Shearing wind helicity and thermal wind helicity |
| |
| Authors: | Ying Han Rongsheng Wu Juan Fang |
| |
| Affiliation: | The Key Laboratory of Mesoscale Severe Weather, Nanjing University, Nanjing 210093,The Key Laboratory of Mesoscale Severe Weather, Nanjing University, Nanjing 210093,The Key Laboratory of Mesoscale Severe Weather, Nanjing University, Nanjing 210093 |
| |
| Abstract: | Helicity is defined as H=V.ω, where V and ω are the velocity and vorticity vectors, respectively.Many works have pointed out that the larger the helicity is, the longer the life cycle of the weather system is. However, the direct relationship of the helicity to the evolution of the weather system is not quite clear. In this paper, the concept of helicity is generalized as shearing wind helicity (SWH). Dynamically,it is found that the average SWH is directly related to the increase of the average cyclonic rotation of the weather system. Physically, it is also pointed out that the SWH, as a matter of fact, is the sum of the torsion terms and the divergence term in the vorticity equation. Thermal wind helicity (TWH), as a derivative of SWH, is also discussed here because it links the temperature field and the vertical wind field. These two quantities may be effective for diagnosing a weather system. This paper applies these two quantities in cylindrical coordinates to study the development of Hurricane Andrew to validate their practical use. Through analyzing the hurricane, it is found that TWH can well describe the characteristics of the hurricane such as the strong convection and release of latent heat. SWH is not only a good quantity for diagnosing the weather system, but also an effective one for diagnosing the development of the hurricane. |
| |
| Keywords: | helicity shearing wind helicity thermal wind helicity hurricane SWH TWH |
| 本文献已被 CNKI 维普 万方数据 SpringerLink 等数据库收录！ |
| 点击此处可从《大气科学进展》浏览原始摘要信息 |
|
点击此处可从《大气科学进展》下载全文 |
|
