Overview of WG3a activities Upper air physical aspects Federico Grazzini, ARPA Emilia-Romagna Servizio Idro Meteo Clima (SIMC)

Scientists working in Physical Aspects - Upper air (WG3a) Renata Pelosini ARPA-Piedmont Francesca di Giuseppe ARPA-SIMC Federico Grazzini ARPA-SIMC Paola Mercogliano CIRA Ulrich Blahak DWD Ekaterina Machulskaya DWD Dmitrii Mironov DWD Matthias Raschendorfer DWD Bodo Ritter DWD Jan-Peter Schulz DWD Axel Seifert DWD Euripides Avgoustoglou HNMS Witek Interewicz IMGW Liliana Velea NMA Tiziano Maestri University of Bologna Ronaldo Rizzi University of Bologna Matteo Caggio Univ. of Ferrara Scientists working in Physical Aspects - Soil and surface (WG3b) Giovanni Bonafe ARPA-SIMC Massimo Milelli ARPA-Piedmont Juergen.Helmert DWD Ekaterina Machulskaya DWD Dmitrii Mironov DWD Bodo Ritter DWD Jan- Peter Schulz DWD DWD Martin Lange DWD Claudia Heret DWD Gerd Vogel DWD Edouard DavinETHZ Grzegorz Duniec IMGW Jean-Marie Bettems MeteoSwiss Reto Reto Stoeckli MeteoSwiss Ekaterina Kazakova Roshydromet Inna Inna Rozinkina Roshydromet Alla YurovaRoshydromet By decision of the STC (April 2011) the former WG3 has split : wg coordinator Jean-Marie Bettems wg coordinator Federico Grazzini

WG3a activities  Boundary layer  Microphysics  Radiation  Deep convection and grid scale precipitation  Diagnostic

SubjectInstitution (contact person) Planned durationBrief Description Reorganization and maintenance of the turbulence scheme DWD M. Raschendorfer OngoingIntroducing the concept of scale separation and interaction terms accounting from other sub-grid scale phenomena in the TKE equation. Interactions terms (shear, SSO wake) have already been formulated and tested. This year efforts are concentrated on interaction term from convection Modification of the surface-layer transfer parameterisations, including the reformulation and tuning of the laminar-layer resistance DWD M. Raschendorfer Not yet started. Initially planned for 2011 The primary aim is to improve the scheme performance in stable stratification. Microphysics and precipitation parametrizations Axel Seifert, Uli Blahak DWD Planned implementation 2011 New microphysics schemes of different complexity have been developed for the COSMO model (2 moments, adding concentration of raindrops to the actual Graupel-Scheme. New melting scheme is still under development, and has to potential to improve forecasts of precipitation phase and snow density. Verification of COSMO models with wind profiler Paola Mercogliano CIRA Validation of COSMO LM 7 and 2.8 km using wind profiler data for some test cases; in particular during temperature inversion and strong wind events. WG3a workplan

Proposed implementation of new schemes deriving from past WG3 activities (to be discussed at SMC) single column modelRaschendorfer (DWD) 2012 saturation adjustmentBlahak and Seifert (DWD) Q ? microphysics: two moment microphysicsSeifert(DWDQ microphysics: melting snowFrick and Seifert (DWD) Q radiation: orographic correctionBuzzi (MeteoSwiss)Q clean up turbulence scheme optionsRaschendorfer (DWD) ? use of monthly aerosol climatologyHelmert (DWD)?

….ongoing problems and future activities

 Too strong outgoing surface heat fluxes during night, lack of low level clouds and excessive mixing in strongly stratified conditions.  2m Temperature diurnal cycle problem, with a warm bias of minimum temperature over low-land and stable conditions PBL issues Problems Research TKE scale separation and interaction terms. Increase interaction and exchange of kinetic energy from of other sub- grid scale phenomena and resolved termo-dynamics with the turbulence scheme (scale interaction terms). M.Raschendorfer, DWD Subscale treatment of surface heterogeneity. It seems absolutely necessary to couple a tiled surface scheme with the PBL turbulence in order to improve the turbulence scheme performance in the stably stratified PBL. D. Mironov, DWD Revision of the surface transfer scheme. M.Raschendorfer, DWD There are indications (Schulz 2011) that the ground heat flux in the TERRA multi layer scheme is systematically overestimated. This has been detected by observations made at Lindenberg and SP Capofiume. It is shown that the soil model can be improved with a new formulation of the soil thermal conductivity (in conjunction with WG3b).

Courtesy of J.P. Schulz and G. Vogel

Results of BaseAlfa obs campaign

A typical day with inversion: OBS

A typical day with inversion: FC+24

A typical day with inversion: ANALYSIS

COSMO-EU:  Overestimation of precipitation during winter  Underestimation of precipitation during summer  Diurnal cycle of convection is wrong, i.e. maximum too early.  Sometimes unrealistic local overestimation of precipitation COSMO-DE:  Underestimation of deep convection, non sufficient interaction between deep convective systems (seen also in -I2 configuration) Convection and precipitation issues ProblemsResearch Testing of 1-Km scale runs. Meteoswiss and ARPA-SIMC are running some test and exploring the feasibility of running at very high resolution. Potential benefits are envisaged although a re-tuning of some parametrization might be required. G. De Morsier (Meteoswiss, A. Morgillo ARPA-SIMC) A comparison of spectral characteristics of COSMO I2 total precip and RADAR estimated precip, has highlighted some differences in the scale of the invariance law. In particular the model spectra is more flat indicating a general inability of separating large-scale precip from convection (…lack of organisation in convection ??). V. Pavan ARPA-SIMC

