Subsetted WRF Output

The raw WRF output has been post-processed into variable subsets, where related variables are grouped into separate files. This will meet the needs of a large percentage of users so they will not need to download the full wrfout files. For example, the primary meteorological state variables like temperature, pressure, and winds destaggered to the center point of the grid cells are all in the met subset category.

The frequency of the available subsets mimics the output frequency from the WRF simulations. So, domains D1, D2, and D3 have subsets every 15 minutes, and D4 has subsets every five minutes.

Most variables in the subset files are directly copied from the wrfout files. However, additional diagnostic variables are calculated to simplify data processing for users. Examples include:

  • Variables that are originally on staggered grids, primarily the winds, are interpolated to the grid cell centers;

  • Normal temperature is calculated from the output potential temperature perturbation;

  • Convective available potential energy (CAPE) and related diagnostics like convective inhibition are calculated.

Another helpful post-processing step is interpolation to alternative vertical grids. Subset groupings are provided on the raw model levels, pressure levels, height above ground, and height above mean sea level. The specific levels are listed in Table 20.

Users interested in generating their own subset files can start with the subsetwrf software provided with LASSO-CACTI and adapt it to suit their needs. For example, some users have wanted more vertical levels than those provided in the height interpolations. Others have wanted the variables grouped differently to assist in their research. More detail about subsetwrf is provided in the software section of the documentation. The subsetting can be done on ARM’s Cumulus2 cluster to avoid having to first download the wrfout files to an outside institution.

Table 20 Levels available for the different subset files, both raw model levels and interpolated to alternate heights.
Level Configuration
(units; count)
Provided Levels

Raw model levels on mass grid (eta; 149)

0.9985125, 0.9954678, 0.9922807, 0.9889451, 0.9854548, 0.981803, 0.9779831, 0.9739879, 0.9698104, 0.9654431, 0.9608783, 0.9561083, 0.951125, 0.9459202, 0.9404855, 0.9348122, 0.9288918, 0.9227152, 0.9162734, 0.9095575, 0.9025581, 0.8952659, 0.8876719, 0.8797667, 0.8715411, 0.862986, 0.8540924, 0.8448515, 0.8352549, 0.8252944, 0.8149619, 0.8042502, 0.7931526, 0.7816627, 0.769775, 0.7574849, 0.7447884, 0.7316829, 0.7181668, 0.7042396, 0.6899024, 0.6751577, 0.6600096, 0.644464, 0.6285287, 0.6122136, 0.5955307, 0.5784943, 0.561121, 0.54343, 0.5254432, 0.5071849, 0.4886823, 0.4699655, 0.4514357, 0.4335449, 0.4163461, 0.3998125, 0.3839184, 0.3686391, 0.3539508, 0.3398306, 0.3262565, 0.3132074, 0.300663, 0.2886038, 0.2770111, 0.2658667, 0.2551534, 0.2448544, 0.2349538, 0.225436, 0.2162865, 0.2074908, 0.1990353, 0.1909069, 0.1830928, 0.175581, 0.1683597, 0.1614177, 0.1547443, 0.1483289, 0.1421617, 0.136233, 0.1305336, 0.1250546, 0.1197876, 0.1147242, 0.1098568, 0.1051775, 0.1006793, 0.09635506, 0.09219806, 0.08820182, 0.08436017, 0.0806671, 0.07711688, 0.07370396, 0.07042304, 0.06726904, 0.06423703, 0.06132228, 0.05852027, 0.05582664, 0.05323719, 0.05074789, 0.04835489, 0.04605443, 0.04384294, 0.041717, 0.03967329, 0.03770861, 0.03581993, 0.0340043, 0.0322589, 0.030581, 0.028968, 0.02741739, 0.02592675, 0.02449377, 0.02311621, 0.02179193, 0.02051887, 0.01929506, 0.01811858, 0.0169876, 0.01590037, 0.01485518, 0.01385042, 0.01288453, 0.01195599, 0.01106337, 0.01020527, 0.009380363, 0.00858737, 0.00782504, 0.007092199, 0.006387707, 0.005710453, 0.005059393, 0.004433527, 0.003831864, 0.003253465, 0.00269744, 0.002162924, 0.001649079, 0.001155109, 0.0006802468, 0.000223749

Heights above ground level (m; 33)

50, 100, 200, 300, 400, 500, 600, 700, 800, 900, 1000, 1100, 1200, 1300, 1400, 1500, 1600, 1700, 1800, 1900, 2000, 2250, 2500, 2750, 3000, 3250, 3500, 3750, 4000, 4250, 4500, 4750, 5000

Heigts above mean sea level (m; 40)

250, 500, 750, 1000, 1250, 1500, 1750, 2000, 2250, 2500, 2750, 3000, 3250, 3500, 3750, 4000, 4250, 4500, 4750, 5000, 5250, 5500, 6000, 6500, 7000, 7500, 8000, 9000, 10000, 11000, 12000, 13000, 14000, 15000, 16000, 17000, 18000, 19000, 20000, 21000

Pressure levels (hPa; 11)

925, 850, 700, 500, 400, 300, 250, 200, 150, 100, 70

Subset Categories

The following lists the different subset categories available to download. Each category link goes to a page listing the specific variables included in the subset.