McIDAS Learning Guide
Version 2006

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Real-time Data Access - Upper-air and Surface Observations

In a previous lesson, you used PTLIST, PTDISP, and PTCON to list, plot and contour data from point source files. These commands are very flexible and can access any type of data stored in MD files. However, SFCCON, SFCPLOT, SFCLIST, RAOBCON, RAOBPLOT, and UALIST are "macro-like" commands that build and run a PTLIST, PTDISP or PTCON command to access surface or upper-air point data.

These short commands are easier to use with real-time data, because the keyword defaults are set up to easily access the most recent data available. So, when you are using these commands, you will not have to specify the DATASET keyword, and you will only have to specify TIME or DAY if you want to look at something other than the most recent real-time data.

In this example, you will list real-time point data using SFCLIST and UALIST, and then you will use RAOBCON, RAOBPLOT, SFCCON, and SFCPLOT to contour and plot real-time surface and upper-air point data.

Listing real-time point data

  1. List the current real-time surface data for the state of Hawaii.
    Type:  SFCLIST HI
    This command defaults to listing data from the current day and time using the RTPTSRC/SFCHOURLY dataset.

  2. Run the same command, but this time sort the stations in chronological order, instead of in alphabetical order.
    Type:  SFCLIST HI SORT=OBTIME
  3. List the current real-time upper-air data for all of the RAOB stations in the state of Texas.
    Type:  UALIST ST=TX

Displaying and contouring real-time point data

  1. Erase both the images and graphics in frames 1 through 4.
    Type:  ERASE F 1 4
  2. Display the two latest GOES-8 IR images on frames 1 and 2 centered on Charlotte, North Carolina. Show each frame and add a map in graphics color level 2.
    Type:  IMGDISP EASTS/CONUS BAND=4 ALL=1 2 STA=CLT SF=YES REFRESH='MAP H 2'
  3. Show frame 1 and plot today's 00 UTC 850 mb heights on the satellite image using data from the real-time mandatory upper air point data set. Plot the height values in incrementing color values every 20m between 1450m and 1550m. Start with color level 2.
    Type:  SF 1;RAOBPLOT Z 850 SAT 00 COLOR=2[1450-1550B20]
    You do not need to specify the DATASET keyword or the DAY positional parameter. Since you are interested in today's data from the RTPTSRC/UPPERMAND dataset, you can just use the defaults for DAY and DATASET. The COL= keyword will plot values 1450-1469 in level 2 (cyan), values 1470-1489 in level 3 (yellow)... values 1530-1549 in level 6 (blue), and value 1550 in level 7 (white). Values less than 1450 are in level 1 (magenta), and values greater than 1550 are in level 8 (gray).

  4. Draw contours over the plot in frame 1 using the same data. Draw the contours in graphics color level 5, with a contour interval of 30.
    Type:  RAOBCON Z 850 SAT 00 COLOR=5 CINT=30
  5. Show frame 2 and plot the current weather symbols on the satellite image using data from the RTPTSRC/UPPERMAND dataset (the default dataset). Draw the symbols in graphics color level 4.
    Type:  SF 2;SFCPLOT WXS COLOR=4
  6. Contour the current temperature over the plot using the same data and conditions as in the previous step. Define a contour level of 5 degrees and draw the contours in color 3.
    Type:  SFCCON T COLOR=3 CINT=5
  7. Plot the winds over South Carolina at 00 UTC today in frame 3. Use data from the surface (the default) and ship point data files and draw the barbs in green (color 4).
    Type:  SF 3;SFCPLOT WINDB SC 00 COLOR=4 DATA=RTPTSRC/SFCHOURLY RTPTSRC/SHIPBUOY
  8. Draw the 00 UTC 200 mb streamlines over the United States in graphics color level 5. Show the frame when the plot is finished.
    Type:  RAOBCON STREAML 200 USA 00 COLOR=5 GRA=4;SF 4

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