1. Application of GPS data on Severe Weather Forecasting To investigate correlation between PWV and VIL, and hence its role in lightning/damaging winds monitoring/nowcasting Summer Internship at the Hong Kong Observatory 2006 Law Ka Hei (CUHK/PHY/3) Supervisor: Linus Yeung

2. Motivation Project Goal  Use PWV for severe weather nowcasting PWV - Precipitable Water Vapor  Represent amount of water vapor in an atmospheric column VIL - Vertically Integrated Liquid  Represent amount of liquid water in an atmospheric column  Highly related to rainfall

3. Calculation of PWV GPS Signal Delay Ionospheric Delay Tropospheric Delay Hydrostatic Delay Wet Delay PWV

4. Selection of Data PWVPWV ErrorRaw Data Source Latest Best Accuracy Center 04a

5. Visualization Tool – Web PWV  http://openlab3/~swirls/2005.html http://openlab3/~swirls/2005.html VIL  http://openlab3/~swirls/vil.cgi?id=0507201200- hksl http://openlab3/~swirls/vil.cgi?id=0507201200- hksl Radar Image  http://openlab3/~swirls/radar_js.html http://openlab3/~swirls/radar_js.html

6. PWV Climatology

7. Mean

8. Standard Deviation

9. PWV before Rainstorm

10. Scatter Plot: VIL vs PWV

11. VIL vs PWV Time Change

13. Thank You Any Questions?