超强台风“桑美”(2006)能量发展的物理因子

应用非线性动力系统的研究方法, 基于NCEP/NCAR再分析资料, 以超强台风 “桑美” (2006) 在我国近海的突然增强和突然减弱过程为例, 从动能角度分析热带气旋能量发展的条件, 将分析结果转化为可用于分析预测热带气旋强度变化的实用指标, 如非热成风涡度、 热成风偏差及其垂直变化。结果表明: 热带气旋中心附近存在非热成风涡度负值中心, 有利于近海热带气旋突然增强; 非热成风涡度的变化与热带气旋中心气压变化有较好的一致性。当扰动自下向上传播时, 在热带气旋增强阶段热成风偏差为正值, 而在减弱阶段为负值; 当外围波扰向内核传播时, 在热带气旋增强阶段热成风偏差垂直变化为负值, 而在减弱阶段为正值, 热成风偏差及其垂直变化的这种变化在对流层中低层更明显。当扰动自下向上、 自外围向内核传播时, 在热带气旋增强阶段非热成风涡度为负值、 热成风偏差为正值、 热成风偏差垂直变化为负值; 减弱阶段则相反。

Physical Factors Contributing to Energy Development of Super Typhoon Saomai (2006)

Taking super typhoon Saomai (2006) which intensified and weakened rapidly over coastal waters as an example, based on the nonlinear dynamic system research methods, the energy development conditions of tropical cyclone (TC) are analyzed from a kinetic view by the use of NCEP/NCAR reanalysis data with horizontal resolution of 1°×1° and vertical resolution of 11 layers. Some physical parameters that can analyze and predict TC intensity, such as non-thermal wind vorticity, thermal wind bias and its vertical shear, are derived as operational forecast indicators. Results show that the existing of a negative non-thermal wind vorticity center near the TC center is favorable to its offshore rapid intensification. Non-thermal wind vorticity variations and the TC central pressure changes are in a better consistency. When the wave disturbance propagates upward, the thermal wind bias is positive/negative in the intensifying/weakening process. When the external wave disturbance spreads to the inner core, the thermal wind bias shear is negative/positive in the intensifying/weakening phase. And the features of thermal wind bias and its vertical shear are more obvious in the lower troposphere. When the wave disturbance propagates upward and from the external to inner core of TC, non-thermal wind vorticity is positive, thermal wind bias is negative and its vertical shear is negative in the intensifying process, and vice versa.