LEO

Finds and displays a polar orbiting satellite image over a point or region.

Format

LEO map channel [keywords]
LEO station channel [keywords]
LEO lat lon channel [keywords]
LEO `city,st,co' channel [keywords]

Parameters

map	map name that defines the geographic region for which to display the image; see the MAP command for a list of valid map names, e.g., FL, MID, USA, EUR (default=value specified for the LOCATE keyword in the LEO.USER /.SITE /.CORE text file; the value is set to USA in LEO.CORE)
station	3- to 5-character station ID or 5-digit ID number at which to center the image
lat	latitude at which to center the image
lon	longitude at which to center the image
`city,st,co'		city or town at which to center the image, where city is the city or town name, st is the two-letter state or province code for the specified city and co is the two-letter country code for the specified city; if city is a U.S. city or town and appears more than once in the state, you can identify the one you want by following the city/town with the county name in brackets, e.g., 'GERMANTOWN[RICHLAND],WI'
channel	satellite channel to display; valid options are VIS, VEG, ICE, SW, IR or SST, where: VIS = visible cloud and surface features (~ 0.6 μm), VEG = visible land vegetation, ocean aerosols (~ 0.9 μm), ICE = near-infrared surface, cloud phase (~ 1.6 μm), SW = shortwave infrared low cloud/fog, fire (~ 3.9 μm), IR = infrared surface/cloud top temperature (~11.0 μm), SST = infrared surface/cloud temperature, low level water vapor (~12.0 μm) (default=VEG if the image time is between one hour after sunrise and one hour before sunset; otherwise default=IR)

Keywords

GRAphic=	graphics frame number to display the map (default=current)
IMAge=	image frame number to display the image (default=current)
MCOlor=	pol cnty		graphics color levels for map's political boundaries and county boundaries (in U.S.); use positive numbers for solid lines, negative numbers for dashed lines, and 0 to suppress drawing (default=value specified for the MCOLOR keyword in the LEO.USER /.SITE /.CORE text file; the value is set to 7 8 in LEO.CORE)
OFF=	op1 . . opN		set specified options to OFF; see the ON keyword for the list of options and their defaults
ON=	op1 . . opN		set specified options to ON; the default for all options is the value specified for the corresponding keyword in the LEO.USER /.SITE /.CORE text file; the options for the OFF= and ON= keywords and their default setting in LEO.CORE are:
		DEBUG	list output from generated commands in text frame (default=OFF)
		ECHO	list generated commands in text frame (default=ON)
		FILTER	apply filter or stretch to image (default=OFF)
		MAPS	display map over image (default=ON)
RES=	resolution, in kilometers, to display image at (default=resolution of the primary dataset if the station, lat lon, or 'city,st,co' command format is used; default=calculated to match the geographic region if the map command format is used)
ZENith=	maximum allowed angle, in degrees, between the satellite sub path and the specified image load point location; a value of 0 means that the satellite passed directly overhead (default=value specified for the ZENITH keyword in the LEO.USER /.SITE /.CORE text file; the value is set to 45 in LEO.CORE)

Remarks

The LEO command uses the LEO.*, MAP.* and LEODATA.* context files (where * = .CORE, .SITE and .USER) to determine which data to use and how to display the data. Default parameter and keyword values are defined in the LEO.* files. Regional map definitions are defined in the MAP.* files. Satellite datasets, their instrument channel and resolution information, and the navigation datasets used to compute overpass day/time estimates are defined in the LEODATA.* files. The datasets in LEODATA.CORE may not be appropriate for users who do not access their satellite data through the SSEC Data Center. Those users may need to create a LEODATA.USER or .SITE file in order to use LEO.

The .CORE files are supplied with McIDAS-X and should not be modified. You can, however, change their settings to your preferences. To do so, copy the .CORE file from ~mcidas/data to your $HOME/mcidas/data or another MCPATH directory, change its extension from .CORE to .USER or .SITE, then edit the settings as needed. The .USER file overrides the .SITE file, which overrides the .CORE file. This order of precedence ensures that your local settings (in the .USER and/or .SITE file) override the settings in the .CORE file.

All images are remapped based on a derived projection and resolution. The projection is determined by the center point latitude of the image region requested by the command. For center point latitudes -30° to 30°, the projection is Mercator (MERC). For center point latitudes -50° to -30° and 30° to 50°, the projection is Lambert Conformal (LAMB). For all other center point latitudes, the projection is Polar Sterographic (PS).

Examples

LEO

This entry finds the most recent image from the polar orbiting satellite datasets in the LEODATA.* file (LEODATA.USER /.SITE /.CORE) whose coverage includes the point or region specified in the LOCATE keyword in the LEO.* file (LEO.USER /.SITE /.CORE) and whose zenith angle to that point or region's center is within the limit set by the ZENITH keyword. It then displays the image at the base resolution of the channel if a point was specified, or at the resolution needed to cover the domain if a region was specified. For most users, the region will be the United States because the LOCATE keyword is set to USA in LEO.CORE. For this and all examples below, unless the channel parameter is specified, LEO displays the land vegetation channel (~0.9 μm) during daylight hours and displays the infrared channel (~11.0 μm) during nighttime hours.

LEO FL

This entry finds the most recent image from the polar orbiting satellite datasets in the LEODATA.* file whose coverage includes the region defined by the map named FL and whose zenith angle to the region's center point is within the limit set by the ZENITH keyword. It then displays the image at the resolution needed to exactly cover the region. For most users, the region will be the state of Florida because that's how FL is defined in the MAP.CORE file.

LEO EUR SW

This entry finds the most recent image from the polar orbiting satellite datasets in the LEODATA.* file whose coverage includes the region defined by the map named EUR and whose zenith angle to the region's center point is within the limit set by the ZENITH keyword. It then displays the shortwave infrared channel (~3.9 μm) at the resolution needed to exactly cover the region. For most users, the region will be Europe because that's how EUR is defined in the MAP.CORE file.

LEO YSSY ZENITH=20 ON=FILTER

This entry finds the most recent image from the polar orbiting satellite datasets in the LEODATA.* file whose coverage includes Sydney, Australia within 20° of zenith. It then displays the image at the base resolution of the channel, centered on Sydney, and applies a filter to provide optimum contrast.

LEO 27 -122

This entry finds the most recent image from the polar orbiting satellite datasets in the LEODATA.* file whose coverage includes 27° North, 122° East within the zenith angle limit set by the ZENITH keyword. It then displays the image at the base resolution of the channel, centered on that point.

LEO `NEW YORK,NY'

This entry finds the most recent image from the polar orbiting satellite datasets in the LEODATA.* file whose coverage includes New York, New York within the zenith angle limit set by the ZENITH keyword. It then displays the image at the base resolution of the channel, centered on New York.

LEO `MADRID,,ES' IR ZENITH=30 RES=3

This entry finds the most recent image from the polar orbiting satellite datasets in the LEODATA.* file whose coverage includes Madrid, Spain within 30° of zenith. It then displays the infrared channel (~11.0 μm) at 3 km resolution, centered on Madrid, Spain. Note that two commas appear between the city (Madrid) and country code (ES) because if only one comma is specified, it's assumed to be a state or province code.

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