Retrieval of meteorological parameters from ROSA on-board Megha Tropiques satellite: evaluation with COSMIC GPS RO, ERA-Interim and radiosonde data

Abstract

ABSTRACTThe Indian Space Research Organization (ISRO), in collaboration with Centre National d’Etudes Spatiales, France, launched radio occultation sounder for atmosphere (ROSA) on-board Megha Tropiques (MT) satellite. In this article, the retrieval of atmospheric parameters from ROSA and its evaluation with a network of in situ (radiosonde), similar satellite (Constellation Observational System for Meteorology, Ionosphere and Climate (COSMIC) GPS RO), and re-analysis (ERA-Interim) data sets are presented. The refractivity is retrieved from the bending angle as a function of impact parameter, and pressure and temperature profiles are derived from the profiles of refractivity. The algorithm has been successfully applied to COSMIC data. We have applied and validated this algorithm for the first time to ROSAon board MT. The algorithm retrieves the refractivity and pressure information from surface to 40 km whereas temperature profiles are restricted between 10 and 40 km. The ROSA algorithm refractivity, pressure, and temperature profiles compare well with independent data sets mentioned above. The mean fractional difference between ROSA and COSMIC, ERA-Interim and radiosonde refractivity and the temperature is found to be 0.1% with a standard deviation of 0.5%. It is shown that the algorithm derives the atmospheric parameters with good accuracies from the ROSA instrument and provides the atmospheric community new data from GPS RO at the verge of existing COSMIC GPS RO and in between upcoming GPS RO missions.