The person wanted to download a few variables from files on the archive, rather than the full file. They also wanted to get data from a specific latitude/longitude location in the model grid.
-------------
Unfortunately, it isn't possible to pluck out specific lat/lon locations from the grid before you download the data. The best thing to do would be to download the full grid for the variables you want.
I have described how to do this on the "Scripting Tips" page under the "cURL and wget" and "Python" tabs.
The approach here is that by knowing the byte range for the grid of a single variable (as found in the .idx file), you can download just that chunk from the file (~1 MB) rather than the full file (>125 MB).
An example .idx file for the model analysis (F00) valid at 0000 UTC on 10 July 2019 is here: https://pando-rgw01.chpc.utah.
This file corresponds to the full GRIB2 file here: https://pando-rgw01.
In this example, if you want surface temperature, you would search the .idx file for the line with the variable TMP:surface
The grid for this variable begins on byte 31889605 and the next variable begins on byte 33367664.
Thus, you can download just that grid, which returns a valid GRIB2 file with one layer, with a curl command:
curl -o 20190710_00zf00_TMPsurface.
Because we don't archive the HRRR on the native grids we don't have the data you need at specific model levels. But we do archive the surface file forecasts (F00-F18) and the pressure file analyses (F00) that interpolate the data on specific levels. These still might be useful for what you want to do.
You can browse the variable names and descriptions here: (though, these pages might not be a complete list)
Surface Files: http://home.chpc.utah.edu/~
Pressure Files: http://home.chpc.utah.
I listed the variables you might be interested in below:
-geopotential (at surface and at first level of model)
HGT:surface(no HGT at first model level)
-wind speeds (u and v components at first level)
UGRD:10 mVGRD:10 mUGRD:80 mVGRD:80 mWIND:surface This is the maximum wind speed at 10 m for the previous hourGUST:surface This is essentially the maximum wind speed in the lowest XX layers (not sure exactly how gust is calculated)(again, wind is not available at first model level)-snow depthSNOD:surfaceSNOWC:surface (snow cover)
-temperature (at surface and at first level)
TMP:surfaceTMP:2 m(Not available at first level)-solar irradianceDSWRF:surface (downward shortwave radiation flux)-relative humidityRH:2 m-cloud fractionTCDC:entire atmosphere (total cloud cover)-hourly precipitation amountThis is a tricky one because precip is an accumulated quantity, thus there isn't a value for the analysis (F00). Instead, you would have to look at accumulated precipitation over some period of time. Some people like to look at the precip accumulated during the F00-F01 period as the "best guess"For example:APCP:surface:0-2 hour acc fcst Is the accumulated precip between F00-F02APCP:surface:1-2 hour acc fcst Is the accumulated precip between F01-F02
If you target the specific variables you want, you will end up downloading much less data than downloading the full files. This will likely save a lot of download time and bandwidth (on your end and our end). It would probably be best to execute a curl command for each variable separately (and for each hour of the day).
I often have to pluck out values at specific lat/lon locations, too. My method is available on github, but there are probably many other ways to do the same thing.
I hope this helps!
Brian Blaylock
Ph.D. Candidate
Atmospheric Science
University of Utah
