DVA Maps SPC Mesoanalysis

[H2Otown_WX]

This past semester I learned that in the vorticity equation, there is a forcing term that relates PVA to rising motion. However, it isn't so much the PVA that forces rising as much as the difference between PVA values with height. An upward increase of PVA tends to 'force' rising motion. So I look at the SPC mesoanalysis map of DVA from 700 to 400 mb and I'm unsure what the positive and negative values mean and I don't see an explanation on their page. I assume it is the value of vorticity advection at 700 mb minus the value at 400 mb? If anyone can clarify this it would be appreciated.

[isohume]

This past semester I learned that in the vorticity equation, there is a forcing term that relates PVA to rising motion. However, it isn't so much the PVA that forces rising as much as the difference between PVA values with height. An upward increase of PVA tends to 'force' rising motion. So I look at the SPC mesoanalysis map of DVA from 700 to 400 mb and I'm unsure what the positive and negative values mean and I don't see an explanation on their page. I assume it is the value of vorticity advection at 700 mb minus the value at 400 mb? If anyone can clarify this it would be appreciated.

 

DVA is positive where vort adv increases with height (DPVA) and negative for the opposite case (DNVA). On the SPC meso page...the blue contours show DPVA and the red indicates DNVA. DVA is always the vort adv at the lower pressure minus the value at higher pressure (ie: H4-H7).

[H2Otown_WX]

DVA is positive where vort adv increases with height (PVA) and negative for the opposite case (NVA). On the SPC meso page...the blue contours show PVA and the red indicates NVA. DVA is always the vort adv at the lower pressure minus the value at higher pressure (ie: H4-H7). 

Okay, thanks for clearing that up isohume!