Operational Rain Assimilation at ECMWF

Transcription

1 Operational Rain Assimilation at ECMWF Peter Bauer Philippe Lopez, Angela Benedetti, Deborah Salmond, Sami Saarinen, Marine Bonazzola Presented by Arthur Hou

2 Implementation* SSM/I TB s 1D+4D-Var Assimilation: Scan-bias correction Interpolation to model grid Air-mass bias correction Pre-screening 1D-Var Observation operator: Lin. Large-scale condensation Lin. Convection RTTOV-SCATT Post-screening TCWV-observation 4D-Var 1D-Var with SSM/I radiance observations inside clouds+precipitation + 4D-Var with TCWV retrievals from 1D-Var inside clouds+precipitation = ~4,/8, 1D-Var s per 6/12-hour assimilation window (~% of 4D-Var computational cost) *Operational implementation with CY29R2 on June 28, 2

3 1-Day Mean TCWV FG-Departures

4 1-Day Mean TCWV AN-Departures

5 1-Day SSM/I Rain-affected Radiance Bias Monitoring 19.3 GHz (v) 8. GHz (v) 19.3 GHz (h) 8. GHz (h) GHz (v) 37. GHz (v) 37. GHz (h) Not corrected for bias Corrected for bias

6 Example of 1D-Var Profile Increments T q w R T q w R w S w L C w S w L C

7 Typhoon Matsa (4/8/2 UTC) Used SSM/I Clear-sky Channel 3 Used SSM/I 1D-Var (GMS IR, DMSP F13-1) (Courtesy G. Kelly)

8 Typhoon Matsa (4/8/2 UTC) TCWV FG-Departures (GMS IR, DMSP F13-1) (Courtesy G. Kelly)

9 TCWV / 9 hpa wind increments (4/8/2 UTC) ECMWF Analysis VT:Thursday 4 August 2 UTC Surface: mean sea level pressure ECMWF Analysis VT:Thursday 4 August 2 UTC Surface: **total column water vapour/hpa v-velocity L 2.m/s 2 H L H 1 1 H L 12 L 12 H L L 996 L L H -2 [%]

10 Mean Cloud Parameter Increments, 249 Experiment - Control 32 en92-en93 an, Param: q_ice :: / :: g/kg.4 9/ Ice water mixing ratio [g/kg] -13.W en92-en93 an, Param: C_Cov :: / :: 6 O S 4 O S 2 O S O 2 O N 4 O N 6 O N 6-13.W 6 O S 4 O S 2 O S O 2 O N 4 O N 6 O N % Cloud water mixing ratio [g/kg] Cloud cover [] en92-en93 an, Param: q_liq :: / :: 6-13.W 6 O S 4 O S 2 O S O 2 O N 4 O N 6 O N [%] g/kg

11 Mean 36h-12h Precipitation Difference, 249 Experiment - Control in mm [mm] [%] Northern Hemisphere: Southern Hemisphere: Europe: Asia: North America: Tropics: Northern Atlantic: Northern Pacific:

12 RMSE scores relative humidity: N. Hem. S. Hem. Tropics N. Pac. 1 hpa EXP: CY29R2 CNTRL: CY29R2 w/o rain ass. against own analysis! 8 hpa hpa 2 hpa score = RMSEEXP RMSE RMSE Worse Better CNTRL Error bars: 9% confidence level CNTRL

13 RMSE scores wind vector: N. Hem. S. Hem. Tropics N. Pac. 1 hpa EXP: CY29R2 CNTRL: CY29R2 w/o rain ass. against own analysis! 8 hpa hpa 2 hpa score = RMSEEXP RMSE RMSE Worse Better CNTRL Error bars: 9% confidence level CNTRL

14 FG-Departure RMSE s Dropsondes Caribbean 8-9/24 Temperature 8 hpa Vector wind 8 hpa Temperature 7 hpa Temperature 2 hpa Vector wind 7 hpa Vector wind 2 hpa w/o rain assimilation

15 Jason MW-Radiometer TCWV Retrieval: 28 JASON TCWV (KG/M2) Entries STATISTICS ENTRIES MEAN ECMWF MEAN JASON BIAS (JASON - ECMWF) STANDARD DEVIATION SCATTER INDEX CORRELATION SYMMETRIC SLOPE REGR. COEFFICIENT REGR. CONSTANT ECMWF AN TCWV (KG/M2) Figure 32.Comparison between JASON JMR and ECMWF (analysis) total column water vapour for August 2 (Global) 9 Entries STATISTICS 3 1 ENTRIES MEAN ECMWF 4 1 MEAN JASON BIAS (JASON - ECMWF) JASON TCWV (KG/M2) 3 1 CY29R1 O-suite STANDARD DEVIATION SCATTER INDEX CORRELATION SYMMETRIC SLOPE ECMWF AN TCWV (KG/M2) Figure 32.Comparison between JASON JMR and ECMWF (analysis) total column water vapour for August 2 (Global) CY29R2 E-suite REGR. COEFFICIENT REGR. CONSTANT (.3).982(.3) (. 92 ) (.3).9871(.3) (. 89 ) Bias: kg m -2 Std. dev.: kg m -2 Correlation:.9942 Adding Rain Assimilation Bias: -.94 kg m -2 Std. dev.: 1.66 kg m -2 Correlation:.9946 (Courtesy S. Abdalla)

