DeGRIB Appendix - MDL
Brief explanation of the directory structure
(Note: When I refer to "/degrib/", on MS-Windows I typically mean: "c:\ndfd\degrib20\" or "/cygdrive/c/ndfd/degrib20/".)
|/degrib/arcview||Contains ESRI specific files to assist with map projections, and legends.|
|/degrib/bin||Contains the main programs (degrib, tkdegrib, etc).|
|/degrib/data||Is the default location for GRIB2 data.
It also contains geographic data for the imageGen program.
|/degrib/docs||Contains project documentation, including man pages, and some papers.|
|/degrib/lib||Contains extra libraries for the GUI tkdegrib|
|/degrib/output||Is the default output location for tkdegrib.
It also contains the images created by imageGen program.
|/degrib/test||Contains any test scripts and answer data.|
|/degrib/src||Contains all the source code used to create degrib.|
|/degrib/src/zlib||Library: Provides gzip compression. (http://www.gzip.org/zlib/)|
|/degrib/src/libpng||Library: Provides png compression. (http://www.libpng.org/pub/png/libpng.html)|
|/degrib/src/jpeg2000||Library: Provides jpeg 2000 compression. Based on a subset of the jasper library. (http://www.ece.uvic.ca/~mdadams/jasper/)|
|/degrib/src/grib2lib||Library: Provides the ability to read GRIB2 messages. g2libc-1.6.0|
|/degrib/src/emapf-c||Library: Provides Lambert Conformal map projection capability. This is a newer copy than the "official" one. (http://www.arl.noaa.gov/HYSPLIT_cmapf.php)|
|/degrib/src/netcdf||Library: Provides netcdf interface. (http://www.unidata.ucar.edu/software/netcdf/)|
|/degrib/src/degrib||Source code for degrib, tcldegrib and tkdegrib. (https://www.weather.gov/mdl/degrib_home)|
Brief description of output files
|*.txt||A '|' delimited ASCII file, containing information ("meta data") about what is in the grids. It is intended to be human readable without requiring previous knowledge of the "WMO GRIB2 Document".|
|*.is0||An ASCII file, containing a dump of the various values in the arrays returned by the grib2_unpacker library. It is intended for debugging purposes.|
|*.shp, *.shx, *.dbf||The combination is known as a "shape file". The .shp file contains the spatial (Lat/Lon) informtaion, the .shx is an index into the .shp file for faster redraws, and the .dbf contains the actual data.|
|*.flt, *.tlf||The .flt file contains the grid in an NxM 4 byte (octet) float file, which starts in the upper left corner, traverses a row, then starts again on the left. The .tlf file is similar, except it starts in the lower left. Typically the .tlf file (aka mosaic file) is "Least Significant Byte first".|
|*.dat||The data cube file (.dat) is very similar to the .flt file, except that it contains multiple messages. It is typically used in conjunction with the .ind file to create a flat file database for fast (CGI) access to the uncompressed form of the NDFD. Note: One idea for the future is to use the .dat file in GrADS instead of the .flt file.|
|*.ind||The .ind file is an index file that contains some meta data, but also refers to a set of .flt files, or a single data cube file (.dat). The purpose of the index file is to allow fast (CGI) access to the uncompressed form of the GRIB data. The index file combined with the .flt files or single .dat file forms a simple free flat file database.|
|*.hdr||An ASCII file, used by ESRI Spatial Analyst to assist it with using the .flt file. Contains information such as the number of points in the X and Y directions, what the missing value is, and whether the data is stored "Most Significant Byte first" or "Least Significant Byte first".|
|*.ctl||An ASCII file, used by GrADS to assist it with using the .flt file. Contains information such as the map projection, the number of points in the X and Y directions, what the missing value is, and whether the data is stored "Big Endian" or "Little Endian".|
|*.csv||An ASCII file consisting of "X, Y, lat, lon, value" for each grid cell in the grid.|
|*.nc||The grid stored as a "NetCDF" file. See the "NetCDF Specifications" for more information.|
|*.grb||The grid or a subgrid stored as a GRIB2 file.|
|*.ave||An ASCII file containing an ESRI ArcView avenue script, which sets up a map projection to match the shape of earth and map projection specified in the GRIB2 message.|