An Overview of Data Assimilation aspects in HyMeX*

THORPEX DAOS WG5, Exeter, June 2011Y. Michel (Météo-France, CNRM-GAME) and coauthors

Elaborated from documents available on the HyMeX website

http://www.hymex.org/Email: hymex@cnrm.meteo.fr

*Hydrological cycle in the Mediterranean eXperiment

HyMeX objectivesScientific topics

Better understanding of the intense events: processes and contribution to the trend

Key questions: What are the ingredients and their interactions necessary to produce an extreme event ?What will be the evolution of intense events with the global climate change ?

Mediterranean cyclogenesesRegional winds

(Mistral, Bora, Tramontana)

Mesoscale convective systemsSlow-moving frontal systems

Coastal orographic precipitation

HyMeX objectivesScientific topics

Observation Strategy (Focus on NW Med TA)

SOP1 in order to document: - Heavy precipitation and Flash-flooding- Ocean state prior the formation of dense water

SOP2 in order to document: - Dense Water Formation and Ocean convection- Cyclogenesis and local winds

?

NW Med TA--- Target Area of the first EOP/SOP series Hydrometeorological sites Atmospheric sites Key regions for dense water formation and ocean convection

TTO & TS7: Data going into the GTS

For real-time data assimilation, additional standard meteorological data measured during HyMex will be transferred via the GTS

Need for a careful monitoring prior to the SOP + extensive test of GTS transmission

• Radiosonde data and AMDAR (TTO1-a)

• Pressurized drifting balloons (TTO1-b)

• Wind profilers (TTO1-c)

• GPS (TTO1-d)

• Radar (TTO1-f)

• Research Vessels radiosoundings?

(TS6-a)

Non-standard meteorological data of research instruments that cannot be assimilated in real-time will be made available to DB and at the HOC.

DOWs (CSWR)

RS DOW (CSWR) NO-XP (NSSL)

SR-2 (OU)

TTO: Some Observations

Upstream monitoring Instrumented balloons (boundary layer pressurized balloons and aeroclippers) launched from upstream sites (Balearic islands) to complement the documentation of low-level inflow. (TTO1b) Two island supersites (Corsica and Balearic Islands) will be used to characterize the far upstream conditions for continental HPE and cyclogenesis (KIT cube and partially based on wind profiler, lidars networks) (TTO1c,TTO1e, TS4a) Increase the operational RS to 4/day in sensitive areas during SOP (as well as increased AMDAR to 1 hour frequency), possibly 8/day RS during IOP (TTO1a) Characterization of the Mediterranean inflow (structure, dynamics, thermodynamics) with the SAFIRE ATR42 (dropsondes, Water vapor DiAL LEANDRE 2, aerosol, Turbulent fluxes, …) aircraft (TS5a)

But also… (see HyMeX website)Air-sea interaction and monitoring of water masses and marine/ocean boundary layersThe microphysical and electrification processes within clouds and precipitation systems Enhancement of observations on Hydrometeorological observatories/sites, super-sites and pilot-sites

AROME_FRANCE (2.5km)AROME_WMED (2.5km)BOLAM (15km) ALADIN-HR (8km)

(BOLD, with assimilation cycle)

WRF-MED1 (50km)WRF-MED2 (7km)BOLAM (11km)MOLOCH (2.7km)MESO-NH (2.5km)

MM5-D1 (22.5km)MM5-D2 (7.5km)MM5-D3 (2.5km)

TS7: Real-time modelling forecast during SOP/EOP

Real-time atmospheric models to guide observation deployement (available at the HOC)

AROME-WMED: Data Assimilation

Assimilation scheme:

3D-Var, assimilation window 3h (Brousseau et al, 2011)

Assimilated observations:

Conventional data : surface data, wind profilers, radiosondes

Ground-based GPS stations

Satellite radiances from geostationnary and polar-orbiting satellites

Radar doppler winds and reflectivities (1D+3D-Var of RH profiles)

Wind derived from satellite imagery

Evaluation against SYNOP + French surface stations

(March 2011)

AROME France v.s. AROME-WMED

940 x 640

Improvements in satellite assimilation courtesy: N. Fourrié

– Enhanced density of assimilated observations (correlations in R)

– Over land (surface emissivity parametrisation and retrieval of skin temperature)

– Mesoscale observation operator in clear sky (Duffourg et al, 2010) and in cloudy conditions (P. Martinet)

– In cloudy conditions (use of model cloud variables for the brightness temperature simulation)

Assimilation of new observations (O. Caumont, A. Doerenbecher…)

– Water vapour lidar (Bielli et al, 2011, TTO1e)

– Moisture related data from wind profilers TTO1c

– Radar refractivity and polarimetric parameters from weather radar Dual polarization radar data (O. Caumont)

– Ground based radiometric data (T and q)

Boundary Layer Pressurized Balloons (CNES-BAMED)

Aeroclippers TTO1b

(C. Basdevant, A. Doerenbecher, Ph. Arbogast…)

Assimilation of new observational data types in AROME

and AROME-WMED related to moisture and hydrometeors.

