McIDAS Learning Guide
[Table of Contents]
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
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.
- List the current real-time surface data for the state of
This command defaults to listing data from the current day and time using
the RTPTSRC/SFCHOURLY dataset.
- Type: SFCLIST HI
- Run the same command, but this time sort the stations in
chronological order, instead of in alphabetical order.
- Type: SFCLIST HI SORT=OBTIME
- List the current real-time upper-air data for all of the
RAOB stations in the state of Texas.
- Type: UALIST ST=TX
- Erase both the images and graphics in frames 1 through 4.
- Type: ERASE F 1 4
- Display the two latest GOES-East 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'
- 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.
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).
- Type: SF 1;RAOBPLOT Z 850 SAT 00
- 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
- Show frame 2 and plot the current weather symbols on the
satellite image using data from the RTPTSRC/SFCHOURLY dataset (the default
dataset). Draw the symbols in graphics color level 4.
- Type: SF 2;SFCPLOT WXS COLOR=4
- Contour the current temperature over the plot using the
same data and conditions as in the previous step. Define a contour interval
of 5 degrees and draw the contours in color 3.
- Type: SFCCON T COLOR=3 CINT=5
- 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
- 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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