On Wet Tropospheric Correction for Altimetry in Coastal Regions

In order to correct the altimeter range from tropospheric humidity, a microwave radiometer is added to altimetry missions (ENVISAT/MWR, Jason/JMR, TOPEX-Poseidon/TMR). Over open ocean, the combination altimeter/radiometer is satisfactory. This is not the case in coastal zones, where the signal coming from the surrounding land surfaces contaminates the measurement and makes the humidity retrieval method unsuitable. In this paper, a radiometer simulator is built, using data from the FETCH experiment (high resolution meteorological model, in-situ measurements, and TMR measurements). This simulator is used to perform sensitivity tests and to evaluate the current methods used up to now to retrieve the wet tropospheric correction in transition areas. Refinements are then proposed. Finally, a method using the proportion of land in the mixed pixel to decontaminate measured brightness temperatures is developed