Transcript NWP and AMMA case studies J.-P. Lafore, F. Beucher, F. Pouponneau, F.

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
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1. Some NWP Scores
Extra-Tropics
(1/3)
Range
Europe Atlantic domain
Geopotential Z - RMS (m) @ 500 hPa
Always in progress!
Reduction of dispersion
1980
1990
2000
évaluation AERES 15-17 janvier 2008
2010
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1. Scores for Tropics: wind field V
Tropiques/RS (55) RMS of V (m/s) @ 250-850 hPa
@ 72h range (1995-2010)
72h
1995
72h
2005
range 1 to 10 days
V250
V250
2000
(2/3)
2010
V850
V850
• Wind RMS error against TEMP observations increases
fast with the forecast range at the same rate for all models
• 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!
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1. African Eaterly Waves scores for 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
EUMETSAT (28-30 June 2011)
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2008
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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
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2. Impact on quantitative prediction of precipitation over Africa (2/7)
CNTR: data from GTS
AMMA: from the AMMA database
Higher scores
for AMMABC
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
évaluation AERES 15-17 janvier 2008
Faccani et al, 2009
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2. Downstream impact
(3/7)
 Impact on geopotential at 500hPa, averaged over 45 days
 72hr forecasts: AMMABC vs PREAMMA
évaluation AERES 15-17 janvier 2008
Faccani et al, 2009
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2. AEW case study in 2006: Pre-Helene TS Torn (2010)
1.
(7/7)
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.
1.
2.
3.
PDF
Growing rate
PDF
Weak skill (<2 days)
Initial state
•
•
Wave: at early stage
mid-layer e: later
Better for CRM
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3.
Propagation
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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
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3. CRMs: precipitation distribution
(2/2)
Precipitation (latitude)
Different distributions of precipitation
• Meridional distribution
• Rain regimes:
ARPEGE
• 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)
Rain regimes contribution
to total precipitation
30th Conference on Hurricanes and Tropical Meteorology
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2012)
évaluation
AERES 15-17 janvier 2008
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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

MSG: aerosols - clouds
00UTC
Forecast in June 2011 during the
FENNEC experiment
– Good forecast skill of convective
dust storm
évaluation AERES 15-17 janvier 2008
Wind, Dust extinction @ surface
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Conclusion
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





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Poor NWP skill over Tropics and especially over Africa is as compared with extratropics
Due to large 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
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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
Regional
Committee
meeting
30th Conference onAfrican
Hurricanes
and Tropical
Meteorology
(15-20 April
2012)
8-10
May 2012,
Geneva,
Switzerland
évaluation
AERES
15-17
janvier 2008
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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
Regional
Committee
meeting
30th Conference onAfrican
Hurricanes
and Tropical
Meteorology
(15-20 April
2012)
8-10
May 2012,
Geneva,
Switzerland
évaluation
AERES
15-17
janvier 2008