WG-MWFR activities Jeanette Onvlee Chair WWRP/WG-MWFR

1JSC meeting, 21-24 February 2011

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WG-MWFR activities

Jeanette Onvlee Chair WWRP/WG-MWFR


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Activities

Help set up / involvement in RDP’s/FDP’s (COPS, Sochi, HYMEX?) Push mesoscale weather research cooperation / proposals in several

fora Last year activities on:

Organize “grey zone” experimentation (WGNE context) Define/promote worldwide standards for mesoscale verification,

and routine model quality assessment and exchange (together with JWGV)

Make inventory of available mesoscale training material, gaps therein

WMO symposia, dedicated workshops on specific topics Liaisons with other WMO WG (e.g. Thorpex/TIGGE-LAM,

WWRP/WGNR, JWGV, WGNE, …)


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COPS main outcomes

Summer 2007: massive observation campaign Joint COPS/D-PHASE Database collected at DKRZ/Hamburg Subsequent analysis of IOP results (2008-2010):

Process studies on the convective life cycle, Model validation studies (clouds, microphysics) Research on new observation types Tests of advanced data assimilation systems and observation impact

studies Verification techniques, impact assessment of convective-permitting

models

Scientific results summarized in dedicated QJRMS issue (online 18 Feb 2011), 23 papers

Short report on lessons to be learned for JSC?


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COPS 4D Data Set: IOP8b, July 15, 2007

Evaluation of moisture fields using University of Hohenheim water-vapor lidar. Generally, models were too humid in lower troposphere.

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RPPreparation Sochi 2014 RDP/FDP

Aim: combined RDP/FDP on nowcasting/mesoscale modelling, as meteorological support of Sochi 2014 Winter Games.

Winter nowcasting/short-range forecasting in complex terrain High resolution prediction of wind speed and wind gust, visibility,

fog, precipitation intensity and time (including downscaled surface systems and fog models)

Assimilation and verification based on remote sensing data (radars!)

Emphasis on more extensive use of remote sensing data for nowcasting, regional data assimilation, and forecast/nowcast validation.

Kickoff meeting with intended participants: March 2011. Exact scope of activities to be decided then.


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Grey zone (1): the problem

Convection partially resolved from hor resolutions of ~5-10km downwards to ???

In this partially resolved range: neither fully parametrized nor fully explicit convection works quite well

Strategies for dealing with grey zone: switch off convection parametrization at some resolution (most models), or gradual shut-down of parametrized deep convection.

Present experiences: Problematic: initial, not-yet-organized stages of deep convection,

where models often show too active growth. Great sensitivity of convective behaviour to details of physics-dynamics interaction, diffusion, microphysics, domain size, …

Need for inherent 3D-treatment of parametrizations, and inclusion of stochasticity in initial stages?


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ALARO/AROME exp at 2, 1 and 0.5kmwith/without deep convection parametrization

•Fractal behaviour •With explicit convection: Strong upward motions, too many high clouds, overestimate of precip peak


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A need for 3D physics?

Present paradigm: parametrize all subgrid processes only in the vertical. This may need to be revised.

Indications for need of 3D-treatment for turbulence: experiments with 3D-turbulence, hor

diffusion great sensitivity of convective

behaviour to turbulence/ horizontal diffusion settings

However, this is a very delicate issue numerically (Piotrovski et al 2009)!

GCSS deep convection working group case 4:• Increasing delay of rain onset with decreasing resolution• 3D turbulence reduces overshoot and difference in time of onset precipitation


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Highly sensitive to details of numerical setup…


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Grey zone (2): proposed studies

Decision at WGNE: subgroup from WGNE, WG-MWFR, GCSS to jointly set up idealized grey zone experimentation

Use experimentation and model intercomparison experiences from GCSS.

Run several LES systems at several 100m resolution as “truth”, make model simulations at stepwise progressively coarser resolutions throughout grey zone range, for different models. 1- and 3D- analysis of outcome.

Need to very carefully consider extended diagnostics! Presently setting up basic experimental framework for a “simple”

extratropical case of cold air outbreak over sea, in 2011-2012 Intention: Later extend this framework and modelling community to

other cases, including e.g. deep convection in tropics, open cell convection over land.


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Mesoscale data assimilation (1)

Area of very intense research; WG is following developments with the view “are we getting answers to:”

How to make best use of large scale nesting analysis? (Partial) downscaling, blending, Jk…? Not easy to achieve

added value over large scale in upper air!

Which observations best to use (on top of large scale analysis)? Surface Boundary layer: ground-based RS; operational perspective? Moisture observations: radar, E-AMDAR humidity (Satellite: channels closer to surface, cloudy radiances)


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Mesoscale data assimilation (2) How complex does DA technique have to be?

