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 1 1, 1999 in the south western part of Germany were simulated. While during t he real event clouds and precipitation were present in most of the model do main cloud free conditions are assumed for the simulation. A temperature de crease of up to 7 K was simulated during the eclipse event close to the sur face. 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 eve nt during the rest of the day. Boundary layer height shortly after the ecli pse 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 v icinity of Lake Constance.