This description is rudimentary but should generally suffice. Further information (possibly more up-to-date) is given at http://www.drjack.info/twiki/bin/view/RASPop/DataFileDescription. If you are seriously interested in using the BLIP data files and have questions about what is written here, post your questions to the on-line Blipmap Forum and I will answer them there.
Data file names and parameters
BLIP data files are available for all BLIPMAP parameters and forecast times. They can be downloaded using standard web html downloading tools (NOT via anonymous ftp) from the same directories in which BLIPMAP plot images are found - they have the same name as the corresponding BLIPMAP plot, except the data file's name tail is ".data.zip" instead of the image's ".png". (However, no data file is associated with "composite" plot filenames since those plot 2 parameters - each of those parameters has its own individual data file.) The easiest way to determine a desired data file name is to view the BLIPMAP plot you are interested in and use that URL with "png" being replaced by "data.zip".
The data files are in compressed "zip" file format, with only one data file per zip file. The zip file name ("outer filename") includes the parameter name, the relative day for NAM files only (e.g. "curr" for current day, "curr+1", etc.), and validation time: an example NAM data file name is "wfpm.curr.21z.data.zip" Note that the model and region is determined by the directory within which the file is located, while the date is referenced to the "current" run date. The archived data file name ( "inner filename") is more complex, providing the model, region, parameter, relative validation day, validation time, forecast period, initialization time, local validation day (YYMMDD), and GMT validation day and time: an example NAM archived file name is: "blipmap_nam_canv_wfpm_curr_21z_9h_12z_061012=061012_21z". Note that the primary purpose of the archived name is to provide information about the file that was archived without needing to unzip the data file itself - it is not normally un-archived using that name, as it is more convenient to ignore the archived filename by unzipping the entire zip file (containing a single archive file) to produce an unzipped file, which can be stored by a more convenient name.
Download is available only for registered BLIPMAP users, access being obtained through use of a DrJack "cookie" or "cookieless" URL query line arguments (see http://www.drjack.info/INFO/registration.html). Subscriber status is required to download all but the "Upward Thermal Velocity" and "Buoyancy/Shear Ratio" parameters.
Data file format
The unzipped ASCII (text) data file consists of:
The data values can often be utilized, for example in plots, without needing to know the latitude/longitude of individual points. But for some purposes the lat/lon values are needed. Files of regional lat/lon values do exist - these are in the same zipped format described above for the data file format, but the lat/lon values are given in floating point (non-integer) numbers. The lat/lon data files have names "latitude.data.zip" and "longitude.data.zip" and are found one directory up from the forecast (FCST) directory used for the parameter data files. It is also possible to calculate the values as needed. For the RUC model this is done using the algorithm in this Fortran file (the algorithm can also be used for NAM forecasts but different map parameter values are needed). The header lines used for these files will not contain all the identifier/value combinations used for the data files since some are not applicable to these files, e.g. "Day" and "Time" identifiers and values are not included.