INSTANTANEOUS NEAR-SURFACE LEVEL HUMIDITY FROM ERS-1 ATSR OBSERVATIONS - A CASE-STUDY IN THE INDIAN-OCEAN/

A relation between near surface level specific humidity(q(a)) and ERS- 1/Along Track Scanning Radiometer's nadir and forward scan observation s is proposed on the basis of radiative transfer simulations for tropi cal atmospheres. The simulation study shows that q(a) can be estimated within an r.m.s. error of 15 per cent when it is compared with the va lues derived from ship observations. As a case study analysis, we have applied the relation to an actual ERS-1/ATSR data dated 3 March 1992. The computed near-surface level specific humidity compared well with values derived from simultaneous ship observations and the r.m.s. erro r was found to be within 15 per cent.