doi:  10.3878/j.issn.1006-9895.1806.18126
不同定义的湿位涡分析及在台风中的诊断

Analysis of Various Moist Potential Vorticities with Different Definitions and Comparison of Their Diagnoses in a Typhoon Process
摘要点击 524  全文点击 292  投稿时间:2018-02-08  
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基金:  北极阁开放研究基金-南京大气科学联合研究中心NJCAR2018ZD03,国家自然科学基金项目41775123、41705037
中文关键词:  湿位涡  位温  干湿分量  台风  诊断
英文关键词:  Moist potential vorticity  Potential temperature  Dry and moist component  Typhoon  Diagnosis
        
作者中文名作者英文名单位
刘赛赛LIU Saisai中国人民解放军31010部队,北京 100081
张立凤ZHANG Lifeng全军危险性天气监测预警研究中心/国防科技大学气象海洋学院,南京 211101
赵艳玲and ZHAO中国人民解放军31010部队,北京 100081
引用:刘赛赛,张立凤,赵艳玲.2019.不同定义的湿位涡分析及在台风中的诊断[J].大气科学,43(3):565-576,doi:10.3878/j.issn.1006-9895.1806.18126.
Citation:LIU Saisai,ZHANG Lifeng,and ZHAO.2019.Analysis of Various Moist Potential Vorticities with Different Definitions and Comparison of Their Diagnoses in a Typhoon Process[J].Chinese Journal of Atmospheric Sciences (in Chinese),43(3):565-576,doi:10.3878/j.issn.1006-9895.1806.18126.
中文摘要:
      本文对不同定义的湿位涡做了理论分析,并利用1522号台风“彩虹”的数值模拟结果对各种湿位涡进行了诊断。主要结论有:经典湿位涡、广义湿位涡和改进湿位涡的差异主要是由不同定义的位温造成的,相当位温、广义位温和修改位温的构成均是在位温基础上添加一显含水汽的附加量;经典湿位涡、广义湿位涡和改进湿位涡的构成均能分为干、湿分量两部分,其干分量表达式相同,都与Ertel干位涡的定义一样,水物质相变潜热的影响隐含在位温中;不同定义湿位涡的本质差异表现在不同的湿分量上,湿分量的表达式中显含了水物质的作用。对台风的诊断分析发现,改进湿位涡分布与Ertel干位涡非常相似,呈现中空分布的位涡塔结构,大值区对应眼墙内侧,改进湿位涡湿分量与经典湿位涡的湿分量分布相似,只是湿分量的绝对值更小,这反映了改进湿位涡既能保持干位涡的分布特征,其分布和演变可反映台风的结构和演变,又能合理地体现水汽分布的影响,所以在台风诊断中有更广泛的应用前景。经典湿位涡在低层表现为负值,这与水汽梯度的分布关系很大,但与垂直速度、潜热加热大值区等都没有很好的匹配关系,用其分析台风结构和演变具有一定局限性;广义湿位涡其形式较复杂,仅在近饱和区域才能发挥其诊断优势。
Abstract:
      In this paper, various moist potential vorticities with different definitions are theoretically analyzed and numerically diagnosed based on the simulation of typhoon Mujigae (1522). The results show that the differences between the equivalent potential vorticity, the generalized moist potential vorticity and the modified moist potential vorticity are mainly caused by the potential temperature that is defined differently. An additional variable with explicit water vapor is added to the conventionally defined potential temperature. The equivalent potential vorticity, the generalized moist potential vorticity and the modified moist potential vorticity can be divided into two parts: the dry component and the moist component. The dry components of these moist potential vorticities are the same as the Ertel potential vorticity and implicitly contain the effect of latent heat in phase changes. The essential difference between these moist potential vorticities is reflected in their moist components, which can explicitly contain the effect of water vapor. Based on simulation results and diagnostic analysis of these vorticities in the typhoon process, it is found that the distribution of the modified moist potential vorticity is like a “hollow tower” and the high value area is located inside of the eye wall, which is very similar to that of the Ertel potential vorticity. And the distribution of the moist component of the modified moist potential vorticity is also very similar to that of the equivalent potential vorticity, but the absolute value of the former is smaller. These results indicate that the modified moist potential vorticity can maintain the characteristics of the original Ertel potential vorticity. It can not only reflect the structure and intensity changes of the typhoon but also reflect the influence of water vapor distribution reasonably. As shown above, the modified moist potential vorticity has a potential application for the diagnosis and forecast of typhoons. The value of the equivalent potential vorticity is negative in the low level, which is largely related to the distribution of water vapor gradient. Note that the equivalent potential vorticity doesn’t have a good matching relationship with vertical velocity, latent heating and other factors, which limits its application in analyzing the typhoon structure and evolution. The generalized moist potential vorticity has a complex form and only has some diagnostic advantages in nearly saturated condition.
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