Remote Sensing of Atmospheric Water Vapor Variation with GPS: On the case of Typhoon EWINIAR

摘要

The Global Positioning System (GPS) provides a relatively inexpensive method to remotely sense atmospheric water vapor in all weather conditions. We apply the GPS Meteorology technique to monitor Precipitable Water Vapor (PWV) Variation during the progress of Typhoon EWINIAR. Typhoon EWINIAR, which caused serious damage, was passed over in Korea peninsula during 8 July to 11 July, 2006. We estimated tropospheric dry delay and wet delay for one hourly using 22 GPS permanent stations and precipitable water vapor was conversed by using surface meteorological data. The Korean weighted mean temperature and air-pressure of versa-reduction to the mean sea level have been used for an accuracy improvement of GPS precipitable water vapor estimation. The time series of the PWV from both GPS and radiosonde clearly increased before and during the passage of the typhoon EWINIAR, and decreased rapidly right after the typhoon EWINIAR passed, and returned to their nominal values later. The root mean square difference (RMSD) between the GPS PWV and the radiosonde-PWV was at the 5.2 mm level. Finally, we compared MTSAT water vapor image, radar image and precipitable water vapor map during a passage of the typhoon EWINIAR. The GPS-PWV and the meteorological data (rainfall, surface air pressure and surface temperature) showed a correlation between the rapid increase of the GPS-PWV and heavy rainfall during a period of severe weather. Thus, a permanent GPS network may be efficiently used as a sensor of water vapor to clarify the complex characteristics of water vapor distribution and its temporal change.