Use of MODIS Images to Quantify the Radiation and Energy Balances in the Brazilian Pantanal

Abstract

MODIS images during the year 2012 were used for modelling of the radiation and energy balance components with the application of the SAFER algorithm (Simple Algorithm for Evapotranspiration Retrieving) in the Brazilian Pantanal area. Pixels from the main sub-regions of Barã o de Melgaç o (BR), Paiaguá s (PA) and Nhecolâ ndia (NH) were extracted in order to process microclimatic comparisons. In general, the net radiation (Rn) relied much more on the global solar radiation (RG) levels than on water conditions and ecosystem types, in accordance with the low Rn standard deviation values. The fraction of the available energy used as latent heat flux (λE) were, on average, 65, 50 and 49% for the BR, PA and NH sub-regions, respectively. Horizontal heat advection, identified by the negative values of sensible heat flux (H), made several pixels with λE values higher than those for Rn in the middle of the year. Taking the evaporative fraction (Ef) as a surface moisture indicator, the Tree-Lined Savanna (TLS) was considered the moister ecosystem class, with 58% of the available energy being used as λE, while the driest one was the modified ecosystem Anthropogenic Changes (AC), presenting a λE/Rn fraction of 0.46. According to the spatial and temporal consistencies, and after comparisons with other previous point and large-scale studies, the SAFER algorithm proved to have sensibility to quantify and compare the large-scale radiation and energy balance components in the different ecosystems of the OPEN ACCESS Remote Sens. 2015, 7 14598Brazilian Pantanal. The algorithm is useful for monitoring the energy exchange dynamics among the different terrestrial and aquatic ecosystem types throughout the seasons of the year.

Large-Scale Spatial Modeling of Crop Coefficient and Biomass Production in Agroecosystems in Southeast Brazil

“…All the regression coefficients of the parameters in Figure 3 and equations below were determined in different areas of Brazil with digital images from different satellites, like Landsat [6,7,13,14,[23][24][25], RapidEye [26], and MODIS [9,27], with field measurements for calibration involving strong contrasting agroecosystems, and under different thermohydrological conditions throughout several years as semiarid areas [9,13,25], wetlands [27], tropical [23], and subtropical areas [6,7,14]. Most of the regressions performed from Landsat-8 were used in this work due to their similarity to the radiometric data on the visible (RGB) and near infrared (NIR) range of the Sentinel-2 satellite [22,28].…”

“…where τ sw is the shortwave atmosphere transmissivity defined as 44% of R G to the incident solar radiation at the top of atmosphere [27] and the a L coefficient from Equation (5) can be explained by variations in 24-h T A values [6] by Equation (8):…”

“…The availability of freely moderate-to-high spatial resolution satellite imagery stimulated the use of remote sensing solutions in spatial modeling, especially after the launch of the Landsat-8 satellite in 2013 [22]. While Landsat-8 imagery (at 30 m spatial resolution) has been widely used for ET mapping [6,7,[23][24][25], other remote sensing imagery, like RapidEye [26] and MODIS [27], with higher and lower spatial resolution than the Landsat-8, respectively, began to be used successfully. A new option is the Sentinel-2 satellite, launched in June 2015, which provides multi-spectral images in 13 bands at different spatial resolutions, including three visible (RGB) and one near infrared (NIR) bands at 10 m spatial resolution, six red-edge and shortwave infrared (SWIR) bands at 20 m, and three atmospheric correction bands at 60 m [28] acquired at a swath width of 290 km and a five-day temporal resolution.…”

Water productivity using SAFER - Simple Algorithm for Evapotranspiration Retrieving in watershed

“…Heat flow in the soil (G) was estimated through its relationship with the net radiation (R n ) (Teixeira et al, 2015c):…”

“…The Simple Algorithm for Evapotranspiration Retrieving (SAFER), which presents itself as a tool for the management of water resources, is based on the modeling of the ET a /ET 0 ratio (Teixeira et al, 2015a) and has been adjusted to the Northwest region of São Paulo (Hernandez et al, 2014) and calibrated for other regions (Teixeira et al, 2015c).…”