INVESTIGATION OF THE URBAN INFLUENCE ON THE SPATIAL PRECIPITATION DISTRIBUTION AROUND A LARGE TOWN USING DIFFERENT STATISTICAL-METHODS

Using data of the dense Viennese precipitation network, the existence of an urban induced precipitation maximum is investigated by different methods. Especially the fact, that such a maximum could be localized with high statistical significance in the lee-side of the urban heat island in four different methods of investigation, makes it rather unbelievable to be natural or random. The urban induced precipitation maximum was then investigated quantitatively. It could be shown that urban induced precipitation amounts existed every year of the past 30 years over an area of 300 to 1000 km2 with their centers 11 to 31 km eastnortheast to southeast of the city-center. The additional precipitation reached in its center maximum amounts of 75 to 240 mm per year and over the whole influenced area a surplus of 20 to 86 millions of m3, which is a precipitation increase of 7,6 to 17,4%. The percental additional precipitation amounts show a trend of an increase of 40% during the last 30 years. © 1979 Springer-Verlag.