A High-Resolution, Precipitable Water Vapor Monitoring System Using a Dense Network of GNSS Receivers

Abstract

This work describes a system aimed at the near realtimemonitoring of precipitable water vapor (PWV) by means of a dense network of Global Navigation Satellite System (GNSS) receivers. These receivers are deployed with a horizontal spacing of 1-2 km around the Uji campus of Kyoto University, Japan. The PWV observed using a standard GPS meteorology technique, i.e., by using all satellites above a low elevation cutoff, is validated against radiosonde and radiometer measurements. The result is a RMS difference of about 2 mm. A more rigorous validation is done by selecting single GPS slant delays as they pass close to the radiosonde or the radiometer measuring directions, and higher accuracy is obtained. This method also makes it possible to preserve short-term fluctuations that are lost in the standard technique due to the averaging of several slant delays. Geostatistical analysis of the PWV observations shows that they are spatially correlated within the area of interest; this confirms that such a dense network can detect inhomogeneous distributions in water vapor. The PWV horizontal resolution is improved by using high-elevation satellites only, with the aim of exploiting at best the future Quasi-Zenith Satellite System (QZSS), which will continuously provide at least one satellite close to the zenith over Japan.

Study of Water Vapor Variations Associated with Meso-γ Scale Convection: Comparison between GNSS and Non-Hydrostatic Model Data

“…2). PWV data used here was derived from the GNSS receiver at the Uji campus, which is one of the receivers of the hyper-dense GNSS network used by the authors in earlier studies (Realini et al 2012;Sato et al 2013). Precipitation intensity at the GNSS station rapidly increased from 2010 LST on 13 August, 2012, reached a maximum of more than 60 mm h −1 within a few minutes, and diminished by 2020 LST.…”

“…Seko et al (2004) employed 75 GPS receivers within an area of 20 × 20 km 2 around Tsukuba, Japan and analyzed the thickening of the humid boundary layer before the generation of a thunderstorm by using a tomography method and GNSS derived slant path delay (SPD) data ). Realini et al (2012) and Sato et al (2013) installed 17 GNSS stations with a horizontal spacing of 1−2 km near Uji campus of Kyoto University, which is located south of Kyoto prefecture, Japan. They succeeded to improve the horizontal resolution of the retrieved PWV maps by analyzing PWV from high elevation SPDs.…”

2D PWV monitoring of a wide and orographically complex area with a low dense GNSS network

“…Existing networks (not specifically designed for meteorological purposes) and specifically designed dense GNSS networks have been used for monitoring the distribution of water vapor in the atmosphere, with particular reference to its lower layer, that is, the troposphere. At least three different approaches have been applied: (1) investigation of the vertical column over a single station (Rocken et al 1997), (2) exploitation of existing national GNSS networks (Seko et al 2007;Inoue and Inoue 2007), and (3) implementation of specifically designed dense and hyperdense GNSS networks (Zhang et al 2008;Realini et al 2012;Sato et al 2013;Tsuda et al 2013;Oigawa et al 2015). In all aforementioned studies, which are surely not exhaustive, the water vapor content was monitored to support weather forecasting, which is useful for interpreting severe meteorological events.…”

“…Zhang et al (2008) designed a mixed singleand double-frequency GNSS network with ~ 5-to 10-km spacing between the stations to support the weather forecasting in the metropolitan area of Beijing (China). Realini et al (2012) and Sato et al (2013) installed a network of 17 dual-frequency GNSS stations, specifically designed for high-resolution PWV measurements. The network has a horizontal spacing of 1-2 km, covers an area of approximately 10 × 6 km 2 , and is located near the Uji Campus of Kyoto University (Japan).…”

Estimation of Local-Scale Precipitable Water Vapor Distribution Around Each GNSS Station Using Slant Path Delay: Evaluation of a Severe Tornado Case Using High-Resolution NHM

“…With an increased number of available SPDs, several studies have proposed utilizing SPDs to retrieve the local distribution of precipitable water vapor (PWV) near each GNSS receiver. Sato et al (2013) compared the results of such studies with those of radiosonde observations and determined that zenith-scaled GNSS SPD, in which the path is closest to a radiosonde path, exhibited better agreement than zenith total delay (ZTD) retrieved using standard GNSS analysis. Utilizing the decomposed components of each SPD (i.e., gradient and higher-order inhomogeneity), Shoji (2013) proposed two new indices to express the degree of water vapor variation near each GNSS station, and Shoji et al (2014) proposed a new method for estimating PWV distribution near ground-based GNSS stations on a scale of several kilometers.…”