Retrieving Precipitable Water Vapor From GPS Observation Data and Primary Discussion of Earthquake PW Anomalies

CHEN Meihua; DENG Zhihui; TAN Zhengguang; LIU Jiping; HAN Yulan; SONG Wenjie

doi:10.13512/j.hndz.2017.01.002

Abstract：The use of the GNSS observation technology for estimating precipitable water vapor (PWV) is a brand-new technique developed in the 1990s.Precipitable water vapor are retrieved from GPS observation data (from China Mainland Tectonic Environment Monitoring Network,CMTEMN and Crustal movement observation network of Guangdong province) and contrast with the ECMWF total column water vapor data.It was found that the GPS PW match to the ECMWF TCWV data,so the authors supplied the ECMWF TCWV data to the GPS PW data to create a database of precipitable water vapor in Guangdong province from 2000 to 2014.In order to search for probable anomalies,the temporal variations of PW before and after several earthquakes (≥Ms 4.8)from 2000 that occurred in Guangdong province are summarized in this paper and so did the PW background.The PW in Guangdong area shows higher value during summer than during winter and higher values in the north region than in south region.The results also show that significant PW anomalies occurred in epicentral area one months before three Ms 4.8 earthquakes since 2000.The abnormal amplitude is more than 30 mm and the high PW area distributed along the tectonic belt.We also found the PW anomalies accompanied by surfacc temperature anomalies.It means the increase of water vapor content is related to the increase of heat function in the epicenter area,which may be due to the strong volcanic activities prior to earthquake.