表面温度が周期的変化する系の凍結・融解に関する解析(続報) : 永久凍土地帯における日毎・季節変動の2重周期変化の場合(熱工学,内燃機関,動力など)

It is important to understand the frozen-melting behavior of thermal active layer in permafrost area for dual periodic temperature changes combined with daily and annual cycles. The numerical results are compared with the single cyclic change and discussed on the temperature profiles in detail. The thermal structures are revealed to be consisted of dual Stokes depths and, in consequence, the net heat fluxes at the surface are illustrated to be affected by daily cycle to a certain extent. The influences on temperature profiles due to daily cycle penetrate only in Stokes depth pertinent to its own cycle, while the entire tempkrature distributions are decided by the annual cycle. Additionally, a simple experiment is performed to demonstrate the validity of the findings, predicted in former paper, regading the temperature decreases in deep underground compared with an average (or initial) surface temperature, which is essential to form the permafrost structure.