Consecutive Observation of Heat Balance on Ground Surfaces with Five Kinds of Covering Materials

Heat balance on a ground surface is one of the greatest element in urban thermal environment． Ground surface samples are made of five covering materials. They are bare ground, lawn, concrete, asphalt and permeable asphalt. Temperature and heat flux on the surface, temperature in the soil and several meteorological elements are measured in and around these samples consecutively. The annual fluctuation of temperature in the soil, the heat balance and the evaporation on the surfaces and so on are examined in this paper. Principal conclusions are as follows: (1) The daily average surface temperatures on the lawn and the bare ground are lower than those on the other artificial materials by 7－10℃ in summer. (2) The soil temperatures at the depth of 80cm under the lawn and the bare ground are lower than those under the other materials by 3－5℃ all year long, (3) The evaporation on the bare ground surface has great influence on the surface temperature. When it is large, the increase of the surface temperature by solar radiation is mitigated. (4) The unpermeable materials can not keep precipitation. The cooling effect by evaporation on these surfaces are hardly found