Background Error Modelling(Y. Michel, T. Montmerle, B. Ménétrier, C. Bishop…)

New correlation models+ Proposal for a large O(102) ensemble to study covariance filtering

EnKF+Schur Wavelet Diagonal Spatial Deformations

Multivariate aspects with geographical masks Montmerle and Berre 2010, Michel et. Al 2011: with hydrometeorCoupled Ocean/Atm. Covariances (NRL)

Cross covariances between errors of humidity (y-axis) and the unbalanced

divergence (x-axis)

The HyMeX DA‐EPS Research Testbed (courtesy V. Wulfmeyer)

DEFINITION: Well‐defined research environment of different DA‐EPSs investigated by expert team (see e.g. COPS, D‐PHASE)

SCIENTIFIC GOAL: Develop general understanding of and guidance on improving DA‐EPS for advanced process and predictability studies.

• Coordination includes driving EPS, domains and resolutions, observations and their error covariance matrices, model forward observation operators, etc.

• Stepwise approach: Case studies and/or operation periods (>1 month)

• Analyses using the same verification data set

V. Wulfmeyer, H.-S. Bauer, T. Schwitalla, K. Warrach-Sag, M.

Grzeschiki, Y. Michel, T. Auligné, A. Montani…

But still need for more people involved

The World Weather Research Program (WWRP) of the World Meteorological Organization (WMO)

HyMeX is endorsed by the WWRP Joint Scientific Committee and the WWRP/THORPEX program

• The World Climate Research Program (WCRP) of WMO Preparatory work (selection of sites and preparation of data) for HyMeX

being a Regional Hydrological Project of GEWEX/CEOP The HyMeX MED-CORDEX regional climate activities are included in

WCRP/CORDEX • ESF/MEDCLIVAR

Joint workshops (within 3rd HyMeX workshop and Plinius conference)

• MISTRALS (Mediterranean Integrated Studies at Regional And Local Scales) In France, HyMeX is inserted in a program cluster (MISTRALS) about

the monitoring and evolution of the habitability in Mediterranean (sponsors: CNRS/INSU, Météo-France, INRA, CNES).

• French ANR funding for data assimilation: IODA-Med project, E. Richard

HyMeX funding, organization and international links

The HyMeX modelling strategy includes: The improvement of convective-scale deterministic forecast systems to improve the prediction capabilities of Mediterranean high-impact weather events. HyMeX field campaigns should provide an unique high-resolution database to validate these new NWP systems: microphysical properties (polarimetric radars, aircraft measurements), marine boundary layer characteristics and air-sea fluxes measurements (buoys, research vessels), novel high-resolution moisture measurements (GPS delays on board ships, radar refractivity, water vapour from lidar, etc).

The design of high-resolution ensemble modelling systems dedicated to the study of the predictability of Mediterranean heavy precipitation and severe cyclogenesis. Quantifying and rating the different sources of uncertainty at various scales that impact the forecast of Mediterranean intense events is one goal of HyMeX through the design of multiscale and nested ensemble forecast systems, possibly based on mesoscale ensemble data assimilation techniques.

The coupling of these ensemble forecast systems with hydrological models to issue probabilistic forecast of the impact in terms of hydrological response. Advances in knowledge of the hydrological and hydraulic responses as well as of the soil water content state before and during the precipitation events should help to improve these hydrological models.

The set-up, validation and improvements of multi-components regional climate models dedicated to the Mediterranean area: ocean, atmosphere, land surface, hydrology in order to study interannual variability, past trends and future climate change

The development of new process modelling, parameterization development, novel data assimilation systems for the different Earth compartments. For example, improvement of air-sea flux parameterizations or development of data assimilation in cloud and precipitation systems are major objectives of HyMeX and part of the observation strategy is designed to serve these objectives.

HyMeX objectives