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20021231: how to display previous surface and radar images



>From: Sridharareddy Duggireddy <address@hidden>
>Organization: USF
>Keywords: 200212311916.gBVJGjt09992 McIDAS

Hi Sridhara,

>   I am trying to display the previous ten maps or images of radar and
>surface maps. I have displayed the current surface map using the command
>
>SFCPLOT PLOT OLAY LATEST GRA=1 BLANK=NO LSIZE=6 DAT=RTPTSRC/SFCHOURLY
>SF=YES
>SFCCON PMSL OLAY FRAME GRA=1 OUT=CON GRIDF=132 BLANK=NO LSIZE=6
>DAT=RTPTSRC/SFCHOURLY SF=YES

OK.

>Now i tried to display the previous ten images by specifying the time
>range for ex. 18-0 (18 UTC TO 0 UTC) instead of LATEST and by specifying
>the relative position like RTPTSRC/SFCHOURLY.-2
>But the above command is not working.

Are you trying to display the last 10 hours worth of surface plots
and contours?  If so, you have to do this in a loop.  SFCPLOT/SFCCON
do not support the concept of plotting loops directly.  You can
setup a loop of plots/contours easily using the McIDAS REPEAT command.

>Can you please specify the correct
>format to display the previous radar and surface maps? After displaying
>the previous ten images I have to loop them.

Displaying a loop of images _is_ easy to do in McIDAS.  And, after you
have a loop of images setup, overlaying them with surface plots/contours
is very easy using the McIDAS LOOPIT command.

One thing to remember when displaying surface data on top of images
is that you usually will want to match the time of the plot/contour
with that of the image.  Since radar images come in multiple times
per hour, your loop will contain radar echos that change, but surface
data that does not.

Perhaps it would be instructive for me to demonstrate how to display
a loop of the last 10 hours or satellite data and then overlay
it with surface plots/contours of data whose time matches the
image times.

Here is one way of doing this:

1) display a loop of the last 10 GOES-East IR images centered over
   Tampa and blown up by a factor of 2:

IMGDISP RTIMAGES/GE-IR ALL=1 10 STA=KTBW MAG=2 EU=IMAGE SF=YES REFRESH='EG 
(GRA);MAP H GRA=(GRA);BAR GRA=(GRA)'

2) setup a loop of the images displayed in frames 1-10.  Then setup the
   loop dwell rate for those frames:

LB 1 10
DR 9*3 20

3) overlay each image in the loop with the corresponding surface station
   model plot:

LOOPIT "SFCPLOT PLOT OLAY FRAME

3) overlay each image in the loop with the corresponding surface pressure:

LOOPIT "SFCCON PMSL OLAY FRAME

LOOPIT will turn looping on when it is finished.

Now, you can use the IMGDISP construct to put up a loop of the last
10 radar images for Tampa:

IMGDISP RTNEXRAD/N0R ID=TBW ALL=1 10 STA=KTBW MAG=1 EU=BREF SF=YES REFRESH='EG 
(GRA);MAP H GRA=(GRA);BAR GRA=(GRA)'

And, you can use the LOOPIT invocations to overlay these images with
station model plots/contours.  If you do, however, you will find out
that most surface plots/contours will not change even though the images
are.  The reason for that, as I said above, is that the surface data
is hourly in nature, while the radar images are available a lot more
frequently (every 10 minutes if the radar is operating in clear air
mode; every 6 minutes if the radar is operating in precip mode; and
every 5 minutes if the radar is operating in storm mode).

>regards,

Tom


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