WG4: interpretation and applications overview and plans Pierre Eckert MeteoSwiss, Geneva

Topics FIELDEXTRA  presentation by JM Bettems CORSO  presentation by G. Rivin COSMO-1 Italy Switzerland Some applications at MeteoSwiss Which posprocessing for the COSMO Consortium?

Status and recent developments COSMO-1 Status and recent developments Oliver Fuhrer With results from the whole COSMO-NExT Team COSMO-GM 13, Sibiu

Project COSMO-NExT ensemble data assimilation: LETKF Boundary conditions: IFS 10km 4x daily Boundary conditions: VarEPS 20km 2x daily ensemble data assimilation: LETKF COSMO-1: 8x daily O(24 hour) forecasts 1.1km grid size (convection permitting) COSMO-E: 2x daily 5 day forecasts 2.2km grid size (convection permitting) O(21) ensemble members Um lokale Vorhersagen zu machen, verwendet man ein 3-stufiges Verfahren: Zuerst ein globales Modell, das das Verhalten der Atmosphäre auf dem ganzen Globus vorhersagt. Dazu wird die Kugel mit einem Gitternetz überzogen, dessen Maschenweite ca. 16km beträgt. Auf einem Ausschnitt über Europa wird die Prognose auf einem Gitter mit 6.6km Maschen verfeinert (COSMO-7). Über dem Alpenbogen wird ein Netz mit 2.2km Machenweite aufgespannt (COSMO-2). Damit erhält man viel mehr Details, wie z.B. die Alpentäler. Das jeweils eingebettete Modell braucht die Vorhersagen des übergeordneten an den Rändern (Ein- und Ausströmen der Luft). Faustregel: eine 24h Vorhersage muss in 30‘ erstellt werden können, damit sie nützlich ist. Je enger die Maschen, desto grösser der Rechenaufwand, deshalb die immer kleineren Gebiete.

Settings for dynamics and physics New fast waves solver (consistent 2nd-order accuracy, strong conservation form of divergence operator, increased divergence damping) Horizontal non-linear Smagorinsky diffusion No artificial horizontal diffusion Rayleigh damping of all variables at upper boundary (test running with condition on w only looks very similar) 6 category microphysics including graupel (as COSMO-2) Standard turbulence and multilayer soil module Explicit deep convection but Tiedtke shallow convection (C-2) Ritter-Geleyn radiation every 6’ Roughness length only from land use (Z0 ≤ 1m) No sub grid scale orography

Stability of dynamical core @1km Not a lot of experience with new fast waves solver and fundamental changes Consistent accuracy in numerics (2nd-order) Strong conservation form of divergence operator Investigation of 10 crashing cases and idealized setups Increase of divergence damping could significantly increase stability No artificial horizontal diffusion required! The stability is sensitive to several parameters (e.g. upper/lower BC, divergence damping, etc.) Vertical level distribution can have an impact on the stability of the model A truly horizontal pressure gradients following Mahrer (1984) shows better results

External parameters Current resolution of external parameters is not sufficient for COSMO-1: Soil type database (FAO @10 km) Topography (GLOBE @900 m) No sub-grid scale roughness information! … The model is not getting a fair chance to be better! Work on the software for the generation of external parameters (EXTPAR) has finished Better topographic dataset (ASTER @30m) Better soil dataset (HWSD @1km)

Summary (so far) We have a 1km setup which runs stably! Fall and winter verification shows good results Better humidity specially in the standard deviation Too strong 10m winds Good precipitation scores Similar upper air scores as COSMO-2 Improvements available or ongoing Configuration External parameters Turbulence

Some applications @ MeteoSwiss From the presentation of Jacques Ambühl

We have to join model performances with user needs

Postprocessing in COSMO No reference to postprocessing in the presently active science plan As shown before, many applications use more or less directly model outputs Most of them are of national interest or are subject to intellectual property restrictions WG4 however strongly recommends that national methods are exchanged and is ready to organise the exchange. What postprocessing on consortium level? (What terms of reference for WG4?)

COSMO-1

COSMO-1

Model interpretation “1 day convection = 10 day synoptics” High-resolution + ENS = Information flood The challenge is to prepeare the relevant information in a clear way. A scale adapted modell interpretation is necessary Derived quantities (SDI) Bulk quantities (temporal and spatial neighbourhood) Intuitive quantities (dBZ) Probabilistic quantities (lagged ensemble, COSMO-E) Situation dependent

My personal view Model Processing Users Meteorologist Verification

Principles of consortium postprocessing Help to understanding the characteristics of model output by analysing (space, time, parameter, ensemble member) combinations of the output fields Provide the users of models (including meteorological forecasters) with recommendations of use of model output The consortium management may define specific strategic areas of consortium postprocessing, for example aviation, energy,…

Thanks for attention

My personal view