Climatological Characteristics of Evolution of East Asian Winter Monsoon
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摘要: 文章主要讨论了东亚冬季风和冷涌的演变特征,并与南亚作了对比,发现在东亚地区,冬季风演变主要表现为10月中旬经向环流的突变及9月初、11月中旬和1月末对流层低层温度的3次突变;而在南亚地区,经向环流的变化不如东亚地区明显,而且高层要先于低层变化,对流层低层温度存在2次突变。在整个冬季,东亚地区冷涌的演变过程,主要表现为南海地区冷涌在12月份出现最高频率,而西太平洋冷涌在1月份出现最高频率;南亚地区冷涌在12月份出现最高频率,但远小于东亚地区且衰减速度很快。另一个不同点是东亚地区的冷涌强度是往上衰减的,而南亚地区的冷涌强度则是往上增强的。这说明东亚冬季风和南亚冬季风的性质有较大的区别。Abstract: Characteristics of evolution of East Asia winter monsoon and cold surge were discussed and compared with those in South Asia. It is found that there exist an abrupt change of meridional circulation in East Asia during middle October, which represents the onset of East Asia winter monsoon circulation. Three abrupt changes of temperature occur in lower troposphere in the early September, middle November and late January. However, the change of the circulation in South Asia is not as strong as in East Asia. The change of meridional wind in upper troposphere is earlier than that in lower troposphere. There exist two abrupt changes of the temperature in lower troposphere, which are weaker than in East Asia longitudinally. Furthermore, in East Asia, the frequency of cold surges has its maximum in South China Sea in December, but in west Pacific in January. On the other hand, in South Asia, the cold surges occur most frequently still in December, but much less than in East Asia, and they decrease quickly with time. Another different aspect is that the clod surge frequencies decrease upward in East Asia, but increase in South Asia
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