摘要
作为一个典型,作者详细分析了1955年2月中旬一次大寒潮过程中,东亚上空的涡度场.涡度用Graham法,由测风记录计算的;由地面到5500m,共分9个层次.发现地面高压中心上空并非单纯的负号涡度区;1000m以下,有小的涡度中心,可正可负,但强度都不大;1000—5500m,地面高压中心前方一般为正号涡度区,后方为负号涡度区;高压中心加强,反映为负号涡度区的逐渐扩充.又考察了涡度方程中各项的概量大小,平流输送项及散度项的概量均为10′×10^(-10)sec^(-2),但后者绝对值要大一些.这几天高空槽脊线的移动与发展往往与涡度平流项的分布情况不符,而可以由散度项的分布得到解释.无论是5500m面或3000m面都不能当作近似于无辐散面.铅直输送项及差异铅直速度项的概量为10°×10^(-10)sec^(-2),肯定是次要的项.Sherman过于强调差异铅直作用项,是不正确的.
As a typical case,the auther examines in detail the vorticity field over East Asia during the ortbreak of a severe cold wave at the middle of February,1955.Vorticity is computed by Graham method from pilot ballon wind data at nine levels from ground up to 5500m.It is discovered that the region over the surface high center is not completely of negative vorticity;below 1000m,there is weak vorticity center,either of positive sign or of negative sign;between 1000m and 5500m,the sign of vorticity is positive in front of the surface high center,and is negative behind the center;the intensification of the surface high center is manifested by the gradual expansion of the region of negative vorticity.The order of magnitude of various terms in the vorticity equation is evaluated.Both the advection term and the divergence term are of the order 10'×10^(-10)sec^(-2);but the latter is greater than the former in absolute magnitude.The movement,as well as the development,of the upper trough and the wedge may by accounted for by the pattern of isopleths of divergence term,but not by that of advection term.Neither 5500m surface nor 3000m surface may be considered approximately as the surface of non-divergence.The order of magnitude of the vertical transfer term and the differential vertical velocity term is 10°×10^(-10)sec^(-2);these terms are definitely of minor importance.It proves incorrect that Sherman lays too much emphasis on the differential vertical verlocity term.
作者
徐尔灏
E.H.HSU(The University of Nanking)
出处
《气象学报》
1958年第4期239-248,共10页
Acta Meteorologica Sinica
基金
中央气象局与南京大学合作的研究成果(1956年度)的一部分
