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Potential impacts of air temperature rise in the hydric balance of Brazilian Pampa biome

da Rocha Najila Souza, Veettil Bijeesh Kozhikkodan, de Carvalho Cibelle Machado, Käfer Pâmela Suélen, Diaz Lucas Ribeiro, Rolim Silvia Beatriz Alves, Cruz Rafael Cabral

Acta Geophysica

2021

Vol. 69, no. 4

1427--1445

Climate change is the meteorological alterations that occurred in the past by natural causes, which is occurring today and being intensifed by the human behavior. Some of the main consequences of these alterations are: increase in the air temperature, changes in the hydrological cycle and occurrence of extreme weather events with greater intensity and frequency. This work was performed in Alto Camaquã in the Pampa Biome, which is considered as a region of stability and of great importance for biodiversity conservation. The main economical and sociocultural activity in the region is livestock run by diferent families, which is also considered fundamental for the maintenance of this biome. The objective of this work was to infer information on hydric defcit in Alto Camaquã watershed related to the increase in the air temperature and its impacts on family livestock. For this purpose, we estimated the climatic water balance (CWB) derived from pluviometric and meteorological data. We also estimated the maximum capacity of available water for the period between 1990 and 2016 and also for the predictive scenarios when an increase as well as no change in the air temperature occur. It has been observed that there will be hydric defcit during the summer, except for Rainy Year, independent on whether a change in the air temperature occurs or not. The results demonstrated that the efects of climate change are already occurring and that, even if the ongoing climate change stops before the predictions come true, the hydric defcit has already been experienced by the society.

Comparison of emissivity retrieval methods from ASTER data using Fourier Transform Infrared Spectroscopy

Rolim Silvia Beatriz Alves, Veettil Bijeesh Kozhikkodan, Käfer Pâmela Suélen, Grondona Atilio Efrain Bica, Iglesias María Luján, Diaz Lucas Ribeiro, Hackmann Cristiano Lima

Acta Geophysica

2020

Vol. 68, no. 6

1867--1876

Land surface emissivity retrieval is important for the remote identifcation of natural materials and can be used to identify the presence of silicate minerals. However, its estimation from passive sensors involves an undetermined function related to radiance data, which is infuenced by the atmosphere. We tested three methods for temperature emissivity retrieval in a dune feld composed of 99.53% quartz (SiO2) using Advanced Spaceborne Thermal Emission and Refection Radiometer (ASTER) imagery. The tested methods were the reference channel method (RCM), emissivity normalization method (ENM), and temperature emissivity separation (TES) method. An average quartz reference spectrum for the dune samples was calculated from an emissivity database based on temperature and used to evaluate the emissivity products of four ASTER images. In general, the three tested methods had a good approximation when analysed the emissivity reference curve, especially for longer wavelengths that ranged between 2 and 4% of emissivity. The RCM and ENM produced very similar results with the coefcients of determination (R2 ) as 0.9960 (RMSE 0.0184) and 0.9959 (RMSE 0.0185), respectively. RCM method presented superior results (R2 : 0.9960, RMSE: 0.0184), compared to the TES method (R2 : 0.9947, RMSE: 0.0197). The TES method showed good results only for shorter wavelengths and, hence, to identify specifc targets using ASTER data, such as silicate minerals, it is better to use the RCM method. The emissivity value selected at the saturation point of the spectral library based on temperature is fundamental in acquiring more reliable data.