The inverse correlation between NDVI and LST is widely known for its long time series. However, when more specific statistical tests were performed, subtle differences in the correlation behavior over time are more clearly observed. In this work, regression analyses were performed between NDVI and LST at intervals of approximately 10 years, quantifying this relationship for an area of transition from vegetation to urban occupation from 1985 to 2018. The removal of vegetation cover (reduction of 51% to 7% in grassland and 14.4% to 0.6% in forest) to occupy impermeable surfaces ( increase of 31% to 91% in urban areas) caused an average LST increase of 4.18 °C when compared to the first and last decades of the historical series. Temporal analysis allowed us to verify the increase in temperature in the four seasons. The largest difference was 6.36 °C between the first and last decade of autumn, 4.40 °C in spring, 4.09 °C in summer, and 2.41 °C in winter. The results also show that LST has a negative correlation with NDVI, especially in urban areas, with an increase in this correlation during the period (1989: R = −0.55; 1999: R = −0.58; 2008: R = −0.59; 2018: R = −0.76). Our study results will help policymakers understand the dynamics of temperature increases by adding scientifically relevant information on the sustainable organization of the urban environment.

Drought is one of the most significant threats to agriculture, affecting crop yields, farmer incomes, and local economic stability. This study evaluates the effects of agricultural drought on crop yields and revenue in Southern Brazil. Methodologically, we apply a fixed-effects econometric model to a municipal-level panel dataset from 1974-2020. Drought impacts are quantified using count variables derived from the Standardized Precipitation-Evapotranspiration Index (SPEI) to capture the intensity and duration of short- and medium-term events. The results show that droughts significantly reduce crop yields, with extreme droughts having the most severe effects. Moreover, rice was more sensitive to medium-term droughts, whereas maize and soybeans were more affected by short-term water deficits. The study estimates substantial revenue losses, totaling USD 4.56 billion for rice, USD 3.55 billion for maize, and USD 14.30 billion for soybeans over the study period. These findings highlight the critical vulnerability of regional agriculture to different timescales and intensities of drought.

Objetivo: Estimar o número máximo de casos prevalentes de COVID-19, internados em unidades de terapia intensiva, e o momento deste pico, em Porto Alegre. Métodos: Empregamos um modelo matemático de equações diferenciais denominado SEIHDR (Suscetível, Exposto, Infectado, Hospitalizado, Morto, Recuperados). Analisamos os casos de hospitalização por COVID-19 em Porto Alegre e RS, desde 9 de março até 25 de julho de 2020 a fim de extrair os parâmetros para construir uma curva epidemiológica do total de casos prevalentes hospitalizados e em unidade de terapia intensiva, assim como estimar a prevalência de pacientes em ventilação mecânica invasiva. Finalmente, ajustamos alguns parâmetros desta curva a partir dos casos reais prevalentes de internados em enfermaria e em unidades de terapia intensiva. Resultados: O modelo matemático corrigido para os dados da pandemia até 25 de julho projetou um pico de 1.354 casos prevalentes hospitalizados: 562 pacientes internados na unidade de terapia intensiva com 378 sob ventilação mecânica no dia 12 de setembro de 2020 (37º semana epidemiológica). Ainda, haveria o pico de 62.514 casos prevalentes de infectados com COVID-19 no início do mesmo mês (36º semana epidemiológica. Calculamos para a pandemia um número de reprodução básico de 1,53 e de reprodução efetiva de 1,29 para 25 de julho de 2020. Conclusão: Como o número atual de leitos de unidade de terapia intensiva seria insuficiente para atender a esta demanda, sugerimos um aumento no número de leitos críticos a fim de evitar o colapso do sistema de saúde em Porto Alegre.

The land surface emissivity (LSE) is an important property in the remote characterization of targets. The estimation of LSE involves the application of an indeterminate function of several variables in radiance data contaminated by a complex modeling atmosphere. In this work, four methods of temperature-emissivity retrieval were evaluated from the radiance data of Advanced Spaceborne Thermal Emission and Reflection Radiometer in a coastal dune field of a sub-tropical region: Normalization Emissivity Method (NEM), Reference Channel Method (RCM), Temperature Emissivity Separation (TES) and Alpha Residuals Method (α-Residual). In order to compare the emissivity curves with a minimal error of initial hypothesis, an average brightness temperature of the dune field was estimated and used to select the signature of pure quartz from the Spectral Library of the Geologic Remote Sensing Laboratory both at 302.15 K. In this article, it was assumed that the atmospheric contribution was corrected with parameterization of physical variables in the Moderate Resolution Atmospheric Transmission (MODTRAN) codes, despite the well-known restrictions for humid atmospheres. As a result, the NEM and RCM methods presented the best approximation when compared to the emissivity reference curve. With regard to the average temperature, NEM and RCM presented the best approximation, both with 302.37 K. TES presented 303.25 K. The TES method obtained a value close to the reference value with a difference of 1.12 K, while for NEM and RCM the difference was 0.1 K. α-Residual method did not generate temperature values, since it does not consider this variable in the estimation of the alpha spectrum. It is dependent on the radiance values and, since it has a very similar geometry related to the RCM and NEM, it can reinforce that the atmospheric effects have an important contribution, at least, in these three methods. The methods tend to overestimate the emissivity due to a complex parameterization of physical variables for atmospheric modeling, in addition to the heterogeneity of the target. In contrast, a good performance was obtained in the individualization of the dune field, satisfactorily preserving the geometry of the spectral curve of the quartz.