land-surface developments at dwd - cosmo model...deutscher wetterdienst cosmo versions implementedin...

Land-Surface Developmentsat DWD

J. Helmert, M. Raschendorfer, U. Schättler, G. Zängl

Background - Developments

§ Customers request

§ Science plan

§ Observed systematic problems in forecasts(ResQMe)

§ Changes in model suite (COSMO to ILAM)

Global NWP systemb) Model development

è Improved treatment of snow cover in the presence of high vegetation

è Retuning (including changes in the process formulation) of the convection scheme to reduce temperature biases in the tropics

è Revision of cloud cover scheme and corrections of the aerosol specification to reduce radiation bias

è Highly simplified 2D prognostic aerosol scheme

G. Zängl, ICCARUS 2019)

Snow cover in the presence of high vegetation

è Verification scores used to indicate dramatic model errors in Siberia and Canada, particularly during the snow melt phase

è Underlying problem: TERRA still lacks a canopy-layer scheme

è ‘Old’ tuning measure introduced several years ago: Artificial reduction of snow-cover fraction of melting snow, creating a snow-free tile or enhancing its fractional area

è New: Parameterization of temperature difference between snow and dark vegetation elements depending on differential radiation absorption and saturation deficit

è Further developed variant of evaporation tuning using (in addition) snow age and maximum snow depth during snow accumulation period to parameterize the difference between the accumulation phase and the melting phase

G. Zängl, ICCARUS 2019)

Developments – Tasks list

New code basisTERRA with (partly optional) implicit treatment of surface

temperatures§ Coupled implicit system of linearized heat equations for the partial snow-free surface,

the partial snow-covered surface (including the snow pack) and the soil below

§ Extensive adaptation of code that was based on an explicit treatment of Tsf/Tsn by

various limitations and explicit restrictions all over the code, including:

§ TURBTRAN, interfaces and treatment of dynamic snow tiles

§ empirical extensions related to surface processes (implemented by G. Zängl)

§ Recent extension towards an implicitly coupled multi-layer heat-equation for snow,

reducible to the single-layer treatment and usable for new multi-layer snow-

hydrology with individual layering for each grid point and time step (as being

implemented through PT SAINT).

M. Raschendorfer, 2019

New code basis for TERRA

• Implicit treatment of processes in snow and soil togetherwith screen level boundary layer

• Multi-layer snow included (heat transfer)

• Enhancement of the approach possible, i.e.• Using first level soil at half level resistance to capture

ROUTI setup• Using skin-layer without mass to capture ROUTP setup• Using canopy features with mass to capture full canopy

scheme

M. Raschendorfer, 2019

Deutscher Wetterdienst

COSMO Versions implemented in the last Year

11.09.19 COSMO General Meeting 2019, Rome, Italy

è 5.06b (to be expected: 20.09.19)

èRevised cloud radiation coupling (T2RC2) (with ifdef CLOUDRAD)

èFurther GPU optimizations (CLAW for graupel; async copy to and fromblock structure)

èRunning COSMO-LEPS in GRIB 2 with new local section 28

è Interpolation to z-levels above ground

èAdditional packing for GRIB 2 (grid_ccsds, grid_jpeg, grid_png)

èOption to write restart files in NetCDF (from CLM)

è (still ongoing work in) Data Assimilation

èSoil and surface schemes: alignment with ICON (similar to Turbulence)

U. Schättler


Status (in terms of source code)Scheme COSMO ICON

Microphysics gscp_hydor

gscp_kessler

gscp_cloudice

gscp_graupel

gscp_kessler

gscp_cloudice

gscp_graupel

Subgrid scale

orography

sso_lottmiller mo_sso_cosmo

mo_sso_ifs

Turbulence turb_[data|diffusion|transfer|utilities|vertdiff]

Surface Schemes sfc_terra_data, sfc_terra_init, sfc_terra

sfc_flake_data, sfc_flake, sfc_seaice

Convection

(Tiedtke-Bechtold)

conv_[many files] mo_cu[many files]

11.09.19 COSMO General Meeting 2019, Rome, Italy U. Schättler


We aim at:Scheme COSMO ICON

Microphysics gscp_hydor

gscp_kessler, gscp_cloudice, gscp_graupel

Subgrid scale

orography

sso_lottmiller

mo_sso_ifs

Turbulence turb_[data|diffusion|transfer|utilities|vertdiff]

Surface Schemes sfc_terra_data, sfc_terra_init, sfc_terra

sfc_flake_data, sfc_flake, sfc_seaice

Convection

(Tiedtke-Bechtold)

conv_[many files]



Plans for the Next Versions



COSMO General Meeting 2019, Rome, Italy

Jul Aug Sep Oct Nov DecCloud RadRadar Forw. OperatorGround water runoffHigher order schemesGPU: Tiedtke-Becht.TERRA-URBCOSMO-EULAGGRIDTOOLSRestart with NetCDFSAINT (*)CLM (*)MESSy (*)

through githubnot through github

11.09.19

?

?

??

U. Schättler


(*) Some Commentsè SAINT:

èFirst implementation is using a TERRA version modified by Matthias Raschendorfer for implicit treatment of heat conduction equation

èThis version has been updated lately by Matthias for treatment of multisnow levels

èPitfall: Do not know when Matthias version of TERRA will be implementedoperationally

è CLM: Unification has started:

èRestart Files in NetCDF: already implementedèDiscussions about additional diagnostics started (new GRIB fields, but

also new "leveltypes")

èSeveral bug fixes and technical modifications already implemented earlierè MESSy: there will also be an update from the MESSy Community


land-surface developments at dwd - cosmo model...deutscher wetterdienst cosmo versions implementedin...

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