标题：Atmospheric thermodynamics and dynamics during convective, stratiform and nonprecipitating clouds over the metropolitan area of Rio de Janeiro – Brazil
摘要：The physical mechanisms involved in the development and forecast of clouds and precipitation are both quite complex and dependent on the local atmospheric environment, especially when severe weather conditions are imminent. Research aimed at understanding the environmental mechanisms favorable to the different atmospheric scenarios can help operational weather forecasters’ empirical knowledge to issue warnings. In light of the above, this paper sought to provide a qualitative and quantitative contribution by employing radiosonde analyses, radar reflectivity, and numerical simulations to evaluate the formation of convective, stratiform, and nonprecipitating clouds over the metropolitan area of Rio de Janeiro, Brazil. The convective available potential energy (CAPE) and lifted index (LI), showed higher values on convective days (CAPE = 2600 J.Kg -1 and LI = -4 °C), followed by nonprecipitating (CAPE = 1500 J.Kg -1 and LI = -2 °C) and stratiform cloud days (CAPE = 1400 J.Kg -1 and LI = -1.5 °C). Highest precipitable water content (56 mm) was found to be associated with the stratiform days, suggesting the moisture importance to support the stratiform clouds analyzed. The dynamic variables presented the higher (absolute values) wind values in the lower (1000-850 hPa) and middle (850-700 hPa) atmospheric levels on convective days convergence (-16.5 s -1 and -9.6 s -1 , respectively). On the other side, in the same atmospheric layers, winds divergence were observed on stratiform (6.4 s -1 and 6.9 s -1 ) and nonprecipitating (9.7 s -1 and 7.3 s -1 ) days. Higher wind divergence (8.3 s -1 ) was verified for the convective days in the upper atmospheric levels (300-200 hPa) in comparison with other analyzed days (3.2 s -1 (stratiform)and 2.8 s -1 (nonprecipitating)). In a general aspect, the results show a coupling of the winds convergence, moisture and energy in the lower atmospheric levels and divergence in the upper atmospheric levels on convective days. Despite the moisture availability observed on stratiform days and the thermodynamic energy on nonprecipitating days, the coupling between these conditions and dynamic triggers was not observed, respectively.
