Improvement of the EDMF Scheme using Kain Fristch approach for Meso-NH and AROME Improvement of the Eddy-Diffusivity Mass Flux scheme using Kain-Fritsch approach for Meso-NH and AROME CNRM/GMME/TURBAU Julien PERGAUD, Sylvie MALARDEL, Valery MASSON July 2006, 3rd

Improvement of the EDMF Scheme using Kain Fristch approach for Meso-NH and AROME Introduction : EDMF scheme and purpose of our work 1/ Description of improved EDMF scheme –Equations for the Updraft Model –Definition of Lateral Mass Exchanges –Closure Assumptions 2/ First Results for different study cases –Eurocs/ARM –Bomex Conclusion : Work in progress and questions

Improvement of the EDMF Scheme using Kain Fristch approach for Meso-NH and AROME Introduction Updraft starting from the ground –Dry BL –Dry BL and shallow Cu –Sc BL (not tested yet) Use of conservatives variables EDMF Scheme EDMF scheme Soares et al,2004 Turbulence Convection scheme Soares et al,2004

Improvement of the EDMF Scheme using Kain Fristch approach for Meso-NH and AROME Introduction EDMF Scheme :Results Eurocs/Arm (Malardel,Auguste) EDMF Rc LES Rc

Improvement of the EDMF Scheme using Kain Fristch approach for Meso-NH and AROME Introduction EDMF Scheme : Results Bomex (Malardel,Auguste) EDMF Rc LES Rc

Improvement of the EDMF Scheme using Kain Fristch approach for Meso-NH and AROME Introduction EDMF Scheme : improvement Soares et al,2004 Continuity of mass flux defintion Better definition of entrainment detrainment

Improvement of the EDMF Scheme using Kain Fristch approach for Meso-NH and AROME Eq for w Eq for conservative variables Description of EDMF improved scheme 1/ Equations for the updraft model EDMF KFB w and MF equations  the fractionnal updraft area  Eq for the Mass flux

Improvement of the EDMF Scheme using Kain Fristch approach for Meso-NH and AROME Entrainment and detrainment in clouds are defined as in the KF formulation (Kain & Fritsch,1990): 2/ Definition of Lateral Mass Exchanges Updraft-Cloud Zone Limit between Updraft and environment DE ENVIRONMENT Description of EDMF improved scheme

Improvement of the EDMF Scheme using Kain Fristch approach for Meso-NH and AROME Entrainment and detrainment in clouds are defined as in the KF formulation (Kain & Fritsch,1990): 2/ Definition of Lateral Mass Exchanges Limit between Updraft and environment Updraft-Cloud Zone Maximum updraft part detrainable to environment ENVIRONMENT Description of EDMF improved scheme

Improvement of the EDMF Scheme using Kain Fristch approach for Meso-NH and AROME Entrainment and detrainment in clouds are defined as in the KF formulation (Kain & Fritsch,1990): 2/ Definition of Lateral Mass Exchanges Updraft-cloud Zone Maximum environmental part entrainable to the updraft Limit between Updraft and environment ENVIRONMENT Description of EDMF improved scheme

Improvement of the EDMF Scheme using Kain Fristch approach for Meso-NH and AROME Entrainment and detrainment in clouds are defined as in the KF formulation (Kain & Fritsch,1990): 2/ Definition of Lateral Mass Exchanges Updraft-cloud Zone Updraft- environmental Mixture Zone Limit between Updraft and environment ENVIRONMENT Description of EDMF improved scheme

Improvement of the EDMF Scheme using Kain Fristch approach for Meso-NH and AROME Entrainment and detrainment in clouds are defined as in the KF formulation (Kain & Fritsch,1990): 2/ Definition of Lateral Mass Exchanges ENVIRONMENT Updraft-environmental Mixture Zone Mu Updraft-Cloud Zone Buoyant Air Heavy Air Buoyant Air Heavy Air  Mt Description of EDMF improved scheme

