In this paper, the author intended to make clear the dependences of wind speed (
U) and net radiation (
Rn) above the bare ground on stability parameter measured by sonic anemometer thermometer. As the stability parameter, we take ζ evaluated from z/L, withz=1.1 m. In the calculation of ζ, L is Obukhov's scale height defined by
L=_??_.
Here, κ(_??_0.40) is von Kármán's constant, θ is the absolute temperature,
g is the acceleration of gravity,
U* is the friction velocity and T,
* is the scaling temperature.
The following results were obtained. Values of show systematical diurnal change taking positive values at night and negative values at daytime. They correspond to the stable and unstable conditions respectively. Whenζ reverses the sign, the outgoing net radiation is balanced with the incoming. The decrease of
log|ζ| with increasing
U is occurred by increasing turbulent mixing as shown in Fig. 5-a and Fig. 5-b. The relation between
log |ζ|and
Rn is approximately linear in the case ofζ< 0, under the unstable condition, as shown in Fig. 6-a, and it is fitted by the line
log|ζ|=0.048
Rn-1.900, In the case ofζ>0, namely under the stable condition, as shown in Fig. 6-b, it is expressed by the equation
log|ζ|=-0.050
Rn-1.096. These relationships mean that the closer
Rngets to zero, the smaller
log|ζ|becomes. Un-der the unstable conditions, the ratio of
Rn/log|ζ|is remarkably large. The correlation between
log|ζ|and
Rn is larger than that between
log |ζ|and
U. Under the stable conditions, on the other hand, large correlation is observed between
log |ζ| and
U as given in Table 2. From the facts described above, it can be concluded that the stability para-meter is estimated from the relationships between
U and
Rn as shown in Fig. 7. A tentative classification of the relations between
U and
Rn is given in Fig. 8.
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