UPPER WAVE - TYPICAL APPEARANCE IN VERTICAL CROSS SECTIONS
by ZAMG
- Isentropes
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Isentropes show mainly frontal character. No impact from Upper Wave - Temperature Advection:
Maximum at 300 hPa or at higher levels, connected to tropopause folding (related to potential vorticity), cold advection below the Wave bulge at lower levels - Vorticity Advection:
Significant maximum of positive vorticity advection at upper levels connected to the sharpening of the upper level trough at 300 hPa - Vertical motion:
Vertical motion indicates rising air, with the maximum at upper levels, due to a rising upper relative stream
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07 February 2003/12.00 UTC - Meteosat IR image; position of vertical cross section indicated
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Temperature Advection
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07 February 2003/12.00 UTC - Vertical cross section; black: isentropes (ThetaE), red thin: temperature advection - CA, red
thick: temperature advection - WA, orange thin: IR pixel values, orange thick: WV pixel values
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Vorticity Advection
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07 February 2003/12.00 UTC - Vertical cross section; black: isentropes (ThetaE), green thin: vorticity advection - NVA, green
thick: vorticity advection - PVA, orange thin: IR pixel values, orange thick: WV pixel values
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Vertical Motion
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07 February 2003/12.00 UTC - Vertical cross section; black: isentropes (ThetaE), cyan: vertical motion (omega) - upward
motion, orange thin: IR pixel values, orange thick: WV pixel values
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Potential Vorticity
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07 February 2003/12.00 UTC - Vertical cross section; black: isentropes (ThetaE), dark green thin: potential vorticity <1
unit, dark green thick: potential vorticity >=1 unit, orange thin: IR pixel values, orange thick: WV pixel values
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Distinction between Wave and Upper Wave according to vertical cross sections
| Upper Wave | Wave |
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| TA indicates a CF in CA, CA dominates | WA dominates at all levels in the area of cloud band |
| Intense PV sinking only down to 400 hPa, PV=0.8 units below 500 hPa, no significant PV at lower levels | PV = 1 down at middle and low levels, interaction with upper levels |
| Maximum of upward motion at higher levels | Strong upward motion throughout the low and mid levels of the troposphere |
Below left is the case of an Upper Wave, below right is the case of a Wave (2nd row below left shows vertical cross section over Wave bulge). While the Upper Wave has no separate maximum of PV>=1 unit at low levels, the Wave case from the 17 February 2003/12.00 UTC shows a distinct maximum at low levels, which is usually more intense and can exceed PV>=2 units.
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07 February 2003/12.00 UTC - Vertical cross section; black: isentropes (ThetaE), dark green thin: potential vorticity <1
unit, dark green thick: potential vorticity >=1 unit, orange thin: IR pixel values, orange thick: WV pixel values
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17 February 2003/12.00 UTC - Vertical cross section; black: isentropes (ThetaE), dark green thin: potential vorticity <1
unit, dark green thick: potential vorticity >=1 unit, orange thin: IR pixel values, orange thick: WV pixel values
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17 February 2003/12.00 UTC - Meteosat IR image; position of vertical cross section indicated
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