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Stonie, See below. You should have the $GEMMAPS/programs directory with sources for ssfgsf and gsfssf if you need additional references. ****************************************************************** GEMPAK MAP FILES GEMPAK map files are stored as direct access, packed binary files in a GEMPAK Standard Format (GSF). This form was chosen for compactness and relatively rapid access. In addition, a Sequential Standard Format (SSF) is defined for storing maps as ASCII sequential files. SSF files are used to create new maps, edit existing map files and transfer map files between computer systems. Since these are ASCII files, they may be created or changed using a text editor. The SSF files use the same format as the NCAR sequential map file. In both the GSF and SSF formats, latitude and longitude are given in degrees. West longitude is negative; all longitudes must be between -180 and +180 degrees. No map segment should cross the International Date Line. FORMAT OF THE SSF FILE: An SSF file contains map segments, each of which has a series of latitude / longitude points to be connected when the map is drawn. Each segment contains the following information: NP2 INTEGER Number of points (np) * 2 RMXLT REAL Maximum latitude in segment RMNLT REAL Minimum latitude in segment RMXLN REAL Maximum longitude in segment RMNLN REAL Minimum longitude in segment PTS (NP2) REAL LAT1 LON1 ... LATnp LONnp These segments are written and read with the FORTRAN format statement: FORMAT ( I4, 14X, 6F9.3, 8X, / ( 8F9.3, 8X ) ) The maximum number of points which may be contained in any segment is 3000. FORMAT OF THE GSF FILE: These files are direct access file with a recordsize of 128 words. The data is written in blocks of two records or 256 words. The first block is the file header, followed by data blocks. Map segments are packed into the data blocks; no map segment spans blocks. The file header has 181 INTEGER*2 words containing: NMBLK INTEGER*2 Total number of blocks LATPTR1 INTEGER*2 Latitude pointer for 90 degrees LATPTR2 INTEGER*2 Latitude pointer for 89 degrees ... LATPTR180 INTEGER*2 Latitude pointer for -89 degrees The GSF files are sorted by maximum latitude. The LATPTR array contains the first block to use given the maximum latitude on the plot. These INTEGER*2 values may be changed to INTEGER*4 if required. However, the changes must be made in the programs GSFSSF and SSFGSF described below, as well as in GDRMAP which is the GEMPLT subroutine used to draw maps. The data blocks contain only 4-byte integer or real words. Each data block contains: NMSEG INTEGER Number of segments ----- ------ Unused NP1 INTEGER Number of points in segment 1 RMNLT1 REAL Minimum latitude RMNLN1 REAL Minimum longitude RMXLT1 REAL Maximum latitude RMXLN1 REAL Maximum longitude ----- ------ Unused RLAT1 (1) REAL Latitude of point 1 RLON1 (1) REAL Longitude of point 1 ... RLAT1 (np1) REAL Latitude of point np1 RLON1 (np1) REAL Longitude of point np1 NP2 INTEGER Number of points in segment 2 RMNLT1 REAL Minimum latitude ... CONVERTING A GSF TO AN SSF FILE: The program GSFSSF, which is in $GEMMAPS/programs, can be used to convert any GSF file to an SSF file. The user is prompted for the existing GSF file name and a name for the SSF file to be created. CONVERTING AN SSF FILE TO A GSF FILE: The program SSFGSF, also in $GEMMAPS/programs, can be used to convert an SSF file to a GSF file. The user is prompted for the existing SSF file name and a name for the GSF file to be created. The user can also enter a latitude / longitude window to subset the data. Any points outside the window will be eliminated from the output file. However, no clipping is done. The minimum and maximum latitude and longitude stored with each segment will be recomputed internally, so the values in the SSF file need not be correct. The intermediate files, DAFIL.INT and SEQFIL.INT, are used by the program and may be deleted after completion. NAMING CONVENTIONS FOR GEMPAK MAP FILES: The map files are named by concatenating the resolution, map boundaries, and area with the three-letter source file type. For example, the