Evaluation and analysis of the precipitable water vapor in Inner Mongolia of China

The Inner Mongolia Autonomous Region is an ecological protective screen in the northern part of China. The precipitable water vapor (PWV) products with high precision and spatiotemporal resolution are critical for climate research in this region. This study aims to comprehensively evaluate and analyze the PWV in Inner Mongolia using the global navigation satellite system (GNSS), radiosonde (RS), the fifth-generation European Center for Medium-Range Weather Forecasts Reanalysis (ERA5), and the Second Modern-Era Retrospective Analysis for Research and Applications (MERRA-2) data. The comparison between GNSS PWV and RS PWV reveals an average bias of -0.68 mm and a root mean square error (RMSE) of 2.17 mm, indicating the high accuracy of GNSS PWV and its potential as an assessment tool of other PWV products. In comparison to PWV of GNSS, PWV of ERA5 and MERRA-2 exhibit an annual average bias of 0.17 and 0.39 mm, respectively, and an annual average RMSE of 1.63 and 2.99 mm, respectively. The monthly average bias and RMSE of ERA5 are 0.41 and 1.79 mm, respectively, while those of MERRA-2 are 0.43 and 3.05 mm, respectively. In the Inner Mongolia region, the diurnal anomaly variation range of PWV for all three datasets is stable within -0.6-0.6 mm. The evaluation results demonstrate that PWV retrieved by ERA5 and MERRA-2 are applicable in the Inner Mongolia region, with ERA5 showing better consistency with GNSS PWV. This study provides valuable insights for understanding the formation, patterns, monitoring, and warning of meteorological natural disasters in the Inner Mongolia region.