Jet Streak Quadrants

[John Peters]

Can anyone find a good write-up describing the dynamics behind jet streak entrance/exit regions and their relationship with ascent/descent (i would prefer a more mathematical explanation)? I'm fairly certain that this phenomena is due to a-geostrophic flow properties, and cannot be represented through QG theory (this is what I've been told at least).

 

[Chad Cowan]

Jeff Haby has a great section on jet stream dynamics here: http://www.theweatherprediction.com/charts/300/ In short, lift is enhanced in the right-rear and left-front quadrants.

 

[Kenny Drake]

Howie Bluestein covers it quite nicely in "Synoptic-Dynamic Meteorology in Midlatitudes" Vol 2 pages Ch. 2.8. The equations are good for a qualitative analysis but as usual with Dynamics it is hard to quantify variables without taking into consideration approximation error. He uses QG analysis in one and SG in another. I consider both volumes good to have in a book collection for referencing.

 

[David Draun]

If we divide a jet streak in half width wise, we can see two circulations. A thermally direct circulation (warm air rises, cool air sinks) in the entrance region, and a thermally indirect circulation (cool air forced upward, warm air sinks) in the exit region. The places where rising air is occurring are the right entrance and left exit quadrants. This is where the upper level divergence is enhanced. Where the air is sinking in the left entrance and right exit quadrants, upper level convergence is maximized.

Boy I love advanced synoptic meteorology. I can actually attempt to explain some of this stuff.

 

[John Peters]

Thanks for the input guys. I guess one could numerically plot a velocity field based on the raw momentum equations and then use finite differences to identify areas of upper level convergence or divergence. Is there a method of manipulating say the QG omega and height tendency equations in order to quasi-quantitatively analyze the vertical motion field? (i guess i consider QG analysis quasi-quantitative)

 

[Chris Nuttall]

For more info, there's a MetEd module titled "Jet Streak Circulations" that is a very good presentation on this exact subject.

 

[Jeff Snyder]

For more info, there's a MetEd module titled "Jet Streak Circulations" that is a very good presentation on this exact subject.

I highly suggest it to any interested party! It's a great overview of jet streak dynamics... The exact link is http://www.meted.ucar.edu/norlat/jetstreaks/ ... You may need to register if you haven't already, but it only takes a minute to register. Again, highly suggested, even for those who don't care about the math of it.