# Drought Propagation in Brazilian Biomes Revealed by Remote Sensing
## 1 Introduction
Moreover, meteorological droughts with similar features (e.g., magnitude and duration) can propagate differently and cause distinct social and economic impacts, evidencing the need to improve the understanding of drought propagation mechanisms [24]. [PERSON] et al. [25] analyzed drought propagation on a global scale and showed that regions with humid climates and large _ET_ rates had a strong response relationship between meteorological and hydrological drought. Considering the effects of a warmed climate, [PERSON] et al. [26] calculated the propagation probability of a meteorological drought turning into a hydrological drought and found that the probability increased significantly under climate change scenarios. To better characterize extreme events, especially considering that regional intense droughts have caused major depletion of water resources in southeastern Brazil, [PERSON] et al. [27] pointed out that further analysis of drought propagation is necessary. In order to address the complex characteristics of droughts (timing, duration, intensity, and spatial extent), as well as their development and cascade propagation through the water cycle, a multi-indicator approach is required [23]. Advances in remote sensing of the terrestrial water cycle have helped in this, enabling the Earth's surface and atmosphere to be monitored at different spatial and temporal resolutions all over the globe and providing a core alternative for regions with a low density of ground measurements [28; 29; 30; 31; 32]. For example, [PERSON] et al. [33] characterized drought cascades in the USA using satellite observations of vapor pressure deficit (_VPD_), \(P\), terrestrial water storage (_TWS_), and reanalysis-based estimates of root zone soil moisture. Moreover, remote sensing data can empower policy and decision makers towards social, economic and environmental policies that promote better adaptation to extreme droughts [6]. Because of Brazil's dimensions, each region and biome has specific climatological and ecological characteristics, in addition to different population densities and occupation patterns, which influence the frequency and intensity of drought impacts in each location. Scientific studies have been published on droughts using remote sensing for different Brazilian regions and biomes [11; 34; 35; 36; 37; 38; 39; 40; 41], although very few studies have been dedicated to biomes such as the Pampa [11; 41]. Furthermore, most research has focused primarily on \(P\) and \(ET\)[42]. Droughts affected most parts of Brazil in last decades [43; 44], with an increasing trend in droughts and heatwaves in some parts of the country [45]. Therefore, the main goal of this study was to understand drought patterns and propagation, and to compare events that occurred in different Brazilian biomes based on remote sensing data. This was accomplished by assessing eight hydrometeorological and land-surface indicators, such as \(P\), \(ET\), soil moisture at surface and sub-surface, \(TWS\), land surface temperature (\(LST\)), enhanced vegetation index (\(EVI\)), and gross primary productivity (\(GPP\)), based on remote sensing data that are publicly available through a cloud computing environment (Google Earth Engine--GEE). We evaluated four extreme drought episodes that occurred in Brazil: the 2010 and 2015 events in the Amazon, the 2012 event in the Pampa, and the 2014 event in the Cerrado biome. The spatial and temporal drought patterns were determined by assessing the response and recovery time of each variable in relation to its anomalies for the extreme drought events. This allowed us to evaluate the drought propagation patterns through the hydrological cycle, in addition to the onset, duration, and maximum intensity of drought events.