proceedings Paper

Cross-calibration of the Oceansat-2 Ocean Colour Monitor (OCM) with Terra and Aqua MODIS
Author(s): Amit Angal; Jake Brinkmann; A. Senthil Kumar; Xiaoxiong Xiong
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Paper Abstract

The Ocean Colour Monitor (OCM) sensor on-board the Oceansat-2 spacecraft has been operational since its launch in September, 2009. The Oceansat 2 OCM primary design goal is to provide continuity to Oceansat-1 OCM to obtain information regarding various ocean-colour variables. OCM acquires Earth scene measurements in eight multi-spectral bands in the range from 402 to 885 nm. The MODIS sensor on the Terra and Aqua spacecraft has been successfully operating for over a decade collecting measurements of the earth’s land, ocean surface and atmosphere. The MODIS spectral bands, designed for land and ocean applications, cover the spectral range from 412 to 869 nm. This study focuses on comparing the radiometric calibration stability of OCM using near-simultaneous TOA measurements with Terra and Aqua MODIS acquired over the Libya 4 target. Same-day scene-pairs from all three sensors (OCM, Terra and Aqua MODIS) between August, 2014 and September, 2015 were chosen for this analysis. On a given day, the OCM overpass is approximately an hour after the Terra overpass and an hour before the Aqua overpass. Due to the orbital differences between Terra and Aqua, MODIS images the Libya 4 site at different scan-angles on a given day. Some of the high-gain ocean bands for MODIS tend to saturate while viewing the bright Libya 4 target, but bands 8-10 (412 nm – 486 nm) provide an unsaturated response and are used for comparison with the spectrally similar OCM bands. All the standard corrections such as bidirectional reflectance factor (BRDF), relative spectral response mismatch, and impact for atmospheric water-vapor are applied to obtain the reflectance differences between OCM and the two MODIS instruments. Furthermore, OCM is used as a transfer radiometer to obtain the calibration differences between Terra and Aqua MODIS reflective solar bands.

Paper Details

Date Published: 2 May 2016
PDF: 8 pages
Proc. SPIE 9881, Earth Observing Missions and Sensors: Development, Implementation, and Characterization IV, 98811Y (2 May 2016); doi: 10.1117/12.2224046
Show Author Affiliations
Amit Angal, Science Systems and Applications, Inc. (United States)
Jake Brinkmann, Science Systems and Applications, Inc. (United States)
A. Senthil Kumar, Indian Institute of Remote Sensing (India)
Xiaoxiong Xiong, NASA Goddard Space Flight Ctr. (United States)

Published in SPIE Proceedings Vol. 9881:
Earth Observing Missions and Sensors: Development, Implementation, and Characterization IV
Xiaoxiong J. Xiong; Saji Abraham Kuriakose; Toshiyoshi Kimura, Editor(s)

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