The influence of a solar eclipse on temperature and wind in the Upper-Rhine Valley - A numerical case study

The effects on temperature and wind caused by the solar eclipse of August 11, 1999 in the south western part of Germany were simulated. While during the real event clouds and precipitation were present in most of the model domain cloud free conditions are assumed for the simulation. A temperature decrease of up to 7 K was simulated during the eclipse event close to the surface. Thermal stability changes from unstable to stable conditions and the temperature gradient reaches values which are comparable to those normally found after sunset. Temperature keeps about 1 K lower after the eclipse event during the rest of the day. Boundary layer height shortly after the eclipse event differs by several hundred meters. The effects on wind speed are rather small with the exception of the slopes of the mountains and in the vicinity of Lake Constance.