WATER VAPOUR VORTICES - KEY PARAMETERS
by KNMI
- Potential Vorticity on an isentropic surface.
PV distribution shows a long narrow elongated zone of high PV values, associated with a Dark Stripe in the WV imagery. Local maxima occur in this elongated zone, connected to the cyclonic centre of the vortex. - Geopotential Height at 500 and 300 hPa
In the large scale geopotential height field a flow can often be seen which is non-zonal. The WV vortex is located in a region where a smaller trough is superimposed on the large scale trough. The geopotential height pattern at 500 hPa shows a small scale trough. At 300 hPa a small scale low can often be found with some enclosed contours. - Windspeed 300 and 250 hPa
The WV Vortex is often located on the cyclonic side of a minor jetstreak, located on the southern (warm) side of the polar jet stream - Curvature Vorticity at 500 and 300 hPa
The field of Curvature vorticity shows a marked maximum close to the centre of the cyclonic circulation - Shear Vorticity at 500/300 hPa
The Shear Vorticity has the following characteristic: The zero-line of Shear Vorticity is located in the transition zone between high and low WV values. A maximum of shear vorticity lies close to the centre of the cyclonic vortex. - Potential Vorticity Advection (PVA)
An area with PVA-max is found at the leading edge of the minor trough. (See Typical appearance in vertical cross section) - Omega
Mostly weak vertical velocity can be seen in the Vertical Cross Section (VCS). At synoptical scale, the vertical velocity is downward (subsidence: negative omega). However, in the VCS small positive values are found near the leading edge of the trough. (See Typical appearance in vertical cross section)Potential Vorticity on an isentropic surface
27 July 2002/06.00 UTC - Meteosat WV image; red: potential vorticity 333K
Geopotential Height at 500 and 300 hPa
27 July 2002/06.00 UTC - Meteosat WV image; geopotential height 500 hPa
Windspeed 300 and 250 hPa
27 July 2002/12.00 UTC - Meteosat WV image; windspeed 300 hPa
Curvature Vorticity at 500 and 300 hPa
19 December 2002/00.00 UTC - Meteosat WV image; blue: curvature vorticity 500 hPa
Shear Vorticity at 500 and 300 hPa
19 December 2002/00.00 UTC - Meteosat WV image; brown: shear vorticity 500 hPa
