This research examines foehn events in Beijing using weather station data from 2015 to 2020. We found an average of 56.5 foehn days annually, primarily in winter. These winds can raise temperatures significantly and are associated with air-pollution levels. Strong foehn winds tend to reduce pollution, while weaker winds may increase it. Our study highlights the impact of foehn events on air quality, providing valuable insights for urban planning and environmental management.

We first present a novel method of monitoring the UHI intensity using GNSS data. We overcomes two major challenges in the algorithm development. The first challenge is the determination of the GNSS tomographic top grid height, and the second challenge is the estimation of temperature from wet refractivity. The result shows that the proposed algorithm can achieve an accuracy of 1.2 K at a 95 % confidence level.

A time-varying global gridded T_s–T_m model with 0.75 × 0.75 degree spatial resolution is developed in our study to precisely estimate water-vapor-weighted mean temperature T_m from surface air temperature T_s. Using multiple statistical tests, we assessed the T_m of our model and its impact on the GPS–PWV retrievals. Comparisons with other models demonstrate that our model has prominent advantages. Matlab codes and arrays used to realize our model are provided in the supplement of this study.

This paper proposes an optimal tropospheric tomography approach with the support of an auxiliary area, which has the ability to use the signals crossing out from the top boundary of the tomographic area. Additionally, the top height of the tomography body is determined based on the average water vapour distribution derived from the COSMIC data. The compared result reveals the superiority of the proposed method when compared to the conventional method.

We proposed a new method to determine the scale height of water vapor, which will improve the quality of vertical constraints. Then, the smoothing factor in the horizontal constraint was determined based on ERA-Interim products. The evaluation results show that the water vapor density quality obtained by the optimized technique is 13.8 % better below 3.8 km and 8.1 % better above 3.8 km than that obtained by the traditional technique.