全球环流系统关联性的时空演化特征研究

Analysis of temporal and spatial characteristics of correlations between the global circulation systems

利用NCEP/NCAR全球高度场和地面气压资料,运用矩阵理论,研究了全球高度场和地面气压序列关联性的时空演变特征。结果表明,各层次高度场的关联性在中低纬度区域较好,并向中高纬度地区逐步递减,呈准带状分布;垂直方向上,低层的关联性较弱,随着高度升高关联性逐渐增强;北太平洋区域从低层至高层大气中均存在一个较强的负关联中心,体现出了一定的特殊性。延迟关联的结果表明,随着延迟天数的增加关联性逐渐衰减,在延迟天数为15d时关联系数的变化趋于平缓,在延迟天数约为60d时存在显著的转折。环流系统关联性随时间衰减及临界点的存在为2周以上尺度的数值预报提供了理论参考。环流系统内部关联的衰减速度表现出低纬度地区向中高纬度地区加快,高层向低层加快的特征。地面气压和3个高度场全球平均关联系数随时间的变化基本保持一致,并且在1978—1982和1996—1998年发生了明显的跃变。

The correlation matrixes are constructed based on the NCEP/NCAR global height field data and the surface pressure data and the characteristics of these two matrixes are analyzed. The results show that the correlations in all levels of height field are better in the middle low latitudes regions and descend to the middle-high latitudes regions, presenting the characteristics of quasi-zonal distribution; in the vertical direction, the correlations in the low levels are weaker and become more and more stron- ger with the increase in height; and there is always a negative correlation center in all levels of height field in the north Pacific region, reflecting a certain degree of particularity. The results of the delayed correlation show that the correlation is decreased with the increasing in the delayed days, the change of correlation gradually flats when the delayed time is 15 days and there is an obvious turning point at the time of 60 days. The fact that the correlation decreased with the increasing in delayed days and existence of the decay critical point provide a theory reference for the numerical prediction of 2 weeks or longer time scale. The decay rate of correlation in the circulation system reflects the feature that the higher the latitude is and/or the lower the level is the stronger the correlation is. Changes over time in the global average correlations for the three height fields and the surface pressure field are almost the same with abrupt changes occurred during 1978 - 1982 and 1996 - 1998.