1. The GPS RO impact study on 2007 typhoon track forecasting
Jhih-Ying Chen and Pay-Liam Lin
Institute of Atmospheric Physics
National Central University, Chung-Li, Taiwan

2. Outline Introduction 2007 typhoon season in Taiwan Experiment design
Results
Summary

3. Introduction
Recent years, there were many new kinds of observation. It can be used to improve the theoretical study, and numerical study.
In this study, we use GPS RO & GTS observed data to simulate 2007 typhoon season in Taiwan area.
Finally, we hope to see how the GPS RO data impact to simulate typhoon track.

4. 2007 typhoon season in Taiwan
In 2007, there were 3 strong typhoon attack taiwan area.
WHIPA
SEPAT
KOROSA

5. WHIPA
KOROSA
SEPAT

7. Experiment design WRF_V2.1.2 + WRVAR_2.1 1 Domain 301x253 (15km)
WSM5 (microphysics)
RRTM+Goddard SW (radiation)
YSU+NoAH LSM (PBL)
K-F (Cmulus)

8. WHIPA
SEPAT 15 26
GPS observation during Exp time
KOROSA 16

9. Results

10. GTS data have strong wind impact not only in low lavel (850hPa) but also upper level (200hPa). The wind speed change is about 5~6 m/s.
For the temperature, the chang is about 0.5 ~ 1 degree.

11. Assimilate GPS RO data have impact in upper level temperature field, but not change wind field too much.
The temperature change is about 0.4~1.6 degree.

12. 2007_TY_SEPAT 2007/08/14/12Z ~ 2007/08/17/12Z unit: km Blue: GPS
Red: CTRL 12 24 36 48 60 72
CTRL
120 52 95
122
160
152
GPS
148
118 45 23 35 30
unit: km

13. 2007_TY_SEPAT 2007/08/14/12Z ~ 2007/08/17/12Z unit: km Blue: GTS+GPS
Red: GTS 12 24 36 48 60 72
GTS 67 33 63 69
111
127
GTSGPS 26 94 70
unit: km

14. 2007_TY_WHIPA 2007/09/16/12Z ~ 2007/09/19/12Z unit: km Blue: GPS
Red: CTRL 12 24 36 48 60 72
CTRL 45
149
194
197
318
497
GPS 53
135 94
124
167
354
unit: km

15. 2007_TY_WHIPA 2007/09/16/12Z ~ 2007/09/19/12Z unit: km Blue: GTS+GPS
Red: GTS 12 24 36 48 60 72
GTS 49
157
227
213
321
449
GTSGPS 31
168
222
198
287
381
unit: km

16. 2007_TY_KOROSA 2007/10/05/12Z ~ 2007/10/08/12Z Blue: GPS Red: CTRL 1224 36 48 60 72
CTRL
128 34
183
168
207
171
OGPS
163 92 56 76 46

17. 2007_TY_KOROSA 2007/10/05/12Z ~ 2007/10/08/12Z unit: km Blue: GTS+GPS
Red: GTS 12 24 36 48 60 72
GTS
127 27
129
180
101
172
GTSGPS 35
156
155
135
191
unit: km

18. SEPAT 12 24 36 48 60 72
CTRL
120 52 95
122
160
152
GPS
148
118 45 23 35 30
GTS 67 33 63 69
111
127
GTSGPS 26 94 70
WHIPA
149
194
197
318
497 53
135
124
167
354 49
157
227
213
321
449 31
168
222
198
287
381
　KOROSA 88 93 79 73
131
217
107 40
153
189
115 89
146 17 91 98 71 58 38 42 99
unit: km

19. 　SEPAT 12 24 36 48 60 72
CTRL 58 18 49 46 90 71
GPS
114 44 77
120 87
GTS
121 53
131 73 95
134
GTSGPS 61
142
118
113
148
　WHIPA 88
169
310
539
634
128
165
289
486
562 63 75
270
255
340
390 52
112
273
260
392
381
KOROSA 34
183
168
207
171
163 92 56 76
127 27
129
180
101
172 35
156
155
135
191
unit: km

20. Summary
For all results, assimilate GPS RO data seems have postive impact to 2007 typhoon season track forecast.
After assimilate GPS RO data, the track forecast will be modifed and move to left. And the GPS RO data will have its effect after 24 hr simulation.
For 4 exp. (CTRL, GPS, GTS, GTS+GPS) shows that assimilate GTS data seems have different impact on typhoon track forecast.
For this project, GPS exp. is the best result.