ATM350 Week 3

Thursday, Feb. 6, 2014

 

Let's continue making some basic products with the Integrated Data Viewer (IDV).  On Tuesday, you were tasked with the first two products below.  Today, let's tackle the remainder.

 

Once again, if you have not completed last Thursday's lab exercise, nor this past Tuesday's, be sure to do those first.

 

So items 3-6 are on our to-do list today:

 

1.    A 24-hour loop of surface observations

2.    A map of RAOB observations at 850 hPa (mb)

3.    A visible satellite image

4.    A loop of forecast 850 hPa height and temperature from the NCEP's NAM model

5.    A national radar reflectivity composite

6.    A Skew-T based on an Albany, NY RAOB

 

Task 1:  Display a visible satellite image

 

Start up the IDV.  If it was already running, clear out any previous displays and datasets by clicking on Edit  As always, you will see the Map View and Dashboard windows pop up.  If you haven't already disabled the Help Tips window, it appears too.

 

As you did last week, in the Map View window, go to the Projections tab and uncheck Auto-set projection and then set your map projection to CONUS. 

 

Now let's go to the Dashboard window.

 

Click on the Data Choosers tab.  In the list of data choices in the left frame, select Images, which appears just below the Sat & Radar header. By default, the data server and dataset should be, respectively, adde.ucar.edu and RTIMAGES. 

 

Click on Connect.

 

For Image Type, select GOES-East 0.65 um Visible.   Select the 6 most recent times, leave the rest of the options unchanged, and click on Add Source.

 

Notice that the Create display box is checked.  Upon clicking the Add Source button, the IDV will retrieve the satellite imagery and then populate the Map View window with a six-frame animation of the most recent satellite images for the visible part of the spectrum:

Do you notice that the eastern part of North America is essentially dark?  Recall that on the visible channel, the satellite "sees" what we would see, and after sunset, the image has no brightness.  Here, we nicely see the shadow of the sunset arcing from north-northwest to south-southeast in the northern hemisphere, as it would for early Feburary.

 

As we've done before, Save your loop as an IDV bundle with the name GOES_East_Vis to your /spare11/atm350/<userid>/idv directory, and also publish it to your folder on the RAMADDA server (both the saving to disk and the publishing  to RAMADDA are done via the Save as dialog window).

 

 

Task 2:  Display a loop of 850 hPa geopotential height and temperature from the most recent run of the NAM forecast model

 

Wipe your IDV slate clean via the Edit Remove all displays and data as you've done before.

 

Back to the Dashboard window and the Data Choosers tab once more.  In the left-hand frame, do you see an entry for Grid, or Model, or the like?

 

Neither did I!

 

For gridded model data, we typically look for them in Catalogs of data servers.  Some of them come directly from NOAA data servers; some from Unidata, where the IDV is developed; and many more from data servers all over the globe, including, as it turns out, our department's RAMADDA server.  For this task, we will "order" from the Unidata catalog.

 

Click on Catalogs.  The default catalog in IDV is http://www.unidata.ucar.edu/georesources/idvcatalog.xml.

Dig down to the 80 km NAM model dataset by clicking/expanding this path:  NCEP Model DataˆNorth American Model (NAM)ˆNAM-CONUS 80kmˆfilesˆLatest NCEP NAM CONUS 80km.

 

 

Click on Add Source.  Once you do this, the Dashboard window displays its Field Selector tab:

 

 

We will create a map that plots geopotential height with contour lines, and also color-filled contours of temperature, at the 850 hPa pressure level. First, let's draw the height contours.  Under the Fields frame, expand the 3d grid entry.  Select Geopotential height @ isobaric surface, contour plan view.  Under the Times tab, leave it as its default value which selects all forecast hours.  For Level, choose 850 hPa.  Leave Region and Stride be.

 

Click on Create Display!  The Dashboard now shows its Displays tab.  Note that on the far left of this window, a View 1 frame includes two entries; the first, the Default Background Maps, which are just your map backgrounds that appear in the Map View window whenever you launch the IDV.  Below it, and highlighted, is an entry for the geopotential height field you just selected.  The main part of the Dashboard window includes various controls which let you manipulate how these contour lines are displayed.

