• Title, Summary, Keyword: precipitable water vapor

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Correlation Analysis between GPS Precipitable Water Vapor and Heavy Snowfall on Gangwon Province in Early 2011 (2011년 강원 폭설과 GPS 가강수량의 상관성 분석)

  • Song, Dong-Seob
    • Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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    • v.30 no.1
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    • pp.97-104
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    • 2012
  • In this paper, the GPS precipitable water vapor was retrieved by estimating of GPS signal delay in the troposphere during the progress of heavy snowfall on the Gangwon Province, 2011. For this period, the time series analysis between GPS precipitable water vapor and fresh snow depth was accomplished. The time series and the comparison with the GPS precipitable water vapor and the fresh snow depth indicates that the temporal change of two variations is closely related to the progress of the heavy snowfall. Also, the periodicity of GPS precipitable water vapor using the wavelet transform method was showed a similar cycle of saturated water vapor pressure as the limitation of this study span. The result shows that the decrement of GPS precipitable water vapor was conflicted with the increment of fresh snow depth at two sites, Gangneung and Uljin. The correlation between the GPS precipitable water vapor and the saturated water vapor pressure for the event was showed a positive correlation, compare with the non-heavy snowfall periods.

Analysis of GPS Precipitable Water Vapor Variation During the Influence of a Typhoon EWINIAR (태풍 에위니아 영향력에서의 GPS 가강수량 변화 분석)

  • Song, Dong Seob;Yun, Hong Sic
    • Journal of The Korean Society of Civil Engineers
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    • v.26 no.6D
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    • pp.1033-1041
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    • 2006
  • In this study, we calculated a space-time variation of GPS precipitable water vapor using GPS meteorology technique during a progress of the typhoon EWINIAR had made an effect on Korean peninsular at 10 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. Finally, we compared MTSAT water vapor image, radar image and precipitable water vapor map during a passage of the typhoon EWINIAR.

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Remote Sensing of GPS Precipitable Water Vapor during 2014 Heavy Snowfall in Gangwon Province (2014년 강원 폭설동안 GPS 가강수량 탐측)

  • JinYong, Nam;DongSeob, Song
    • Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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    • v.33 no.4
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    • pp.305-316
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    • 2015
  • The GPS signal delays in troposphere, which are along the signal path between a transmitting satellite and GPS permanent station, can be used to retrieve the precipitable water vapor. The GPS remote sensing technique of atmospheric water vapor is capable of monitoring typhoon and detecting long term water vapor for tracking of earth’s climate change. In this study, we analyzed GPS precipitable water vapor variations during the heavy snowstorm event occurred in the Yeongdong area, 2014. The results show that the snowfall event were occurring after the GPS precipitable water vapor were increased, the maximum fresh snow depth was recorded after the maximum GPS precipitable water vapor was generated, in Kangneug and Wuljin, respectively. Also, we analyzed that the closely correlation among the GPS precipitable water vapor, the K-index and total index which was acquired by the upper air observation system during this snowstorm event was revealed.

Characteristics of Precipitable Water Vapor and Liquid Water Path by Microwave Radiometer (마이크로웨이브 라디오미터에서 관측된 가강수량 및 구름물량 특성 분석)

  • Yang, Ha-Young;Chang, Ki-Ho;Cha, Joo-Wan;Choi, Young-Jean;Ryu, Chan-Soo
    • Journal of the Korean earth science society
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    • v.33 no.3
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    • pp.233-241
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    • 2012
  • Based on the observation of the microwave radiometers at Cheongju, Hapcheon and Daegwallyeong in Korea, the precipitable water vapor and liquid water path have been analyzed for spatio-temporal characteristics. The observed datas have been validated by comparing precipitable water vapor between the microwave radiometer and the radiosonde near the sites. It resulted in the correlation coefficient of more than 0.8 in all three sites. For three regions, the precipitable water vapor shows similar seasonal variation and diurnal cycle, and that amount of precipitable water vapor increases from around 1000 LST and has a maximum value at 1900 LST. On the other hand, the liquid water path of microwave radiometer has regional differences for its seasonal variation, which seems to be caused by the geographical characteristics including the frequent fog and clouds in Daegwallyeong, a high mountain region (834 m from sea level), almost flat land in Chengju, and Sobaek Mountains in Hapcheon that blocks the westerly clouds.

Diurnal variation of atmospheric water vapor based on GPS observations over Taiwan

  • Cheng, Chihan;Liou, Yuei-An
    • Proceedings of the KSRS Conference
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    • pp.1036-1038
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    • 2003
  • Diurnal variations in the atmospheric vapor at Banchiao of Taiwan are studied by analyzing 30 min-averaged data in the summer of 1998. The surface meteorological measurements were mainly obtained from the Central Weather Bureau (CWB) of Taiwan. It is found that precipitable water (PW) is increased in the afternoon. The maximum of precipitable water appears at around 0900 LST. The diurnal range of precipitable water is larger on the days with than without rainfall events. Rainfall events often occur in the afternoon and early morning. We also examine the difference in the characteristics of the PW signatures with and without rainfall according to the occurrence of the times for the rainfall peak and the onset of rainfall.

