Kashima Space Research Center, Communications Research Laboratory 2. Geodetic Observation Center, Geographical Survey Institute 3

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1 GPS Meteorology i Japa ICHIKAWA, R. 1, Hataaka, Y. 2, Maoji, N. 3, Shimada, S. 4, Yabuki, T. 5, Aoashi, K. 6, Noguchi, N. 6, Heki, K. 7, Naito, I. 7 1 Kashima Space Research Ceter, Commuicatios Research Laboratory 2 Geodetic Observatio Ceter, Geographical Survey Istitute 3 Numerical Predictio Divisio, Japa Meteorological Agecy 4 Natioal Res. Ist. for Earth Sciece ad Disaster Prevetio 5 Hydrographic Departmet of Japa, Maritime Safety Agecy 6 Meteorological Research Istitute, Japa Meteorological Agecy 7 Earth Rotatio Divisio, Natioal Astroomical Observatory Techical Workshop APT & APSG 1996 (TWAA96) December 10-12, 1996 Kashima, Japa

2 Motivatio Wet troposphere delay is crucial source of error for space geodesy (VLBI, GPS, I-SAR, Satellite Altimetry ad so o). Difficulty of accurate vertical positioig Necessity of high spatial ad temporal resolutio Water vapor plays a key role i meteorological pheomea. High spatial ad temporal variability Large latet heat associated with waterõs phase chages Isufficiet uderstadig for meso scale ad local scale pheomea (ex. heavy rai fall, severe storm, effects of topography, etc.)

3 Scheme of GPS Meteorology i Japa Geodesy GPS etwork Fmoitorig crustal deformatio Fmoitorig sea level chage Fetc. Water Vapor Noise Sigal Meteorology Numerical Weather Predictio (NWP) Fweather predictio Fresearch for severe weather Fetc. More accurate positioig PWV Wet Delay More accurate weather predictio Correctio of Wet Delay Water Vapor Iformatio Database Iitial coditio of NWP

4 Scheme of GPS Meteorology Groud-based Space-Based Busiger et al.(1996) ->

5 Outlie of Japaese Cooperative Study (1) Title "Establishmet of Water Vapor Iformatio Database by GPS Meteorology ad Its Applicatios to Numerical Weather Predictio, Geodetic Research ad Hydrology" is adopted to Feasibility Study i 1996 Japaese budget year, ad submitted to Sciece ad Techology Agecy (STA) of Japaese Govermet for five years cooperate study ( ). Characteristics Dese permaet GPS sites (891 sites i domestic by the ed of March, 1997) by GSI Dese umerical weather predictio model (grid size = 20 km, 36 vertical levels) by JMA GPS receivers as water vapor sesor Numerical predictio data for tropospheric delay correctio

6 Outlie of Japaese Cooperative Study (2) Goal Establishmet of Water Vapor Iformatio Database Cotets Evaluate of precipitable water vapor (PWV) by GPS measuremets Estimate ad evaluate GPS PWV ä Iclude GPS domestic campaigs Study o umerical predictio based o GPS PWV Observe GPS PWV i cotietal ad oceaic regio Study o improvemet of precisio of space geodesy Approach of tropospheric delay correctio usig umerical predictio data ä Iclude GPS domestic campaigs Revisio of GPS aalyzig software R&D of GPS water vapor iformatio database Developmet of rapid GPS aalyzig techique Developmet of GPS water vapor iformatio database Evaluatio by meteorological, geodetic, ad hydrological users

7 Japaese Cooperative Study Group Govermetal Istitutes Geographical Survey Istitute (GSI) Japa Meteorological Agecy (JMA) Hydrographic Departmet of Japa (HDJ) Nat. Res. Ist. for Earth Sc. Disaster Prevetio (NIED) Commuicatios Research Laboratory (CRL) Meteorological Research Istitute of JMA (MRI) Natioal Astroomical Observatory (NAO) Natioal Ist. of Agro-Evirometal Sciece Natioal Agriculture Research Ceter Uiversities Tohoku Uiversity Fukushima Uiversity Joetsu Uiversity of Educatio Tsukuba Uiversity Guma Uiversity Chiba Uiversity Earthquake Research Istitute, Uiversity of Tokyo Shizuoka Uiversity Nagoya Uiversity Disaster Prevetio Research Istitute, Kyoto Uiversity Radio Atmospheric Sciece Ceter, Kyoto Uiversity Kochi Uiversity Kyushu Uiversity Nagasaki Uiversity Kagoshima Uiversity

