Trends in Water Vapor in North America Based on GNSS observation and ERA5 reanalysis

Abstract. Atmospheric precipitable water vapor (PWV) is a very important meteorological factor for weather forecasting and climate change monitoring. GNSS observation and ERA5 reanalysis for the period of 2010–2022 are used to analyse the overall and seasonal distribution and interdecadal trend of PWV in North America. The results indicate that GNSS and ERA5 are in good agreement between the distribution and interdecadal trend of PWV. The overall PWV change from 2010 to 2022 shows an obvious upward trend. The mean PWV is less than 20 mm in most regions of North America except for the Southeast where mean PWV is more than 30 mm. The change trend and correlation of PWV and temperature in North America from 1940 to 2022 based on ERA5 reanalysis data are analysed. The results show that the PWV increases more significantly with the interdecadal trend of 0.17 mm decade^-1. The results illustrate that there is a significant correlation between PWV and temperature with the correlation coefficient of 0.96, and that there are some differences between the actual increase and ideal increase of water vapor content derived from Clausius-Clapeyron equation for every 1 K increase in North America. In addition, the results also show a significant increase of PWV during strong El Nino events and a significant decrease of PWV during strong La Nino events, thereby indicating that El Nino and La Nino events have an important influence on the change of PWV in North America.