 

 

We'll get back to that in a second, but now, go to your Map View window.  It should look something like this:

 

Not bad, but the blue contours don't look great against our blue map background.  Let's fix that by clicking on the Geopotential_height_isobaric link just underneath the Plan Views header in the Legend frame.  Note that this brings back up your Dashboard window with its Displays tab active, just as you saw immediately above.

 

Next to the Color Table entry, click on the Default button.  This will bring up a variety of color tables you can choose, including ones that you added when you installed the six color table plugins last week.  Following the screen shot below, choose a white, solid color for your contour lines:

 

 

Once you click on the white color, the change takes effect immediately, as you can see on the Map View window:

 

Now it's time to overlay isotherms at the 850 hPa level.  Go back to your Dashboard and select the Field Selector tab.  Note that it retains the settings you made.  Make just two changes now; select Temperature @ isobaric surface and Color-filled contour plan view. 

 

Click on Create Display.  Here's what our Map View displays:

 

 

Satisfied?  You shouldn't be.  We've got a couple problems here; first; our map backgrounds have seemingly disappeared, as have the labels of our geopotential height contour lines.  We'll correct the former now, and save the explanation for the latter for next week.

 

Why did the map backgrounds vanish?  Here, we have to remember that the IDV "knows" about 3-dimensional views.  Click on the Default Map Backgrounds link in the Map View Legend frame to bring up its properties once again:

 

Look at the Position slider.  It is set all the way to the left, at the bottom of the Map View window.  It turns out that the 850 hPa surface is higher than the bottom, in the IDV's 3-d view space.  Our filled contours of temperature have effectively obscured the map background.  So, our geographical map outlines did not disappear after all!  The simplest thing to do is just place the map backgrounds at the very top of the view window.  So just slide the Position slider all the way to the Top.  The effect is visible in the Map View  window immediately:

 

So our map is not perfect, but it's getting better.  Try zooming in or out so that you get the NAM model data (remember, the NAM is a regional model that just covers part of North and Central America) filling more of the Map View window.  Play the animation to see how the geopotential height and temperature contours change as the forecast cycle progresses.  Then, do a Save As and name your IDV bundle 850hPaZandT; as always, don't forget to publish it to RAMADDA.

 

Task 3:  Display a loop of NEXRAD base reflectivity, national composite

 

Remove all displays and data.  This time, under the Projections tab in the Map View window, check the Auto-set projection box.  In the Dashboard, under Data Choosers, select Images as you did for the GOES-East Visible task earlier today.  While you will still connect to our old faithful adde.ucar.edu data server, this time, scroll down in the Dataset box and select NEXRCOMP.  Click on the Connect button.  For Image Type, please choose 1km N0R Base Reflectivity Composite.  Select the 10 most recent times. 

 

Leave the rest of the window options as they are set by default, and click on Add Source.

 

Compared to the battle the previous task gave us, this is pretty straightforward, and looks pretty good.  Play the animation to see the progression of the echoes.  Save the bundle in the usual manner as NationalBaseRefl.

 

Task 4:  Create a loop of Skew-T profiles for Albany, NY

 

Remove all displays and data.  In the Dashboard's Data Chooser tab, select RAOB under the Observations header in the left-hand frame.  By default, the Soundings: Remote tab is active.  The data server remains the same, adde.ucar.edu; the Group is RTPTSRC (sounds like real time point source, ehh?).  Be sure the 00 & 12Z box is checked.  Click on Connect:

 

Use a combination of the zoom and directional buttons at the bottom of the world map that appears until you see Albany's RAOB site number, 72518.  Click on it so it turns red.  Choose a date and time of your source (beware ... the latest time may actually be after the current time!).

Click on Add Source.  The Field Selector tab of the Dashboard appears. 

 

 

Make no changes; just click on Create Display.  Up pops your skew-t:

 

 

We'll explore it more next week; one thing you may notice is that there is no option here for relative time selections.  Thus, when you save this as an IDV bundle, it will always be tied to the date and time you selected here.  Save your settings as a bundle called AlbSkewT to your ATM350 and RAMADDA directories.

 

You've now created a variety of real-time products with the IDV!  Next week and beyond we will explore additional products, as well as ways to improve on the look of the products you have made.

 

Exit out of the IDV, and remember to log out of your workstation!

 

Enjoy your weekend and see you next Tuesday!