A new unified boundary-layer scheme for RACMO: The DualM-TKE scheme

Stephan de Roode

with contributions from

Geert Lenderink

Roel Neggers

Reinder Ronda

Wim de Rooy

Pier Siebesma

Bert van Ulft

Martin Koehler (ECMWF)

EDMF: from fundamental turbulence studies to 3D RACMO simulations

1. Design dualM-TKE scheme

2. SCM results for Cabauw

3. Outlook

Large Eddy Simulation (LES) ModelsCloud Resolving Models (CRM)

Single Column Mode (SCM)lVersions of Climate Models

3d-Climate ModelsNWP’s

Time range for developing new scheme is more than 10 years

The Eddy-Diffusivity Mass-Flux (EDMF) scheme

2i

1i

i,di,ui,cψ Mz

K''w• Nonlocal transport through strong updrafts in clear and cloudy boundary layer by advective Mass Flux (MF) approach

• Remaining (local) transport done by an Eddy Diffusivity (ED) approach

ED MF

Advantages of EDMF

•One updraft model for : dry convective BL, subcloud layer, cloud layer.

•No trigger function for moist convection needed

•No switching required between moist and dry convection needed

•Easy and natural transition to neutral and stable PBL

•Possible extension to deep convection

Courtesy: Martin Kohler (ECMWF)

Further Reading:Soares et al QJRMS (2004)

Siebesma et al JAS (2007)

De Rooy and Siebesma Accepted for MWR (2008)

Neggers et al (submitted to JAS)

Status EDMFStatus

•ECMWF model : Ready. Running in Test Suite. (Roel Neggers)

•RACMO model: Ready. Will be used in next climate scenario runs (Stephan de Roode,

Geert Lenderink)

•Harmonie: Final checks in Single Column Model mode. 3D tests will start early 2008. (Wim de Rooy, Sylvie Malardel)

Running Single Column Models (SCMs) for the Cabauw column

- use RACMO 3D large-scale forcing for 2002-2003

- Run three SCM versions with RACMO 3D forcing

ECMWF Cycle 31R1

Cycle 31 with dualM (future ECMWF version)

RACMO dualM-TKE

- Reset to RACMO3D profiles every 24 hours at 0000 UTC

- differences in modeling results are due solely to

differences in the turbulent transport schemes

PDF LWP for low clouds only C31-R1dualM-TKEC31-dualM

Cloud base level PDFs C31-R1dualM-TKEC31-dualM

Outlook RACMO 3D

• dualM-TKE has been implemented in 3D RACMO and is running

- compare cloud statistics with observations (CloudNet, MSG-SEVIRI)

- verify stable boundary layer structure,

e.g. Baas et al. (2008), parameterization test bed Roel Neggers

• Simulate Hadley circulation (e.g. EUROCS Pacific case)

• Clouds and radiation

- Consider implementation of new ECMWF Cycle 32 Monte-Carlo

Independent Column Approximation (McICA) radiation

scheme