 RTE contains severe approximations and limitations mostly due to computing time restrictions.The most critical issue in this context originates from the need to integrate solutions of the RTE over all energetically relevant wavelengths RADIATION Problems Research Monte Carlo Spectral Integration. Bodo Ritter, DWD Adaptive scheme. It combines accurate and fast parametrization making use of spatial and temporal correlation in the atmosphere. V. Venema, DWD Extramural research

Atmosphere – Ocean interaction ProblemsResearch  Wind generated waves influence the atmosphere and determine the fluxes from the ocean to the atmosphere. At the moment there is no direct effect on the roughness, the model doesn’t feel the waves.  Waves are driving currents and currents are modulating the waves. This interaction is also not included.  Parameters that controls the laminar exchanges over sea are not optimally tuned. Work has been done to couple COSMO (Atmosphere), WAM (Waves) and ROMS (Currents) models. Preliminary results are encouraging (coupling atm and wam). Some comparison with observed fluxes over marine bounday layer are needed for further tuning. CNMCA could invest some human resources with some help from PBL expert. (L. Torrisi CNMCA, in collaboration with A. Roland-ISMAR and V. Romaniello-INGV)

Large differences in surface wind speed between the same model version running on different machines: IBM SP6 and Linux cluster PLX. The problem with the PLX runs was found to be in the module “src_turbdiff.f90” Compiling this module with the -O0 option solved the problem at the expenses of the running time that increases by 20% Isotachs [m/s] of surface wind on model level 40

Further steps towards a scale separated turbulence scheme: Matthias Raschendorfer DWD Aim: General valid (consistent) description of sub grid scale (SGS) processes Problem:Closure assumptions are constraints additional to the only valid first principals  General valid closure assumptions can’t exist  SGS turbulence and e.g. convection can’t be described by one set of 2-nd order equations Solution:Scale separation  A system of closure equations for each scale separated process with specific closure assumptions wake vortices by SSO (sub grid scale orography) blocking horizontal shear vortices surface induced density flow patterns shallow and deep convection patterns Complication:Larger scale SGS processes are interacting with turbulence!!  Scale interaction terms Validation: COSMO Rome 2011  Operational verification  Statistical procession with the package TMOS using ACARS turbulence data

 saturation adjustment is formulated as an isobaric process and does not conserve mass. There is more condensation than evaporation with a net sink of mass (liquid water and total mass). Microphysics and precipitation issues (2) Problems Research Use of volume conserved formulation: Isochoric processes. Implications: Change of thermodynamic, adding pressure diagnosis after adjustment (→ let the model deal with the introduced pressure perturbation) Isochoric saturation adjustment does conserve mass and seems to increase precipitation for both EU and DE. Also influence on precipitation structure Preliminary results seems encouraging. Nevertheless, it will be more thoroughly tested in the framework of „65 levels for COSMO-DE“. Blahak and Seifert, DWD

Proposal of new activities (from Jean- Marie) WG3a Two layers vegetation, in particular to better represent the forest Is this important? Are forests correctly represented in COSMO? WG3a Subscale treatment of surface heterogeneities - Based upon recent LES findings of Peter Sullivan of NCAR and Dmitrii, it seems absolutely necessary to couple a tiled surface scheme with the PBL turbulence in order to improve the turbulence scheme performance in the stably stratified PBL. WG3a Improve fresh snow density With the new multi-layers snow model, a better representation of the snow pack is expected. A revised formulation of the density of the fresh snow could further improve the characteristics of the snow pack. 1. Jason Milbrandt of Environment Canada has developed a parameterization of fresh snow density which makes use of the assumptions and variables of the bulk microphysics scheme. He has shown results that this can improve the forecasts of snow depth. 2. Together with colleagues from ETH Zurich (Claudia Frick, Heini Wernli) we are currently developing a new microphysics scheme with a prognostic liquid water fraction of snow, i.e. we will explicitly model the melting behavior of falling snow by using an additional prognostic variable for the meltwater on the snowflakes. This could then improve the forecasts of precipitation phase and, maybe, snow density near 0 C temperature. We hope to have a first version of this scheme early next year. WG3a Revision of tuning on the basis of the data pool The current COSMO model is very well tuned, which often masks any improvement of the current SVAT. A revision of the tuning on the basis of the latest developments of the SVAT model is needed. Typical parameters which can be modfied are e.g. the minimal stomatal resistence, the heat conductivity and the hydraulic conductivity of the soil. Mathias R. has developed a methodic which should be applied to this problem. WG5 Routine diagnostic of the soil/surface layer of all COSMO models on the basis of the data pool. A similar action was started by G.Bonafe and G.Vogel a couple of years ago. A recent example for such a study is given by Schulz et al. (2011) showing that the ground heat flux in the TERRA multi layer scheme is systematically overestimated. This has been detected by observations made at Lindenberg and SP Capofiume. It is shown that the soil model can be improved, but further studies need to be done on the formulation of the soil thermal conductivity and itsdependence on soil moisture.