WET TROPOSPHERIC RANGE CORRECTIONS FOR RADAR ALTIMETER OVER INDIAN-OCEAN

A relation between wet tropospheric range correction and precipitable water has been proposed for correcting satellite-borne radar altimeter data over the Indian Ocean region for south-west monsoon months (May-July). The proposed regional relation, which used data from May-July 1979, gave an rms error of 1.53 mm as compared to rms error of 4.54 mm for Liu and Mock's relation using global data. The precipitable water values ranged from 30 mm to 75 mm with larger concentration of data points between 40 to 65 mm. The wet tropospheric range correction could be useful for analysing ERS-1 radar altimeter data over Indian oceans whose dual angle split thermal IR channels and/or microwave channels could be used for estimating total precipitable water with an accuracy of 2 to 4 mm. We have also investigated the variability of equivalent temperature with precipitable water and air temperature and found that they are not strongly correlated with each other.