16 TC Katrina Forecast 282 UTC + 96 Hours 1 FC 2/8/2/+96 EXP FC 2/8/2/+96 Thursday 2 August 2 UTC ECMWF Forecast t+96 VT: Monday 29 August 2 UTC Surface: **large scale precip/surf: mean sea level pressure/8hpa vorticity 9 W 8 W 7 W Thursday 2 August 2 UTC ECMWF Forecast t+96 VT: Monday 29 August 2 UTC Surface: **large scale precip/surf: mean sea level pressure/8hpa vorticity - 9 W W 7 W 1 Both forecast have similar location errors but rain assimilation produces deeper cyclone 14 2 N 2 N 9 W 8 W W ECMWF Analysis VT:Monday 29 August 2 UTC Surface: **mean sea level pressure/8hpa vorticity 14 9 W - 2 N 2 N 2 N 2 N 9 W 8 W 1 AN 2/8/29/ EXP AN 2/8/29/ ECMWF Analysis VT:Monday 29 August 2 UTC Surface: **mean sea level pressure/8hpa vorticity 14 9 W 14-8 W 7 W 2 N 2 N W 7 W W [mm] 9 W 8 W 7 W 9 W 8 W 7 W

17 TC Katrina Forecast 2826 UTC + 72 Hours 1 FC 2/8/26/+72 EXP FC 2/8/26/+72 Friday 26 August 2 UTC ECMWF Forecast t+72 VT: Monday 29 August 2 UTC Surface: **large scale precip/surf: mean sea level pressure/8hpa vorticity 9 W 8 W 7 W Friday 26 August 2 UTC ECMWF Forecast t+72 VT: Monday 29 August 2 UTC Surface: **large scale precip/surf: mean sea level pressure/8hpa vorticity 9 W 8 W 7 W Both forecast have similar location errors but rain assimilation produces deeper cyclone N 2 N 9 W 8 W W ECMWF Analysis VT:Monday 29 August 2 UTC Surface: **mean sea level pressure/8hpa vorticity 14 9 W N 2 N 9 W 8 W 1 AN 2/8/29/ EXP AN 2/8/29/ ECMWF Analysis VT:Monday 29 August 2 UTC Surface: **mean sea level pressure/8hpa vorticity 14 9 W 14-8 W 7 W 2 N 2 N N 2 N W 7 W W [mm] 9 W 8 W 7 W 9 W 8 W 7 W

18 TC Katrina GOES-12 IR Image Simulation: 2829 GOES-12 Simulated IR Imagery 2829, Experiment 1 GOES 12 First Infrared Band Monday 29 August 2 UTC GOES-12 Simulated IR Imagery 2829, Experiment eped Operations Observations Operations w/o rain assimilation (Courtesy M. Szyndel)

19 TC Katrina Dropsonde Departure Statistics: Radiosonde: Specific humidity exp: (12) TEMP-q Carib used q exp - ref STD.DEV Pressure (hpa) nobsexp BIAS background departure o-b(ref) background departure o-b analysis departure o-a(ref) analysis departure o-a Dropsonde: Windspeed Dropsonde: Temperature exp: (12) Drop-windspeed Carib used U exp - ref STD.DEV Pressure (hpa) nobsexp exp: (12) Drop-T Carib used T exp - ref STD.DEV Pressure (hpa) nobsexp background departure o-b(ref) background departure o-b analysis departure o-a(ref) analysis departure o-a BIAS OF SPEED BIAS background departure o-b(ref) background departure o-b analysis departure o-a(ref) analysis departure o-a CY29R2 w/o rain ass.: exp CY29R2: 1 Area: Friday 26 August 2 UTC ECMWF Forecast t+48 VT: Sunday 28 August 2 UTC Surface: **large scale precip/surf: mean sea level pressure/8hpa vorticity 9 W 8 W 7 W N 2 N W 8 W 7 W.1

20 Summary and Plans Assimilation of rain affected SSM/I radiances operational since June 2 with CY29R2 Main areas of technical research: - Improvement of the description of model background errors in precipitation - Improvement of the description of observation operator errors Main areas of impact research: - Precipitation forecast evaluation over Australia/Europe/US (gauge networks) - Precipitation forecast evaluation over US (NEXRAD) - Precipitation forecast evaluation over tropical oceans (TRMM PR) - More systematic analysis of tropical and extra-tropical cyclones forecasts Future developments: - Extension to land surfaces using sounder channels (+, 183± GHz): SSMIS - Direct assimilation of SSM/I (+) radiances in 4D-Var planned for 27