1. Pedro M. M. Soares* Pedro M. A. Miranda* João Teixeira^ *University of Lisbon, CGUL, IDL, Lisbon, Portugal ^Jet Propulsion Laboratory – California Institute of Technology, Pasadena, CA, USA A new parameterization for Momentum Transport in the CBL CFMIP/GCSS BL WG Workshop

2. OUTLINE 1.EDMF parameterization for momentum 2.Case studies 3.Results 4.Conclusions Motivation To illustrate the potential, of a poor’s man EDMF, for momentum transport in the CBL… without any tuning

3. EDMF Parameterization Turbulent transport for heat and moisture: for clear BL (Siebesma and Teixeira, 2000; Teixeira and Siebesma, 2000) for clear and cumulus boundary layers (Soares et al. 2004) improved updraft model Siebesma et al. 2007 … Also turbulent transport of Momentum: clear BL Soares et al. 2007 (personnal communication) clear and cumulus BLs (today…)

4. EDMF formulation (MesoNH – old) Ascending parcel Entrainment Vertical speed Entrainment & detrainment Initial buoyancy TKE closure Clear BL/Sub-cloud Cloud MF ED + Soares et al. 2004

5. EDMF formulation (adding for momentum) For deep convection Kershaw and Gregory (1997), the updraft momentum components are given by: Gregory et al. (1997) showed dependency of this term with the average shear: for u: Brown 1999 – LES Bomex Carr and Bretherton 2001 – CMT Tropical Pacific: Budget estimates

6. Entrainment / detrainment formulation UPDRAFTS Ascending parcel with entrainment Determine: ; BL height, z i ; if condensation, LCL, and cloud top. DCBL CuBL (De Rooy and Siebesma, 2008) guarantee a zero M at cloud top

7. CASE studies (inspired on): Nieuwstadt Bomex 1D Meso-NH LES DALES Nieuwstadt Bomex

8. Nieuwstadt case (without shear) u01 new - edmf also for momentum old - edmf only in thl, qt

9. Nieuwstadt case (without shear) ED and MF cont. to total flux u01 momentum transport made by organized updrafts (MF) contribute significantly to the total turbulent flux

10. Nieuwstadt case (without shear) Average and Updraft profiles u01

11. Nieuwstadt case (with shear) u02 ws – without shear term

12. Nieuwstadt case (with shear) zoom in: u02 the shear term impact on the momentum seems to be is small

13. Nieuwstad case (with shear) u03

14. Bomex case (standard) 00 new - edmf also for momentum old - edmf only in thl, qt

15. Bomex case (modified 1) 01

16. Bomex case (modified 2) 02

17. Conclusions The extension of the EDMF (simple version) to represent momentum transport in the CBL shows promising results; the results show improvements in momentum average profiles both for clear and shallow cumulus BLs; for the nieuwstadt cases the shear term seems to have a reduced impact (opposite from Brown 1999 in Bomex); need of LES updraft analysis to understand the relative importance of each contribution; the mass-flux formulation in the cloud layer needs improvements, for example through.