エントロピー交換率極小の気候

Abstract

An entropy balance equation including radiative heating is developed to examine the principle of minimum entropy exchange hypothesized by Paltridge. It is shown that the thermodynamic dissipation (entropy production) due to latent and sensible heat transport cannot be negligible in the entropy balance model. The zonally averaged two-latitude and ten-latitude models with ten radiative heating levels are used to find climates at minima of the entropy exchange rate. The models are examined under two different conditions of the water vapor distribution: one is the case with a given distribution of absolute humidity and the other the case with a given distribution of relative humidity. Multiple minima are found in the former case, while no minima in the latter case. In the former case, one of the minima corresponds to a climate with distributions of temperature and cloud amount similar to those in the present climate. However, it does not correspond to the least minimum of the entropy exchange rate. It is demonstrated that climates at minimum entropy exchange are very sensitive to the parameterization of the humidity distribution.