SARAL/AltiKa Mission: Applications Using Ka-band Altimetry
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Observations from AltiKa (nadir altimeter in Ka-band) on board the Satellite with ARGOS and AltiKa (SARAL) mission have been used for exploring new, unique and challenging areas. These application areas are coastal altimetry, inland hydrology and cryosphere (continental and sea ice). High rate (40-Hz) data from AltiKa has been exploited for retrieving very useful oceanic parameters (sea surface height anomaly, significant wave height and ocean surface wind) in the coastal waters (up to ~ 3 km off coast) of Indian landmass region. Validation carried out using buoys and tide gauge suggest exceedingly high correlation (~ 0.7–0.9) in the region of 3–10 km from the coast for each of these parameters. AltiKa is able to provide reasonably good quality ocean parameters much nearer to the coast (up to 3–10 km) as compared to Jason-2 (up to 8–10 km). Under the land hydrology, some of the extreme events such as flood wave (Brahmaputra river) and hydrological drought (Ukai reservoir) over India have been captured extremely well by AltiKa data. Brahmaputra river flood plain experiences flood waves almost every year. Flood wave of Brahmaputra river was captured using the AltiKa data on 9th June 2015. Two important aspects of cryospheric applications of AltiKa data has revealed interesting findings. During 2013–2015, East Antarctica is gaining ice with maximum change of 0.6 m in many regions. While in the west near Thwaites glacier and Pine Island glacier, more than 2 m reduction in the elevation has been observed. Winter sea ice freeboard thickness values were found to be higher than those estimated during summer period in both Arctic and Antarctic regions.
KeywordsSARAL/AltiKa 40-Hz data Coastal geophysical parameters Inland water level Ice sheet surface elevation
Special thanks to Shri Tapan Misra, Director, Space Applications Centre (SAC) for his constant encouragement and motivation. Thanks are due to Dr. I. M. Bahuguna, Dr. D. R. Rajak, Ms. Maya Suryawnanshi, Mr. Aditya Chaudhary and Dr. S. Chander of SAC for the innovative research work, discussed here. Tide gauge and wave rider buoy data provided by INCOIS is acknowledged herewith. Authors are extremely grateful to Indian Space Research Organization, India and Centre National d’Etudes Spatials, France for the AltiKa mission, which provided the opportunity to work with unique data set that helped in exploring new science areas like, coastal, hydrology and cryospheric science.
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