Enhanced Nighttime Fog and Low Stratus Occurrence Over the Landes Forest, France

Understanding the drivers of fog and low stratus (FLS) cloud occurrence is important for traffic, ecosystems, and climate models, but it is challenging to analyze due to the complex interactions between meteorological factors and land cover. Here, we use active and passive satellite data, as well as reanalysis data to investigate nighttime FLS occurrence over the expansive Landes forest in France from 2006 to 2015. We find significant FLS enhancement over the forest compared to surrounding areas, especially in summer and fall. Lower wind speed and lower temperatures are found over the forest at night, which can enhance FLS development over the forest. Still, other drivers, such as biovolatile organic compounds acting as cloud condensation nuclei, are most likely important as well. The results show that the influence of forests on boundary layer clouds is not limited to convective daytime conditions.

Automated summary

Understanding the factors driving the occurrence of fog and low stratus (FLS) clouds is crucial for various aspects including transportation, ecosystems, and climate models. A study on the nighttime FLS occurrence over the Landes forest in France from 2006 to 2015 using satellite and reanalysis data reveals a significant enhancement of FLS occurrence over the forest compared to surrounding areas, particularly in summer and fall. The findings suggest that factors such as lower wind speed, lower temperatures, and biovolatile organic compounds may contribute to the development of FLS over the forest.