WRF Physics Options

Jimy Dudhia

diff_opt=1

2nd order diffusion on model levelsConstant coefficients (khdif and kvdif)km_opt ignored

diff_opt=2

2nd order horizontal diffusionAllows for terrain-following coordinateUses km_opt 1: constant (khdif and kvdif used) 2: 1.5-order TKE prediction 3: Smagorinsky (deformation/stability

based K)

damp_opt=1

Upper level damping layerEnhanced horizontal and vertical diffusion at topCosine function of heightUses additional parameters zdamp: depth of damping layer dampcoef: nondimensional maximum

magnitude of damping

mp_physics=1

Kessler schemeWarm rain – no iceIdealized microphysics

mp_physics=2

Purdue Lin et al. scheme5-class microphysics including graupel1.2 includes ice sedimentation

mp_physics=3

NCEP 3-class schemeFrom RSM scheme (Hong)3-class microphysics with iceIce processes below 0 deg C1.2 includes ice sedimentation

mp_physics=4

NCEP 5-class schemeAlso from RSM scheme (Hong)5-class microphysics with iceSupercooled water and snow melt1.2 includes ice sedimentation

mp_physics=5

Ferrier (new Eta) schemeOne prognostic total condensate variableDiagnostic ice and water species and liquid fractions

mp_physics=99

Zhao-Carr (old Eta) schemeCloud/ice predictionDiagnostic precipitation evaporation

ra_lw_physics=1

RRTM scheme from MM5Spectral schemeK-distributionLook-up table fit to accurate calculationsInteracts with cloudsOzone from climatology

ra_lw_physics=99

GFDL longwave scheme used in EtaSpectral scheme from global modelAlso uses tablesInteracts with cloudsOzone from climatology

ra_sw_physics=1

MM5 shortwave (Dudhia)Simple downward calculationClear-sky scatteringWater vapor absorptionCloud albedo and absorption

ra_sw_physics=2

Goddard shortwaveSpectral methodInteracts with cloudsOzone effects

ra_sw_physics=99

GFDL shortwaveUsed in Eta modelOzone effectsInteracts with clouds

bl_sfclay_physics=1

Monin-Obukhov similarity theoryTaken from standard relations used in MM5 MRF PBLProvides exchange coefficients to surface (land) schemeShould be used with bl_pbl_physics=1

bl_sfclay_physics=2

Monin-Obukhov similarity theoryModifications due to JanjicTaken from standard relations used in Eta model, including Zilitinkevich thermal roughness lengthShould be used with bl_pbl_physics=2

bl_surface_physics=1

5-layer thermal diffusion model from MM5Predict ground temp and soil tempsThermal properties depend on land useNo effect for waterProvides heat and moisture fluxes for PBL

bl_surface_physics=2

OSU/MM5 Land Surface ModelVegetation effects includedPredicts soil temperature and soil moisture in four layersPredicts snow cover and canopy moistureDiagnoses skin tempProvides heat and moisture fluxes for PBL

bl_pbl_physics=1

MRF PBL scheme from MM5Non-local mixing in dry convective boundary layerDepth of PBL determined from critical bulk RiVertical diffusion depends on Ri in free atmosphere

bl_pbl_physics=2

Mellor-Yamada-Janjic (Eta) PBL1.5-order, level 2.5, TKE predictionLocal vertical mixing in boundary layer and free atmosphere

cu_physics=1

New Kain-Fritsch As in MM5 and Eta test versionIncludes shallow convectionCAPE removal time scaleMass flux type with updrafts and downdrafts, entrainment and detrainmentIncludes cloud detrainment

cu_physics=2

Betts-Miller-JanjicAs in Eta modelAdjustment type schemeNo explicit updraft or downdraft

cu_physics=99

Kain-Fritsch As in MM5CAPE removal time scaleMass flux type with updrafts and downdrafts, entrainment and detrainmentIncludes cloud detrainment

(1) Level 2.5 TKE

(2) Level 2

3d Smagorinsky

(3) Constant

diffusion

Subgrid Turbulence

IN WORKING ON PLANNED

2d Smagorinsky(mesoscale)

Microphysics

(1) Kessler

(2) Lin et al. [Purdue]

(3) Cloud3 [NCEP]

(4) Cloud5 [NCEP]

(5) Eta (Ferrier)

(6) Zhao-Carr(old eta)

Goddard

New Cloud3/5

Lin et al. 2

Reisner 2

IN WORKING ON PLANNED

Radiation

(1) RRTM

(2) Eta (GFDL)

IN WORKING ON PLANNED

Goddard

Lon

gS

hor

t (1) Dudhia [MM5]

(2) Goddard

(3) Eta (GFDL)

Boundary Layer

(1) MRF

(2) Mellor-Yamada-

Janjic

(1) MRF Similarity

(2) Eta Similarity

Bou

nd

ary

laye

rS

urf

ace

laye

rL

and

surf

ace (1) 5-layer soil temp

(2) OSU/MM5 LSM

IN WORKING ON PLANNED

TGS LSM (RUC)Unified NOAH LSM

New MRF

CLM

(1) New Kain-Fritsch

(2) Betts-Miller-Janjic

[ETA]

(3) Old KF

New Grell

Cumulus

IN WORKING ON PLANNED