Structure and Evolution of Mountain Waves Produced by the WRF Model

Lab Overview:

The purpose of this lab is for you to learn about the structure and evolution of mountain waves.  You will do this by examining output from a real-time WRF forecast at 10 km horizontal resolution over the northeastern United States.

1. Download the following two files to your home directory:
   • http://apollo.lsc.vsc.edu/classes/met470/labs/mntwaves/xsect.cgm
   • http://apollo.lsc.vsc.edu/classes/met470/labs/mntwaves/planview.cgm
2. Get a feel of the forecast by perusing through the planview.cgm file.  To do so, you will need to log onto the models computer and use "idt" to view the file.

QUESTIONS TO ANSWER:

In answering these questions, you will need to view both the planview.cgm and xsect.cgm files.  We will discuss the fields shown in both files in class.  Create a ppt file that contains answers to the questions below.  Your answers should include both textual discussion and sample images.

1. What time period do you see prominent mountain waves in this forecast?
2. Do they appear to produce down sloping winds?  Are these winds making it to the surface?
3. Do the waves propagate up through the atmosphere?  If so, how high do you see them?
4. Is the Froude number equal to or slightly larger than 1 during the time of mountain wave activity?
5. Draw a schematic diagram showing the relationship between vertical velocity and potential temperature for the mountain waves you see.  Save a sample image of real data to support your schematic.  Physically explain this relationship.
6. Draw another schematic diagram showing the relationship between vertical velocity, the height field, and surface pressure for the waves.  Save a sample image of real data to support your schematic.  Physically explain this relationship.
7. Would you expect these waves to be producing wave clouds?  Why or why not?