Calibration and Validation of the sensors onboard various
satellites has become important to monitor the quality and
performance and continually upgrade the ability to calibrate these
sensors. Calibration is the process of monitoring by way of
comparing the accuracy of measuring instrument with a standard.
Vicarious calibration refers to the techniques that make use of
natural or artificial ‘targets’ on the surface of Earth for the
post-launch calibration of satellite sensors. For satellites, this
exercise is essential in order to improve/maintain the
quality/accuracy of the bio-geo-physical products derived by the
satellite data over the entire mission life of the satellite.
deployed for calibration at Mt. Abu
function, field photographs and response of the deployed Corner
Reflectors as seen in RISAT MRS Image of 10th March 2016 at
Desalpar, Rann of Kutchh, Gujarat.
Space Applications Centre is involved in vicarious
calibration of sensors onboard ISRO’s Earth observation satellites
and validation of its bio-geo-physical products using controlled
and instrumented sites over land, ocean and atmosphere. These
satellites include INSAT-3D, OCEANSAT-2, RESOURCESAT, CARTOSAT,
RISAT-1, MEGHA-TROPIQUES and SARAL. Instruments like
Sun-photometer, underwater radiometer, radar tide gauge,
micro-rain radar, disdrometer, bucket rain gauge, corner
reflectors, radiosonde, fluorometer are being regularly used for
calibration and validation of satellite data/products.
Chlorophyll, Sea surface temperature, rainfall, temperature and
humidity profiles, sea surface height, aerosol optical depth etc.
are some of the satellite derived bio-geophysical products which
are being regularly validated with the measurements by state of
art instruments installed at various calibration/validation sites
in the country.
buoy for calibration of OCEANSAT-2 at Kavaratti, Lakshwadeep
measurement at Great Rann of Kutchh, Gujarat