Defense
Student: Camila Fernanda Aparecida Silva
Program: Meteorology
Title: "Study of temperature, precipitation, and solar radiation trends in the states of São Paulo and Rio Grande do Norte"
Advisor: Profa. Dra. Marcia Akemi Yamasoe
Judging Comitee:
- Profa. Dra. Marcia Akemi Yamasoe - Presidente e Orientadora - IAG/USP
- Profa. Dra. Michele Simões Reboita - UNIFEI
- Prof. Dr. Cristiano Prestrelo de Oliveira - UFRN
Other Members:
- Profa. Dra. Rosmeri Porfírio da Rocha - IAG/USP
- Profa. Dra. Gizelly Cardoso Lima - UFRN
- Prof. Dr. Carlos Antonio Costa dos Santos - UFCG
Abstract:
Climate change represents one of the major scientific and social challenges of the 21st century, with consistent evidence of changes in temperature, precipitation, and solar radiation patterns across different regions of the planet. This work investigated the trends of these climatic variables in the states of São Paulo and Rio Grande do Norte over the period from 1990 to 2024, using observational data from weather stations of the National Institute of Meteorology (INMET) and the National Water Agency (ANA) (2004-2024), integrated with satellite products as the Climate Hazards Group InfraRed Precipitation with Station (CHIRPS), the Geostationary Operational Environmental Satellite (GOES), and the CM SAF Cloud, Albedo and Surface Radiation dataset from Advanced Very High Resolution Radiometer (AVHRR) data - Edition 3 (CLARA-A3) and with reanalysis data from the ECMWF Reanalysis v5 - Land (ERA5-Land), produced by the European Centre for Medium-Range Weather Forecasts (ECMWF). Validation across data sources showed good to very good agreement for precipitation (R = 0.7-0.9), excellent for temperature (R >= 0.9), and excellent for solar radiation (R ~ 0.9). Climatic trends were detected using the Mann-Kendall test and quantified through Sen's slope estimator, with a seasonal analysis. The results showed warming trends in São Paulo, ranging from 0.3 to 0.7 °C per decade, while in Rio Grande do Norte the trends were lower, varying between -0.15 and 0.3 °C per decade, with few regions exhibiting statistical significance in both states. Radiation trends were predominantly positive across both states. Precipitation exhibited highly variable behavior: in São Paulo, negative trends predominated, although with low statistical significance, whereas in Rio Grande do Norte, high interannual variability hindered the identification of statistically significant trends. The quantitative analysis of the relationship between land cover and climatic variables, based on MapBiomas data, demonstrated that urbanization is the main anthropogenic factor associated with local thermal changes. In São Paulo, approximately 93.8% of the grid cells showed a statistically significant association between urbanization and temperature, with a median regression coefficient of beta_med = 4.75, indicating high thermal sensitivity and clearly characterizing the urban heat island effect. In Rio Grande do Norte, only approximately 2.0% of the cells showed a significant association. Native vegetation formations showed more limited influence: in Rio Grande do Norte, the reduction of savanna formation showed little direct relationship with climatic variables, with the highest significance of 39.5% found for solar radiation; in São Paulo, forest cover played a more perceptible moderating role, with significance of 68.7% for temperature and 55.2% for solar radiation. Finally, the subregional analysis for Rio Grande do Norte revealed detectable associations between land cover change and local temperature trends, something that was not evident at the state level. Caatinga loss was associated with greater warming (r = -0.5), Pasture expansion showed a positive correlation (r = +0.5), indicating that the increase in its cultived area was related to higher temperatures, and the Agropastoral Mosaic showed a negative association (r = -0.5), all three cases reaching statistical significance.
Keywords: Climate change; Climate trends; Land cover; São Paulo; Rio Grande do Norte; Temperature; Precipitation; Solar radiation.