First results of a high resolution surface automatic station network during COPS

During the COPS field phase, the University of Vienna group operated amongst other instruments a high resolution net of more than a 100 automatic weather stations at Supersite S on the East slope of the Black Forest, Southwest of Stuttgart. This area is characterized by a moderately complex terrain, with a terrain elevation variation of a few hundred meters. The station distance was chosen approximately 1km and the temporal resolution 1 minute.

Much effort was undertaken before, during and after the experiment to calibrate and check the sensors and to learn about the absolute and relative accuracy of the instruments. It could be shown that the observed values of temperature, humidity, wind and precipitation were of such quality, that meaningful fields of these parameters can be constructed. Only atmospheric pressure required some sophisticated correction procedures to become suitable for the spatio-temporal analysis.

Fortunately a series of convective events and frontal passages hit the region of supersite S during the field phase between June and August 2007, so that the evaluation of the data could address the following questions:

- Is the chosen spacing and time resolution sufficient to resolve the scale of single convective, rain producing cells?

- How strong is the micro climatic effect of the station location influencing the detection of transient weather systems?

- Are derived field quantities like moisture flux divergence in moderately complex terrain useful predictive quantities?

- What is the small scale variability of the field variables during synoptically undisturbed conditions?

- How well can small scale structures like convective outflow boundaries be detected?

- How good is the coincidence between radar derived and in situ observed precipitation?

- What is the added value of such dense surface networks in conjunction to remote sensing platforms?

- How do the areal mean values of the parameters vary with changing station distances?

The list of questions may be easily extended in the framework of the Experiment.

First anwers to these question - some of them quite surprising - have been tried to obtain by conducting case studies during different weather events and will be discussed in the presentation.