GLOBAL WARMING - EVIDENCE FOR ASYMMETRIC DIURNAL TEMPERATURE-CHANGE
GLOBAL WARMING - EVIDENCE FOR ASYMMETRIC DIURNAL TEMPERATURE-CHANGE
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DOI：
10.1029/91gl02900
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发表时间：
1991-12-01
影响因子：
5.2
通讯作者：
FU, CB
中科院分区：
文献类型：
--
作者：
KARL, TR;KUKLA, G;FU, CB
对年-月平均最高和最低地表温度记录的分析现在已经更新和扩大，以涵盖北方半球的三个大国（毗连的美国、苏联和中华人民共和国）。 他们指出，在过去的四十年里，这些地区发生的大部分变暖都可以归因于平均最低温度（主要是夜间）的增加。 平均最高温度（主要是白天）显示很少或没有变暖。 在美国和苏联（无法获得中国的数据），极端季节温度的变化也反映了类似的特征，例如，极端最低温度增加，极端最高温度变化不大或没有变化。 最低温度持续升高，最高温度总体变化不大，导致平均（和极端）温度差减小，这是气候变率的一个重要量度。不对称日变化的原因尚不确定，但有一些证据表明，云量的变化起着直接作用（云量的增加导致最高温度降低，最低温度升高）。 不管确切的原因是什么，这些结果意味着：（1）气候模式的预测考虑到随着温室气体水平的增加，日温差的预期变化是低估的。（高估）日最小值（最大值）相对于最大值（最小值）的上升，或（2）在北方相当一部分陆地上观测到的变暖明显受到与增强的温室效应无关的因素的影响。
Analyses of the year-month mean maximum and minimum surface thermometric record have now been updated and expanded to cover three large countries in the Northern Hemisphere (the contiguous United States, the Soviet Union, and the People's Republic of China). They indicate that most of the warming which has occurred in these regions over the past four decades can be attributed to an increase of mean minimum (mostly nighttime) temperatures. Mean maximum (mostly daytime) temperatures display little or no warming. In the USA and the USSR (no access to data in China) similar characteristics are also reflected in the changes of extreme seasonal temperatures, e.g., increase of extreme minimum temperatures and little or no change in extreme maximum temperatures. The continuation of increasing minimum temperatures and little overall change of the maximum leads to a decrease of the mean (and extreme) temperature range, an important measure of climate variability.The cause(s) of the asymmetric diurnal changes are uncertain, but there is some evidence to suggest that changes in cloud cover plays a direct role (where increases in cloudiness result in reduced maximum and higher minimum temperatures). Regardless of the exact cause(s), these results imply that either: (1) climate model projections considering the expected change in the diurnal temperature range with increased levels of the greenhouse gases are underestimating (overestimating) the rise of the daily minimum (maximum) relative to the maximum (minimum), or (2) the observed warming in a considerable portion of the Northern Hemisphere landmass is significantly affected by factors unrelated to an enhanced anthropogenically-induced greenhouse effect.