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NWP and AMMA case studies

NWP and AMMA case studies. J.-P. Lafore , F. Beucher, F. Pouponneau, F. Rabier, C. Faccani, N. Fourrié, F. Karbou, P. Moll, M. Nuret, J-L Redelsperger, J. Stein CNRM-GAME, Météo-France and CNRS, Toulouse, France With thanks to:

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NWP and AMMA case studies

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  1. NWP and AMMA case studies J.-P. Lafore, F. Beucher, F. Pouponneau, F. Rabier, C. Faccani, N. Fourrié, F. Karbou, P. Moll, M. Nuret, J-L Redelsperger, J. Stein CNRM-GAME, Météo-France and CNRS, Toulouse, France With thanks to: A. Agusti-Panareda, P. Bauer (ECMWF, Reading), O. Bock, P. Drobinski (IPSL/LMD and LATMOS, France), G. Berry, C. Thorncroft (SUNNY, US), W. Thiaw (NCEP, US), J. Heming (UKMET), R.D. Torn (NCAR, U. New York), J-B Ngamini (ASECNA, Senegal), Z. Mumba (ACMAD, Niger)… WWRP-THORPEX African Regional Committee meeting 8-10 May 2012, Geneva, Switzerland

  2. 1980 1990 2000 2010 1. Some NWP Scores Extra-Tropics (1/3) Range Europe Atlantic domain Geopotential Z - RMS (m) @ 500 hPa Always in progress! Reduction of dispersion évaluation AERES 15-17 janvier 2008

  3. V250 V850 • Wind RMS error against TEMP observations increases fast with the forecast range at the same rate for all models 1995 2005 2010 2000 1. Scores for Tropics: wind field V (2/3) Tropiques/RS (55) RMS of V (m/s) @ 250-850 hPa@ 72h range (1995-2010) range 1 to 10 days • Wind intensity is a more pertinent variable in the Tropics • Its RMS @72h is large ~5 m/s 850 hPa) and increases with altitude (~8 m/s 250 hPa) • Dispersion between models is ~1 to 2 m/s (850 to 250 hPa) • Progresses are slow! 72h V250 72h V850 évaluation AERES 15-17 janvier 2008

  4. EUMETSAT (28-30 June 2011) WMO RAI Dissemination Expert Group 2nd Meeting 1. African Eaterly Waves scoresfor 4 NWPs in 2007(3/3)Correlation coefficients as fct of the range of 700 hPa curvature vorticity at 3 longitudes • Weak forecast skill for AEWs ( 2 days) • Large dispersion between models for the Wave-Convection link and the variability Private communication by Gareth Berry et al. 2008 évaluation AERES 15-17 janvier 2008

  5. 2. AMMA opportunity (1/7) • AMMA-1 International project 2002-2012 (Redelsperger et al. 2006) http://amma-international.org/ • AMMA legacy: • Better understanding of the West African Monsoon • Observations of the WAM: improvement of the operational observation network (soundings…), GPS, driftsondes, surface conditions, satellite, research observations (lidar, radar, aircraft…) •  opportunity to evaluate NWP models and the impact of observations 30th Conference on Hurricanes and Tropical Meteorology (15-20 April 2012) évaluation AERES 15-17 janvier 2008

  6. 2. Impact on quantitative prediction of precipitation over Africa (2/7) Higher scores for AMMABC CNTR: data from GTS AMMA: from the AMMA database AMMABC: AMMA + bias correction PreAMMA: with a 2005 network NOAMMA: No Radiosonde data Lowest scores for NO AMMA • Positive impact of the assimilation of AMMA dataset • Very poor performances of NOAMMA • Best performance of AMMABC Faccani et al, 2009 évaluation AERES 15-17 janvier 2008

  7. 2. Downstream impact (3/7) • Impact on geopotential at 500hPa, averaged over 45 days • 72hr forecasts: AMMABC vs PREAMMA Faccani et al, 2009 évaluation AERES 15-17 janvier 2008

  8. 1. Rain, Curvature Vort. (mean, var) • Ensemble-Based (96 members) Sensitivity Analysis (EnKF) • WRF model (36-12-4 km) • Sensitivity to: initial state, convection schemes, resolution 2. Propagation PDF Growing rate PDF • Weak skill (<2 days) • Initial state • Wave: at early stage • mid-layer e: later • Better for CRM 3. 2. AEW case study in 2006: Pre-Helene TSTorn (2010)(7/7) évaluation AERES 15-17 janvier 2008

