热带气旋在陆地上重新加强的数值模拟

Numerical Study of Reintensification of a Tropical Cyclone over Land

摘要:

以2006年1月澳大利亚北部地区热带气旋“NT2006”为例，以宾夕法尼亚州立大学和美国国家气象研究中心联合研制开发的中尺度模式（MM5）为基础，通过轴对称的观点对其登陆后的重新加强进行了数值模拟研究.结果表明，由于“NT2006”的高度不对称性，其“涡热塔”的融合并不呈现明显的轴对称化，因此采用Hendricks的“涡热塔”机制来解释其在陆地上重新加强的机理存在一定困难.通过基于方向平均的绝对角动量面分析，认为Smith的绝对角动量径向辐合机制能较成功地解释“NT2006”在陆地上重新加强和衰减的原因.

Abstract:

Numerical simulations were conducted to investigate the reintensification of a tropical cyclone formed to the north coast of the Northern Territory of Australia in January 2006 (NT2006) with axisymmetric view. The calculations were made using the numerical model (MM5) of Pennsylvania State University/National Center for Atmospheric Research. The results show that the mergers of ‘vortical hot towers’ are nonaxisymmetric due to the high asymmetry of NT2006, which leads to the failure of Hendricks’ ‘vortical hot towers’ mechanism to illuminate the reintensifying process over land. Therefore, the azimuthally averaged absolute angular momentum surfaces were analyzed to prove that the mechanism of the radial convergence of the absolute angular momentum proposed by Smith et al. (2009) can successfully explain the reintensification and spin down of NT2006 over land.