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Preliminary tests on the Cycle of Hourly Assimilation and Forecast system in Guangzhou

Preliminary tests on the Cycle of Hourly Assimilation and Forecast system in Guangzhou. WAN Qi-lin, CHEN Zi-tong, DING Wei-yu, HUANG Yan-yan Institute of the tropical and marine meteorology, CMA, Guangzhou. Outline. Motivation system introduce Some tests conclusions. Motivation.

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Preliminary tests on the Cycle of Hourly Assimilation and Forecast system in Guangzhou

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  1. Preliminary tests on the Cycle of Hourly Assimilation and Forecast system in Guangzhou WAN Qi-lin, CHEN Zi-tong, DING Wei-yu, HUANG Yan-yan Institute of the tropical and marine meteorology, CMA, Guangzhou

  2. Outline • Motivation • system introduce • Some tests • conclusions

  3. Motivation • How to make use of high frequent observation data for improving numerical analysis and forecast . • How to give a good support to nowcasting

  4. system introduce For short, the system is named as CFAF CHAF - The Cycle of Hourly Assimilation and Forecast based on Grapes - Global/ Regional Assimilation PrEdiction System

  5. Domain • Grid resolution:0.12° CHAF domain

  6. GRAPES-Model GRAPES-Var GRAPES_ MODEL GRAPES_ 3DVAR System flow chart Observation DATA background Cycle Pretreatment Increment interpolation Simple Cloud analysis Increment Digital Filter nudging Boundary (from coarse model) Operation Prediction

  7. The Case choosing to understand the basic character of CHAF • The case is about a typhoon , the typhoon is landing and tend to weaken. • At 12UTC, 13 August,2005, a typhoon have been landing at Guangdong Province. • In the simulation test, we chose 12UTC as initial time ,and have performed 24h forecast.

  8. The scheme of experiment--to check if the cycle would give birth to noise, and if the cycle would benefit to improve analysis filed. Test 1：The model run 24 hour, without cycle; Test 2：The model run 24 hour, with the cycle of hourly assimilation and forcast. The DFI window is six hour（-3，+3），and, the observation was not import。 Test 3： The model run 24 hour, with the cycle of hourly assimilation and forcast. The DFI window is six hour（-3，+3），and, the Sounding and surface observation was ingest。

  9. Test 1 –Control test

  10. Test1 Test2 Test 2 test3 test1 test2

  11. Test 3 Sounding Surface observation Surface observation

  12. Initial field_SLP12z 13AUG Cycle- test 3 observation Control Test

  13. SLP12H Forecast00z 14AUG Test 3 observation Test 1

  14. 500hPa Height12H forecast Test 3 observation Test 1

  15. 12H FORECAST Rainfall：6H Accum00z14AUG Test 3 observation Test 1

  16. conclusion • According to the result of the tests , we think that: the cycle of CHAF system did not arouse additional error evidently, the CHAF system must be capable of assimilation some high frequent observation.

  17. The tests to assimilate high frequent observation. Cloud-drift wind Airline observation ( AMDAR ) Calculated Cloud (Cloud analysis)

  18. Hourly asimilation of cloud-drift wind The Vector of cloud-drift wind on200hpa （2005-07-11 00：00~12：00UTC）

  19. The scheme of comparative experiment • Test 1 Analysis field at 12UTC Initial value 00UTC forecast Hourlr assimilate cloud-drift wind • Test 2 • Analysis field • at 12UTC • Initial value • 00 UTC forecast

  20. Height and Wind on 500hpa (analysis) a b • With cloud-drift wind • Without CDW c．Velocity difference between a and b d．NCEP analysis c d

  21. 24H precipitation（2005-7-11 12：00UTC~2005-7-12 12：00UTC） a b • a．With cloud-drift wind b．without c．Difference d．Real c d

  22. Test about Air report assimilation The observation distribution from Air report between 00－23UTC on 18 Jun. 2（left: time-height cross-section ; right: planform – look down） The three-dimensional distribution of Airline observation between 04－06UTC on 18 Jun.

  23. The comparative test of Air report assimilation Test2:1-h assimilation of Air report,and sounding,surf,ship 24hForecast 00Z18Jun 12Z18Jun 00Z18Jun 12Z18Jun 24h Forecast Test1:1-h assimilation of sounding,surf,ship

  24. The 24H precipitation Without With airline observ-ation Obs. Difference

  25. The 3km cloud at 2005082012UTC . The below pictures are thecomparing the calculated rain content and the reflection of radar

  26. The 5km cloud at 2005082012UTC . The below pictures are thecomparing the calculated rain content and the reflection of radar

  27. The nudging of analysis cloud has effect on 0-1h precipitation forecast With nudging cloud Without Obs. Difference

  28. The nudging of calculated cloud has effect on 1-2h precipitation forecast With nudging cloud Without Obs. Difference

  29. The case of Real time Running cycle obs Red－CYCLE;Green－operation；Black－observation 3day 2day 1day

  30. Summary • In the CHAF system, the cycle did not arouse additional error evidently. • The analysis and forecast can be improved by use of high frequent observation data. • The CHAF system would have a good future in application to nowcasting. But • More research must be done to improve the cloud analysis,3DVAR, cycle system flow, etc. • Farther, a long time running must be performed to inspect the CHAF system.

  31. The end, thank you !

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