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Summary of OSE and OSSE Activities at ECMWF

This summary provides an overview of the OSE and OSSE activities conducted at ECMWF, including investigations into the complementarity of space-based and terrestrial observing systems, the impact of MetOP instruments, and the use of GPS Radio Occultation data. The findings highlight the significant contributions of various observational systems and their impact on forecast skill.

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Summary of OSE and OSSE Activities at ECMWF

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  1. A summary of OSE and OSSE activities at ECMWF.Erik Andersson, Graeme Kelly, Jean-Noël Thépaut, Gabor Radnoti, Peter Bauer and Sean HealyAcknowledgements:EUCOS, EUMETSAT, JCSDA/NCEP Three major sets of OSEs Investigating the complementarity between space based and terrestrial observing systems The impact of MetOP instruments Impact of GPS Radio Occultation data The Joint-OSSE, followed by Conclusions

  2. 1: The Space-Terrestrial StudyInitiated and funded by EUCOS. • BASELINE: all satellite observations currently used in NWP (radiances, cloud-drift winds, scatt winds) + GUAN R/S + GSN surface land data + buoys (no ship data) • BASELINE + aircraft data • BASELINE + non-GUAN R/S wind profiles • BASELINE + non-GUAN R/S wind and temp profiles • BASELINE + wind-profiler data • (iv) + aircraft data • BASELINE + non-GUAN R/S wind, temp and humidity profiles • CONTROL: the combined observing system • BASELINE + non-GUAN R/S temperature profiles (winter) • BASELINE + aircraft temperature data (winter)

  3. OSE assimilation system configuration • Resolutions: • Model resolution T511 (50 km), L60 • Analysis at T511/T159 L60, • 12-hour 4D-Var • Winter Experiments: • 20041204-00 to 20050125-12 (including 10 day warm up) • Model cycle 29R1 • Summer experiments: • 20050715-00 to 20050915-12 (including 10 day warm up) • Model cycle 29R2 • NOAA18 included (AMSU-A and MHS)

  4. Winter results: Baseline – Control (Z500)Impact of terrestrial, non-climate, observations NH EUR

  5. Control-Baseline (Z500)Normalised forecast error difference, Day-3

  6. Z scores: Impact of R/S 1000 hPa 500 hPa NH EUR

  7. Baseline – [ Baseline + aircraft]Z500 Impact of aircraft data NH EUR

  8. [Baseline + aircraft] - Baseline (Z500)Normalised forecast error difference FC+12h

  9. Z scores: Impact of aircraft 1000 hPa 500 hPa NH EUR

  10. Wind scores: Impact of aircraft 850 hPa 300 hPa NH EUR

  11. [(i) + R/S T+W] – [ (i) + R/S T+W + aircraft]Z500 Impact of aircraft in the presence of R/S NH EUR

  12. [(i) + R/S T+W + aircraft] – [(i) + R/S T+W] (Z500)Z500 Impact of aircraft in the presence of R/S

  13. [(i) + R/S T+W] – [ (i) + R/S T+W + aircraft]W300 Impact of aircraft in the presence of R/S NH EUR

  14. [(i) + aircraft] – [ (i) + R/S T+W + aircraft]W300 Impact of R/S in the presence of aircraft NH EUR

  15. [(i) + R/S T+W] – [ (i) + R/S T+W+Q]RH700 Impact of R/S humidity NH EUR

  16. EUCOS Space-Terrestrial, Conclusions (1) • Even in presence of satellite observations, degrading the current terrestrial Observing System has a significant negative impact on the forecast skill. • Starting from the degraded baseline (GUAN+GSN+…): • Additional R/S (T+Wind) and aircraft (T+Wind) contribute more or less equally to the Observing System (slight advantage for R/S) • These two Observing Systems are complementary • Aircraft add forecast skill to R/S • R/S add forecast skill to Aircraft

