RADIATIVELY DETERMINED TEMPERATURE IN THE MIDDLE ATMOSPHERE IN THE POLAR REGION

• Main Authors: シバタ キヨタカ, Kiyotaka SHIBATA
• Format: Report
• Language: English
• Published: ABSTRACT 1991
• Subjects: Polar meteorology and glaciology; polar night; Proceedings of the NIPR Symposium on Polar Meteorology and Glaciology
• Online Access: https://nipr.repo.nii.ac.jp/?action=repository_uri&item_id=3656; http://id.nii.ac.jp/1291/00003656/; https://nipr.repo.nii.ac.jp/?action=repository_action_common_download&item_id=3656&item_no=1&attribute_id=18&file_no=1

Radiatively determined temperature, i. e., time-marched temperature under the absence of dynamical warming, in the middle atmosphere is investigated for various conditions. The model used in this study extends from the surface to the middle mesosphere at about 70km. First, the temperature change during the polar night is studied. For a clear atmosphere, the surface temperature of which is calculated from the radiation heat budget, temperature decreases uniformly with respect to height except for the first 20 days. The decrease rate becomes very small as temperature becomes low, and hence even the lowest temperature at the surface cannot reach 100K for the polar night. When the surface temperature is prescribed to have the climatological value, the temperature in the stratosphere and mesosphere decreases in a similar way. However, there appears a relatively high temperature region from about 150mb to 30mb. This is because CO_2 and O_3 absorb longwave radiation from the warm surface. Second, the temperature change is studied after the sun reappears. It is found that according to the intensity of warming, the stratosphere can be separated into 3 regions : upper (P<10mb), middle (10mb<P<100mb), lower (100mb<P). The temperature in the upper and middle stratosphere is restored to the climatological value in a rather short time, 1 to 2 months. On the other hand, the temperature in the lower stratosphere rises far more slowly and remains much lower than the climatological value. This suggests that the dynamical warming plays a crucial role in the lower stratosphere.