Constructing Precipitable Water Vapor Map from Regional GNSS Network Observations without Collocated Meteorological Data

Abstract

Abstract. Surface pressure ( ) and weighted mean temperature ( ) are two necessary variables for the accurate retrieval of precipitable water vapor (PWV) from global navigation satellite system (GNSS) data. The lack of or information is a concern for those GNSS sites that are not collocated with meteorological sensors. This paper investigates an alternative method of inferring accurate and at the GNSS station using nearby synoptic observations. and obtained at the 15 nearby synoptic sites are interpolated onto the location of GNSS station by performing both vertical and horizontal adjustments, in which the parameters involved in and calculation are estimated from ERA-Interim reanalysis profiles.In addition, we present a method of constructing high quality PWV map through vertical reduction and horizontal interpolation of the retrieved GNSS PWVs. To evaluate the performances of the and retrieval and the PWV map construction, GNSS data collected from 58 stations of the Hunan GNSS network and synoptic observations from 20 nearby 20 sites in 2015 were processed to extract the PWV so as to subsequently generate PWV map. The retrieved and and constructed PWV maps were assessed by the results derived from radiosonde and ERA-Interim reanalysis. The results show that (1) accuracies of and derived by synoptic interpolation are within the range of 1.7-3.0 hPa and 2.5-3.0 K, respectively, which are much better than the GPT2w model; (2) the constructed PWV maps have good agreements with radiosonde and ERA reanalysis data with overall accuracy better than 3 mm; and (3) PWV maps can well reveal the moisture 25 advection, transportation and convergence during heavy rainfall.