WRF Model: Physics Implementation OUTLINE Physics Schemes Three_level Structure Rules for WRF physics WRF Physics Features WRF Language What you might.

WRF Model:

Physics Implementation

OUTLINE

Physics SchemesThree_level Structure

Rules for WRF physicsWRF Physics Features

WRF LanguageWhat you might need to do

Shu-hua ChenNCAR/AFWA

(UC Davis, Sep.)

Scheme Selection

Simple schemes for operation

Complicated schemes for research

Physics Schemes

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

User friendly •• Simple

Different dynamics cores •Three-level structure =>

Solver

Physics_driverSELECT CASE (CHOICE) CASE ( NOPHY ) CASE ( SCHEME1 ) CALL XXX CASE ( SCHEME2 ) CALL YYY CASE DEFAULTEND SELECT

Individual physics scheme ( XXX )

Three-level Structure

WRF … solve_rk ADV TENDENCIES

phy_init

ADVANCE VARS

…

INIT

.

.

.

microphysics_driver

Radiation_driver

Cumulus_driver

pbl_driver

phy_prep

moist_physics_prep

phy_prep & moist_physics_prep

• Decouple variables

• Convert variables from C grid

to A grid

Solver




Physics Standard Interface

SELECT CASE (CHOICE) CASE ( NOPHY ) CASE ( SCHEME1 ) CALL XXX(…) CASE ( SCHEME2 ) CALL YYY(…) CASE DEFAULTEND SELECT

Physics_driver

Solver




Domain size: ids, ide, jds, jde, kds, kde

Memory size: ims, ime, jms, jme, kms, kme

Tile size: its, ite, jts, jte, kts, kte

Three Sets of Dimensions

(ids,ide)

Logical Domain (ids,kds,jds)

halo

halo

halo

hal

o

(ids,ide)

patchpatchpatch

patch

patch patch

patch patch

patch(ims,ime)

Memory size (ims,kms,jms)

Tile size (its,kts,jds)

halo

halo

haloh

alo

(ims,ime)

tile

tile

tile

tile

tile

tile

(its,ite)

WRF … solve_rk ADV TENDENCIES

phy_init

ADVANCE VARS

…

INIT

.

.

.

microphysics_driver

Radiation_driver

Cumulus_driver

pbl_driver

phy_prep

moist_physics_prep

Coding rules

Rules for WRF Physics

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

a) Replace continuation characters in the 6th column with f90 continuation `&‘ at end of previous line

1. F90

Coding Rules


1. F90

b)Replace the 1st column `C` for comment with `!`

c This is a test

F77

! This is a test

F90

Coding Rules


1. F90

b)Replace the 1st column `C` for comment with `!`

2. No common block

3. Use “ implicit none ”

5. Variable dimensions and do loops

Coding Rules

4. Use “ intent ”

Coding rules


Naming rules

One scheme one module

xxx = individual scheme

ex, module_cu_kf.F

Naming Rules

module_yy_xxx.F (module)

yy = ra is for radiation bl is for PBL cu is for cumulus mp is for microphysics.

YY = ra is for radiation bl is for PBL cu is for cumulus

Naming Rules

RXXYYTEN (tendencies)

XX = variable (th, u, v, qv, qc, … )

ex, RTHBLTEN

Coding rules

Vectorized code preferred

( might depend on which physics component )


Naming rules

One scheme one module

• Unified global constatnts

(module_model_constants.F)

WRF Physics Features

REAL , PARAMETER :: r_d = 287. REAL , PARAMETER :: r_v = 461.6 REAL , PARAMETER :: cp = 7.*r_d/2. REAL , PARAMETER :: cv = cp-r_d . . .




• Vertical index (kms is at the bottom)

• Unified common calculations

(saturation mixing ratio)

Solver







• Unified common calculations

(saturation mixing ratio)

• Vertical index (kms is at bottom)

• kme = kte + 1 (physics)

kme = kte (dynamics)

WRF Language

• 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 ) . . .

P_QV, P_QC, P_QR, …

Registry

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 ?

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,

Run existing codes

Modify existing codes

Plug in your own codes

What you might need to do ?

WRF Development Team

Numerics and Software

(J. Klemp)

Data Assimilation (T. Schlatter)

Analysis and Validation

(K. Droegemeier)

Community Involvement

(W. Kuo)

Operational Implementation

(G. DiMego)

Ensemble Forecasting

(D. Stensrud)

Data Handling and Archive (G. DiMego)

NCEP Requirements

(G. DiMego)

AFWA Requirements

(M. Farrar)

Wo

rkin

g G

rou

ps

Standard Initialization (J. McGinley)

3-D Var (J. Derber)

4-D Var (D. Barker)

Dynamic Model Numerics

(W. Skamarock)

Software Architecture,

Standards, and Implementation (J. Michalakes) Regional Climate

Modeling (proposed)

Workshops, Distribution, and Support

(J. Dudhia)

Model Physics (J. Brown)

Atmospheric Chemistry (P. Hess)

Analysis and Visualization (L. Wicker)

Model Testing and Verification

(C. Davis)Land Surface

Models (proposed)

WRF Model: Physics Implementation OUTLINE Physics Schemes Three_level Structure Rules for WRF physics WRF Physics Features WRF Language What you might.

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