Abstract
The spatial and temporal variations in global precipitable water (PW) derived from satellite and radiosonde observations during 2007–2016 are compared and analyzed in this study. The two observations show a good agreement in global spatiotemporal distributions and trends in PW. Generally, PW shows apparent latitudinal and seasonal variations. The averaged PW peaks in the tropical region, with the value of 40 mm or higher, and then decreases apparently to the polar region, less than 10 mm. PWs are larger in warm seasons and smaller in cold seasons for both hemispheres. It is indicated that the spatial and seasonal variabilities of PW are highly related to water vapor source and surface temperature as a direct heat source. The global PWs have changed in the past 60 years and, to some extent, strongly in the recent 10 years. It is found that PWs at Australian stations present statistically significant decreasing trends in last 60 years, while PWs at most stations in the United States have increasing trends. According to the global observations, it is found that PWs show uptrends over land and downtrends over the ocean in last 10 years, implying the widespread increase of water vapor in the troposphere over land.
Highlights
As one of the most significant constituents in the atmosphere, water vapor has been a major concern for decades
Radiosondes have provided detailed measurements of global atmospheric water vapor since 1938 [3] and there are over 2700 stations distributed all over the world, which provides us the chance to study the characteristics of Precipitable water (PW) for global climate change and weather prediction
In order to compare the PW derived from radiosonde observations with COSMIC satellite data in details, we selected eight stations for the case study, with consideration of latitude, elevation and the distance to the ocean
Summary
As one of the most significant constituents in the atmosphere, water vapor has been a major concern for decades. There are various kinds of methods to obtain PW from observations, and they are usually divided into two types: ground-based and space-based measurements Among these observations, radiosondes and satellites are two popular instruments to detect water vapor in the atmosphere. Radiosondes have provided detailed measurements of global atmospheric water vapor since 1938 [3] and there are over 2700 stations distributed all over the world, which provides us the chance to study the characteristics of PW for global climate change and weather prediction. In Xu et al.’s [11] research of wet profiles obtained from GPS RO and radiosonde over China, temperature differences between two observations were found positively correlated with station altitudes in the Qinghai–Tibet Plateau region, while pressure, water vapor pressure, as well as refractivity differences, were negatively correlated with altitudes.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
