Nocturnal Cooling Near the Ground : (2)Characteristics of the Nocturnal Cooling Obtained from Numerical Simulation Model

We tried a computer simulation for the drop of soil temperatures during night by giving various values to the boundary conditions and found a very good correspondence between measured values and calculated values. The numerical analysis showed that factors affecting on nocturnal cooling near the ground were effective radiation, wind speed, degree of dryness of soil and advection of cold air in upper air layer. The sensible heat flux related to the strength of wind speed and soil heat flux related to the thermal properties of soil are important to heat supplying source to the surface of the ground during the period of nocturnal cooling. The response time of temperature from surface to upper air layer which was obtained from observation of air temperature changes with time is approximately proportional to the response time of the eddy transfer by assuming to be Z^2/4K.

eddy transport

nocturnal cooling

radiative cooling

simulation experiment