Derived Parameters
In this chapter the satellite images will be further investigated in combination with derived meteorological parameters assumed to be key parameters in the development of an instant occlusion:
Temperature Advection 700 hPa, IR Images: time sequence
In the following chapter the cloud configurations seen in satellite images are related to temperature advection. 6-hourly sequences are shown.
Jets (Isotachs) + PVA 300 hPa, IR Images: time sequence
In the following chapter the cloud configurations seen in satellite images are related to isotachs and PVA. 6-hourly sequences are shown.
PVA 500 hPa, IR Images: time sequence
In the following chapter the cloud configurations seen in satellite images are related to PVA. 6-hourly sequences are shown.
TFP + Rel. Topography, IR Images: time sequence
In the following chapter the cloud configurations seen in satellite images are related to the thermal front parameter. 6-hourly sequences are shown.
Height of PV=2 unit, WV Images: time sequence
In the following chapter the cloud configurations seen in satellite images are related to PV=2. 6-hourly sequences are shown.
Summary of the investigations in this chapter
The following conclusions can be drawn from the presented parameters:
- Cold advection is connected to the area behind the cold front where the development of the comma-like cloud feature takes place. At the merging stage the distribution of TA is nearly like in an ideal case of an instant occlusion.
- The jet stream is coming from NW direction and its axis follows the rear side of the cold front band. The merging of the comma and the frontal cloud band takes place in the area of strong PVA which is linked to the left exit region of the jet streak.
- The comma feature is superimposed by strong PVA at 500 hPa as well as the cloud band of the cold front. During the merging process these two maxima of PVA merge as well.
- A maximum of the thermal front parameter is typically found at the leading edge of the cold front.
- An unusually high PV Anomaly is involved in the process. This could be an explanation for the deep cyclogenesis and high wind speeds. The maximum of PV=2 coincides well with the dark areas in WV images.