Convergence & Divergence in SRV

[Jason McClintock]

Can someone try to explain to me how to detect divergence and convergence in storm relative velocity? If you know of any images those might help also

 

[Greg Blumberg]

No problem. I'll try to find some pictures, but here's the basics: If the green pixels are further away from the radar than the red, that's convergence. But if it's the other way around, it's divergence. Green towards, Red away. Keep in mind that the green and red areas need to be more than just one pixel color.

I really need to find a picture. This is pretty hard to describe.

 

[Greg Blumberg]

Here you go. There's a slide on here that provides an example for convergence. Slide 17 I think. Divergence just happens if you flip the colors around.

http://moe.met.fsu.edu/~acevans/cases/radar.ppt

 

[Jason McClintock]

Thanks a lot, this site is great. Very fast too, lol

 

[Greg Blumberg]

I think you just caught all of us at a good time...when severe weather is happening.

 

[Jason McClintock]

I am still a little confused, how do you know which ones are farther away if they are gate to gate?

 

[Greg Blumberg]

If you mean gate to gate shear, then that is a type of cyclonic or anticyclonic rotation. I haven't heard of gate-to-gate measurements of convergence or divergence. Let me see if I can explain the convergence/divergence/rotation using ASCII pictures.

G = Green (towards)
R = Red (away)
Radar = location of the radar

Examples from different sides of the radar...

Convergence:

(G)(R) Radar

or...

Radar (R)(G)

Divergence:

(R)(G) Radar

or...

Radar (G)(R)


Thus, if the difference of velocity directions exist on the same radial (beam indicated by the line of pixels), then convergence or divergence exists.

However, if it looks like this:

(G)(R)

Radar

(R)(G)


Then the signatures are indicating rotation or shear. If it's a mix of both the signatures of rotation and convergence/divergence, then we call that rotational convergence/divergence. I'd indicate that this works for the other two sides of the radar on all my diagrams, etc., but the HTML is being screwy. When reading velocity data, make mental arrows based on the areas of red and green in order to figure out how air is moving. Hope that helps!

 

[Jason McClintock]

Awesome post, very nice that is what I wanted to know. Thanks again

 

[Jason McClintock]

So if i had a radial the was representing convergence and right after the area of convergence it shows rotation would that be rotational convergence? I mean the converging pixel area is directly connected to the rotation, I will post a pic if you want.

 

[Greg Blumberg]

A picture would be great! Lol. I would assume that you're right with your assumption, but a picture would help be sure.