A satellite-based analysis of fog and low stratus life cycle processes in the Po valley, Italy

A better understanding of fog and low stratus (FLS) life cycle processes can help traffic safety, improve solar power planning and enhance the understanding of ecosystem processes in fog-prone regions. Nevertheless, large-scale analyses of FLS life cycle processes are challenging due to the high spatial variability of FLS and complex interactions between the land surface and the atmosphere.

Here, we use a satellite-based FLS formation and dissipation time data set, as well as reanalysis data to investigate regional variations in the FLS life cycle in the Po valley region in northern Italy. With its large spatial extent, relatively low topographic variability and high FLS occurrence, the Po valley is an ideal area to study FLS life cycle processes in central Europe. In a case study approach, we analyze FLS life cycle processes pertaining to variations in land surface characteristics and atmospheric drivers. First results reveal the importance of the temporal development of temperature, specific humidity and boundary layer height for FLS formation during radiation-driven FLS events. These effects are further modified by the local topography and the synoptic situation.

This analysis provides a basis to set up further process-oriented sensitivity studies using explainable machine learning, which has shown to be an ideal tool to gain a deeper understanding of the effect of non-linear land-atmosphere interactions on the FLS life cycle.