Validation of GNSS-observed climate variables over Tibetan Plateau

Atmospheric variables over high elevation areas such as the surface temperature of the Qinghai-Tibetan Plateau, with an averaged altitude of 4-5 km, is rising at a rate of ~0.3°C/decade, more than twice the rate of global temperature rise. Here we use independently obtained surface temperature and water vapor pressure (WVP) data from a variety of satellite platforms, models and in situ data around Lhasa, Qinghai-Tibetan Plateau, to study the consistency of the evolution of these two atmospheric variables. We used data products from the FORMOSAT-3/COSMIC radio occultation data, NWP reanalysis model (ERA-Interim and JRA-25), MODIS and AIRS passive microwave data products, and in situ data at the Lhasa GPS station. Despite the altitude of the study region at ~4,000 km, there are significant differences between the satellite observables and NWPs, including large relative biases. We concluded that the various observables have significant relative biases between each other and further study is needed to unravel the source of these biases.