Dynamic Response of Surface Layer Turbulence due to Solar Radiation Change

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Atmospheric turbulence measurements were carried out with solar radiation measurement at various surface conditions. The observation system consists of 3-dimensional sonic anemometer, thermocouple psychrometer, infrared hygrometer/carbon dioxide meter and temperature profile system.1. According to the measurements at various surface condition, such as sea surface, paddy field farm land and bare soil, it is found that influence of solar radiation change is most sensitive to heat capacity of the surface. The surface boundary layer over sea surface is less sensitive to solar radiation change.2. Based on the measurements over paddy field, turbulent flux of sensible heat is mostly influenced by radiation change and water vapor flux and carbon dioxide flux are less sensitive. We should take into account of plant physiology when surface vegitation are observed.3. Temperature fluctuations were observed at 8 logarithmic levels up to 1.28m from the bare soil surface. It is found that surface temperature responds to solar radiation change with time constant of 2-2.5 minutes. Air temperature follows to surface temperature change. The air temperature at higher levels responds with a small delay than the lower level. The peak of air temperature is not always consistent to surface temperature but it reaches to a peak before the surface temperature maximum.4. The mechanism of surface boundary layer response is found as follows. Surface. temperature changes due to solar radiation change. and increase the temperature turbulence. As a result, sensible heat flux increases and finally it turns to higher air temperature.