Mobile Observation Field Experiment of Atmospheric Vertical Structure and Its Application in Precipitation Forecasts Over the Tibetan Plateau

Abstract

We carried out the first Mobile Field Observation Campaign of Atmospheric Profiles (MFOCAP) in the southeast Tibet and the Three-River Source Region (TRSR) of the Tibetan Plateau (TP) by adopting two vehicle-mounted integrated mobile observations (MO) system from July 18 to 30, 2021. Reliable MO data sets of air temperature (Ta), water vapor density (WVD) and relative humidity (RH) with high spatio-temporal resolution over the TP were obtained and assimilated to improve precipitation forecast using the four-dimensional variational (4DVAR) data assimilation (DA) method. The results show that Ta, WVD and RH profile data retrieved with the mobile microwave radiometer (MR) are credible over the TP. The atmospheric vertical structure measured by the mobile MR can reproduce the spatio-temporal evolution characteristics of water vapor transport, temperature stratification and cloud structure. The distribution pattern of 24-hr accumulated rainfall prediction with Ta profile DA was closer to measurements, and 6–12 hr forecasts for low to moderate rainfall in the central and western regions of Qinghai province were improved significantly. Data assimilation with air temperature retrievals from mobile MR observations were found beneficial for accurate simulation of water vapor transport, convergence and divergence of wind field, and upward motion associated with precipitation events. The finding of this study highlights the value of MR remote sensing observations in improving the rainfall monitoring and forecasts over the TP and downstream regions.