Abstract
Fluctuations of wind speed and ambient air temperature were measured in an urban and a rural area with a sonic anemometer and a fast response thermocouple in order to obtain sensible heat fluxes by the eddy correlation method. The results may be summarized as follows. (1) Heat storage in the roof is 25〜35% of the net radiation during the day and 50〜100% during night. (2) Roughness parameter in the urban area is 3.4m and 0.41m in the rural area. (3) Measured vertical eddy diffusivities (D_z) are approximately proportional to the wind speed except in case of windless convection. D_z is invariable in the vertical direction and D_z in the urban area is five times as large as in the rural area. (4) Comparing measured sensible heat fluxes at the lower observing sites with fluxes predicted by Tennekes' formula, a constant α_f in the formula is assumed to be 0.3. Sensible heat fluxes in constant flux layer (q_h) are in linear relation to the net radiation (R_n). Sensible heat fluxes in the urban area are usually upward flow and 60〜100W/m^2 larger compared with in the rural area. The rural fluxes are approximately proportional to the net radiation and qn/R_n ratios are 20〜25%.
