南半球における気温変動傾向の地域的差異

抄録

Recent temperature trends in the Southern Hemisphere are investigated by analyzing the hemispheric patterns of temperature differences between the three decades from the 1950's to the 1970's.
In January (summer), increasing temperature trends were found in Antarctica and on the east coast region of Australia during the period 1951_??_1978. On the other hand, decreasing temperature trends were shown in the northeastern part of South America and in a part of Africa. Hemispherically, temperature trends from the 1950's to the 1960's seemed to be compensated by the inverse trends from the 1960's to the 1970's.
As for July (winter), such compensatory trends were not apparent. From the 1960's to the 1970's, temperature increased remarkably in Antarctica, Australia and New Zealand.
Change in the atmospheric circulation, which was characterized by the 500mb height field, was examined from the 1960's to the 1970's. The polar vortex (cold air mass) was reduced and weakened in the 1970's. Meridional heat transfer increased around the mid-latitudes. These trends at the 500mb level were related with the increasing temperature trend in the higher latitudes and the decreasing temperature trends in the mid-latitudes.
In the Northern Hemisphere, the polar vortex had an expanding trend from the 1960's to the 1970's. This suggests that the compensatory trend also exists between the Arctic and the Antarctic.
More detailed studies will become possible with the accumulation of the climatological data in the Southern Hemisphere.