摘要:
把任一气象要素分为对赤道对称和对赤道反对称的两部分，利用Oort等的气候资料进行分析，发现在全年中，许多气象要素，如500和1000百帕纬圈平均的高度、温度和西风等，主要呈对称分布。对称部分的绝对值和其沿经圈分布曲线的起伏，都远远大于其反对称部分的对应值。而且，对称部分的曲线起伏，除1000百帕的西风和高度不太明显外，在1—7月普遍呈减小的趋势。至于反对称部分，其变化趋势则与对称部分相反。为了解释上述现象，还对年平均的非绝热加热、摩擦和地形等进行了分析。发现地面拔海高度的反对称部分最明显。在12—2月和6—8月，净辐射、地面雷诺应力、地面（包括海洋）和大气之间的热交换（包括辐射、感热和潜热）的反对称部分也很明显，有时和对称部分相当，甚至超过；但它们在这两个季节的沿经圈分布的位相是相反的。这看来和上述气象要素中反对称部分的产生，以及对称运动维持及其随季节变化有密切关系。
Abstract:
Based upon Ort’s computations, the symmetric and the antisymmetric components of the mean zonal geopotential, temperature and zonal wind with respect to the equator at 500 and 1000 hPa levels are analysed. It is found that at 500 and 1000 hPa levels these elements are, roughly speaking, symmetrically distributed with respect to the latitude all the year round, and as a whole, regardless of level and element, the absolute values and the undulation ranges of the curves of the symmetric components (hereafter referred to as symmetric curves) are much greater than the corresponding values and ranges of the curves of the antisymmetric ones (antisymmetric curves). Further, the undulation ranges of the symmetric curves, in most cases, decrease from January through July and increase from July through January. But, the corresponding undulation ranges of the antisymmetric curves, on the contrary, increase from January through July, and decrease from July through January. At 1000 hPa, there are variations similar to but not so striking as those at 500 hPa. Finally, the cause of the generation of asymmetric motion are discussed. It seems to be possible that asymmetric distribution of diadatic heating, friction and orography might be the main factors.
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