## 2 Materials and Methods  
### Study Areas: Brazilian Biomes  
In this study, biome refers to the six main biomes of Brazil as defined by the Ministerio do Meio Ambiente (MMA) as regions sharing morphoclimatic and phytogeographical characteristics: Amazon, Caatinga, Cerrado, Pampa, Pantanal, and Atlantic Forest [102]). Figure 1 shows the Brazilian biome limits utilized in this study. These biomes are used as a large spatial scale basis for comparisons of the high resolution satellite-based SIF measurements across regions for the whole country of Brazil, which covers an area of about 850 million ha [103]. Table S1 shows a list of all abbreviations used in the study.  
The Amazon is the largest biome (about 50-60% of all Brazil) with a humid tropical climate, low seasonal temperature variability, approximately 1000-2000 mm of annual precipitation, containing approximately half the world's tropical rainforest, and critical for biodiversity and the global carbon balance [84; 104; 105]. The Cerrado is second in area to the Amazon (about 22-25%), with about 1200-1800 mm of precipitation, experiences seasonal periods of tropical followed by dry climate, and has a great diversity of vegetation types and canopy covers, with savanna, woody savanna, dry grasslands, wet grasses, and tropical forests, often heavily fragmented for agriculture [96; 97; 106; 107; 108]. The Pantanal is one of the largest wetlands in the world (160,000 km\({}^{2}\)) with a dynamic yearly flooding regime and is a United Nations Educational, Scientific and Culture Organization (UNESCO) World Heritage site containing tropical wetlands with arid tropical species alongside dry shrubland and grasses as well as xeric species [109; 110; 111]. The Pantanal contains a unique hydrologic structure of seasonal inundation fed by the upper Paraguay River and average yearly rainfall of 1000-1400 mm, alternating patterns of salt and freshwater lakes (bahias and salinas), and the highest species diversity and concentration of wildlife in the world, yet it makes up only about 2% of the area of Brazil [110; 112; 113; 114; 115]. Despite often being referred to as a desert, the Caatinga is a semi-arid region, making up about 10% of the country, has only about 700 mm of rainfall per year, falling sometimes erratically with high temperatures and low humidity [116; 117]. and the dominant vegetation is woody shrub land and savanna with abundant xerophytic species, but contains mosaics of seasonally dry tropical forests and is one of the most populated semi-arid regions of the world [96; 116; 117; 118; 119]. The Atlantic Forest covers a wide longitudinal area and has been heavily fragmented to only about 10% of the native vegetation remaining after once having about 150 million ha of rainforest [88; 120]. The Atlantic Forest makes up about 13% of the country's area and much of this is along the Atlantic coast having vegetation ranging from deciduous and tropical forest to mangroves and vast managed forestry plantations, other agriculture, and urban areas [120; 121; 122; 123]. The average rainfall in the Atlantic forest varies greatly from coastal areas (more than 4000 mm/year) to inland (~1000 mm/year), along elevation gradients (~1600 mm/year at sea level to up to 3600 mm/year in high altitude mountain regions) and along the latitudinal expanse of the biome [120]. The Pampa is the southernmost border biome, occupies approximately 2% of Brazil, and has a transition from tropical to temperate climate, thus having four seasons, supporting grasslands and deciduous forest, and a large amount of agricultural development [124; 125]. The Pampa lies within the South temperate zone with subtropical and temperate climates averaging approximately 1200-1600 mm/year precipitation [124].