Improvement of the EDMF Scheme using Kain Fristch approach for Meso-NH and AROME Entrainment and detrainment in clouds are defined as in the KF formulation (Kain & Fritsch,1990): 2/ Definition of Lateral Mass Exchanges ENVIRONMENT Updraft-environmental Mixture Zone E Mu Buoyant Air Heavy Air Updraft-Cloud Zone Buoyant Air Heavy Air D E Description of EDMF improved scheme

Improvement of the EDMF Scheme using Kain Fristch approach for Meso-NH and AROME KF formalism : E and D depends on  v between environment and updraft where with - f(x) is a gaussian type distribution with f(0)=f(1)=0, -  c is the critical mixed fraction and  the environmental mass fraction linked to the buoyancy - Ro is the cloud Radius 2/ Definition of Lateral Mass Exchanges Description of EDMF improved scheme

Improvement of the EDMF Scheme using Kain Fristch approach for Meso-NH and AROME 2/ Definition of Lateral Mass Exchanges From the ground to the Condensation Level, entrainment and detrainment are defined as in Lappen & Randall,2001: Lup and Ldn are the downward and upward BL89 mixing lengths  is the fractionnal updraft area. In Lappen & Randall (2001) C E =1.0 and C D =1.5 This formulation needs   diagnosed Link with the turbulence Description of EDMF improved scheme

Improvement of the EDMF Scheme using Kain Fristch approach for Meso-NH and AROME 3/ Closure assumptions Initialisation of the parcel characteristics using Soares et al (2004) with  =0.3 Moreover the mass flux at the ground is defined as : where C Ms corresponds to a fractionnal updraft area defined for each study case Description of EDMF improved scheme

Improvement of the EDMF Scheme using Kain Fristch approach for Meso-NH and AROME First Results for different study cases 1/ Eurocs/ARM Evolution of Mean r c (kg/kg) LES1 D

Improvement of the EDMF Scheme using Kain Fristch approach for Meso-NH and AROME First Results for different study cases 1/ Eurocs/ARM Profile of Mass flux, Entrainment and Detrainment averaged between 8 and 9 hours Mass FluxEntrainmentDetrainment LCL

Improvement of the EDMF Scheme using Kain Fristch approach for Meso-NH and AROME First Results for different study cases 1/ Eurocs/ARM 1D Results Average between 8 and 9 hours Evolution of flux over 15 hours LES Results Average between 8 and 9 hours Evolution of flux over 15 hours

Improvement of the EDMF Scheme using Kain Fristch approach for Meso-NH and AROME First Results for different study cases 1/ Eurocs/ARM LES Results Average between 8 and 9 hours Evolution of flux over 15 hours 1D Results Average between 8 and 9 hours Evolution of flux over 15 hours

Improvement of the EDMF Scheme using Kain Fristch approach for Meso-NH and AROME First Results for different study cases 2/ BOMEX LES1 D Evolution of Mean r c (kg/kg)

Improvement of the EDMF Scheme using Kain Fristch approach for Meso-NH and AROME First Results for different study cases 2/ BOMEX Profile of Mass flux, Entrainment and Detrainment averaged between 8 and 9 hours Mass FluxEntrainmentDetrainment LCL

Improvement of the EDMF Scheme using Kain Fristch approach for Meso-NH and AROME First Results for different study cases 2/ BOMEX LES Results Average between 5 and 6 hours 1D Results Average between 5 and 6 hours

Improvement of the EDMF Scheme using Kain Fristch approach for Meso-NH and AROME Conclusion : Work in progress and questions The next stages in our work will be to Improve the closure asumption : surface mass flux Assess the sensibility of the scheme to different parameters : a and b in the w equation, C E and C D, and Ro Test the scheme with others cases : dry Bl or Sc Bl Implement the scheme in AROME and test in 3D runs

Improvement of the EDMF Scheme using Kain Fristch approach for Meso-NH and AROME Conclusion : Work in progress and questions Some questions are interesting Must we use a prognostic approach to have a better view of the convection? for example Links with deep convection, 3D runs ?