SPATIAL AND TEMPORAL VARIABILITY IN MICROCLIMATE AND EVAPORATION OVERLAKE KINNERET - EXPERIMENTAL EVALUATION

Microclimate characteristics and latent and sensible heat fluxes were measured continuously and simultaneously over Lake Kinneret, Israel, d uring two consecutive summers at the eastern (fin Gev) and western sho res (Sapir) of the lake. The data were used to characterize the variab ility in basic meteorological variables (air temperature and humidity, water surface temperature, and wind velocity) and in evaporation rate s. Analysis of the data on an hourly basis reveals the combined effect of local physical processes occurring during airflow over water surfa ces and the diurnal regional phenomena of the inland penetration of th e Mediterranean sea breeze downslope into the area during the afternoo n hours. The resulting strong, hot and dry westerly winds at the weste rn coast become weaker, cooler, and more humid as they reach the easte rn shore after a delay of 1-2 h. Consequently, the maximum evaporation rate at Sapir was occasionally twice the corresponding rate at fin Ge v. The data on a daily basis depicted the influence of synoptic system s on the regional climate. Commonly, the mean evaporation rate from th e entire lake is assumed to be equal to that evaluated at a specific s ite. Considering the observed variability, this assumption might lead to errors as large as 100% on the daily basis and of 15% on the season al basis.