  9. 3. CRMs: AEWs - Convection (1/2) • AMMA well-documented case 23-29 July 2006 Barthe et al., 2010, Cuesta et al. 2010 • Monsoon surge + AEW + Convection Observations AROME (CRM @ 5 km) ARPEGE RR (mm/h) + Vm (m/s) • NWP at low resolution: Wrong diurnal cycle and AEW-convection coupling • High-resolution (CRM): Better representation of the AEW-convection link évaluation AERES 15-17 janvier 2008

  10. Rain regimes contribution to total precipitation 30th Conference on Hurricanes and Tropical Meteorology (15-20 April 2012) 3. CRMs: precipitation distribution (2/2) Precipitation (latitude) Different distributions of precipitation • Meridional distribution • Rain regimes: • ARPEGE: weak events are too frequent intense events are rare • CRM: distribution of events in better agreement with TRMM • QPF scores • improved for CRM • positive impact of data assimilation (AMSU-B) ARPEGE évaluation AERES 15-17 janvier 2008

  11. 00UTC Coupling with Dust • AROME (5 km) coupled with a dust module on a large domain • Evaluation on the March 2006 dust storm (Kocha et al 2011) • Positive feedback of dust on the cold surge intensity • Simulation of the whole June 2006 month • Diurnal cycle, dust lifted by convective wakes • Negetive feedback on the Heat Low • Forecast in June 2011 during the FENNEC experiment • Good forecast skill of convective dust storm Wind, Dust extinction @ surface MSG: aerosols - clouds évaluation AERES 15-17 janvier 2008

  12. Conclusion • Poor NWP skill over Tropics and especially over Africa is as compared with extra-tropics • Due tolarge Roosby Radius (non-balanced flow, except TC), to the lack of observations and to the key role played by the physics (dry and moist convection, surface, radiation, turbulence, aerosols…) • Nevertheless large scale thermodynamical and dynamical structures are rather well depicted and are very useful for forecasters. • Major progresses in recent years especially in the assimilation area (microwave data) and the dispersion between models decrease • Nevertheless the forecast skill of the water cycle and of precipitation progresses very slowly • CRMs (few km) improve drastically some aspects of forecasts relative to convection (life cycle, duration, propagation…), the diurnal cycle, dusts… • Need to improve the representation of convection (dry air issue for Africa) and its coupling with AEWs, surface, aerosols… • Intra-seasonal variability potential predictability to be exploited évaluation AERES 15-17 janvier 2008

  13. 30th Conference on Hurricanes and Tropical Meteorology (15-20 April 2012) Further work • Treatment of the Ougadougou flood case (2009) • Comparison of different CRMs: • COSMO (KIT, Germany) • AROME (Météo-France) • New metrics (MCS tracking…) • Ensemble simulations (COSMO) • Analysis at different scales (link with the ISV) • Predictability • Wave-convection link • Coupling with the surface WWRP-THORPEX African Regional Committee meeting 8-10 May 2012, Geneva, Switzerland évaluation AERES 15-17 janvier 2008

  14. 30th Conference on Hurricanes and Tropical Meteorology (15-20 April 2012) Some References Agustí-Panareda A, Beljaars A, Cardinali C, Genkova I, Thorncroft C. 2010a. Impact of assimilating AMMA soundings on ECMWF analyses and forecasts. Wea.Forecasting 25: 1142–1160. doi: 10.1175/2010WAF2222370.1. Andreas H. Fink et al., 2011: “Operational meteorology: observational networks, weather analysis and forecasting”. Atmospheric Science Letters, Volume : 12, Issue : 1, Special Issue : Sp. Iss. SI, Pages : 135-141. Doi : 10.1002/asl.324 Faccani C, Rabier F, Fourri´e N, Agust´ı-Panareda A, Karbou F, Moll P, Lafore JP, Nuret M, Hdidou FZ, Bock O. 2009. The impact of the AMMA radiosonde data on the French global assimilation and forecast system. Weather and Forecasting 24: 1268–1286. Karbou F, Rabier F, Lafore JP, Redelsperger JL, Bock O. 2010b. Global 4D-Var assimilation and forecast experiments using AMSU observations over land. Part II: impact of assimilating surface sensitive channels on the African Monsoon during AMMA. Weather and Forecasting 25: 20–36. Redelsperger J-L, Thorncroft CD, Diedhiou A, Lebel T, Parker DJ, Polcher J. 2006. African Monsoon Multidisciplinary Analysis: An international research project and field campaign. Bull. Am. Meteorol. Soc. 87: 1739–1746. Torn R. D. 2010: Ensemble-Based Sensitivity Analysis Applied to African Easterly Waves.. Weather and Forecasting 25: 20–61-78. doi: 10.1175/2009WAF2222255.1 WWRP-THORPEX African Regional Committee meeting 8-10 May 2012, Geneva, Switzerland évaluation AERES 15-17 janvier 2008

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