The role of GPS-RO at ECMWF"!!!! COSMIC Data Users Workshop!! 30 September 2014! ECMWF
WE ARE Intergovernmental organisation! 34 Member and Cooperating European states! 270 staff at ECMWF, in Reading, UK! ECMWF
SOME FACTS & FIGURES" Nearly 40 years old" 270 employees representing over 30 countries" 20 Member States, 14 Co-operating States" Annual budget of around $80m" Commercial licences in over 29 countries" Research partnerships with institutions worldwide" Over 40 million observations analysed every day" Twice daily forecasts produced for weather services" and businesses" ECMWF
Outline! Satellite data assimilated at ECMWF! Recent observing system experiments! Hurricane Sandy impact! Reanalysis applications! Impact of number of GPS-RO observations! COSMIC-2 polar: potential impact!
Metop
Example of 6-hourly satellite data coverage" LEO Sounders LEO Imagers Scatterometers GEO imagers Satellite Winds (AMVs) GPS Radio Occultation
Observing system experiments (OSEs) at ECMWF: for March to July 2014!
Observations Considered! All conven)onal (in situ) data All Satellite Data Microwave sounding radiances Infrared sounding radiances All GEO data (AMVs and radiances) GPS- RO bending angle data Microwave imager radiances ScaSerometer surface wind data CONV SAT MWS IRS GEO GPS MWI SCAT TEMP/AIRCRAFT/SYNOP/SHIP 7 x AMSUA, 1 x ATMS, 4 x MHS 2 x IASI, 1 x AIRS, 1 x HIRS 2 x GOES, 2 x METEOSAT, 1 x MTSAT, polar AMVs COSMIC, 2 x METOP- GRAS, GRACE- A 1 x TMI, 1 x SSM/IS 2 x ASCAT
Importance of SAT v CONV data in northern hemisphere! ½ day of skill gained!"
Importance of SAT v CONV data in southern hemisphere! 2 days of skill gained!"
Forecasts for day 3 Z500 for northern hemisphere! Calculate errors relative to the CONTROL, normalised by the CONTROL errors! NO SAT NO CONV NO MWI NO SCAT NO GEO NO GPS NO MWS CTRL NO IRS 0 5 10 15 20 25 NO IRS CTRL NO MWS NO GPS NO GEO NO SCAT NO MWI NO CONV NO SAT NO CONV NO MWS NO IRS NO GEO NO GPS NO MWI NO SCAT Series1-0.05 0 0.05 0.1 0.15 0.2 Forecast error (m)! Fractional errors!
Z500 NH 1 day! NO CONV NO MWS NO IRS NO GPS Series1 NO MWI NO GEO NO SCAT - 0.05 0 0.05 0.1 0.15 0.2 0.25 0.3
Z500 SH 1 day! NO CONV NO MWS NO GPS NO IRS Series1 NO MWI NO GEO NO SCAT - 0.02 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 0.18
Z500 NH day 6! NO CONV NO MWS NO IRS NO GEO Series1 NO SCAT NO MWI NO GPS - 0.04-0.02 0 0.02 0.04 0.06 0.08 0.1 0.12
Z500 SH day 6! NO MWS NO IRS NO GPS NO CONV Series1 NO GEO NO SCAT NO MWI - 0.06-0.04-0.02 0 0.02 0.04 0.06 0.08 0.1
Lower level humidity in the Tropics: a small impact!
24hr 850RH in the Tropics! NO MWI NO CONV NO SCAT NO GEO NO IRS NO GPS NO MWS NO GEO NO SCAT NO MWS NO CONV NO MWI NO GPS NO IRS 0 0.05 0.1 0.15 0.2 0.25
Upper level temperatures: a larger impact!
GPS-RO impact on temperature at 100mb in tropics!
Hurricane Sandy: very little impact!
Hurricane Sandy: day 5!
Reanalysis applications!
Consistency of two re-analyses since 2007 when GPS-RO data have been used Extratropical-mean temperatures: ERA-Interim and JRA-55 Values are relative to ERA-Interim means for 1981-2010!
Impact of the number of GPS-RO observations!
Reducing the ensemble spread " Saturation? EDA spread Number of GNSS RO profiles! Ensemble spread provides an estimate of the uncertainty of analyses and short-range forecasts.!! Compute ensemble spread as a function of (simulated) GNSS-RO number.!
Sensitivity to number GPS-RO profiles" Analysis of temperature at 100 hpa ~ 50 % of the impact of 128 000 profiles ~ 25 million bending angles per day today Large improvements up to 16000 profiles per day" Even with 32000 128000 profiles still improvements possible" " no evidence of impact saturating up to 128000 profiles"
Impact of COSMIC-2 polar on uncertainty in temperature analysis! COSMIC-2 EQ and POLAR! No RO! COSMIC-2 EQ! tropopause!
Improving ECMWF s use of GPS-RO! GPS-RO will be assimilated with a 2D operator in the next operational cycle (see talk tomorrow by Sean Healy)! We aim to improve the error covariance matrix used to assimilate RO data!
Conclusions! GPS-RO positive attributes:!! No bias correction needed! Good vertical resolution compared to sounders! Good for upper trop and stratospheric temperature! Some signal even for lower troposphere humidity! WMO 2025 Roadmap calls for at least 10,000 profiles and further profiles are beneficial even beyond 128,000 per day! Polar component of COSMIC-2: valuable in further reducing errors! Global observing system and operational NWP rely on free access to global observations!