McIDAS Learning Guide
Version 2006

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Real-time Data Access - Satellite Imagery (Continued)

Displaying Satellite Images Using GEO and LEO

GEO and LEO are "macro-like" commands which build and run multiple McIDAS commands to access satellite data.

GEO finds and displays GEOstationary satellite images over a specified point or region, while LEO finds and displays polar orbiting (or Low Earth Orbit) satellite images. GEO uses the GEO.*, MAP.*, and GEODATA.* context files, where .* refers to .CORE, .USER, and .SITE. Default parameter and keyword values are found in the GEO.* context files, regional map definitions are found in the MAP.* context files, and satellite coverage, instrument channels, resolution information, and boarding image datasets are defined in GEODATA.* context files. LEO uses the same context files, except for a change in name to LEO.* and LEODATA.*.

If you do not access your real-time data at SSEC, GEO and LEO may not work without changing the dataset names in the GEODATA.* and LEODATA.* files.

GEO and LEO have been designed so that the user does not need to know which satellite covers which earth location. The only thing the user needs to input is the geographical location that they are interested in. The commands find the applicable dataset(s) and display the images automatically.

1. List and read through the GEO help.

   Type:  HELP GEO

2. Erase frames 1 through 4.

   Type:  ERASE F 1 4

3. Find and display a geostationary visible image centered over Torrance, California (KTOA) on frame 1.

   Type:  SF 1;GEO KTOA VIS

   First, the command searches for the latitude and longitude of the location defined in the first positional parameter. Then, it uses GEODATA.CORE to find the closest geostationary satellite to use. Next, if the user has not specified which channel to use, GEO will determine the channel, either visible or infrared, depending on the time of the day. Also, if the center point is at the edge of the satellite coverage, GEO will take the adjoining satellite and merge enough data to cover the rest of the image to create the composite. Finally, GEO will display the image with a map on the current frame.


4. Find and display a geostationary water vapor image centered over Paris, France using a filter. Display the image on frame 2.
   
   First, find the station ID for Paris/Le Bourget, France.

   Type:  STNLIST CO=FR MATCH=PARIS

   IDN ID Station Name Data Types ST CO LAT LON ELE ----- ----- -------------------- ----------------- -- -- ---------- ---------- ---- 07156 ---- Paris-Montsouris FR 48:49:00 -2:20:00 75 07150 LFPB Paris / Le Bourget M T FR 48:58:00 -2:27:00 66 07157 LFPG Paris-Aeroport Charl M T FR 49:01:00 -2:32:00 118 07149 LFPO Paris-Orly M 36 T FR 48:44:00 -2:24:00 89 --- LFPW Paris Met Center M FR 48:50:00 -2:20:00 75 Number of stations listed: 5 STNLIST: Done

   After locating the station ID, use the GEO command to display the image.

   Type:  SF 2;GEO LFPB WV ON=FILTER

   Use the ON= keyword to set any of the four GEO options, such as FILTER, to on or off. The parameter WV indicates to display a water vapor image.


5. On frame 3, display the previous day's geostationary image centered over your home town from the current time.

   Type:  SF 3;GEO 'FORT ATKINSON[JEFFERSON],WI,US DAY=2004158'

   In the example above, the brackets [ ] indicate the county location. The DAY= keyword allows you to specify a day other than the current one. Valid entries for this keyword will depend on how many days of data are kept online in your servers.


6. Display the 12 UTC geostationary infrared image centered over Bruxelles, Belgium on frame 4.

   Type:  SF 4;GEO 'BRUXELLES,,BE' IR TIME=12 RES=3

   This example displays the closest 12 UTC infrared image centered over Bruxelles and displays it with a 3 km resolution. Note that two commas appear between the city (Bruxelles) and country code (BE) because if only one comma is specified, it's assumed to be a state or province code.


