Department of Earth System Science

In this paper, GPS RO stratospheric temperatures are compared with different satellite and different model data sets. The data sets used for comparison include Japanese 25-year Reanalysis (JRA-25), UK Met office (MetO), ERA-Interim, GEOS5, and satellite temperatures are AIRS_Aqua, HIRDLS, Aura_MLS and SABER. Apart from the comparison, we also studied the seasonal variation of temperature during summer and winter in both the hemispheres. The seasonal and latitudinal variation of temperature by GPS (CHAMP+COSMIC) with other reanalysis (JRA-25, GEOS5 and METO) and satellite measurements (AURA_MLS and SABER) for both the hemispheres show reasonably good agreement. The difference of about ±0.5 to ±0.75 K is observed at 20 km, ±1K to ±1.75K at 35 km while the high values of ~3 to 4 K are observed at upper stratosphere and lower mesosphere height regions (50 km to 60 km). The GPS RO temperatures above 35 km are noticed to be warmer than reanalysis and satellite data sets in SH region. This tendency increases with increasing height and reaches its maximum at 60 km, with magnitude of 3 K to 4 K with reanalysis data sets and 2 K to 3.5 K with satellite measurements. The calculated SAO and AO amplitudes based on GPS data are found to be comparable with the earlier results.