Height Contours 1000 hPa:
- Upper Wave S of Ireland:
There is a pronounced surface trough, typical for a Cold Front, but it is not to the rear of the cloud band
in the area of the Wave bulge but closer to the leading edge of it. This is typical for an Upper Wave.
- Upper Wave over the Atlantic (40N/30W):
There is no frontal trough configuration at this stage. Indeed, the isolines are part of a high pressure area.
Height contours 500 hPa:
- Upper Wave S of Ireland:
There is a broad, pronounced upper level trough behind the cloud bulge of an Upper Wave. A narrowing and
intensification of this trough, common for Upper Waves, cannot be seen yet.
- Upper Wave over the Atlantic (40N/30W):
The broad trough behind both parts of the frontal system shows a sharpening of the trough immediately behind
the small Wave bulge. This is a typical indicator of an Upper Wave.
Height Contours 300 hPa:
- Upper Wave S of Ireland:
There is a broad pronounced upper level trough behind the cloud bulge of an Upper Wave; a narrowing and
sharpening of this trough , as it is very usual for Upper Waves cannot be seen yet.
- Upper Wave over the Atlantic (40N/30W):
The broad trough behind both parts of the frontal system shows a sharpening of the trough immediately behind
the small Wave bulge. This is a typical sign for an Upper Wave.
Isotachs 300 hPa:
- Upper Wave S of Ireland:
There is a distinct jet streak, and the bulge in the Upper Wave cloud is in the right entrance region. This is
very typical for the initial stages of an Upper Wave.
- Upper Wave over the Atlantic (40N/30W):
There is also a pronounced jet streak and the slight Wave bulge is in the jet streak entrance region. However,
the jet streak and jet axis is shifted to the south in relation to the cloud edge
Curvature Vorticity 300 hPa:
- Upper Wave S of Ireland:
There is a distinct maximum in curvature at high levels indicating a sharp upper level trough. This is a
typical sign for an Upper Wave.
- Upper Wave over the Atlantic (40N/30W):
The same is true for the second Upper Wave, but the curvature maximum is even stronger.
Shear Vorticity 300 hPa:
The zeroline of shear vorticity at 300 hPa which is a good measure for the jet axis is along the rearward boundary of
the cloud band. This is very typical for the conceptual model of a Cold Front and an Upper Wave within this Cold Front.
Especially at the cyclonic side of the W-E oriented part of the cloud band a distinct maximum of shear vorticity
indicates a pronounced jet streak there.
PVA 300 hPa:
- Upper Wave S of Ireland:
There is a distinct PVA maximum at 300 hPa within, but a bit downstream from the cloud bulge of the Upper Wave.
If this parameter is compared to that showing curvature vorticity, the connection of both fields is clearly
seen. This is very typical for an Upper Wave.
- Upper Wave over the Atlantic (40N/30W):
There is a distinct PVA maximum at 300 hPa within, but a bit downstream from the cloud bulge of the Upper Wave.
If this parameter is compared to that showing curvature vorticity, the connection of both fields is clearly
seen. This is very typical for an Upper Wave. This western Upper Wave has stronger values of curvature and PVA
than the Upper Wave to the east.
Height of PV=2 units:
- Upper Wave S of Ireland:
On the rear side of this Upper Wave the gradients show that dry stratospheric air is not directly behind the
Upper Wave but further to the NW. This is also connected to the fact that the upper level trough has not yet
sharpened.
- Upper Wave over the Atlantic (40N/30W):
In this case there is already a PV anomaly with dry stratospheric air reaching down to 450 hPa. This is in
accordance with the already very sharp upper level trough behind the Wave bulge. And this is also typical for
a well developed Upper Wave.
TFP:
The TFP accompanies the whole frontal cloud band. While it is close to the leading edge of the Cold Front band in the
W-E oriented part, indicating an Ana Cold Front, it is more to the rear of the N-S oriented cloud band. Both
configurations are in agreement with the conceptual model of an Upper Wave.
Temperature Advection 700 hPa:
- Upper Wave S of Ireland:
There is CA in the whole area of the Upper Wave cloud bulge, as well as in the surrounding area of the Cold
Front cloud band. This is the most important parameter to determine whether a cloud bulge is a classical Wave or
an Upper Wave. In this example there is a very typical distribution of temperature advection.
- Upper Wave over the Atlantic (40N/30W):
In this more western Upper Wave there is also an extended area of CA which provides a hint for identifying this
Wave bulge as an Upper Wave. But WA can be seen in the leading edge of the Cold Front. Whilst this contradicts
somewhat the classical situation, this Wave bulge does appear as a very distinct Upper Wave, so this small
deviation in TA from normal is not so important.