World Meteorological Organization Working together in weather, climate and water Report from the Fifth WMO Workshop on the Impact of Various Observing Systems on NWP Sedona, May WMO Lars Peter Riishojgaard Chair, OPAG-IOS, WMO Commission for Basic Systems Lidar Working Group, Boulder, Oct

Overview WMO context –RRR, WMO Impact Workshops, role of NWP Impact Studies Sample results from Fifth WMO Impact Workshop Select key conclusions from Sedona October 16-17, Lidar Working Group, Boulder CO

RRR in WMO Rolling Review of Requirements is the process for developing WMO guidance on performance versus requirements for observing systems Within the WMO Structure, CBS/OPAG-IOS has overall responsibility of the RRR –ET-EGOS Application Area (12) Points of Contact Rapporteur on Scientific Evaluation of Impact Studies by NWP Centers Ad hoc interfaces to other TC’s and their Expert Teams –Other OPAG-IOS Expert Teams –WMO Impact Workshops October 16-17, Lidar Working Group, Boulder CO

WMO Workshops on the Impact of Various Observing Systems on NWP Five Workshops held so far: 1 st - Geneva, nd – Toulouse, rd – Alpbach, th – Geneva, Workshop Report available on 5 th – Sedona (AZ, USA), May Workshop Report will be available late Oct 2012, presentations are on Workshops aim to bring together major NWP centers and representatives from the research community to discuss the contribution to forecast skill of various elements of the global observing system; guidance to participants provided well in advance of Workshop itself. October 16-17, Lidar Working Group, Boulder CO

Fifth WMO NWP Impact Workshop, Sedona, May CBS Ext (10) in Namibia: US extended an invitation to host the 5th WMO Impact Workshop in 2012 –Erik Andersson (ECMWF), R-SEIS, SOC –Lars Peter Riishojgaard (JCSDA), CBS OPAG-IOS Chair, LOC October 16-17, 2012Lidar Working Group, Boulder CO5

Scientific Organizing Committee Erik Andersson, ECMWF, (Chair), (R-SEIS) Carla Cardinali, ECMWF (THORPEX) John Eyre, Met Office UK (CBS/ET-EGOS) Ron Gelaro, NASA/GSFC (THORPEX) Miroslav Ondras, WMO Secretariat Florence Rabier, Meteo-France (THORPEX) Lars Peter Riishojgaard, JCSDA (CBS/OPAG-IOS) Yoshiaki Sato, JMA (R-SEIS) Workshop funding provided by WMO (OBS and THORPEX), NASA and NOAA (GOES-R Program Office)

Sedona in brief The largest WMO Impact Workshop so far: –3½ days –59 participants from 13 countries –40 presentations distributed in three sessions Ample discussion time during and after the sessions Very broad attendance from NWP community Space agencies and other NWP and observing system managers also represented –They are keenly aware of the power of NWP diagnostics as aids for decision making October 16-17, 2012Lidar Working Group, Boulder CO7

Role of NWP diagnostics NWP is a foundational activity for most weather and climate applications Objective, quantitative metrics: –NWP poses a well-defined prediction problem with a “right” answer (and an infinity of wrong ones) –Well-defined measures for quality of output –Well-established methodologies for assigning merit (or blame) to individual observing systems October 16-17, 2012Lidar Working Group, Boulder CO8

NWP Diagnostics (I), OSE OSEs (Observing System Experiments) are based on data denial (or addition): –1. Run a control with operational data –2. Add (or subtract) data to be tested –3. Compare Impact focuses on the medium to long range Results show the impact of withdrawing (or adding) certain data Absolute metric (score of perfect forecast has a known value) October 16-17, 2012Lidar Working Group, Boulder CO9 Jung et al., WMO Impact Workshop in Sedona, May 2012

NWP Diagnostics (II), FSO FSO (Forecast Sensitivity to Observations) are based on the adjoint of the model/analysis system or an ensemble approach Approach focuses exclusively on the short (quasi-linear) range Results show the impact of observations in the presence of all other observations Relative metric (numerical value not meaningful by itself) October 16-17, 2012Lidar Working Group, Boulder CO10 Gelaro et al, Fifth WMO Impact Workshop, Sedona 2012

1. Satellite data October 16-17, 2012Lidar Working Group, Boulder CO11

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ATOVS AIRSSCAT IASI GPS-RO SEVIRI 2010 SSMI Monthly number of observations used in the global model SSMI/S 2011 WMO Workshop on the Impact of Various Observing Systems on NWP Sedona – May

Forecast impact experiment from Dec to Jan Impact Impact / Obs. number WMO Workshop on the Impact of Various Observing Systems on NWP Sedona – May 2012 AMSU-A

15 FNMOC and GMAO Observation Impact Monitoring Current Operations much larger relative impact of AMVs in Navy system ms/fp/obs_impact/ _main_od.html Gelaro et al., Sedona May 2012 October 16-17, 2012Lidar Working Group, Boulder CO GMAO: AMSU-A

16 Northern Hemisphere Southern Hemisphere Lidar Working Group, Boulder CO Jung, 5 th WMO Impact Workshop, Sedona 2012 No Satellite / No Conventional Data (JCSDA w/ NCEP GFS) October 16-17, 2012 Strong impact of satellite data overall in both hemispheres

17 No AMSU-A / No MHS Northern Hemisphere Southern Hemisphere Lidar Working Group, Boulder CO Jung, 5 th WMO Impact Workshop, Sedona 2012 October 16-17, 2012

18 No RAOBs / No Aircraft Northern Hemisphere Southern Hemisphere Lidar Working Group, Boulder CO Jung, 5 th WMO Impact Workshop, Sedona 2012 October 16-17, 2012 Strongest signal of any individual GOS component!

