GEMPAK Manual |
Programs | Parameters
GAREA
GAREA is the graphics area. This is the area which will be displayed
on a graphics device.
GAREA can be specified in the following:
1. lat1;lon1;lat2;lon2
This defines a latitude/longitude range where (lat1, lon1) is
the lower left corner and (lat2, lon2) is the upper right corner.
West longitude is negative.
#clat;clon;dlat;dlon
This defines a latitude/longitude range by the center latitude
and longitude. The lower left corner is (clat-dlat; clon-dlon);
the upper right corner is (clat+dlat; clon+dlon). No corrections
are made for the poles or the International Date Line.
2. GEOG
This is an abbreviation for a geographic area defined in the
GEMPAK geographic table which includes abbreviations for states,
provinces, and countries, as well as other names. A suffixed + or *
will decrease the extent of the geographic area. A suffixed - will
increase the extent of the geographic area.
3. STN
This defines an area centered on a station found in the GEMPAK
station table, which currently contains US, Canadian and
Mexican stations. A suffixed + or * will expand, and - will reduce
the area.
4. Graphically using the CURSOR command.
Note that the other ways of specifying AREA are not valid for GAREA.
For all projections, the lat/lon corners defined will be used exactly.
(If GAREAX is used with the CURSOR command, the display area attempts
to fill the entire view area, extending the area defined by the selected
lat/lon). For projections which include the pole, if lat1 = lat2 and
lon1 = lon2, then lat1 will specify the range of data from the pole and
lon1 will specify the central longitude. If the projection has been
rotated so that a geographic pole is no longer at the center and
lat1 = lat2 and lon1 = lon2, then lat1 will determine the range of data
from the rotated pole and lon1 specifies the central longitude as before.
If a cylindrical equidistant projection has been rotated for any angle1
between 90 and -90 degrees, then the entire world can be displayed
by entering GAREA=0;0;0;0. The central longitude is taken from the
PROJ specification for angle2. This works for angle1 = 0 as well.
West longitude is negative.
For overlay on satellite and radar imagery, PROJ must be set to
SAT and RAD, respectively.