作　　者： ; ; ;

机构地区： 广东省气象台

出　　处： 《广东气象》 2013年第4期1-6,共6页

摘　　要： 利用台风观测、FY2/MTSAT卫星资料和NCEP分析资料,采用天气学分析、物理量诊断等方法,对1206号强热带风暴"杜苏芮"偏心结构特征及其成因进行了初步分析。结果表明,"杜苏芮"动力热力结构均存在明显不对称性特征:深对流云系几乎完全偏于TC的西南侧,TC中心周围仅有浅薄稀疏的低云云线,特别是中高层风场TC仅表现为气旋性特征较弱的东风波动,且明显偏于TC中心的西南侧。西太平洋副高加强西伸是"杜苏芮"中高层偏心结构的主要成因:一方面副高快速向西跃进,与南侧TC间位势梯度加强,形成强盛的偏东气流,不利于对流发展;另一方面副高内部干燥下沉气流抑制了TC北侧气旋性环流发展。而在低层,副高的带状分布和西伸特点不如中高层明显,造成了TC环流在高低层的错位。而低层强盛的西南季风和越赤道气流使得低层的气旋性环流偏心不明显。而中层卷入西南气流偏弱且存在切断,对中层的气旋性环流发展和维持是不利的。再者,强的风垂直切变也是造成TC南侧对流发展旺盛的成因之一。 Using observations, data from the weather satellite FY2/MTSAT and NCEP reanalysis, this work performed a preliminary study on the eccentric structure of Severe Tropical Storm Doksuri （coded 1206） and its causation by synoptic analysis and diagnoses based on physical quantities. The results are shown as follows. Doksuri was significantly asymmetric in both the dynamic and thermodynamic structure so that deep-convection cloud systems were almost all on the southwest side of the storm, low-cloud lines dis- tributed around the eye that were both shallow and far between, and its mid- and higher-level wind field was only with easterly waves that were slightly cyclonic and much deviated to the southwest side of the eye. The strengthening and westward extension of the western Pacific subtropical high （WPSH）are mainly responsible for the eccentric structure of Doksuri at the mid- and higher-levels. On the one hand, the WPSH advanced rapidly to the west while the geopotential gradient strengthened between it and the storm, constituting to a powerful easterly airflow that checked the development of convection. On the other hand, the airflow was dry and descending inside the WPSH, inhibiting the development of cyclonic circulation north of the storm. At lower levels, the WPSH was less stripe-distributed and west-extended as at the mid- and higher-levels, con- tributing to inconsistent location of the storm circulation between the high and low levels. Besides, lower lev- els were prevalent with a strong southwest monsoon and cross-equatorial airflow so that the eccentricity of the low-level cyclonic circulation was not as obvious. As the southwest airflow entrained into the mid-level storm was both weak and broken-off, cyclonic circulation was not helped develop and maintain at that level. Fur- thermore, the presence of strong wind shear was also one of the factors accounting for the vigorous develop- ment of convection south of the storm.

关 键 词： 天气学 强热带风暴 不对称 偏心结构 副高

领　　域： [天文地球]