Monitoring environmental indicators by coupling remote sensing and weather data: applications to the Brazilian biomes

Abstract

The SAFER (Simple Algorithm for Evapotranspiration Retrieving) algorithm and the radiation use efficiency (RUE) model were coupled to test large-scale environmental indicators in the Brazilian biomes. The MODIS MOD13Q1 reflectance product and weather data were used along the year 2016. The analyzed biomes were Amazon (AM), Caatinga (CT), Cerrado (CE), Pantanal (PT), Atlantic Forest (AF), and Pampa (PP). Significant differences on precipitation (P), actual evapotranspiration (ET), and biomass production (BIO) yielded differences on water balance (WB = P - ET) and water productivity (WP = ET/BIO). The highest WB and WP along the year were for the wettest AM, AF, and PP biomes, when compared with the driest CT. Precipitation (P) distribution along the year affected the magnitude of the evaporative fraction (ETf), i.e, the ratio of ET to reference evapotranspiration (ET0), however there was a gap between ETf and WB, what can be related to the time needed for recovering the good conditions of soil moisture levels after rainfalls. For some biomes, BIO was related to the levels of absorbed photosynthetically active radiation (PARabs), which depends on the leaf area and soil cover (AM, AF, and PP), while for others BIO followed the soil moisture levels, represented by ETf (CT, CE, and PT). The large-scale modelling presented suitability for monitoring environmental parameters at a 250-m spatial and 16-day spatial and temporal resolutions, with great potential to subsidize public policies regarding the management and conservation of the natural resources, with possibility for replication of the methods in other countries.