7. List and read through the LEO help.

   Type:  HELP LEO

8. Display the most recent polar orbiting land vegetation image over the United States.

   Type:  LEO USA VEG

   This entry finds the polar oribiting satellite whose coverage includes the region defined by the map named USA in the MAP.USER /.SITE /.CORE file. It then displays the satellite's most recent image at the resolution needed to cover the region. For most users, the region will be the country of the United States because that's how USA is defined in the MAP.CORE file.


9. Display the polar orbiting image over Japan with no map and no command output in the text frame.

   Type:  LEO 33 -130 OFF=ECHOS MAPS

10. Display a polar orbiting image over Stoughton, Wisconsin in Dane County with the state boundary in green, and the county boundaries in orchid.

    Type:  LEO 'STOUGHTON[DANE],WI' MCOLOR=4 12

Manipulating Satellite Images

1. Display the Meteosat-7 Full Disk IR image in its original resolution (5 km) on frame 1. Center the image on earth coordinates 0° and 0°, and show frame 1 once the image is loaded.

   Type:  ERASE F 1 4

   Type:  IMGDISP MET/FD 1 BAND=8 LAT=0 0 SF=YES;MAP

   Remember, if you receive a partially black image, the image is probably in the process of being ingested. Try the command again in a few minutes. If you're still having problems, contact the server administrator.


2. Decrease (blow down) the image resolution of the Meteosat-7 Full Disk image by a factor of 5 and display it on frame 3.

   Type:  IMGDISP MET/FD 3 BAND=8 LAT=0 0 SF=YES MAG=-5;MAP

3. Magnify (blow up) the image resolution of the Meteosat-7 Full Disk image by factor of 5 and display it on frame 2.

   Type:  IMGDISP MET/FD 2 BAND=8 LAT=0 0 SF=YES MAG=5;MAP

4. Change the loop sequence to view the images in the order of increasing resolution.

   Type:  LS 3 1 2

5. Loop the frames.

   Press:  Alt L

6. When finished viewing the loop, turn the looping off.

   Press:  Alt L

7. Change the loop sequence back to loop through the first four frames.

   Type:  LB 1 4

8. Remap the latest Meteosat-7 IR image to a mercator projection centered on London's Heathrow Airport, and place it in the fourth position in the MYDATA/IMAGES dataset. Change the output resolution, but only create a 480x640 sized image.

   Type:  IMGREMAP MET/B MYDATA/IMAGES.4 STATION=EGLL PRO=MERC RES=5 SIZE=480 640 BAND=8

   Since we're only interested in the geographical coverage around London, use the MET/B dataset instead of the full disk dataset. By using MET/B, less data will be transferred.

9. List out the directory information for these images.

   Type:  IMGLIST MET/B FORM=BAND;IMGLIST MYDATA/IMAGES.4 FORM=BAND

   Image file directory listing for:MET/B Pos Satellite/ Date Time Center Res (km) Image_Size sensor Lat Lon Lat Lon --- ------------- ------------ -------- ---- ---- ----- ----- ------------ 8584 METEOSAT7 14 JAN 03014 15:30:00 40 0 Band: 1 0.75 um Daytime cloud detection 2.88 2.88 1251 x 2500 Band: 8 11.5 um Nighttime cloud detection 5.77 5.77 625 x 1248 Image file directory listing for:MYDATA/IMAGES Pos Satellite/ Date Time Center Res (km) Image_Size sensor Lat Lon Lat Lon --- ------------- ------------ -------- ---- ---- ----- ----- ------------ 4 METEOSAT7 14 JAN 03014 15:30:00 51 0 Band: 8 11.5 um Nighttime cloud detection 3.11 3.11 480 x 640

   Notice that the second image now has a different center lat/lon and is a different size than the original image.

10. Display the new image in frame 4 and draw a high-resolution European map.

    Type:  IMGDISP MYDATA/IMAGES.4 4 SF=YES;MAP FILE=OUTLEURO

11. Loop all of the Meteosat-7 images.

    Press:  Alt L

    By looking at these four images, you should be able to see how simple it is to create different products from the same source image (frame 1) without ever moving the source image from the remote server.


12. When finished viewing the loop, turn the looping off.

    Press:  Alt L

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