Contribution of tide gauges to altimeter calibration in the Spanish sites Contribution of tide gauges to altimeter calibration in the Spanish sites

Juan Martinez Benjamin1, Marina Garcia1, Begoña Perez Gomez6, Enrique Fanjul6, Miquel Angel, Ortiz Castellon2, Gema Rodriguez Velasco3, Jose Davila4, Jorge Pasquin4, Pascal Bonnefond5, J Lopez Marco1, Cristina Garcia (+12 others)
In this work the contribution of the tide gauges to the experiences on space altimeter calibration are summarized. In the Spanish Western Mediterranean several cal/val campaigns of the TOPEX-side B and Jason-1 altimeters have been conducted in the areas of Begur Cape and Ibiza island. The three Begur Cape experiences on radar altimeter calibration and marine geoid mapping were made on 1999, 2000 and 2002 with support of l'Estartit and Llafranc tide gauges. One campaign has also been made in
more » ... 2003 at the Ibiza island area. In this case the marine geoid has been used to relate the coastal tide gauge data from Ibiza and San Antonio harbours to offshore altimetric data. All of these campaigns have been The San Antonio tide gauge was deployed by IMEDEA institute by the beginning of 2002 in the framework of the calibration and validation activities for the ENVISAT radar altimeter RA-2. Data from both, Ibiza and San Antonio tide gauges, have been analysed for the period with data available, in order to obtain harmonic constants and mean sea levels (Fig.4). This zone presents a very small tide and is characterized as microtidal, that is one of the reasons to select this area for the altimeter calibration and validation. The quality of monthly mean sea levels have been checked for the whole 2003 year at Ibiza, a comparison was also made with the monthly means obtained for the Valencia station (in the Peninsula coast, in front of Ibiza. The evolution of monthly means are due to a great extent to regional meteorological conditions, so it has to be rather similar between stations not too far away. The annual mean sea level at Ibiza for the 2003 year is 327.8 mm with respect to the tide gauge zero (from a 91% of valid data, the most important gap occurring in January). Monthly means during 2003 in Valencia, Ibiza and San Antonio tide gauge agree reasonably. 3.2. Ibiza 2003 campaign ACKNOWLEDGMENTS