How to get best/longest impact from moisture data? Bg error modelling, more flow-dependency, masking, …

Cycling practical constraints/use for nowcasting RUC or not, optimize for NWC, different needs for NWC – 6-

24h range?

Hybrid ens/DA systems: how to optimize for each use? (input from Bologna workshop)

Mesoscale DA element in COPS, Sochi, Hymex. Contacts with obs community, GLASS, WG-NR, TIGGE-LAM

To tackle: what form could voluntary international experimental cooperation take?


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Workshop “Use of mesoscale NWP in support of nowcasting”

Nowcasting tools: Purely observation-based (e.g. radar extrapolation) NWP used indirectly as input in dedicated nowcasting applications Increasing push for more direct use of high-resolution NWP in some

form of RUC mode. But what are its limitations?

Joint WGNR-WG-MWFR Workshop:

Aims:Strengthen interaction between NWP and NWC communitiesConfront present and future prospects of NWP for NWC with challenges

of NWC, come up with recommendations on way forward (how to optimize NWP in support of NWC, and how/when to best use it (or not))

~30 participants (invitation only). 27-29 June 2010, Boulder. JSC support already given in principle, request for final approval


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LAM EPS research “Synoptic scale” LAMEPS:

Added value over global EPS shown, but still far from optimal?

Multi-model LAM EPS involving different physics generally better than the individual systems. Simple bias corrections insufficient, reforecasting calibration probably important but hard to achieve?

Convection-permitting EPS: How to construct them? Technology moves faster than the

science! Surface perturbations: too little attention yet.

Hybrid ens/DA: how to optimize for LAM EPS and for DA purposes?

Ease interpretation by users: Use of ensembles for interpretation of rare events (upscaling,

…) Training on LAM EPS use Coupling to downstream application (hydrology, others??)


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>100mm precip in several hours


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DMI’s 5km 25-member HIRLAM EPS:is three members enough to warrant an

alarm?

EPS plaatje?

But with upscaling 7-8 members indicated the chance of heavy precip!


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Mesoscale verification

Unlike global models, no commonly accepted “gold standards” exist to assess and intercompare mesoscale model quality by routine verification

New spatial/object-based verification methods are required, in particular for precipitation (new standards for this are being pushed by JWGV) and clouds (no standards from JWGV yet).

Lack of overlap in operational model domains => little or no exchange of objective verification results in practice.

Still, model improvement is clearly stimulated by a better understanding of the relative strengths and weaknesses of different models, and by some “friendly competition”!

2010: WG-MWFR and JWGV started cooperation, aiming to define recommended basic set of quality measures and verification methods to be used in routine verification of mesoscale models, and to promote this verification and exchange of verification results between models worldwide


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Training material

Recently started activity: Make inventory of available training material on

mesoscale aspects of NWP modelling for forecasters and users

Idem for training activities and capacity building by the various mesoscale modelling groups

Aims: provide descriptions and links to existing material

and promote its use identify gaps and try to fill them


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Liaisons with other WG’s JWGV

(spatial) verification techniques (precip, clouds, extreme weather, LAM EPS, ...)

Define/promote quality standards for routine monitoring of mesoscale models

WGNR Workshop on use of NWP as tool in support of nowcasting Joint interest in development/characterization of new

observation types WGNE/GCSS

Grey zone experimentation Follow up with mesoscale DA experimentation proposal,

mesoscale quality assessment reporting? TIGGE-LAM

Development, use and improvement of LAM EPS systems worldwide (research component of TIGGE)

GLASS: Surface / surface DA aspects Obs community: E-AMDAR panel, EUCOS, OPERA, ...


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Dedicated workshops:

Physiographic data for km-scale NWP Quality and spatial detail of physiographic databases crucial to

mesoscale surface modelling Spatial quality of land surface information sometimes

inhomogeneous even in good databases Methods and limitations for aggregating dm-scale satellite info

into physiographic data little known in NWP community Need to go to resolutions finer than 1km in the coming years

Goals workshop: make physiographic db community aware of NWP needs Make NWP community aware of physiographic database

collection process, quality and limitations

Status: …


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Scientific issues considered Mesoscale data assimilation:

What analysis setup is most appropriate for mesoscale/nowcasting? How best to analyze moist processes, with minimal spinup? How to add small scale information while retaining the strengths of

the larger scale nesting analysis? What is best way to use radar, cloud, hydrometeor information?

Convection and complex topography: Grey zone for convection/turbulence: how to handle in models? How to best represent steep orography?

Surface modelling Initiation and modelling of new, more realistic components (e.g. snow, urban) High-quality high-resolution physiographic data

Predictability and probabilistic forecasting What influences predictability on convection-permitting scales, and how to

describe it? Towards convection-permitting ensembles: practical methods, cross-fertilization

of ensemble and DA techniques?

Underlying all: suitable verification and validation methods

WG-MWFR activities Jeanette Onvlee Chair WWRP/WG-MWFR

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