Meteorology / ARL Data FTP

The ARL web server contains several meteorological model data sets already converted into a HYSPLIT compatible format in the public directories. Direct access via FTP to these data files is "hardwired" into the GUI. The data files are automatically updated on the server with each new forecast cycle. 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. Alternatively, there is an option to download the files directly from the NOAA nomads website via HTTP (http:// Some of the files are not available on NOMADS (see below).

Note that the NOAA models run by NCEP may be at 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 GRIB encoded files must be obtained and converted as described in the data conversion section. GRIB decoding can be difficult. Although the required software is provided through the GUI, the large file size downloads may limit the practical application of these real-time data files.

Meteorology / Data FTP / Current Forecast

Forecast data are available for NOAA's Global Forecast System (GFS), the North America Model (NAM), and the High-Resolution Rapid Refresh (HRRR). Forecast model data are available at various resolutions, projections, and forecast time durations. The files are updated at two to four hours after the cycle time. Forecast files are available for the last several days depending upon the server and not all files are on all servers. All forecast files follow the same file naming convention of hysplit.t{cycle}z.{name}, where cycle represents the initial UTC time of the forecast (e.g. 00,06,12,18) and the names are as follows:

Additional information about the forecast data on the ARL server can be found at the ARL web page.

Meteorology / Data FTP / Appended Forecast

The appended forecast files consist of a special time extraction of the previous seven (-48 hr) forecast cycle files to create a series of pseudo-analysis (0-hour initialization) and short-time (+3 h or +1,+2,+3,+4,+5) forecasts that have been appended to each other to create a continuous data time series for the previous 48 hours in a single file. These special time extracts are only available for the following files. For the NAM hybrid-level (nams) files the time period is instead for the 24 hours prior to the forecast.

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