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Châteauneuf-Grasse, France

Babu K.N.,Space Applications Center | Shukla A.K.,Space Applications Center | Suchandra A.B.,Space Applications Center | Arun Kumar S.V.V.,Space Applications Center | And 5 more authors.
Marine Geodesy | Year: 2015

The Kavaratti calibration-validation site in India at Lakshadweep Sea has been improved to carry out absolute calibration of SARAL/AltiKa altimeter. This site is augmented with a down-looking radar gauge and a permanent GPS receiver. The Kavaratti Island is located near a repeating ground track of SARAL/AltiKa and ∼12 km away from the point of closest measurement of Jason-2, SARAL/AltiKa crossover point. Additionally, the altimeter and radiometer footprints do not experience any land contamination. This article aims at presenting the initial calibration-validation results over cycles 001-011 of AltiKa. The absolute sea surface height bias has been found to be −48 mm at Kavaratti calibration site. In this preliminary study the effect of environmental variables such as winds and pressure are not considered in calculations. © 2015, Copyright © Taylor & Francis Group, LLC. Source


Bonnefond P.,Observatoire de la Cote dAzur GeoAzur | Exertier P.,Observatoire de la Cote dAzur GeoAzur | Laurain O.,Observatoire de la Cote dAzur GeoAzur | Guillot A.,French National Center for Space Studies | And 3 more authors.
Marine Geodesy | Year: 2015

The geodetic Corsica site was set up in 1998 in order to perform altimeter calibration of the TOPEX/Poseidon (T/P) mission and subsequently, Jason-1 and OSTM/Jason-2. The scope of the site was widened in 2005 in order to undertake the calibration of the Envisat mission and most recently of SARAL/AltiKa. Here we present the first results from the latter mission using both indirect and direct calibration/validation approaches. The indirect approach utilizes a coastal tide gauge and, as a consequence, the altimeter derived sea surface height (SSH) needs to be corrected for the geoid slope. The direct approach utilizes a novel GPS-based system deployed offshore under the satellite ground track that permits a direct comparison with the altimeter derived SSH. The advantages and disadvantages of both systems (GPS-based and tide gauges) and methods (direct or indirect) will be described and discussed. Our results for O/IGD-R data show a very good consistency for these three kinds of products: their derived absolute SSH biases are consistent within 17 mm and their associated standard deviation ranges from 31 to 35 mm. The AltiKa absolute SSH bias derived from GPS-zodiac measurement using the direct method is −54 ±10 mm based on the first 13 cycles. © 2015, Copyright © Taylor & Francis Group, LLC. Source


Bonnefond P.,Observatoire de la Cote dAzur GeoAzur | Exertier P.,Observatoire de la Cote dAzur GeoAzur | Laurain O.,Observatoire de la Cote dAzur GeoAzur | Jan G.,Formerly at NOVELTIS
Marine Geodesy | Year: 2010

The Corsica region of the western Mediterranean, including sites at Ajaccio-Aspretto, Cape Senetosa, and Capraia (Italy), hosts a dedicated, long-term experiment to support absolute calibration of space-borne radar altimeters. The objective of the experiment is to continuously monitor the bias and drift of the altimeter measurement systems. In addition, with complementary data from a local weather station, we have derived GPS-based wet tropospheric path delay measurements that are compared with those from the on-board Microwave Radiometers at the overflight times. In this article, we focus on the analysis of data from the Formation Flight Phase of Jason-1 and Jason-2. © 2010, Taylor & Francis Group, LLC. Source

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