1 results listed
Accurate wind products generation, depends on the accuracy of sigma-0 estimation from the scatterometer data. Similar to Oceansat- 2(OSCAT) Scatterometer, SCATSAT-1 scatterometer works on dual pencil beam (Inner beam HH and Outer beam VV) approach at 13.5 GHz frequency by conically scanning the Earth surface and collecting the backscatter. The data is radar processed onboard and radiometrically corrected on ground like OSCAT, however the sensor is designed with advanced techniques and modified for providing better sigma-0 than OSCAT, thus it is required to assess the data quality. Level-1B scan Mode is the basic data and it is very significant to evaluate and monitor the quality of this data as it forms the basic input to the Level-2A cell-grid sigma-0, which in turn results to wind formation. The level-1B product carries information about the radiometry (sigma-0, SNR), geometry (Azimuth Angle, Incidence angle, geolocation), calibration constant and sigma-0 quality flag at both slice and footprint level. For evaluation of data quality these parameters are categorised into static and dynamic parameters based on the sensor scan mechanism and the wave target interaction. Doppler frequency, X-Factor, Range, incidence angle and azimuth angle are the static parameters which varies systematically over the orbit data and shows consistency and are well within the specification. Dynamic parameters like Sigma-0, SNR and Brightness Temperature (BT) are observed for the scan mode data acquired for each orbit/revolution. For calibration/validation, Sigma-0 and BT of wellknown calibrated sites (viz. Amazon Rainforest, Antarctica) are monitored and results show that variation in Sigma-0 over the Amazon rainforest is less than 0.5 dB, as expected. Results from trend analysis ensures that parameters are behaving well within the specifications and assures stability and consistency of the system.
International Workshop on GeoInformation Science
GEOADVANCES
M. Gupta
A. Sharma
B. Kartikeyan