Distribution of precipitable water in southern Greece in support of solar radiation models

Precipitable water by reflecting the total water vapour amount in zenith direction between the surface of the earth and the top of the atmosphere is considered an important parameter for solar radiation models. However, lack of ground data and/or radiosoundings in the examined area results in the inability to calculate precipitable water with further implications in the results of solar radiation models. The aim of this study is the estimation of the probability distribution function of the annual mean of precipitable water for Southern Greece. For the purpose of the study, radiosoundings of the National Meteorological Agency at Hellinicon station were used to obtain the daily values of water vapour for the period 1974-1995. Results were compared to measurements to show satisfactory agreement, a fact which allows their use for solar energy studies - as well as for energy budget calculations - in Southern Greece where in situ measurements are missing.