RT Dissertation/Thesis T1 On the temperature profile of the lower stratosphere and the sharpness of the tropopause in the extratropics T2 Sobre el perfil de temperatura en la baja estratosfera y la agudeza de la tropopausa en los extratrópicos A1 Ferreira, António Paulo K1 2501 Ciencias de la Atmósfera K1 2501.10 Estructura Atmosférica K1 2501.23 Transferencia Radiactiva AB The interaction between the troposphere and the stratosphere is an important part of our planet's climate system. The tropopause, as the boundary between these two layers, occupies a central place in the study of such interaction. The main objective of our doctoral research is to identify the causes for the sharpness of the extratropical tropopause, due to the inversion layer that normally occurs right above the tropopause: ‘tropopause inversion layer’ (TIL). This phenomenon has received much scientific attention; however, it is still not well understood. Since the TIL is part of the lower stratosphere, which is the scenario of seasonal changes in thermal structure, the present study will attempt to develop a simple theoretical model to describe the temperature profile of the lower extratropical stratosphere in different seasons of the year. The empirical tests of the model will be based on radiosonde data dedicated to the measurement of temperature, water vapor and ozone in the upper air, including the stratosphere up to 20-30 km in altitude. On the other hand, the concept of ‘tropopause sharpness’ will be discussed and analysed. In general, the research hopes to clarify the radiative and dynamic factors of the typical sharpness of the extratropical tropopause. YR 2017 FD 2017-11-23 LK http://hdl.handle.net/11093/896 UL http://hdl.handle.net/11093/896 LA eng DS Investigo RD 11-nov-2024