McIDAS-X Learning Guide
Version 2020

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Real-time Data Access - Satellite Imagery

In the first part of this exercise, you will access real-time satellite imagery and review many of the associated McIDAS commands. You will use these commands to display real-time satellite imagery, as well as list information about the data. A good review of satellite data and McIDAS AREA files can be found in the Basic Concepts section of the Satellite Imagery chapter.

Displaying Satellite Data

1. List all datasets of type IMAGE in your routing table.

   Type:    DSINFO IMAGE

   This will list all of the IMAGE datasets that you have access to in your routing table.

2. Erase graphics frames 1 through 4.

   Type:    ERASE G 1 4

3. List the area directories for the four most recent GOES-East images.

   Type:    IMGLIST RTGOESR/FD.-3

   Image file directory listing for:RTGOESR/FD Pos Satellite/ Date Time Center Band(s) sensor Lat Lon --- ------------- ------------ -------- ---- ---- ------------ 192 GOES-16 4 MAR 21063 18:40:16 0 75 1-16 191 GOES-16 4 MAR 21063 18:30:16 0 75 1-16 190 GOES-16 4 MAR 21063 18:20:16 0 75 1-16 189 GOES-16 4 MAR 21063 18:10:16 0 75 1-16 IMGLIST: done

4. Display the four most recent GOES-East IR images chronologically by using the ALL keyword. Place the images in frames 1 through 4 and center them on Miami.

   Type:    IMGDISP RTGOESR/FD BAND=13 ALL=1 4 STA=MIA

   Because real-time satellite data is updated often, it is possible to view an image that has not yet been fully ingested by the server. If you attempt to access the most recent image in a dataset, you may get unexpected results. For GOES images, the image may be all black if the band requested isn't available yet on the server. This is normal behavior with GOES ABI imagery. When viewing older GOES GVAR images, you could see images filling the screen line-by-line as data was being ingested.

5. Set the loop bounds to loop through frames 1 through 4 and loop the frames. Stop the looping when you are finished looking at the images.

   Type:    LB 1 4
   Press:   Alt L
   Press:   Alt L

Listing Image Information

When you display an image on a frame, McIDAS creates a frame directory for the image which lists the frame number, sensor source, date, image time, band number, image coordinates, magnification factors, and ADDE dataset name and file position number. The FRMLIST command lists the frame directory.

The IMGPROBE command lists data from the area represented on the image at the cursor center. It lists the area number, area coordinates, image coordinates, raw, brightness, and when present, temperature and radiance values. IMGPROBE can be invoked with its default parameters by pressing Alt-D.

Even though the data is not located on your local machine, but rather on some remote server, you can still access information about the data.

1. List the frame directory for all of the images in frames 1 through 4.

   Type:    FRMLIST 1 4

   Information about the frame number, sensor source, band, date, time, and ADDE dataset/position number is displayed for each image.

   Frame Satellite [panel] Sensor Band Date Time Data Source --------- ------------ ---- ------------ -------- ----------------------------- 1[1] GOES-16 13 04 Mar 21063 18:40:16 RTGOESR/FD.189 2[1] GOES-16 13 04 Mar 21063 18:50:16 RTGOESR/FD.190 3[1] GOES-16 13 04 Mar 21063 19:00:16 RTGOESR/FD.191 4[1] GOES-16 13 04 Mar 21063 19:10:16 RTGOESR/FD.192

2. List the area values for the element at the center of frame one .

   Type:    SF 1;PC C;IMGPROBE MODE=N

   Alternate method:

   Type:    SF 1;PC C
   Press:   Alt D

   The area number, area coordinates, image coordinates, raw, and brightness values are listed. Because this is an infrared image, the temperature and radiance values are also listed. (Note: It is possible a Frame/Image mismatch error will occur with the IMGPROBE or D command. This occurs when a new image becomes available on the server, and the absolute position number changes of the displayed image. You can redo the IMGDISP command in step 4 above and rerun the IMGPROBE/D commands to get the expected output.)

   Image Name Day Nominal Time Scan Time Band ---------------- ------- ------------ --------- ---- RTGOESR/FD.189 4 Mar 21063 18:40:16 18:42:19 13 File Nominal Image RAW RAD TEMP BRIT Lat/Lon Line/Element Line/Element * K 25:45:53/ 80:29:21 1364/ 2443 5457/ 9773 2258 101.61 297.86 64 * milliwatts/meter**2/steradian/(cm-1) IMGPROBE: Done

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