気温変化に対する水蒸気・気温減率の変化とその放射効果

Abstract

The changes in the vertical distributions of temperature and water vapor accompanying the change in the surface air temperature are obtained and their contributions to the longwave radiation fluxes are estimated for clear sky in winter (Tateno) and summer (Wajima).The net upward longwave radiation fluxes at the tropopause increase by 3.10 W/m^2 and 3.82 W/m^2 in winter and summer, respectively, when the surface air temperature increases by 1K with fixed temperature lapse rate and water vapor.The contributions from the change in the temperature distribution in the upper air (the change in the lapse rate) are + 0.12 W/m^2 and - 0.57 W/m^2 for winter and summer, respectively, and the corresponding contributions of water vapor are -0.17W/m^2 and - 1.22 W/m^2.As a whole the net longwave radiation fluxes at the tropopause increase 3.06 W/m^2 and 2.03 W/m^2 in winter and summer respectively, showing that the effects of temperature lapse rate and water vapor are greater in summer than winter.It is shown that the water vapor density has decreased in last 20 years and the contribution to the greenhouse effect is beyond cancelling that due to the increase in carbon dioxide for this period.