Urban heat budget and waste water heat discharge in Moscow

Urban heat island (UHI) phenomena is the central subject in urban climate investigations. Mesoscale air temperature anomalies in urbanized areas are the result of anthropogenic impact on natural energy transport, absorption and exchange processes as well as the emission of heat, used for heating, hot water supply and in transportation sector. These are the anthropogenic entry parts of urban canopy layer (UCL) heat balance. This study quantifies the amount of heat, discharging from urban area via sewerage systems with waste water. This way of heat loss is the main anthropogenic spending part of UCL heat balance. The waste water heat discharge (WWHD) goes in two major ways: heat eliminated from the city with the warmed water of Moscow river and by sewerage collectors to the water treatment stations located in rural area. Thus estimation of monthly mean and annual WWHD were carried out with the use of data set (initial and outgoing water volume and temperature), received from regular hydrological observations and obtained from municipal authorities responsible for sewerage. As is shown for the period 1998-2002 WWHD from the total area of Moscow ranges from 2.5 to 6 · 10⁹ J s^-1 in summer and in winter respectively, exceeding 26.3 ·10⁶ J m^-2 in January in residential districts. This value is twice as big as a sum of direct solar radiation (11·10⁶ J m^-2 ) and consists a half of total incoming solar radiation (63·10⁶ J m^-2 ) in this month. These values are substantial enough to be not ignored in urban climate investigations.