Analysis of the implicit mistakes in the several schematic diagrams for the implication of convective temperature with its application to forecasting

KeyWord:Convective temperature;Convective condensation level;Thermodynamic diagram;Implicit mistakes;Local convection

Abstract:

      The convective temperature is commonly used to the analysis and prediction of local convection, while the convective condensation level (CCL) is often used to estimate the base height of local convective cloud. There is certain precondition when the convective temperature and CCL are utilized to analyze local convection, and its inherent physical meaning is abundant. In this paper, thermodynamic diagrams of the convective temperature in the several classical books are analyzed, and some implicit mistakes are pointed out, which includes violating elementary knowledge of the atmospheric stability, opposing to theory of atmospheric energy, and conflicting with its inherent meaning. It is further pointed out that not being strict, and not knowing the inherent meaning of convective temperature thoroughly are the main factors in the process of making convective temperature diagram which cause these mistakes. A new diagram of convective temperature is constructed in this paper, with clearly physical meaning and more correspondingly to the basic meteorological theory. Observation data is employed to analyze the basic characteristics of convective clouds in summer Beijing, including occurrence numbers of convective clouds and occurrence time. Attempt is made to predict both the genesis and base height of convective cloud by using the convective temperature and CCL respectively. The results show that there exists some indicative significance of convective temperature as to local convection, and CCL can reflect the cloud base height of convective cloud to certain extent. The critical success index (CSI) reaches 45% when the difference between the maximum temperature and the convective temperature no more than 1℃ is assigned to be the judgment of local convection development.