Current research issues. Philippe Bougeault, Météo France

Transcription

1 Current research issues for short range NWP Philippe Bougeault, Météo France

2 The expectations from government and society as seen from Météo France Improve the accuracy of short range forecasts for security of people and properties, health, transport, defense and the energy market Intense rainfall and flash floods Severe windgusts Visibility (in visible wavelengths but also inrared) Risks of coastal submersion Snowfalls and snow at ground Health threats from air quality Develop climate services, ie improve seasonal prediction and assess decadal prediction Frequency and severity of heat waves and droughts Sea level changes Expertise in geo engineering

3 Current forecast models at Météo France ARPEGE Resolution 10km Forecasts to 3-4 days AROME Résolution 2,5km Forecasts to 30 hours

4 Increasing success in QPF Yellow > 20mm in 24h

5 Example of poor QPF: A recent disaster in south-east France: Draguignan, 15 juin 2010 (convective cluster) Forecast rainfall Arome 15/06/2010 0TU Observed Rainfall over 24h (15-16 juin) Forecast rainfall Arome 15/06/2010 6TU

6 Fog forecast by AROME

7 Trends for NWP systems Integrated NWP systems (for efficiency) nowcasting, short range, medium range, monthly, seasonal and decadal should be part of an integrated set of codes Seamless forecasts (more easy to explain to users) transition smoothly from on time range to the next Continued trend in increased resolution global grid <10km, regional grid < 500m expected in 2020 Generalization of ensembles Ensembles of impact models Towards the end of the «deterministic forecasts»?

8 Model dynamics Revisiting the basic equations for nonhydrostatic dynamics More scalable dynamical cores, optimizing the data flux between processors More «local» discretization methods, Possibly giving up the SI SL and the spectral approach (???) Towards unstructured grids to better represent steep orography (like in ocean models)

9 New compute grids in the future? The «Yin-Yang» grid (Met Office) The «icosaédral» grid (DWD-MPI)

10 Model physics Towards more conservative variables Marquet s «entropic potential temperature»θs More advanced microphysics two moment schemes will become the minimum complexity for a microphysics scheme Accounting for horizontal exchanges by turbulence and radiation for grid cells < 1km Parametrization of convection remains a difficult problem for grid cells > 5km More «grey zone» problems as the integrated forecasts systems will be used at various resolutions

11 New coupling requirements (Earth system) Coupling with atmospheric composition MACC project as a forerunner Aerosols first for cloud/aerosol interactions, fog forecasts, then ozone, CO2, etc More requirements in mass conservation Coupling with continental surfaces Emergence of tiled surface models as independant (complex) systems, coupled to the atmosphere, and in need of their own data assimilation Need for more realistic representations of urban surfaces and boundary layers Coupling with the ocean and the sea ice Also increasingly for short range NWP Possibly with an explicit description of the ocean waves

12 Sand and dust storm in Feb 2000

13 The Eyjafjoll volcano plume (April 2010)

14 Californian wildfires in October 2002

15 Data assimilation techniques Evolution driven by both progress in science and constraints from massively parallel machine architectures Increasingly hybrid methods (ensemblesvariational) 4D EN VAR now explored in several centres Avoids the need for TL and AD models Requires more storage of data

16 New observations: High spectral resolution IR sounders on geostationnary satellites (MTG in 2020) Space wind lidars (Aeolus in 2015) Advanced usage of met radars Doppler, polarimetry, refractivity More international exchange of radar data Towards radars/wind farms cohabitation, specific issues to explore New types of observations Surface wind lidars, Mode S aircraft data, opportunity data from telecom networks, etc.

17 Les satellites d observation de la Terre Source: WMO

18 Number of observations assimilated at Météo France SEVIRI IASI ATOVS SCAT AIRS GPS

19 Data information content for various types of observing systems (degree of freedom per signal method) IASI Radiosondes airplanes 19

20 ESA Aeolus mission will provide first ever wind measurements from space Doppler lidar from 2016

21 Trends for Ensembles Work on improving description of model uncertainty Improve link between deterministic and stochastic physics Develop suitable verification techniques Couple atmospheric ensemble with impact models Hydrology (flood ensemble forecasts), ocean waves, air quality (MACC regional ensemble), accidental pollution, etc..

22 The future AROME ensemble at Météo France Typical exemple from the HYMEX field campaign where forecast ressemble reality but with phase error mm Deterministic forecast of rainfall Reality (radar+raingauges) quantile 92% of the ensemble (antilope)

23 Hydrological model ensemble for fast flood risk Ensemble AROME Ensemble ISBA-TOPMODEL Thèse B. Vié Thèse B. Vincendon

24 Verification techniques Classic NWP scores are saturating at 24 48h forecast ranges High resolution requires probabilistic approach to verification The development of ensemble requires more effort in ensemble verification techniques

25 Upstream research Observation techniques Drones (UAV), integrated profiling systems, turbulence profiling from doppler lidars Field campaigns Mediterranean (HYMEX, CHARMEX, etc ) Atlantic (T Nawdex) Arctic campaigns Urban surface energy budget and structure of the urban boundary layer

26 Research satellites: example of Aqua Train (now) and EarthCare (soon)

27 Thank you!