Spatio-Temporal Characteristics and Variability of GNSS-Derived Atmospheric Precipitable Water Vapor From 2010 to 2023 in Fujian Province, China

Atmospheric precipitable water vapor (PWV) is a crucial factor affecting precipitation and the atmospheric environment. To quantitatively investigate the spatio-temporal distribution and characteristics of the PWV in Fujian, China, its diurnal and seasonal variations are analyzed based on the global navigation satellite system (GNSS) data from 2010 to 2023, ground meteorological observations, meteorological sounding data and ERA5 data. Moreover, the spatio-temporal characteristics of the monthly PWV are assessed by using the empirical orthogonal function (EOF), the Mann-Kendall test and the sliding t-test. The results indicate that the ground-based GNSS PWV data is able to reveal the distribution and variation of PWV over Fujian. Specifically, the diurnal distribution of the PWV varies remarkably with time, and the PWV in the eastern coastal areas is generally higher than in the western mountainous areas. The seasonal variation characteristics of the PWV are consistent with the atmospheric circulation variations, with the largest amount of PWV in summer, followed by spring, autumn and winter. Moreover, the EOF spatial modes show that the PWV distributions are different in the eastern coastal areas and inland mountainous areas. The oscillation intensity of the PWV strengthens from the northwest to the southeast, and the corresponding time series of the PWV displays apparent seasonal variations. The observed precipitation is inconsistent with the PWV and is more affected by local terrain and thermodynamic conditions. The Mann-Kendall test and the sliding t-test indicate that the PWV over Fujian has not undergone abrupt changes during the past 13 years, but there is a possibility of sudden changes in the future. The atmospheric PWV is an essential source of atmospheric precipitation, and analyzing the spatio-temporal characteristics and variability of the atmospheric PWV based on ground-based GNSS data is of great importance for improving the accuracy of precipitation forecasts and climate predictions. Through the GNSS data, ERA5 data, and meteorological observations data, we find that the PWV in Fujian has remarkably spatio-temporal variations, that is, the PWV is higher in coastal areas than in inland mountainous areas, and the PWV is higher in spring and summer than in autumn and winter. Moreover, the main spatial modes indicate that the fluctuation amplitude of the PWV gradually increases from the west to, the east. In particular, the actual rainfall areas are located in the inland mountainous areas rather than the coastal areas with the higher PWV. It is found that the main reasons are the influences of terrain and thermodynamic conditions. From the results of the Mann-Kendall and the sliding t-test, it can be found that there is no abrupt change in the PWV during 2010-2023, but it may occur in the future. The above analyses provide references for the evaluation of cloud water, short-term precipitation forecasts and the assessment of artificial precipitation conditions in Fujian. Precipitable water vapor (PWV) in Fujian is higher on the coast than inland, and is the highest in spring and summer From 2010 to 2023, the PWV decreases slightly, and abrupt change may occur in the future Topographic effect is a key factor contributing to the inconsistency between the distribution of the PWV and the observed precipitation