500hPa气候高度场强度及谱结构的季节变化与半球际差异

Seasonal Variation and Hemispherical Difference of the Intensity and Spectrum Structure of 500 hPa Climatic Height Fields

用半球气候场强度指数 ( Ic)及球函数分析改进方案 ,分析了北、南半球50 0 h Pa气候高度场的环流特征 ,得到如下主要结论 :1 )半球 50 0 h Pa气候高度场强度冬强于夏 ,南半球强于北半球 ;半球环流向夏季的转换速度北南半球相当 ,而向冬季的转换北半球较南半球快。2 )半球 50 0 h Pa气候高度场具有简单的球函数谱结构 ,它们主要由超长波波段的球函数 ( 0≤m、k≤ 3,m、k不全为 0 )、特别是其中的带状球函数 ( m=0 )构成 ,因而具有低阶、低维的特征。 3)对北半球用约 2 0个重要球函数分量 (按 r*m,k≥ 0 .0 5%标准 )即可相当精确地拟合其 50 0 h Pa气候高度场 ,而对南半球仅用 1 0个重要球函数分量即可相当精确地拟合其 50 0 h Pa气候高度场 ;因此 ,北半球气候高度场球函数谱结构较南半球复杂。 4 )北半球 50 0 h Pa气候高度场的季节变化较南半球明显。

The circulation character of 500hPa climatic height fields in two hemispheres is investigated by using hemispherical climatic field intensity( I c) and the improved scheme for spherical function analysis.The main findings are as the followings:1)the intensity of 500hPa hemispherical climatic height field of winter(Northern Hemisphere) is stronger than that of summer(Southern Hemisphere);the transition velocity of hemispherical circulation from winter to summer about the same in two hemispheres but the transition from summer to winter in Northern Hemisphere is more rapid than in Southern Hemisphere.2)The spherical function spectrum structure of 500hPa hemispherical climatic fields is simple,and the fields are mainly composed of ultra-long waves(0≤ m,k ≤3; m,k not equal to 0 simultaneously),specially of zonal spherical function( m =0),thus showing a low order and dimension on feature.3)The 500hPa climatic height field can be accurately fitted by using 20 important spherical function components(criteria by r * m,k ≥0.05%) in Northern Hemisphere, but by using only 10 in Southern Hemisphere,that is to say,the spectrum structure in Northern Hemisphere is more complicated.4)The seasonal variation of 500hPa climatic height fields in Northern Hemisphere is more remarkable than that in Southern Hemisphere.