8 Prepared Proposals of Cooperative Study at CRL Evaluate PWV by GPS Ivestigatig temporal scale ad spatial dimesio of PWV Compariso PWV by GPS to WVR observatio Compariso GPS PWV to umerical predictio data R&D of correctio method for wet tropospheric delay based o the umerical predictio data Japaese domestic ad the Wester Pacific GPS etworks VLBI etwork Available data sets Japaese GPS data umerical predictio data of JMA

9 Objectives of GPS Met. at CRL R&D of KSP-VLBI as a water vapor sesor real-time R&D of ew method for correctig wet troposphere delay usig NWP data Ivestigatig ad cosiderig Azimuthal Asymmetry of Atmosphere Evaluatig availability of ew correctio method usig NWP data

10 Period July 8-14, 1996 VLBI Data Aalyses Data Aalysis Software: CALC VLBEST Source Coordiates: ICRF94 Site Coordiates: ITRF94 Atmospheric Delay: Saastamoie Model (Dry) + Estimatio with 3hrs. iterval (Wet) mappig fuctio: MTT mappig fuctio Earth Orietatio Parameters: EOP90C04 (daily IERS Bulleti values) GPS Data Aalysis Software: Berese 3.4 Ephemeris: CODE Site Coordiates: ITRF94 Atmospheric Delay : Saastamoie Model (Dry) + Estimatio with 3hrs. iterval (Wet) mappig fuctio: Saastamoie Model

11 KSP geodetic etwork The project to moitor regioal crustal deformatio i the Tokyo metropolita area by usig space geodetic techiques has bee started i 1993 by CRL. It is plaed that four statios surroudig Tokyo are equipped with both Very Log Baselie Iterferometry (VLBI) ad Satellite Laser Ragig (SLR) facilities. Daily routie geodetic VLBI/SLR observatios are performed i this etwork to detect precursory crustal movemet that may occur pre-seismically.

12 GPS ad VLBI Observatios at CRL Kogaei Kashima

13 0.1 Baselie Legth Kashima - Kogaei Baselie Legth (m) VLBI (L m) GPS (L m) 0 7/7/1996 7/9/1996 7/11/1996 7/13/1996 7/15/1996 TIME

14 0.03 Horizotal Compoet of Kogaei Site 0.05 North-South VLBI GPS East-West North-South Compoet (m) East-West Compoet (m) 0 VLBI GPS VLBI GPS /7/1996 7/11/1996 7/15/1996 DATE

15 Vertical Compoet of Kogaei Site 0.15 Vertical Compoet (m) VLBI GPS /7/1996 7/9/1996 7/11/1996 7/13/1996 7/15/1996 DATE

16 Typhoo (a) 7/8/96 12:00 JST (c) 7/10/96 12:00 JST (b) 7/9/96 12:00 JST (d) 7/11/96 9:00 JST

17 Surface Meteorology Surface Pressure of Water Vapor (hpa) Kashima Kogaei Temperature Kashima Water Vapor Pressure Kogaei /7/1996 7/9/1996 7/11/1996 7/13/1996 7/15/1996 TIME(JST) Temperature ( C) Pressure (hpa) Surface Pressure 980 Kashima Kogaei 970 7/7/1996 7/9/1996 7/11/1996 7/13/1996 7/15/1996 TIME(JST)

18 PWV estimated by GPS ad VLBI Precipitable Water Vapor (cm) Precipitable Water Vapor (cm) Tsukuba SONDE GPS 0 7/8/1996 7/12/1996 7/16/1996 TIME(JST) Exp.1 Exp.3 Exp.2 Exp.5 Kogaei Exp.6 Exp.7 Precipitable Water Vapor (cm) 2 Exp.4 VLBI GPS 0 7/8/1996 7/12/1996 7/16/1996 TIME(JST) Exp.1 Exp.2 Exp.3 Exp.5 Kashima Exp.6 Exp.7 2 VLBI Exp.4 GPS 0 7/8/1996 7/12/1996 7/16/1996 TIME(JST)

19 Precipitable Water Vapor (cm) PWV estimated by GPS ad VLBI Exp.1 Exp.2 Exp.3 Exp.4 Exp.5 0 7/8/1996 7/12/1996 (1 hour iterval) Kogaei Exp.6 VLBI GPS Exp.7 Exp.1 Exp.2 Exp.3 Exp.4 Exp.5 Kashima Exp.6 VLBI GPS Exp.7 7/8/1996 7/12/1996 7/16/1996 TIME(JST) TIME(JST)

20 Simulatio of Positioig Error due to Azimuthal Asymmetry of Wet Troposphere Delay Mi. Elev. = 15 (GPS) Mi. Elev. = 5 (VLBI) 500 km 500 km 300 km 100 km Tsukuba 300 km 100 km Tsukuba = 10 cm (cm)