2. Reemergence of the importance of conventional observations October 16-17, 2012Lidar Working Group, Boulder CO 19

Lidar Working Group, Boulder CO 20 October 16-17, 2012

AMDAR coverage (6-hour period ) October 16-17, 2012Lidar Working Group, Boulder CO 21

Impact summary 5/22/20125th WMO Workshop on the Impact of Various Observing Systems on NWP (Sedona, AZ, USA) 22 Total impactsImpacts per 1 obs All observation types have positive impacts on average. For the total impact, 1: aircraft, 2: AMSU-A, 3: radiosonde, 4: IASI, 5: GPSRO For impact per 1 obs., 1: radiosonde, 2: GPSRO, 3: aircraft, 4: Scatterometer wind, 5: marine surface observation Forecast error reduction Winds Ensemble-based FSO diagnostics, NCEP GFS, Ota et al., WMO, Sedona, May 2012

Radiosonde and aircraft 5/22/20125th WMO Workshop on the Impact of Various Observing Systems on NWP (Sedona, AZ, USA) hPa hPa hPa hPa

Radiosonde and aircraft 5/22/20125th WMO Workshop on the Impact of Various Observing Systems on NWP (Sedona, AZ, USA) 24 Radiosonde Aircraft Radiosonde observations on mid- to lower troposphere have larger impacts compared to the aircraft observations. RAOBs: Mid- to lower troposphere; as expected based on sensitive structures Aircraft: Upper troposphere; this is where we have data!

Radiosonde impacts 5/22/20125th WMO Workshop on the Impact of Various Observing Systems on NWP (Sedona, AZ, USA) 25 Total impacts of radiosonde (12UTC October 21 to 06UTC October 28) Most observations have positive impacts on average Relatively large impacts for East Asia, Western US, Canada, and South America.

Aircraft impacts 5/22/20125th WMO Workshop on the Impact of Various Observing Systems on NWP (Sedona, AZ, USA) 26 Total impacts, moist total energyImpacts per 1 obs ( hPa) Aircraft observations over US, Europe and East Asia have large positive impacts. The impact of aircraft observations is extremely large over US, however impact per 1 observation is small.

300mb Wind Speed (2010) GFS / ECMWF Root-Mean Square of Analysis Differences: 300mb Wind Speed Note the very significant effect of in-situ wind observations: Radiosondes and Commercial Aircraft ms Langland and Maue 2011 Langland, Sedona 2012 October 16-17, 2012Lidar Working Group, Boulder CO 27

October 16-17, 2012Lidar Working Group, Boulder CO Some conclusions (with LWG implications)

© Crown copyright 2007 Conclusions (from presentation by John Eyre) Good progress on assimilation of IR sounder radiances cloud-affected and over land more progress expected implications for balance of observing system over land Dangers of “observation-free zones” in data assimilation examples: mesospheric temperature, upper tropospheric humidity GPS-ZTD - significant impact on forecasts of surface variables AMV and scatterometer impacts: Positive impact from all AMV types Polar AMV have more impact per ob, but fewer of them FSO statistics show which obs compensate when AMV/scatt denied Don’t forget the high latitudes!

ECMWF Slide 30 Observation impact in global NWP The highest ranked contributors for the forecast error reductions are:  AMSU-A, AIRS/IASI, radiosonde, aircraft, AMVs  GPS-RO also has substantial impact, but the data volume is declining approaching the end of COSMIC lifetime. Several satellite sensors contribute to forecast skill. There is not a single, dominating one  More complementarity is seen, compared to previous years.  The GOS has become more resilient, but this resilience is threatened by expected decline of the operational polar orbiting satellites  When one observation type is missing or removed the contribution of other systems tend to increase without fully compensating These are (or include) wind measurements! (slide shown by Erik Andersson, Workshop Chair, at EMS, September 2012)

ECMWF Slide 31 Workshop Recommendations Augment the profiling network e.g. by extending coverage of ascending and descending aircraft observations to regional airports There is a need to invest in enhanced wind observations in the tropics and over the oceans especially. Study observation impact that is more closely related to high-impact weather (including TCs) and service delivery to customers and forecast users Encouraged studies of impact per observing system or per observation linked to their cost Define appropriate impact metrics for  humidity and  regional NWP including precipitation and other surface weather elements (slide shown by Erik Andersson, Workshop Chair, at EMS, September 2012)

General Conclusions from the Fifth WMO Impact Workshop in Sedona, May 2012 Modern, 4-dimensional data assimilation methods (4D-VAR, ENKF) have led to greatly improved use of data, especially of –Asynoptic data (e.g. aircraft, satellite observations) –Observations with complex relationships between measured and model variables (satellite radiances, GPSRO, radar,…) Broad consensus about highest-ranking contributors to forecast skill, but not necessarily about their ranking order: –AMSU-A (microwave temperature sounder) –AIRS/IASI (hyper-spectral infrared sounders) –Radiosondes –Aircraft observations –Atmospheric motion vectors (feature tracking satellite winds) Investment in additional winds observations is a high priority October 16-17, 2012Lidar Working Group, Boulder CO 32