Future climate scenarios point to an increase in the frequency of extreme droughts events, even in humid biomes. Throughout the 21st century, large areas of the Amazon basin experienced the most severe droughts ever recorded with special emphasis on the 2005 and 2010 events due to their severity and extent. Currently, there is an increased demand to understand the geographic extent and seasonal variability of climate variables during drought events, especially with respect to the social and environmental impacts. In this study, we aim to compare the observed climate conditions during the drought episodes of 2005, 2010 and 2015. We perform a detailed assessment of the measured precipitation, land-surface temperature (LST) and solar radiation anomalies. We provide evidence that the anomalous precipitation deficit during 2015 exceeded the amplitude and spatial extent of the previous events, affecting more than 80% of Amazon basin, particularly the eastern portion. The pronounced lack of rainfall availability during late spring and early summer, coincident with radiation and temperature surpluses during these years are significant and notable. Changed meteorological spatial patterns were observed, with precipitation and radiation being the most prominent parameters in 2005, whereas precipitation and LST were most relevant in 2010. Understanding the behaviour and interactions of pertinent meteorological variables, as well as identifying similar or divergent patterns over the region during distinct extreme events, is essential for the improvement of our knowledge of Amazon forest vulnerability to climate fluctuation changes.

An increase in the frequency of extremely hot and dry events has been experienced over the past few decades in South America, and particularly in Brazil. Regional climate change projections indicate a future aggravation of this trend. However, a comprehensive characterization of drought and heatwave compound events, as well as of the main land–atmosphere mechanisms involved, is still lacking for most of South America. This study aims to fill this gap, assessing for the first time the historical evolution of compound summer drought and heatwave events for the heavily populated region of Southeast Brazil and for the period of 1980–2018. The main goal is to undertake a detailed analysis of the surface and synoptic conditions, as well as of the land–atmosphere coupling processes that led to the occurrence of individual and compound dry and hot extremes. Our results confirm that the São Paulo, Rio de Janeiro and Minas Gerais states have recorded pronounced and statistically significant increases in the number of compound summer drought and heatwave episodes. In particular, the last decade was characterized by two austral summer seasons (2013/14 and 2014/15) with outstanding concurrent drought and heatwave conditions stemmed by severe precipitation deficits and a higher-than-average occurrence of blocking patterns. As result of these land and atmosphere conditions, a high coupling (water-limited) regime was imposed, promoting the re-amplification of hot spells that resulted in mega heatwave episodes. Our findings reveal a substantial contribution of persistent dry conditions to heatwave episodes, highlighting the vulnerability of the region to climate change.

Abstract:The Brazilian Cerrado is significantly affected by anthropic fires every year, which makes the region an important source of pyrogenic emissions. This study aims at generating improved 1 km monthly burned area maps for Cerrado based on remote-sensed information. The algorithm relies on a burn-sensitive vegetation index based on MODIS daily values of near and middle infrared reflectance and makes use of active fire detection from multiple sensors. Validation is performed using reference burned area (BA) maps derived from Landsat imagery. Results are also compared with MODIS standard BA products. A monthly BA database for the Brazilian Cerrado is generated covering the period 2005-2014. Estimated value of BA is 1.3 times larger than the value derived from reference data, making the product suitable for applications in fire emission studies and ecosystem management. As expected the intra and inter-annual variability of estimated BA over the Brazilian Cerrado is in agreement with the regime of precipitation. This work represents the first step towards setting up a regional database of BA for Brazil to be developed in the

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