  17. EUCOS Space-Terrestrial, Conclusions (2) • R/S impact: • R/S winds contribute little on their own • Radiosonde T contribute marginally more • This is the combination of wind/T which really provides the impact of the RS on the forecast skill • Aircraft impact: • The results are consistent with that of R/S. Aircraft-T alone bring relatively little. Combination of T/Wind makes a big impact

  18. EUCOS Space-Terrestrial, Conclusions (3) • Humidity from R/S add very little in terms of scores • Noticeable but small impact on relative humidity scores up to day 3 • Impact of wind profilers: • Winter impact: • The short range forecasts are improved by the US and japanese profilers • The signal blurs away after day 4-5 and large scale interactions appear • European profilers do not bring much • In summer, the impact is smaller than during the winter period (in absolute but also relative terms)

  19. 2a: Assessment of the space component of the GOSInitiated and funded by EUMETSAT Winter period: 20041204-20050125, Summer period: 20050715-20050915 (cycle 29r1) • BASELINE all conventional observations used in NWP (radiosonde + aircraft + profiler network + surface land data + buoy observations + ship data) • REFERENCE= BASELINE + AMVs from GEO+MODIS • REFERENCE + HIRS radiances • REFERENCE + AMSUA radiances • REFERENCE + AMSUB radiances • REFERENCE + SSMI radiances • REFERENCE + GEO Clear Sky Radiances (CSRs) • REFERENCE + AIRS radiances • REFERENCE + SCAT winds • BASELINE + GEO AMVs (no MODIS)

  20. 2b: Assessment of the space component of the GOSInitiated and funded by EUMETSAT Winter period: 20061205-20070214 (31r1), Summer period: 20060601-20060815 (31r2) • BASELINE all conventional observations used in NWP (radiosonde + aircraft + profiler network + surface land data + buoy observations + ship data) • REFERENCE= BASELINE + AMSUA Noaa 16 • REFERENCE + AMVs from GEO+MODIS • REFERENCE + AMSUA radiances • REFERENCE + AMSUB radiances • REFERENCE + GEO Clear Sky Radiances (CSRs) • REFERENCE + AIRS radiances • REFERENCE + SCAT winds • CONTROL full operational system (all above observations)

  21. Average Z 500 anomaly correlation scoresThe AMV reference and the AMSU-A reference S.Hem N.Hem All AMVs ref All AMVs ref S.Hem N.Hem One AMSUA_ ref One AMSU_A ref

  22. Z500 impacts, S.Hem (REFERENCE_AMV) AMSU-B, SSMI, GEO_CSR HIRS, AMSU-A, AIRS Scat, GEO_AMV, GEO_CSR

  23. Relative Humidity 850hPa impacts, S.Hem (REFERENCE_AMV) AMSU-B, SSMI, GEO_CSR HIRS, AMSU-A, AIRS Scat, GEO_AMV, GEO_CSR

  24. AMSU-B, SSMI, GEO_CSR Vector wind 200 hPa impacts, S.Hem (REFERENCE_AMV) HIRS, AMSU-A, AIRS Scat, GEO_AMV, GEO_CSR

  25. Impact of removing MODIS from the REFERENCE_AMV

  26. Space component, Summary • Very encouraging that all the space base sensors contribute in a positive way to the overall performance of the ECMWF forecast system. Sensors like AMSU-A, AIRS and HIRS are the most important. • The humidity analysis requires AMSUB (also MHS), GEO CSRs and SSMI. • Amongst the wind data, SCAT has a clear positive impact on the surface wind in the Southern Hemisphere, and a clear beneficial impact of AMVs and MODIS winds has been demonstrated.

