Abstract:
The complex terrain and various underlying surface conditions of the Tibetan Plateau present significantly challenges for accurate detection of the atmospheric boundary layer. COSMIC-2, a GNSS-RO satellite, offers high-precision and global observation capabilities, making it a promising tool for atmospheric boundary layer research over the Tibetan Plateau. However, its performance in this region has not yet been comprehensively evaluated. This study utilized observational data from the intensive observation period of the “Land-Atmosphere Interaction and Climate Effects” campaign during the Second Tibetan Plateau Scientific Expedition and Research in October 2019 and June 2022, as well as ERA5 reanalysis data, to systematically assess the accuracy of COSMIC-2 atmospheric profile data and boundary layer height estimates. The results demonstrate that COSMIC-2 temperature and atmospheric refractivity data show high consistency with observational data, with mean biases of −0.02 ℃ and 0.34, respectively, effectively capturing the vertical distribution of the lower to mid-troposphere (1~6 km). Boundary layer height estimates derived from the refractivity gradient method exhibited a mean bias of −0.16 km, performing other estimation methods. Moreover, COSMIC-2 effectively captured the diurnal variations of boundary layer height, with correlations of 0.61–0.87 between COSMIC-2 and ground-based observations, and a mean bias of less than 0.3 km across different observation sites. However, in the eastern Tibetan Plateau, COSMIC-2 data did not adequately reflect the influence of water vapor on seasonal boundary layer variations, particularly during summer, where a significant positive bias of approximately 1.1 km was observed. Overall, COSMIC-2 data are well-suited for monitoring mid-to-upper tropospheric structures and boundary layer height variations over the Tibetan Plateau but exhibit limitations in detecting stable lower boundary layers. These findings provide valuable insights into the application of COSMIC-2 data for atmospheric boundary layer studies over complex terrain and contribute to advancing the understanding of boundary layer processes in the Tibetan Plateau region.