WRF Variables¶

Coordinate types¶

Variables are stored with coordinates appropriate to their type:

Surface variables: (time, height_Xm, y, x) -- named height coordinate (e.g. height_0m, height_2m, height_10m)
Level-interpolated variables: (time, height, y, x) or (time, pressure, y, x)
Soil variables: (time, depth, y, x)

When a surface variable shares a cfdb name with a 3D level-interpolated variable (e.g., T2 and T both map to air_temp), the surface variant is suffixed with its height (e.g., air_temp_2m) to avoid conflicts.

Surface variables¶

Fixed height above ground, stored as (time, height_Xm, y, x):

Key	cfdb Name	Height	Source Vars	Transform
`T2`	`air_temp`	2 m	T2	direct
`THETA2`	`potential_temperature`	2 m	T2, PSFC	potential temperature
`THETA_E2`	`equivalent_potential_temperature`	2 m	T2, Q2, PSFC	equivalent potential temperature
`Q2`	`mixing_ratio`	2 m	Q2	direct
`Q2_SH`	`specific_humidity`	2 m	Q2	mixing ratio to SH
`RH2`	`relative_humidity`	2 m	T2, Q2, PSFC	Bolton (1980)
`TD2`	`dew_temp`	2 m	Q2, PSFC	inverse Bolton
`PSFC`	`surface_pressure`	0 m	PSFC	direct
`SLP`	`mslp`	0 m	SLP (fallback: PSFC, T2, HGT)	native; fallback = hypsometric reduction
`WIND10`	`wind_speed`	10 m	U10, V10	wind rotation
`WIND_DIR10`	`wind_direction`	10 m	U10, V10	wind rotation
`U10`	`u_wind`	10 m	U10, V10	wind rotation
`V10`	`v_wind`	10 m	U10, V10	wind rotation
`VORT10`	`vorticity`	10 m	U10, V10	relative vorticity
`RAIN`	`precip`	0 m	RAINNC, RAINC	accumulation increment
`RAIN_TR`	`precip_tr`	0 m	TR_RAINNC, TR_RAINC	accumulation increment
`SWDOWN`	`shortwave_radiation`	0 m	SWDOWN	direct
`GLW`	`longwave_radiation`	0 m	GLW	direct
`HFX`	`sensible_heat_flux`	0 m	HFX	direct
`QFX`	`moisture_flux`	0 m	QFX	direct
`ALBEDO`	`albedo`	0 m	ALBEDO	direct
`EMISS`	`emissivity`	0 m	EMISS	direct
`TSK`	`soil_temp`	0 m	TSK	direct
`SNOWH`	`snow_depth`	0 m	SNOWH	direct
`HGT`	`terrain_height`	0 m	HGT	direct
`LU_INDEX`	`land_use_modis`	0 m	LU_INDEX	direct
`XLAND`	`land_sea_mask`	0 m	XLAND	1/2 to 1/0 conversion
`SEAICE_VAR`	`sea_ice`	0 m	SEAICE	direct
`SST_VAR`	`sea_surface_temp`	0 m	SST	direct
`SNOW_VAR`	`snow_water_equiv`	0 m	SNOW	direct

Column-integrated and moisture-transport variables¶

Vertically integrated quantities, stored as surface variables at height_0m. On recent WRF builds (wrf-auto-runs-intel-wvt:1.12+) these are emitted directly and read as a native passthrough; on older wrfout files the same cfdb output is reconstructed from 3D fields via the fallback shown in parentheses. See Native passthrough vs. computed fallback in the WRF guide for how resolution works.

Key	cfdb Name	Source Vars	Transform
`PWAT`	`pwat`	PWAT (fallback: QVAPOR, P, PB)	native; fallback = precipitable water
`PWAT_TR`	`pwat_tr`	PWAT_TR (fallback: qv_tr, P, PB)	native; fallback = tracer precipitable water
`VIMF_U`	`vimf_u`	VIMF_U (fallback: QVAPOR, U, V, P, PB)	native; fallback = (1/g)∫ q·u dp
`VIMF_V`	`vimf_v`	VIMF_V (fallback: QVAPOR, U, V, P, PB)	native; fallback = (1/g)∫ q·v dp
`VIMF_TR_U`	`vimf_tr_u`	VIMF_TR_U	native only (WRF ≥ 1.12)
`VIMF_TR_V`	`vimf_tr_v`	VIMF_TR_V	native only (WRF ≥ 1.12)
`IVT`	`ivt`	IVT	native only (WRF ≥ 1.12)

3D level-interpolated variables¶

Interpolated to user-specified target_levels on height or pressure coordinate:

Key	cfdb Name	Source Vars	Transform
`T`	`air_temp`	T, P, PB, PH, PHB	potential to actual temperature
`THETA`	`potential_temperature`	T, PH, PHB	potential temperature
`THETA_E`	`equivalent_potential_temperature`	T, P, PB, QVAPOR, PH, PHB	equivalent potential temperature
`WIND`	`wind_speed`	U, V, PH, PHB	unstagger + rotation
`WIND_DIR`	`wind_direction`	U, V, PH, PHB	unstagger + rotation
`U`	`u_wind`	U, V, PH, PHB	unstagger + rotation
`V`	`v_wind`	U, V, PH, PHB	unstagger + rotation
`QVAPOR`	`mixing_ratio`	QVAPOR, PH, PHB	level interpolation
`Q_SH`	`specific_humidity`	QVAPOR, PH, PHB	mixing ratio to specific humidity
`RH`	`relative_humidity`	T, P, PB, QVAPOR, PH, PHB	Bolton (1980)
`TD`	`dew_temp`	QVAPOR, P, PB, PH, PHB	inverse Bolton
`VORT`	`vorticity`	U, V, PH, PHB	relative vorticity (unstagger + rotation)
`GHT`	`geopotential_height`	PH, PHB	unstagger z, /9.81
`W`	`vertical_velocity`	W, PH, PHB	unstagger z

Soil variables¶

Stored on a depth coordinate derived from WRF's DZS (soil layer thicknesses):

Key	cfdb Name	Source Vars	Transform
`SMOIS`	`soil_moisture`	SMOIS	direct (per layer)
`TSLB`	`soil_layer_temp`	TSLB	direct (per layer)