Tropopause Pressure???

[Jim Parsons]

I am looking for an explanation of the tropopause pressure maps. What are they? How would they play into the forecasting of severe weather? Any info on this topic would be great...Thanks.

 

[Mark Blue]

Jim,

I use Haby Hints http://www.theweatherprediction.com/habyhints/ quite a bit when an atmospheric question comes up that I need more information on. I searched the Haby Hints website for tropopause and found the following results:

http://bit.ly/b6buq3

I'm sure someone like Patrick Marsh or Jeff Snyder (or any of our other highly qualified mets) will be able to get into all of the technical details of your question, but this is a good place to start.

Thanks,
Mark

 

[Jeff Duda]

The tropopause pressure field is simply the pressure value at the tropopause. I can't think of anything much more complex to consider. Maps of such probably wouldn't offer you any more help in forecasting severe weather than would analyzing a map of 300 mb, 250 mb, or 200 mb heights. They'd tell you almost the same thing. I suppose you can get information on tropospheric folds or the intensity of an upper level trough/disturbance, but again, looking at heights would tell you just about the same thing. I suppose, however, that since the equilibrium level (EL) is a function in some way of the height of the tropopause, then any parameters that are a function of EL are thus a function of tropopause pressure. One such variable is CAPE. Since unstable parcels rapidly become stable with continued upward motion into the tropopause, the lower the tropopause, the lower a parcel will lose its buoyancy and momentum. Another such variable is effective bulk shear. But a parameter like effective bulk shear seems to concentrate on shear in the lower half of the troposphere, so the actual level of the tropopause doesn't have any huge effect on this parameter.

 

[Patrick Marsh]

I don't have much tonight to post, but thought I'd mention that tropopause pressure maps tend to be used heavily in what is known as "IPV" thinking. (IPV = Isentropic Potential Vorticity). IPV thinking is another way of analyzing the troposphere, similar to looking at pressure maps, isentropic maps, etc. It's the pressure in the upper-troposphere where we reach a specified threshold of "Potential Vorticity Units" (PVU). A lot of people use 1.5 or 2 PVUs as their threshold.

You can view a layer version "Potential Vorticity" on the SPC Forecast Tools page under upper air products (Example shown here: http://w1.spc.woc.noaa.gov/exper/mesoanalysis/s19/padv/padv_sf.gif)

If I get some time this weekend, I'll post about some thing to look for with Tropopause Pressure maps and IPV thinking in general.

 

[mikegeukes]

Some Links that may be useful:
http://wind.mit.edu/~reanal/pv.html
http://asp1.sbs.ohio-state.edu/imageg.php?dispimg=/upperair/tropopause&imgname=Tropopause+Height
http://www.atmos.albany.edu/student/mjd/maproom.html
http://www.atmos.albany.edu/facstaff/rmctc/DTmaps/animSelect.php
http://www.atmos.washington.edu/~hakim/tropo/info.html