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Determination of Algerian Weighted Mean Temperature Model for forthcoming GNSS Meteorology Application in Algeria

  • Song, Dong-Seob;Boutiouta, Seddik
    • Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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    • v.30 no.6_2
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    • pp.615-622
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    • 2012
  • Since the accuracy of precipitable/integrated water vapor estimates from GNSS measurements is proportional to the accuracy of water vapor Weighted Mean Temperature Model (WMTM), the WMTM is a significant formulation in the retrieval of precipitable water vapor from zenith wet delay of GNSS signal. The purpose of this paper is to develop available the WMTM to apply for GNSS meteorology in the region of Algeria, by using the Algerian radiosonde network in the World Meteorological Organization (WMO). It can be concluded that the available GNSS precipitable water vapor which is retrieved by the developed Algerian Weighted Mean Temperature Equation (AWMTE) can be useful technique for sensing of water vapor in the Algeria, after Algerian Continuously Operating Reference System (CORS) will be constructed.

Analysis on Characteristics of Radiosonde Bias Using GPS Precipitable Water Vapor

  • Park, Chang-Geun;Baek, Jeong-Ho;Cho, Jung-Ho
    • Journal of Astronomy and Space Sciences
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    • v.27 no.3
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    • pp.213-220
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    • 2010
  • As an observation instrument of the longest record of tropospheric water vapor, radiosonde data provide upper-air pressure (geopotential height), temperature, humidity and wind. However, the data have some well-known elements related to inaccuracy. In this article, radiosonde precipitable water vapor (PWV) at Sokcho observatory was compared with global positioning system (GPS) PWV during each summertime of year 2007 and 2008 and the biases were calculated. As a result, the mean bias showed negative values regardless of the rainfall occurrence. In addition, on the basis of GPS PWV, the maximum root mean square error (RMSE) was 5.67 mm over the radiosonde PWV.

ESTIMATING NEAR REAL TIME PRECIPITABLE WATER FROM SHORT BASELINE GPS OBSERVATIONS

  • Yang, Den-Ring;Liou, Yuei-An;Tseng, Pei-Li
    • Proceedings of the KSRS Conference
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    • pp.410-413
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    • 2007
  • Water vapor in the atmosphere is an influential factor of the hydrosphere cycle, which exchanges heat through phase change and is essential to precipitation. Because of its significance in altering weather, the estimation of water vapor amount and distribution is crucial to determine the precision of the weather forecasting and the understanding of regional/local climate. It is shown that it is reliable to measure precipitable water (PW) using long baseline (500-2000km) GPS observations. However, it becomes infeasible to derive absolute PW from GPS observations in Taiwan due to geometric limitation of relatively short-baseline network. In this study, a method of deriving Near-Real-Time PW from short baseline GPS observations is proposed. This method uses a reference station to derive a regression model for wet delay, and to interpolate the difference of wet delay among stations. Then, the precipitable water is obtained by using a conversion factor derived from radiosondes. The method has been tested by using the reference station located on Mt. Ho-Hwan with eleven stations around Taiwan. The result indicates that short baseline GPS observations can be used to precisely estimate the precipitable water in near-real-time.

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Comparison of the Characteristics of Precipitable Water Vapor Measured by Global Positioning System and Microwave Radiometer

  • Sohn, Dong-Hyo;Park, Kwan-Dong;Won, Ji-Hye;Cho, Jung-Ho;Roh, Kyoung-Min
    • Journal of Astronomy and Space Sciences
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    • v.29 no.1
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    • pp.1-10
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    • 2012
  • In this study, global positioning system (GPS)-derived precipitable water vapor (PWV) and microwave radiometer (MWR)-measured integrated water vapor (IWV) were compared and their characteristics were analyzed. Comparing those two quantities for two years from August 2009, we found that GPS PWV estimates were larger than MWR IWV. The average difference over the entire test period was 1.1 mm and the standard deviation was 1.2 mm. When the discrepancies between GPS PWV and MWR IWV were analyzed depending on season, the average difference was 0.7 mm and 1.9 mm in the winter and summer months, respectively. Thus, the average difference was about 2.5 times larger in summer than that in winter. However, MWR IWV measurements in the winter months were over-estimated than those in the summer months as the water vapor content got larger. The results of the diurnal analysis showed that MWR IWV was underestimated in the daytime, showing a difference of 0.8 mm. In the early morning hours, MWR IWV has a tendency to be over-estimated, with a difference of 1.3 mm with respect to GPS PWV.

Analysis of Temporal and Spatial Variation of Precipitable Water Vapor According to Path of Typhoon EWINIAR using GPS Permanent Stations

  • Won, Jihye;Kim, Dusik
    • Journal of Positioning, Navigation, and Timing
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    • v.4 no.2
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    • pp.87-95
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    • 2015
  • In this study, the temporal and spatial variation in precipitable water vapor (PWV) was analyzed for typhoon Ewiniar which had made landfall in the Korean peninsula in 2006. To make a contour map of PWV, zenith total delay (ZTD) was calculated using about 60 GPS permanent stations in Korea, and the pressure and temperature data of nearby AWS stations were interpolated and applied to the equation for calculating the PWV. While Typhoon Ewiniar was migrating north from the southern coast to the eastern coast of Korea, the PWV migrated showing a spatial distribution similar to that of rainfall. Also, the fluctuating pattern of the normalized PWV was analyzed, and the moving speed of the PWV was estimated using the delay time of the increase/decrease pattern in the eight-test stations. The result indicated that the moving speed of the PWV was about 35 km/h, which was similar to the average moving speed of the typhoon (38.9 km/h).