Ogólna charakterystyka termiczna doliny Wisły w obszarze Warszawy = A general thermal characterisation of the Vistula Valley in Warsaw

Abstract

Rivers flowing through cities and their valleys serve many functions, having also a special role in the amelioration of the urban climate. Within the city limits of Poland’s capital city, Warsaw, the River Vistula flows over a distance of 31.5 km, in a valley of maximum width 2 km. The river is regulated and enclosed within flood embankments. Its left bank, in the districts of Śródmieście and Żoliborz especially, is high and partly built over with boulevards; while the right bank is low and natural, with sandy beaches and walking and cycling paths. Despite the long-term transformation, the Vistula Valley still has an extremely valuable role in the natural system. Most of it enjoys Natura 2000 protection (from the points of view of flora, fauna and the Valley itself). While the Vistula Valley in Warsaw certainly constitutes the city’s main and most effective area of ventilation and air regeneration, knowledge of its thermal conditions remains scant. That is somewhat paradoxical, given worldwide study of urban climate since the 1830s, with considerable urban-focused interest among Polish climatologists also not leading to much elucidation of the river-valley climate within the city. Through the work carried out it proved possible to demonstrate differences in the thermal regime in Warsaw’s Vistula Valley, depending on the location and the immediate vicinity of the studied point. The amplitude in average daily air temperature is lower where density of buildings is greater, and where the ratio for the presence of biologically active areas is lower. The northern and southern parts of the Valley in Warsaw are characterised by similar thermal conditions, while the downtown part differs clearly from these places, being much warmer, but also much more likely to play host to the “cold spot” phenomenon.