Laboratory for
Climatology and Remote Sensing

Abstract:

Fog is a weather phenomenon that affects all of us, both in the business and private sectors. On the one hand it is vital for entire ecosystems worldwide, on the other hand it can lead to immense economic damage (airport etc.) and even life-threatening situations, for example in road traffic. The positive as well as the negative implications demonstrate the urgency of a good understanding of fog events and their prediction. Fog forecasting has been a subject of research for many years. However, due to the complex interactions of a wide variety of variables relevant for fog formation, accurate prediction still remains very difficult. One reason for this is that the simulation of parameter interactions which are difficult to capture by modelling is affected by errors due to the complexity of the system. Another reason is the neglected but most likely important combination of temporal and spatial variables, which is currently not taken into account by the models. This is mainly due to the lack of suitable approaches for the combination of temporally high-resolution station measurements of fog-relevant variables and area-wide high-resolution satellite data.

Abstract:

A European fog climatology of fog frequency and fog properties which is based on a 10-years time series of NOAA-AVHRR data is under preparation. In this paper, preliminary results are presented. A fog map for 63 days provides a clear distinction of fog frequency in Europe: The pre-alpine basins reveal the highest fog frequency, a secondary maximum is observed for the river valleys of the lower mountain ranges and the fog minimum is located in the transition zone between the maritime coastal fog of the North Sea and the area of continental valley fog of the river valleys. The potential of VIS and MIR data for the calculation of fog optical and microphysical properties are discussed in the scope of a case study.