The OCM instrument mounted on IRS-P4 will be launched by PSLV
and placed in a polar sunsynchronous 720 kilometer altitude orbit. Equatorial
crossing is at 12 noon ±20 min, descending node. The satellite has
provision for data recording onboard and will also transmit real time data to
ground stations in X-band. The ground station at Hyderabad, India will acquire
data over the Indian subcontinent and the adjacent Arabian Sea and the Bay of
Bengal. IRS-P4 OCM data may also be acquired by other ground stations with
suitable augmentation / modification.
DATA PRODUCTS
Raw Level-1 data will be provided to users. Standard Level-2 products will be
generated after applying corrections for radiometric, atmospheric and panaromic
corrections. Specific data products can also be generated from OCM data through
appropiate pre-processing and applying the essential corrections for
atmospheric path radiances. These value-added products will be generated after
validation of OCM data on request. Details of the data products are given in
Table 3.
Table 3 : Types of data products from IRS-P4 OCM
Level
|
Type of Products
|
Remarks
|
Level 1 |
Browse product |
Raw product |
Level 2 |
Standard product |
|
Level 2.1 |
Raw + Gain & bias |
This product is geometrically and radiometrically
corrected. Gain and bias values for each CCD element will be provided with
data. |
Level 2.2 |
Radiometrically corrected |
Product is geometrically raw. Top of the atmosphere (TOA)
data will be provided. |
Level 2.3 |
Atmospherically corrected |
Product is corrected for atmospheric path radiances and
panoramic corrections for across track direction. |
Level 3 |
Special products |
The derived products such as chlorophyll, suspended
sediment maps. |
APPLICATIONS
A comprehensive programme for IRS-P4 OCM data utilisation has been drawn up in
India along with a host of users. The IRS-P4 OCM data would be extremely useful
for estimation of phytoplankton in oceanic /coastal waters, detection and
monitoring of phytoplankton blooms, coastal upwelling, suspended sediment
dynamics, location of fronts, identification of water mass boundaries and oil
pollution. With additional input from other sensors as well as conventional
data, IRS-P4 OCM data will provide detailed information on the coastal region
owing to its increased spatial resolution. The information on pigments, in
conjuction with sea surface temperature, will greatly assist in identification
of potential fishery zones in coastal and oceanic waters. The potential end
users of the OCM data products include fisheries management, marine industries,
environmental management and studies related to the estimation of primary
productivity in the oceanic basins. IRS-P4 OCM, along with other ocean colour
sensors such as IRS-P3 MOS, SeaWiFS , MERIS and MODIS will assist the ocean
colour community in filling data gaps, and can also be used for the
inter-calibration of different ocean colour sensors.
REFERENCES
Indian Remote Sensing Satellite IRS-P4 utilisation plan,
SAC-RSA/IRS-P4-UP/PP-02/97, Space Applications centre (ISRO), Ahmedabad 380
053, India, May 1997.
Detailed Design and Analysis report on IRS-P4 Ocean colour monitor.,
SAC/IRS-P4/01/05/98, Space Applications Centre (ISRO), Ahmedabad 380 053,
India, May 1998. |