Assessments of GMI-Derived Precipitable Water Vapor Products over the South and East China Seas Using Radiosonde and GNSS

Biyan Chen,Zhizhao Liu,Wujiao Dai,Lixin Wu,Pengfei Xia

doi:10.1155/2018/7161328

Abstract

Satellite remote sensing of the atmospheric water vapor distribution over the oceans is essential for both weather and climate studies. Satellite onboard microwave radiometer is capable of measuring the water vapor over the oceans under all weather conditions. This study assessed the accuracies of precipitable water vapor (PWV) products over the south and east China seas derived from the Global Precipitation Measurement Microwave Imager (GMI), using radiosonde and GNSS (Global Navigation Satellite System) located at islands and coasts as truth. PWV measurements from 14 radiosonde and 5 GNSS stations over the period of 2014–2017 were included in the assessments. Results show that the GMI 3-day composites have an accuracy of better than 5 mm. A further evaluation shows that RMS (root mean square) errors of the GMI 3-day composites vary greatly in the range of 3∼14 mm at different radiosonde/GNSS sites. GMI 3-day composites show very good agreements with radiosonde and GNSS measured PWVs with correlation coefficients of 0.896 and 0.970, respectively. The application of GMI products demonstrates that it is possible to reveal the weather front, moisture advection, transportation, and convergence during the Meiyu rainfall. This work indicates that the GMI PWV products can contribute to various studies such as climate change, hydrologic cycle, and weather forecasting.

Highlights

Atmospheric water vapor represents a small portion of the total atmosphere mass but is closely linked to climate change, weather pattern, atmospheric radiation, and hydrologic cycle [1,2,3,4,5]
GNSS precipitable water vapor (PWV) shows a good agreement with radiosonde PWV as their regression line is very close to 1 : 1 line with a high correlation coefficient of 0.976. e probability density function (PDF) of PWV difference shown in Figure 2(b) indicates that there is a higher probability of negative PWV difference occurrence
The comparison results confirm the high quality of GNSS PWV, which can be employed as a good data source to assess water vapor measurements from other independent systems

Summary

Introduction

Atmospheric water vapor represents a small portion of the total atmosphere mass but is closely linked to climate change, weather pattern, atmospheric radiation, and hydrologic cycle [1,2,3,4,5]. Accurate knowledge of water vapor can lead to an enhanced understanding in all of these fields and to a better correction of wet delay for many space geodetic observations. A variety of water vapor observation techniques have been developed over the past decades. Radiosonde has long been the principal in situ observation tool for measuring the water vapor throughout the troposphere [6]. Remarkable progress in GNSS (Global Navigation Satellite System) meteorology achieved in the last decades has made GNSS being a potent means for observing the water vapor with high spatiotemporal resolution [10,11,12,13]. Space-based sensor system is widely recognized as the only effective way to monitor the atmospheric water vapor on a global basis [14]

Methods

Results

Conclusion