Intermediate-scale Disturbances appearing in the ITC Zone in the Tropical Western Pacific

[摘要] A statistical study is made for the intermediate-scale disturbances reported by Murakami (1971) from the analysis of precipitation. In this study, method of spectrum analysis is applied for the data in the Marshall Islands obtained in 1956 and 1958.It is re-examined and confirmed that these disturbances of about 3 days period propagate eastward and have a wavelength about 1, 000km. In agreement with this, it is shown that the disturbances accompany small dimensional area of wind convergence. The analysis also shows that the variation of wind velocity associated with the disturbance is prominent in the divergent part of the wind.By the method of inter-level cross-spectrum analysis, the vertical structure of the disturbances is obtained. The feature of cold core appears in the lower levels. The feature of warm core in the upper levels is clear in 1956, but not in 1958.

[学科分类] 大气科学