王绍武. 1963. 北半球500毫巴月平均环流特征及演变规律的研究——西风指数[J]. 气象学报, 33(3):361-374, doi:10.11676/qxxb1963.034
北半球500毫巴月平均环流特征及演变规律的研究——西风指数
A PRELIMINARY STUDY ON THE CHARACTERISTICS AND EVOLUTION OF MEAN MONTHLY CIRCULATION, Ⅰ.ZONAL INDEX
投稿时间:1963-03-15  
DOI:10.11676/qxxb1963.034
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作者单位
王绍武 北京大学地球物理系 
摘要点击次数: 2366
全文下载次数: 1983
中文摘要:
      本文是作者研究近10年大气环流特征及演变規律工作的第一部分.应用1951-1960年北半球500毫巴月平均图計算了历年逐月35°-55°N西风指数.主要結果如下:(1)近10年中緯度西风强度比40年代約增强5-10%,西半球(180°-10°W)主要是夏半年(5月-10月)增强,东半球(0°-170°E)却在冬半年(11月-4月)增加最多.但比1900-1939年稍有减弱.(2)北半球西风指数(I)的半年平均值有明显的周期性振动,主要周期为10年、5.5年及26个月三种.前两种可能与太阳活动11年周期有关.(3)东半球与西半球半年平均西风指数(IEIW)之間,夏半年为正相关(0.77),多半年为負相关(-0.54).这可能与环极气流中心偏离北极有关.(4)夏半年与其后之冬半年IE(IW)有負(正)相关,由冬半年到夏半年变化趋势相反.(5)这种半年之間的联系实际即造成东西两半球西风指数的两年周期,因为半球之間只有90°位相差,故北半球亦有显著两年周期.(6)夏半年內或冬半年內西风指数經常維持同一特征.东半球高指数形势持续性强,西半球則低指数形势持續性强.
英文摘要:
      This paper is the first report of a research project concerning.the characteristics and evolution of the general circulation in recent ten years. The results of the analysis of the monthly tonal index in the temperate latitude belt (35°-55°N) derived from the mean monthly 500 mb charts show that the tonal circulation is characterized by: 1. The mean tonal index in the period from 1951 to 1960 is about 5-10% higher than that in the period from 1941 to 1950, but slightly lower than that in the period. from 1900 to 1939. In western hemisphere (180°W-10°W) the westerlis,is strenthened mainly in the summer half year (May-October), whereas in the eastern hemisphere (0°-170°E) this trend is more pronounced in the winter half year (November-April). 2. The half yearly.mean tonal index shows a clear periodic fluctuation, the length of most prominent periods are 10,years, 5.5 years and 26 months. It is highly probable that the first two periods are related to the 11-years sunsport cycle. 3. In the summer half year there exists a high positive correlation between the half yearly mean index of eastern hemisphere. and that of western hemisphere, the correlation coefficient is about 0.77. But in the winter half year the correlation becomes negative and its value is about -0.54. Other analysis suggests that this may be O due to the asymmetry of circumpolar current. 4. The summer half yearly mean index has a negative (positive) correlation coefficient with that of following winter half year in eastern (western) hemisphere. But from winter to summer there is a reverse trend in the change of zonal index. 5. This association of tonal index from one half year to another, indeed, induces a binnial oscillation. This is not only concerned in eastern and western hemisphere separately, but also in northern hemisphere as a whole, becouse the oscillations of the tonal index in eastern and western hemisphere are 900 out of phase. 6. The monthly mean tonal index has a tendency to keep the same characteristic through-out the winter or summer half year period. Moreover in eastern hemisphere the high tonal index pattern shows a greater persistence them the low tonal index pattern, while in western hemisphere, to opposite of this, the low tonal index pattern usually persists from month to month.
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