To change the meteorology data, you must take the following steps:
Determine what format your air quality model will accept for meteorology data and convert data to I/O API format if needed.
If you are modeling with CMAQ or MAQSIP, then the data will be in the I/O API format created by MCIP or MCPL that SMOKE can accept. If you are modeling with UAM, REMSAD, or CAMX, then you must check to see which meteorology format the model accepts. Some versions of these models can use the same I/O API format as for CMAQ, but some cannot.
If your meteorology data are not in the correct format, then you will need to convert the data. There is currently no utility provided with SMOKE to convert the meteorology format needed by some versions of UAM, REMSAD, and CAMX to SMOKE input format.
Ensure required variables are included in meteorology data
Ensure meteorology data cover the correct time period
In general, the meteorology data need to cover the same time period as the episode that you are modeling. The only exception to this is for on-road mobile sources using MOBILE6. MOBILE6 computes 24-hours of emission factors at a time, and the 24 hours are from 6AM local time to 5AM local time the following day. SMOKE’s Premobl program converts the gridded, hourly meteorology that is in a single time zone (usually GMT) into hourly meteorology for each MOBILE6 run in local time. This can cause Premobl to process hours of meteorology data that are not actually in the episode in an attempt to meet MOBILE6’s 6 AM to 5 AM requirement. A similar problem can happen at the end of an episode. These problems cause Premobl to end with an error.
If Premobl complains about missing meteorology data in this way and the meteorology data are not available, the following approach can
be used to copy extra data to the beginning of your first episode day and to the end of your last episode day. These instructions
require that you first install the I/O API utilities m3tshift and m3xtract and that you have added the path of these utilities to your $path shell variable. This variable includes paths for all executables and is set in the UNIX .cshrc file in your home directory. To add the m3tshift directory to your path, you can modify your .cshrc file to include the following command.
set path = ($path <directory with m3tshift>)
After your .cshrc file has the command listed above, you must login again. Now, if you type m3tshift or m3xtract at the UNIX prompt, the programs will be found and will start running.
The following steps copy the first day of meteorology data to the beginning of your meteorology files and the last day of meteorology data to the end of your meteorology files.
At the UNIX prompt, type the following commands. The “>” symbol represents the UNIX prompt.
> setenv INFILE <file name of existing 1st day of meteorology>
> setenv OUTFILE <new file name for meteorology file for day before current first day>
> m3tshift
This program can copy the data from INFILE to OUTFILE and change the time stamps in the file. We are using it to copy the first day to the day before the first day. Follow the
instructions on the screen as m3tshift is running. The duration need only be 25 hours at most. For example, if the current first day Julian date is 1996171, the
target Julian date is 1996170 and the starting times are the same:
Starting date = 1996171 (this is YYYYDDD format)
Starting time = 120000 (this is HHMMSS format)
Target starting date = 1996170
Target starting time = 120000
Duration = 250000 (this is HHHMMSS format)
Repeat step (a) except the input file will be the last day and the output file will be the day after the last day. The starting date will be the last day and the target starting date will be the day after the last day.
Edit your METLIST file to include the new first day and new last day files.
Ensure meteorology data are on the correct grid
As described in Section 4.5.9.2, “Installing or changing spatial input files” step 5, check that the meteorology grid and modeling grid are consistent.
Install meteorology data
The meteorology data should be installed in the $METDAT
Ensure that the meteorology data names match with the names in the Assigns file
Edit the Assigns file and look for the $METDAT variable. Ensure that it is consistent with the actual location of the meteorology files. Also check the settings for GRID_CRO_2D, GRID_CRO_3D, MET_CRO_2D, MET_CRO_3D, and MET_DOT_3D and make sure that the naming scheme for these files is consistent with your file names.