1. IV WMO Impact Workshop 2008Alexander Cress Global impact studies at the Deutscher Wetterdienst (DWD) Alexander Cress, Reinhold Hess Detlef Pingel Andreas Rhodin Heinz Werner Bitzer German Weather Service, Offenbach am Main, Germany Email: Alexander.Cress@dwd.de Introduction Impact of satellite sounding data from ATOVS radiances Quality and impact of radio occultation data General impact of atmospheric motion vector winds Impact of MTSAT-1R AMV wind vectors Use of direct broadcasting MODIS winds Use and impact of scatterometer data (ASCAT) Summary and Outlook

2. Global Model GME Operational NWP Model of DWD gridpoint model, hexagonal triangular grid 40 km mesh size, 36870 grid points/layer 40 layers (hyprid, sigma/pressure) prognostic variables: p s, u, v, T, q v, q c, q i, o 3 intermitient data assimilation (OI, 3-hourly) -> 3DVAR (PSAS) system incremental digital filter initialization (P.Lynch) At 00 UTC and 12 UTC: forecasts for 174 hours At 18 UTC: forecasts for 48 hours IV WMO IMPACT WORKSHOP 2008 Alexander Cress

3. IV WMO IMPACT WORKSHOP 2008 Alexander Cress Assimilation of IFS Pseudo Temps Profiles of IFS/4D-Var Analyses (temperature, humidity and wind) as Temps for OI/GME use of humidity profiles only above 700 hPa Assimilation one time per day for 0 UTC into Main Analysis only Data Coverage (operational since Dec 17 2003)

4. IV WMO Impact Workshop 2008 Alexander Cress Use of Satellite Radiances (ATOVS) AMSU-A of NOAA 15, 16, 18 and AQUA (on top of pseudo-temps) METOP/AMSU-A in trial run 1D-Var retrievals assimilated by OI as SATEMS (geopotential thicknesses) (only 1D-Var analysis increments assimilated) Tuning of background and observation errors for 1D-Var Assimilation with reduced resolution (120km, previously 60 km) with neutral impact Use of IFS forecasts above GME model top (10 hPa) for RTTOV studies with statistical linear regression from stratospheric channels Direct Use of ATOVS radiances in 3D-VAR AIRS/IASI: monitoring, cloud detection, bias correction, trial runs, etc. available work deferred for personal resources

5. IV WMO Impact Workshop 2008 Alexander Cress Use of AMSU-A auf NOAA-15, 16, 18 und AQUA – since 5.7.2007

6. IV WMO Impact Workshop 2008 500 hPA ANOC, 0 UTC, for Routine, 4638 (Pseudo+1D-VAR) 1D-Var (with PT) further improves compared to Routine (with PT) for 0 UTC Alexander Cress

7. IV WMO Impact Workshop 2008 Improvement of GME forecasts with tuned error statistics: Red: old R and B, Blue: tuned R and B Tuning of Covariance Matrices B and R for 1D-Var Alexander Cress

8. IV WMO Impact Workshop 2008 Alexander Cress Anomaly correlation coefficient of geopotential height in 500 hPa 2007051400 – 2007053100 (18 forecasts)

9. IV WMO Impact Workshop 2008 Alexander Cress Anomaly correlationcoefficient for 500 hPa 2008030112 – 2008032612 (26 forecasts) NH SH

10. Use of AMSU-A Data from METOP Reinhold Hess DWD, Offenbach Offenbach, 2007

11. IV WMO Impact Workshop 2008 Alexander Cress Use of AMSU-A auf NOAA-15, 16, 18 und AQUA – since 5.7.2007

12. IV WMO Impact Workshop 2008 Alexander Cress Use of AMSU-A auf NOAA-15, 16, 18, AQUA und METOP-A (seit 21.11.07)

13. IV WMO Impact Workshop 2008 Alexander Cress Bias correction of Metop-1: Without Bias correction

14. IV WMO Impact Workshop 2008 Alexander Cress Bias correction of Metop-1: after Bugfix in scanangle correction

15. IV WMO Impact Workshop 2008 Alexander Cress Use of METOP: clear positive benefit of 500hPa ANOC in SH, minor impact for EUR at 00 UTC

16. IV WMO Impact Workshop 2008 Alexander Cress Use of METOP: small positive impact of the 500hPa ANOC in NH and EUR for 12 UTC

17. Parallelroutine: clear positive impact for all areas (00 UTC)

18. Measurement geometry of Radio Occultation Use of Radio Occultation data A electromagnetic signal, transmitted by a GPS satellite, is delayed due to the presence of free electrons in the ionosphere an the refractivity of the atmosphere The refractivity is directly linked to horizontal and vertical variation of temperature, pressure and water vapour The refraction of the GPS signal corresponds to a shift in its phase, recorded at the receiving LEO satellite. Additionally, the signal path undergoes a bending in the atmosphere, resulting in a bending angle Relative geometry of the GPS and LEO and the Earth changes during the occultation event, the signal path intersects the atmosphere vertically, thus providing a vertical profile of bending angle. Observation error can be derived from the signal-noise-ratio of the amplitude of the signal Observed quantity to be assimilated can be bending angle (DWD) or refractivity (Met Office) profiles Benefits: High vertical resolution, independence of cloud conditions, lack of fundamental biases, uniform global coverage

22. IV WMO Impact Workshop 2008Alexander Cress AMV Impact Experiment Following an initiative by Mary Forsythe and Lars Peter Riishojgaard Data denial experiment with 3DVAR No use of geostationary and polar AMV wind vectors Winter period (12 th Dez. 2007 – 12 th January 2008) 00 UTC and 12 UTC forecasts

