Synoptic Situation: Numerical parameters
In this chapter the set of satellite images are discussed in combination with a range of NWP parameters. These parameters are derived from the large scale ECMWF model and the smaller scale Aladin model. The ECMWF models is used to describe the synoptic scale patterns that make the conditions for the convection over Germany and Austria, whereas the Aladin model is used to picture the smaller scale details associated to convection such as divergence, ThetaE850 and a stability index such as the Showalter Index. Below the surface analysis of 19th June 2006 as done by the Meteorologists at KNMI is presented in 6 hour interval. Around 00UTC at the 19th of June a depression can be seen over Scotland. As the day evolves this depression slowly moves Northeast in the direction of Skandinavia.
At 06UTC the Meteorologists anlyse a Wave structure in the Cold Front over Normandy. Over Switzerland a high pressure system is analysed and as the convection is about to start several troughs are recorded over Germany and Austria.
ECMWF
Meteosat 8 IR10.8 and Geopotential Height 1000 hPa.: time sequence
In the following chapter the cloud configurations seen in satellite images are related to the basic field of surface pressure represented by geopotential height in 1000 hPa. 6-hourly sequences are shown.
Meteosat 8 IR10.8 and Geopotential Height 300 hPa.: time sequence
In the following chapter the cloud configurations seen in satellite images are related to the basic field of the upper level height in 300 hPa. 6-hourly sequences are shown.
Meteosat 8 IR10.8 and Wind 850 hPa.: time sequence
The convection as a result of the rising motion from the surface are pictured using ECMWF model, in this case 850 hPa.
Meteosat 8 IR10.8 and Thermal Front Paramater and Equivalent Thickness: time sequence
In this chapter the large frontal zone over Western Europe is presented using the Thermal Front Parameter. Along with this parameter also the relative topography is shown.
ALADIN
Meteosat 8 IR10.8 and Temperature Advection 700 hPa.: time sequence
Since thermal advection is analysed on a more synoptic scale it is not likely to play a direct role in the local development of thunderstorms. The horizontal distribution of warm air advection and identifying its maxima is important since it can slightly contribute to upward motion and convection. In this chapter the Thermal Advection at 700 hPa is described in relation to the prefrontal convergence. It is overlayed on Meteosat 8 IR10.8 imagery and presented in 3-hour sequences.
Meteosat 8 IR10.8 and Divergence 925 hPa.: time sequence
Using a LAM model (Aladin) the converging movements near the surface, in this case 925 hPa, can be numerically clarified.
Meteosat 8 IR10.8 and ThetaE 850 hPa.: time sequence
Second way of representing the characteristics of the stability of the atmosphere is by making use of ThetaE 850. In this chapter ThetaE 850hPa is presented, overlayed on Meteosat 8 IR10.8 imagery, in 3 hour sequence.
Meteosat 8 IR10.8 and Showalter Index: time sequence
One way of characterising the stability of the atmosphere is by making use of the Showalterindex. Values under 0 are a sign of a lable atmosphere. Values under -3 are very unstable and are related to thunderstorms. In this chapter the Showalterindex is presented, overlayed on Meteosat 8 IR10.8 imagery, in 3 hour sequence.
Summary of the investigations in this chapter
In this chapter the numerical model fields from both ECMWF and the smaller scale LAM model Aladin where superimposed on Meteosat 8 IR10.8 and WV6.2 images. The set of NWP shows us an extremely unstable situation in the warm sector of a frontal system over the North Sea. The convection is tight to a thickness ridge and in the antcyclonic flow the windfields shows especially near the surface continuing confluent movements. This is also reflected in the convergence at 925 hPa. In small scale situations like convection the higher resolution models are in this case a big advantage as smaller structures can be identified and related to the convective development.