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File templates are generalized representations for file names that utilize standard sets of naming conventions.
Standard templates utilize replacement characters to match certain data fields, or characters that will be substituted with other values when needed. Templates with the "*" wildcard character can be used to represent more than one set of files.
File name templates can be used in listing and mapping programs to obtain the most recent file of a specific type. For example, use SFFILE=metar to obtain the latest surtface observation file, or GDFILE=nam in grid data programs to access the most recent NAM model run. An optional date/time may be specified following the template name to find the file which contains the time for the specified template. As an example, GDFILE=nam|0000 will find the most recent 00Z NAM file, while GDFILE=nam|050828/1200 will specify the 12Z run for August 28, 2005.
Template definitions are maintained in $GEMTBL/config/datatype.tbl. The datatype.tbl file maintains the location where the data files are stored, and naming conventions used with each data set type, as well as the time range and menu options used within NMAP/NMAP2. Template names are also refered to in the $GEMTBL/nmap/ configuration files for menu pulldowns. A typical filename template uses the following replacement characters:
YYYY - Year with century YY - Year without century MM - Month of Year DD - Day of Month HH - Hour of Day NN - Minute of the HourSome decoders provide additional replacement characters for other data fields.
In order to use file name templates, the programs must be able to find the data within specified data directories. This data location is called the PATH. The FILE TEMPLATE is the representation of the file names contained within the PATH directory. For example, the datatype.tbl file contains the following:
!FILE TYPE |PATH |FILE TEMPLATE CATEGORY|SUBCAT |#FRM|RANGE |INTRVL ! | | | | | | METAR $GEMDATA/surface YYYYMMDD_sao.gem CAT_SFC SCAT_SFC 10 2880 60When file names are used in GEMPAK programs, the program will first try to find the file name explicitly. If the file does not exist, then the program attempts to find a template that matches, and if sucessful, will look for files that match the specified template in the data path directory. If more than one file matches the template, the most recent file will be returned.
The other entries in the datatype.tbl file are used by NMAP for the default data ranges for the type of data in question. We will see how they are used later in the NPROGS section.
The "*" wildcard character may be used in the FILE TEMPLATE to match more than one file name. In this case, the file that matches the template will be references using the FILE_TYPE:TEMPLATE_STRING. Suppose we are running the WRF model locally for several domains or nested domains. We could use a separate FILE TYPE for each domains, however, we would have to know in advance each possible domain that would be available. Instead, a "*" character can represent that part of the file name which varies. Given WRF output for 3 domains with file names YYYYMMDDHHfFFF_d01, YYYYMMDDHHfFFF_d02 and YYYYMMDDHHfFFF_d03, a single FILE TEMPLATE YYYYMMDDHHfFFF_* can be used. The FILE TYPE alias for each of these data sets would then be WRF:d01, WRF:d02, and WRF:d03. NMAP will even compile the list of grid file entries for us.
Other Aliases
One additional type of template is available. It is the parameter alias. The file $GEMTBL/config/prmlst.tbl provides a list of aliases, or shorthand names, for frequently used plots.
Aliases are available to make it easier for the user to plot typical surface data by using pre-set parameters and colors. To use an alias, enter the alias name for SFPARM and leave COLORS blank. If the user does not leave COLORS blank, the selected colors will be used instead of the pre-set alias colors.
Current aliases for surface data located in PRMLST.TBL are as follows:
METAR (standard surface data)
WINTER (standard parameters for winter months)
SUMMER (standard parameters for summer months)
SHIP (standard parameters for ship data)
WAVES (standard parameters for wave information)
NMAP uses the aliases to provide menu options for the different types of plots that are available for specified data sets.
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