Spatial-Temporal Variability of Global GNSS-Derived Precipitable Water Vapor (1994-2020) and Climate Implications

Precipitable water vapor (PWV) is an important component in the climate system and plays a pivotal role in the global water and energy cycles. Over the years, many approaches have been devised to accurately estimate the PWV. Among them, global navigation satellite systems (GNSS) have become one of the most promising and fastest-growing PWV acquisition methods because of its high accuracy, high temporal and spatial resolution, and ability to acquire PWV in all weather and in near real time. We compared GNSS-derived PWV with a 5 min resolution globally distributed over 14,000 stations from the Nevada Geodetic Laboratory (NGL) from 1994 to 2020 with global radiosonde (RS) data, temperature anomalies, and sea height variations. Then, we examined the temporal and spatial variability of the global PWV and analyzed its climate implications. On a global scale, the average bias and root mean square error (RMSE) between GNSS PWV and RS PWV were similar to 0.72 +/- 1.29 mm and similar to 2.56 +/- 1.13 mm, respectively. PWV decreased with increasing latitude, and the rate of this decrease slowed down at latitudes greater than 35 degrees, with standard deviation (STD) values reaching a maximum at latitudes less than 35 degrees. The global average linear trend was similar to 0.64 +/- 0.81 mm/decade and strongly correlated with temperature and sea height variations. For each 1 degrees C and 1 mm change, PWV increased by similar to 2.075 +/- 0.765 mm and similar to 0.015 +/- 0.005 mm, respectively. For the time scale, the PWV content peaked similar to 40 days after the maximum solar radiation of the year (the summer solstice), and the delay was similar to 40 days relative to the summer solstice.

Automated summary

Precipitable water vapor (PWV) plays a crucial role in the climate system and can be accurately estimated using global navigation satellite systems (GNSS). By comparing GNSS-derived PWV with other data and analyzing its temporal and spatial variability, we found that PWV decreases with increasing latitude and is strongly correlated with temperature and sea height variations. Additionally, the maximum PWV content occurs approximately 40 days after the summer solstice.