  27. 3: OSEs for the evaluation of degraded EPS/Post-EPS instrument scenarios (EUMETSAT) The objective is to assess the detrimental impact of potential loss of the main EUMETSAT Polar System (EPS) instruments on global NWP. • REFERENCE: All conventional data + 2*AMSU-A, 2* DMSP, AIRS and IASI, ASCAT and QuikSCAT. • REFERENCE – HIRS • REFERENCE – AMSU • REFERENCE – MHS • REFERENCE – SOUNDERS • REFERENCE – IASI • REFERENCE – ASCAT • REFERENCE – METOP

  28. METOP forecast impact 500 hPa geopotential height RMS error difference when METOP data withdrawn T+12 hours T+24 hours [%/100]

  29. Preliminary results on Metop (ongoing study) • The fit to temperature-sounding instruments (e.g. NOAA-18 AMSU-A) is improved when Metop instruments are present. • The fit to moisture-sounding instruments (e.g. AIRS, MHS, GOES) is improved when Metop MHS, all Metop sounders or IASI are present • The presence of ASCAT data slightly improves the fit to QuikSCAT wind data, and products from Envisat and Jason altimeters • The synergy of Metop instruments produces a much stronger impact than its individual instruments

  30. GPS radio-occultation. Current 6-hour data coverage.

  31. December 2006: Assimilation of RO data at ECMWF All 6 satellites Wave-like bias disappeared

  32. GPSRO impact on Southern hemisphere geopotential height forecasts 6 COSMICs+CHAMP+GRACE-A (setting only, z > 5 km) – no GPSRO 1100 observations/day, 66 cases, winter 2006/2007, own analyses 1000 hPa 500 hPa 200 hPa 100 hPa (Sean Healy)

  33. GPSRO impact on Southern hemisphere geopotential height forecasts 6 COSMICs+CHAMP+GRACE-A (setting+rising, z > 5 km) – no GPSRO 1600 observations/day, 66 cases, winter 2006/2007, own analyses 1000 hPa 500 hPa 200 hPa 100 hPa (Sean Healy)

  34. Advanced infrared sounders: AIRS and IASI AIRS • Operational at ECMWF since October 2003. • 324 channels received in NRT. • One FOV in nine used. • Up to 155 channels may be assimilated (CO2 and H2O bands). IASI • Operational at ECMWF since June 2007. • 8461 channels received in NRT. • All FOVS received; only 1-in-4 used. • 366 Channels routinely monitored. • Up to 168 channels may be assimilated (CO2 band only).

  35. IASI forecast impact 500 hPa geopotential anomaly correlation (56 cases, spring 2007, normalized RMSE difference, own analysis) IASI better NH IASI worse Mean error difference uncertainty IASI better SH IASI worse

  36. Choosing 10 IASI Water Vapour Channels

  37. Fit to other observations Best value at 1.5K Normalized Analysis Departure Std. Dev. Increasing assumed IASI H2O channels’ error ∞

  38. The Joint OSSE Nature Run • Collaboration with NCEP (Michiko Masutani) to plan, produce, deliver and evaluate the NR. Consultation with the Joint-OSSE group in the US, EUCOS, ESA, EUMETSAT and ECMWF • T511 NR: 13 months T511/L91. • Data set size ~2.5 Tbyte. Shipping to the US on 4 disks • Yearly, quarterly and monthly comparison with climate and observations = 831 plots. Posted on NCEP web site • Extensive evaluation of the NR by US partners • T799 NR: Two 6-week periods have been run at T799/L91 with hourly post processing: TC-season, Convective season

  39. Nature Run, 12-month total cloud cover

  40. Nature Run, 12-month total cloud cover, difference with respect to MODIS observations

  41. Comparison of extra-tropical cyclones in the NR against cyclones in the NCEP analyses for 5 recent years (green bars), showing central pressure (hPa, left) and life span (days, right panel). Courtesy Joe Terry (NASA).

  42. OSEs and OSSE activities at ECMWFConclusions • Space-terrestrial study (EUCOS) completed • Assessment of space-component of the GOS (EUMETSAT) completed • Assessment of Metop impact (EUMETSAT) is ongoing • Comprehensive reports are available • ECMWF Newsletter No 113, page 16-28 (Kelly and Thépaut) • Metop-IASI and GPS-RO constitute significant new additions to the GOS • Joint-OSSE framework being developed, attracting a lot of interest, generating wide-spread collaboration

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