23. IV WMO Impact Workshop 2008 Alexander Cress 00 UTC 12 UTC Anomaly correlation coefficient for the Geopotential Height in 500 hPa 20071212 - 20080112 Crtl Crtll without AMVs

24. IV WMO Impact Workshop 2008Alexander Cress RMSV Wind Vector in 200 hPa 2007121212 - 2008011212 NHSH TR Routine Routine without AMVs

25. IV WMO Impact Workshop 2008Alexander Cress Analysis and forecast impact of MTSAT-1R Usage extratropics over oceans; tropics over oceans and land IR between 1000 and 700 hPa and above 400 hPa QI > 85 WVcloudy above 400 hPa QI > 85 WVclear is not used VIS below 700 hPa QI > 85 FG check: asymmetric to remove negative OBS-FG bias Thinning: 1 wind per pre-defined thinning box (200 km;15 vertical layers). data selection by highest noFirst Guess QI in a box One month analysis and forecast experiment (June/July 2007)

26. IV WMO Impact Workshop 2008Alexander Cress OBS – FG Statistics for MTSAT-1R for July 2007 > 400 hPa QI > 80 IR WVcloudy

27. IV WMO IMPACT WORKSHOP 2008Alexander Cress Crtl Crtl plus MTSAT-1R Crtl Crtl plus MTSAT-1R Crtl Crtl plus MTSAT-1R NHSH EU Anomaly correlation coefficent Date: 2007060912 - 2007070912

28. IV WMO IMPACT WORKSHOP 2008Alexander Cress Direct Broadcast MODIS Winds Motivation and Usage MODIS polar winds are not available in time to be used in operational (main) run. Only available in update run Direct broadcasting winds from Tromso, McMurdo ~ 100 minutes earlier Provide only partial coverage and only Terra can be received in the NH At DWD, no MODIS winds could be used in the main runs. Using DB winds, some polar winds can be used also in the main run. Additionally, more polar winds can be used in the update cycle runs Monitoring results show same quality as conventional MODIS winds Experimental use of DB polar winds in the same way as conventional MODIS winds Experiment: 23 days in November 2007

29. IV WMO IMPACT WORKSHOP 2008Alexander Cress

30. Read SCATT (25 km BUFR data) Data from data base or file or ECMWF MARS System Pre SCATT - read in original Bufr - data selection within analyses time window - eliminates overlapping orbits - computes KNMI rain flag; data flaging - computes direction check; data flagging - computes bias correction - data selection based on quality control - thinning - output options: Bufr; netCDF, ascii OI - Analyses - (u/v) most likely wind - coded as Pseudo-Buoy (Bufr) 3DVAR - Analyses - (u/v) more than one wind - coded as Bufr/netCDF Offline Monitoring - colloc. with GME -FG/Ana - analyses of data quality Use of scatterometer data at DWD 10 m wind vectors (most likely wind) QuikScat and ASCAT Global and regional Use of multiple wind solutions (planned) Experiments with OI and 3DVAR IV WMO IMPACT WORKSHOP 2008 Alexander Cress

31. IV WMO IMPACT WORKSHOP 2008Alexander Cress Scatterometer Data Coverage 2008022500 +/- 1.5 H ASCAT (red) QuikScat (blue)

32. IV WMO IMPACT WORKSHOP 2008Alexander Cress

33. IV WMO IMPACT WORKSHOP 2008Alexander Cress Crtl Crtl plus ASCAT Crtl Crtl plus ASCAT Anomaly correlation coefficient for sea level pressure Period: 2007070812 – 2007080812 Northern Hemisphere Southern Hemisphere

34. IV WMO IMPACT Workshop 2008Alexander Cress ANOC Crtl Crtl plus ASCAT Time series of anomaly correlation coefficient for Europe Mean sea level pressure VV=72h Start of the forecasts 00 UTC

35. IV WMO Impact Workshop 2008Alexander Cress Summary I Satellite sounding data from TOVS radiances are most important data source AMSU-A radiance data from Metop A are very import for NWP in Europe AMV wind vectors are still a valuable observation source for NWP at DWD Quality information of the AMV’s are very important Positive impact of MODIS winds and MTSAT-1R after height assignment correction Direct broadcast MODIS winds very helpful to get polar winds into main forecast run (short cut-off)

36. IV WMO Impact Workshop 2008Alexander Cress Summary II ASCAT wind observations smaller bias than QuikScat. No bias correction Scatterometer data have positive impact of single analyses/forecast General small positive impact on forecast quality for both hemispheres predominantly on the Southern Hemisphere Small structures are difficult to analyses due to broad scale error correlation functions Radio occultation is a new and promising data source for NWP Bending angles are assimilated at DWD. Benefit: High vertical resolution, independence of cloud conditions, near uniform global coverage and lack of biases Impact on Southern Hemisphere half the impact of AMSU A radiances

37. IV WMO Impact Workshop 2008Alexander Cress Outlook 3D-VAR (PSAS) assimilation system will become operational in summer 2008 New computer platform at DWD (IBM -> NEC 9X) Use of AMSU-B and MHS sounding profiles Use of sounding profiles from the IASI instrument onboard of Metop Use of wind profiler and VAD winds (USA, Europe, Japan) New scatterometer from India (ISCAT) should become available Investigate the impact of AVHRR polar wind vectors and AMV wind vectors from the Chinese satellite Fenyun Use of lidar wind profiles from the ADM space mission of ESA