斜压Ertel-Rossby不变量在梅雨锋降水过程中的研究与应用
The Study and Application of Baroclinic Ertel-Rossby Invariant in Meiyu Front Precipitation Process
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摘要: 绝热无摩擦下,位涡(PV)的守恒性、不可渗透性和可反演性使之非常广泛地应用在中高纬度天气学诊断分析中,但由于其本身不包含力管项,无法描述强烈天气的快速流形等局限性,因此分析了Zdunkowski and Bott(2003)提出的斜压Ertrl-Rossby 不变量(ERI),结果表明,绝热无摩擦条件下的ERI在其表达式中就已经明确地包含了螺旋度和PV的表达式,同时也涵盖了斜压大气中的力管项效应,可以描述快速流形的天气系统,具有PV所不能取代的优点,这使得它具有非常广泛的潜在应用价值。在此基础上,还利用ERI诊断了2003年7月3～6日的一次梅雨降水过程,结果表明,ERI完整地刻画了这次降水带南移及降水强度变化的特点,随着24 h累积降水带的移动,ERI低值区也随之移动,二者吻合非常好。和PV相比,ERI对降水落区及强度变化的诊断能力更强。Abstract: In adiabatic and frictionless flow,Potential Vorticity (PV),characterized by its features of conservation,impermeability,and inversion,is widely used in diagnosis and analysis of the weather system over middle-high latitude. Due to its limitations of excluding the term of solenoid and of incapable of describing “fast-manifold” severe weather system, baroclinic Ertel-Rossby Invariant (ERI) proposed by Zdunkowski and Bott(2003) is analyzed and applied. The results show that under the condition of adiabatic and frictionless atmosphere,the expression of ERI includes the helicity,PV, and solenoid,and it can depict the “fast-manifold” systems,which make it possess huge potential practical value. Furthermore,the authors invoke ERI to diagnose a Meiyu front precipitation process from 3 Jul to 6 Jul 2003. The experiment reveals that the minimum of ERI coincides well with the 24-h accumulated rain band. Compared to PV,ERI is much capable in depicting and diagnosing the rainfall areas and rainfall amount.
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