medium-resolution political world map from Goddard Space Flight Center is called MEPOWO.GSF. RESOLUTION FEATURES AREA SOURCE ToP POlitical WOrld GSFc HIgh COastline NW quadrant NWS MEdium REgional NE quadrant CIA LOw CouNty SE quadrant USGeol survey MiXed CountrY SW quadrant NCeP RiVers North Hemisphere RFC InterState highways South Hemisphere CPC U.s. Highways US State Highways Us Oceans RoaDs North America River Forecast Cntrs Atlantic North County Watch Areas Atlantic1 ZoNes Atlantic2 High Seas Atlantic3 OffShore Pacific North Forecast Bounds Pacific East AViation Pacific Surface Flight Info region Pacific1 Convective Sigmet Reg Pacific2 Tpc High seas Pacific3 Tpc Sigmets MarylanD Tpc surface Bounds Basic Weather Tpc surface Analysis Medium Range Tpc aViation bounds Qpf Verification Continental Divide Western Region Mar pred ctr Offshore Arkansas-Red Basin River fcst ctr Basins Lower Mississippi Climate Zones Middle Atlantic Palmer climate Zones Missouri Basin STates North Central LaKes NorthEast OHio SouthEast West Gulf AlasKa The maps from GSFC were obtained for GEMPAK Version 1.0. The history of these maps is unknown. The CIA map files were created from a subset of the CIA map database. The United States Geological Survey maps were converted from the USGS databases. The NWS maps were obtained from the NWS/Modernization Systems Implementation Group. The NCEP map files were developed at the NWS/National Centers for Environmental Prediction. The RFC map files were provided by the Arkansas-Red Basin River Forecast Center. There are 5 maps designed to be used for the seamless surface analysis which shows the area of responsibility for the Tropical Prediction Center, Marine Prediction Center and the Hydrometeorological Prediction Center. Also, these maps have the numbers 050 and 215 in their names which refer to the amount of time after the analysis time; 50 minutes past and 2 hours and 15 minutes past the analysis time. CIA MAP FILE WITH NAMES: A subset of the CIA map database which has a geographical name attached to each record is included in the complement of GEMPAK maps. The names in this file were originally added by Joseph Fulson-Woytek at Goddard Space Flight Center. The map file name is: cia.nam. The program NAMSSF is included to convert a subset of this database into a sequential format file (SSF). The program will prompt for the following inputs: AREA: This may be any geographic name or a range of records specified by the start and stop records separated with a "-". REGION: A character string listing the regions to be used (a blank defaults to all) where the valid regions are: C - Continental borders I - Islands L - Lakes S - State borders N - National borders R - Rivers T - Tectonic plates M - Miscellaneous Example: Create a map containing only Mexico borders AREA: mexico REGION: cn Note that adding S will include "New Mexico" and I will include "Gulf of Mexico Islands". The program NAMPLT will plot individual records listing the record and waiting for a <CR> after each record. This can be used for debugging the map file. GPMAP must be run first to select the graphics area and device. The files doc.nam and rec.nam include the detailed documentation and a list of records for the map elements, respectively. If changes are made to the data base, they should be returned to the GEMPAK developers in order to be included in the original dataset from which the map file was created. ******************************************************* Steve Chiswell On Thu, 21 Aug 2003, Stonie R. Cooper wrote: > Clint, > > How are things going for you? I hope well . . . > > I did a search on the web for a mysterious "GEMPAK map files document" so I > could create some custom maps for GEMPAK . . . and came across a reference > that you had looked for . . . and found . . . the same thing I'm looking for. > > Would you mind sharing where you found it? I don't have any ascii map files > in my distro of GEMPAK (5.6.j), so they must have removed them to save space > . . . but now, no doc that I can find. > > Thanks in advance for any pointers. > -- > Stonie R. Cooper > Planetary Data, Incorporated > (402) 782-6611 >