Atmospheric Water Vapor Real-Time Monitoring System in Pearl- River-Delta Region Using GPS/GNSS 珠三角地区基于 GPS/GNSS 技术的大气水汽实时监测系统

Transcription

1 Atmospheric Water Vapor Real-Time Monitoring System in Pearl- River-Delta Region Using GPS/GNSS 珠三角地区基于 GPS/GNSS 技术的大气水汽实时监测系统 刘志赵 1 李敏 1,2 1 Department of Land Surveying & Geo-Informatics The Hong Kong Polytechnic University lszzliu@polyu.edu.hk 2 GNSS Research Center, Wuhan University 第八屆京港澳測繪技術交流會 香港理工大學, 2013 年 5 月 23 日至 24 日

2 李敏博士 was at Department of Land Surveying & Geo-Informatics The Hong Kong Polytechnic University now at GNSS Research Center Wuhan University

3 Acknowledgment This research is supported by the project 3D Water Vapor Tomographic Modeling by Assimilating Multiple Sensors to Support Extreme Weather Forecasting in Hong Kong and Mainland China funded by Hong Kong Research Grants Council (RGC) General Research Fund

4 Special Acknowledgment (1) Survey & Mapping Office (SMO), Lands Department, Hong Kong SAR (2) Hong Kong Observatory (HKO), Hong Kong SAR (3) Macau Cartography and Cadastre Bureau (DSCC), Macau SAR (4) Macau Meteorological and Geophysical Bureau, Macau SAR (5) Guangdong Meteorological Bureau, Guangdong Provincial Gov. (6) Shenzhen Meteorological Bureau, Shenzhen Municipal Gov. (7) Wuhan University

5 Outline Introduction PPP for Precipitable Water Vapor (PWV) estimation PWV Real-time Monitoring System (PWVRMS) in Pearl-River-Delta PWV Results Conclusion

6 China Precipitation Map Pearl-River-Delta Region Piao et al. (2010), Nature, Vol 467, doi:

7 Typhoons hit South China Frequently South China coastal area is one of the coastlines most frequently affected by Typhoons in the world In the past 50 years, 6.14 typhoons/year landing on the south China coast within 500 km of Hong Kong The Pearl-River-Delta (PRD) region probably is the most populated region and the most economically dynamic region in the world Hong Kong alone, has a population of 8 million, and visitors 48 million (48,615,113 to be exact) in

8 Typhoons hit South China Frequently Kai-Tak Typhoon (level 8) hit South China, August

9 Typhoons hit South China Frequently IMG_0384.jpg Vicente Typhoon (level 10) hit Hong Kong, July 23,

10 Outline Introduction PPP for Precipitable Water Vapor (PWV) estimation PWV Real-time Monitoring System (PWVRMS) in Pearl-River-Delta PWV Results Conclusion

11 Atmospheric Effect on GNSS Signals 11

12 Basic Principle of PWV Monitoring using GPS GNSS Signal Atmospheric Delay Ionospheric Delay Tropospheric Delay (ZTD) Hydrostatic Delay (ZHD) Wet Delay (ZWD) Precipitable Water Vapor (PWV) D trop = ZTD M ( E) = ZHD M ( E) + ZWD M ( E) ZHD PWV = Π ZWD ZWD

13 Comparison of PPP and DD Processing Strategies Precise Point positioning (PPP) Network using double differencing (DD) Advantages Work with one station Small NEQ CPU burden increases linearly with # of sites / parameters (e.g. ZTD every 15 min, estimation of gradients) Investigating site dependent effects Correlations between parameters of all stations are taken into account For small networks, no need of external products (precise data) Disadvantages NO correlations between stations Need external products (e.g. precise orbits & precise clocks) Does NOT work with single station; need multiple GPS stations Large NEQ CPU burden increases with number of iterations/parameters Software GIPSY EPOS Napeos PANDA GAMIT BERNESE

14 PWV Real Time Monitoring System (PWVRMS) GPS predicted orbit (From IGS/WHU) Real Time (RT) GPS satellite clock (estimated from IGS RT data streams) RT PWV for networks Framework of PWVRMS system

15 Introduction of PANDA PANDA : Positioning And Navigation Data Analyst To derive possible information from GNSS/SLR data in real-time and post-mission Developed at Wuhan University since 2001 PolyU has a strong collaboration with Wuhan University Current Applications POD of GNSS & GEO (COMPASS, GPS) POD of LEOs, CHAMP GRACE (Delft University), COSMIC (JiaoTong Uni. Taiwan) Huge Network (NEIS) PPP+Ambiguity-Fixing(GFZ, Nottingham Uni)..

