The ARL web server contains several meteorological model data sets already converted into a HYSPLIT compatible format on the public directories. Although these directories do not have read permission, file access is permitted via FTP if the file name is known. The data file names are "hardwired" into the GUI. The data files are automatically updated on the server when each new forecast cycle becomes available. Only an email address is required for the password to access the server. The "FTP menu" is locked until the FTP process is completed, at which point a message box will appear indicating the file name that was just transferred.
Pre-processed forecast data are available for NOAA's ETA (now called NAM) model at 40-km resolution covering North America out to +60 h or +84 h depending upon the forecast cycle. Output from the GFS is available at several different resolutions. The AVN run of the global aviation model, on hemispheric projections (northern and southern) at 191-km, is available out to +72 h. The GFS is also output on its usual global 1-degree latitude-longitude grid out to +96 h, an extended (GFSX) duration out to +180 h, and to a much longer range (GFSLR) at a coarser resolution (2-degree) to about 12 days. The rapid update cycle (RUC) model is updated hourly. Available from the Air Force Weather agency are MM5 forecasts at 15-km and 45-km resolution.
Except for the GFSLR, model output files are updated every 6 h with the most recent forecast data. Note that NOAA NCEP models are run at much higher spatial resolution than what is archived in a HYSPLIT compatible format on the ARL server. If calculations using higher resolution data are required, then the original NAM or GFS GRIB encoded files must be obtained and converted as described in that section's documentation. GRIB decoding can be difficult. Although much of the software is provided, no additional guidance except for the information contained in this report is available.