Physics Implementation Three_level Structure What you might need to do WRF Model: Physics Implementation Shu-hua Chen NCAR/AFWA (UC Davis, Sep.) OUTLINE F S C I Y H P R W Physics Schemes Three_level Structure Rules for WRF physics WRF Physics Features WRF Language What you might need to do

Scheme Selection W F R Simple schemes for operation Y H P R W Simple schemes for operation Complicated schemes for research

Physics Schemes W F R P I H C Y S Physical Process Available Microphysics Kessler, Lin et al. , Ncloud3, Ncloud5 Cumulus KF, BMJ Subgrid scale turbulence TKE, Smagrinsky, Constant K Radiation RRTM(L), Dudhia(S), Goddard(S) PBL MRF Surface layer Similarity theory Land-surface layer 5-layer soil temperature

• Physics Interface Design W F R Simple User friendly Different dynamics cores Three-level structure =>

Three-level Structure F S C I Y H P R W Solver Physics_driver SELECT CASE (CHOICE) CASE ( NOPHY ) CASE ( SCHEME1 ) CALL XXX CASE ( SCHEME2 ) CALL YYY . CASE DEFAULT END SELECT Individual physics scheme ( XXX )

W F R . . . P I H C Y S phy_prep phy_init Radiation_driver pbl_driver … microphysics_driver Radiation_driver Cumulus_driver pbl_driver INIT . WRF solve_rk … moist_physics_prep ADV TENDENCIES . ADVANCE VARS .

phy_prep & moist_physics_prep F S C I Y H P R W • Decouple variables • Convert variables from C grid to A grid

Three-level Structure F S C I Y H P R W Solver Physics_driver SELECT CASE (CHOICE) CASE ( NOPHY ) CASE ( SCHEME1 ) CALL XXX CASE ( SCHEME2 ) CALL YYY . CASE DEFAULT END SELECT Individual physics scheme ( XXX )

Physics Standard Interface W SELECT CASE (CHOICE) CASE ( NOPHY ) CASE ( SCHEME1 ) CALL XXX(…) CASE ( SCHEME2 ) CALL YYY(…) . CASE DEFAULT END SELECT Physics_driver

Three-level Structure F S C I Y H P R W Solver Physics_driver SELECT CASE (CHOICE) CASE ( NOPHY ) CASE ( SCHEME1 ) CALL XXX CASE ( SCHEME2 ) CALL YYY . CASE DEFAULT END SELECT Individual physics scheme ( XXX )

Three Sets of Dimensions C I Y H P R W Domain size: ids, ide, jds, jde, kds, kde Memory size: ims, ime, jms, jme, kms, kme Tile size: its, ite, jts, jte, kts, kte

Logical Domain (ids,kds,jds) F S C I Y H P R W (ids,ide)

Memory size (ims,kms,jms) F S C I Y H P R W patch (ids,ide) halo (ims,ime)

Tile size (its,kts,jds) W F R P I H C Y S tile (its,ite) (ims,ime) halo (ims,ime) tile (its,ite)

W F R . . . P I H C Y S phy_prep phy_init Radiation_driver pbl_driver … microphysics_driver Radiation_driver Cumulus_driver pbl_driver INIT . WRF solve_rk … moist_physics_prep ADV TENDENCIES . ADVANCE VARS .

Rules for WRF Physics F S C I Y H P R W Coding rules

Coding Rules W F R P I H C Y S 1. F90 Replace continuation characters in the 6th column with f90 continuation `&‘ at end of previous line Subroutine kessler(QV, T, & its,ite,jts,jte,kts,kte, & ims,ime,jms,jme,kms,kme, & ids,ide,jds,jde,kds,kde) F77 Subroutine kessler(QV, T, . . . & its,ite,jts,jte,kts,kte,& ims,ime,jms,jme,kms,kme,& ids,ide,jds,jde,kds,kde ) F90

Coding Rules W F R P I H C Y S 1. F90 Replace continuation characters in the 6th column with f90 continuation `&‘ at end of previous line b)Replace the 1st column `C` for comment with `!` c This is a test F77 ! This is a test F90

Coding Rules W F R P I H C Y S 1. F90 2. No common block Replace continuation characters in the 6th column with f90 continuation `&‘ at end of previous line b)Replace the 1st column `C` for comment with `!` 2. No common block 3. Use “ implicit none ” 4. Use “ intent ” 5. Variable dimensions and do loops

Rules for WRF Physics W F R Coding rules One scheme one module P I H C Naming rules

Naming Rules W ex, module_cu_kf.F F R cu is for cumulus Y H P R W module_yy_xxx.F (module) yy = ra is for radiation bl is for PBL cu is for cumulus mp is for microphysics. xxx = individual scheme ex, module_cu_kf.F

Naming Rules W F R ex, RTHBLTEN P I H C Y S cu is for cumulus RXXYYTEN (tendencies) XX = variable (th, u, v, qv, qc, … ) YY = ra is for radiation bl is for PBL cu is for cumulus ex, RTHBLTEN

Rules for WRF Physics W F R One scheme one module Naming rules P I H C Coding rules One scheme one module Naming rules Vectorized code preferred ( might depend on which physics component )

WRF Physics Features W F R • Unified global constatnts P I H C Y S (module_model_constants.F) REAL , PARAMETER :: r_d = 287. REAL , PARAMETER :: r_v = 461.6 REAL , PARAMETER :: cp = 7.*r_d/2. REAL , PARAMETER :: cv = cp-r_d .

WRF Physics Features W F R • Unified global constatnts (module_model_constants.F) • Unified common calculations (saturation mixing ratio) • Vertical index (kms is at the bottom)

Three-level Structure F S C I Y H P R W Solver Physics_driver SELECT CASE (CHOICE) CASE ( NOPHY ) CASE ( SCHEME1 ) CALL XXX CASE ( SCHEME2 ) CALL YYY . CASE DEFAULT END SELECT Individual physics scheme ( XXX )

WRF Physics Features W F R • Unified global constatnts (module_model_constants.F) • Unified common calculations (saturation mixing ratio) • Vertical index (kms is at bottom) • kme = kte + 1 (physics) kme = kte (dynamics)

WRF Language W F R • Patch, tile, …. S C I Y H P R W • Patch, tile, …. • Moisture field, moist(i,k,j,?), is 4D • ? = P_QV, P_QC, P_QR, P_QI,P_QS, P_QG (module_state_description.F) • PARAM_FIRST_SCALAR IF ( P_QI .ge. PARAM_FIRST_SCALAR ) . . .

W P_QV, P_QC, P_QR, … F R Registry P I H C Y S package kesslerscheme mp_physics==1 - moist:qv,qc,qr package linscheme mp_physics==2 - moist:qv,qc,qr,qi,qs,qg package ncepcloud3 mp_physics==3 - moist:qv,qc,qr package ncepcloud5 mp_physics==4 - moist:qv,qc,

What you might need to do ? F S C I Y H P R W Run existing codes (namelist.input) Physics Buffet mp_physics = 2, ra_lw_physics = 1, ra_sw_physics = 1, bl_sfclay_physics = 1, bl_surface_physics = 1, bl_pbl_physics = 1, cu_physics = 1,

What you might need to do ? F S C I Y H P R W Run existing codes Modify existing codes Plug in your own codes

WRF Development Team F S C I Y H P R W