16 PANDA System Structure

17 Real Time Applications by PANDA Input Real Time data Observation data stream GNSS products stream Output PPP Based Real-Time Products Real Time GPS orbits Real Time GPS Satellite Clock Offsets Real Time kinematic & static Precise Point Positioning

18 Outline Introduction PPP for Precipitable Water Vapor (PWV) estimation PWV Real-time Monitoring System (PWVRMS) in Pearl-River-Delta PWV Results Conclusion

19 GNSS Resources in PRD Region HKSatRef:12 stations,10 minutes by ftp PolyU:1 station, hourly by ftp MoSRef: 3 stations, hourly by ftp GuangDong CORS: 20 stations 1 second by streams

20 GNSS Resources in PRD Region Each station in Hong Kong network: o GPS/GLONASS Leica Rx o Meteorological sensor o Tilt sensor

21 GNSS Resources in PRD Region There are abundant GNSS resources in PRD region They are not fully utilized, e.g. the Macau s GNSS data were not used for GPS PWV production Hong Kong Observatory (HKO) recently utilizes Hong Kong s CORS network data for water vapor estimation based on traditional double difference (DD) algorithm. However, the derived water vapor accuracy is not great. The latency of computing water vapor data is also large. A better solution to integrate all the PRD region GNSS resources is needed. 21

22 GNSS Resources in PRD Region Since early 2012, PolyU Researchers started to develop a GPS precipitable water vapor realtime monitoring system (PWVRMS) based on Precise Point Positioning (PPP) technique. This PWVRMS system is developed using the PANDA software as a platform, but with modifications to suit for water vapor estimations. 22

23 PWVRMS -- A Close Collaboration We get free GPS data from: Since 26 March 2012, SatRef GPS Network data of Lands Department of HKSAR PolyU, at interval of 10 minutes Since 14 June 2012, MoSRef GPS Network data of Macao Cartography and Cadastre Bureau (DSCC) of Macao SAR PolyU, at interval of 60 minutes Since 15 July 2012, Guangdong GPS Network data Wuhan University (domestic GPS data can only be used domestically), at interval of 1 second We provide free PWV data to: Since 19 April 2012, PolyU Hong Kong Observatory (HKO) Since 24 May 2012, PolyU Macao Meteorological and Geophysical Bureau Since 08 June 2012, PolyU Shenzhen Meteorological Bureau Since 21 July 2012, PolyU Guangdong Meteorological Bureau We get high-rate PWV data for research.

24 Outline Introduction PPP for Precipitable Water Vapor (PWV) estimation PWV Real-time Monitoring System (PWVRMS) in Pearl-River-Delta PWV Results Conclusion

25 HKO PWV vs PolyU PWV (410-day dataset, both use radiosonde as reference) # of (unit:mm) Min Max Mean Std RMS data points HKSC_HKO HKST_HKO HKSC_PolyU HKST_PolyU PWV difference with Radiosonder (mm) PANDA HKO Day of Year 2011(day) HKSC PWV difference with Radiosonder (mm) PANDA HKO Day of Year 2011(day) HKST Data: ~ , 410 days

26 HKO PWV vs PolyU PWV (287-day dataset, both use radiosonde as reference) PWV difference with Radiosonde (mm) 20 Mean: 0.79 mm, STD: 1.65 mm, RMSE: 1.83 mm PPP Mean: 1.36 mm, STD: 3.56 mm, RMSE: 3.81 mm Double Difference DOY ( ) From to , 287 days.

27 3D Time series of GPS PWV in Hong Kong The 3D time series of GPS PWV is shown here. The 3D time series is computed based on the tomographic modeling.

28 Outline Introduction PPP for Precipitable Water Vapor (PWV) estimation PWV Real-time Monitoring System (PWVRMS) in Pearl-River-Delta PWV Results Conclusion

29 Conclusion This is the first GPS PPP-based Water Vapor Monitoring System in Pearl-River-Delta Region. It has been in successful continuous, 24/7 operation since 19 April We have demonstrated that monitoring PWV with PPP has many advantages: PWV results RMS error of ~2.0 mm, much smaller than ~4-5 mm error from DD solutions. Much faster & flexible than DD algorithm Bad data at one station will NOT affect the results of the whole network This PWVRMS system will utilize the Beidou signals once the current CORS networks are upgraded to Beidou-capable ones.

30 Conclusion Our future goal is to keep this system in operation permanently To support better weather forecasting in Pearl-River-Delta region To provide valuable scientific data for climate change research in Pearl-River- Delta region To provide valuable water vapor correction data for GPS, InSAR and other remote sensing satellites To further improve the PWV accuracy and reliability

31 Atmospheric Water Vapor Real-Time Monitoring System in Pearl- River-Delta Region Using GPS/GNSS 珠三角地区基于 GPS/GNSS 技术的大气水汽实时监测系统 刘志赵 1 李敏 1,2 1 Department of Land Surveying & Geo-Informatics The Hong Kong Polytechnic University lszzliu@polyu.edu.hk 2 GNSS Research Center, Wuhan University 第八屆京港澳測繪技術交流會 香港理工大學, 2013 年 5 月 23 日至 24 日

32 招聘博士生 / 博士后 欢迎有意到香港理工大学攻读 GPS 及大地测量相关方面的博士学位的申请者, 与刘志赵联系 现时, 博士生月奖学金 : 港币 1 万 4 千 2 百 / 月, 提供奖学金 36 个月 同时, 也欢迎博士后来香港工作 lszzliu@polyu.edu.hk 电话 : ( 办公室 ) 电话 : ( 手机 )