Time response characteristics for the atmosphere-plant-interaction, measured during the total solar eclipses in southern Germany on August 11, 1999 (Formerly paper P1.7)

The atmosphere - plant - interaction processes (photosynthesis, evapotranspiration) are forced by insolation. The determination of response times is important to im-prove our knowledge about the different mechanisms of exchange processes. The solar eclipse on Aug. 11, 1999 in Southern Germany was an ideal event for study-ing these response times. A special experiment within the Bavarian Solar Eclipse Experiment 'BaySoFi' was held near Freising/Weihenstephan over a well transpi-rating maize field. Measurements of all radiation fluxes, turbulent fluxes of heat, water vapour and CO2 as well as photosynthesis were done. We found the response times on the rapidly changing incoming radiation clearly showed different time scales from two minutes for photosynthesis up to 10 and 20 minutes for turbulent fluxes. With the beginning of the eclipse totality the turbulence suddenly collapsed and night time conditions occurred. The turbulence was closely linked to an increase of all turbulent fluxes and recovered about 20 minutes after totality ended.