Field measurement of the influence of large urban river on urban thermal climate

To obtain the specific influence of urban river on urban thermal climate in summer, fixed-point observation method is used to one-month field measurements in the section of Songhua River Basin in Harbin, and the data collection and analysis on temperature variations from several underlying surfaces and the atmosphere and dynamic thermal budgets have been finished. The results indicate that during the sunny days, ground surface temperature is mostly affected by solar radiation, and it is about 14°C higher than atmosphere temperature above the river, while water temperature is about 3°C lower than atmosphere temperature above the river. Meanwhile, net radiation rate reaches to 700 W/m², while sensible heat flux and latent heat flux account for a small proportion of net radiation: only 0.2% and 1.8% respectively. The majority of net radiation could be considered to penetrate into the water through heat conduction and transmission while most of which is taken outside city as the river flows during sunny day. During the rainy days, the water temperature is about 2°C higher than atmosphere temperature above the river, and the net radiation is about 100 W/m², while the proportion of the sensible heat flux and latent heat flux in the whole net radiation is about 9.5% and 51.3%, respectively, which means that the main of net radiation from water surface returns to the atmosphere in the way of convective heat transfer and mass transfer.