Assessing uncertainties in estimating surface energy fluxes from remote sensing over natural grasslands in Brazil

Evapotranspiration (ET) is one of the main fluxes in the global water cycle. As the Brazilian Pampa biome carries a rich biodiversity, accurate information on the ET dynamics is essential to support its proper monitoring and establish conservation strategies. In this context, we assessed an operational methodology based on the Simplified Surface Energy Balance Index (S-SEBI) model to estimate energy fluxes over the natural grasslands of the Pampa between 2014 and 2019. The S-SEBI is an ET model that requires a minimum of meteorological inputs and has demonstrated reasonable accuracy worldwide. Therefore, we investigated the model performance considering radiation data from both ERA5 reanalysis and Eddy Covariance measurements from a flux tower. Furthermore, comparisons from satellite-based estimates with in situ measurements were performed with and without energy balance closure (EBC). Results indicated that the meteorological inputs have low sensitivity on daily ET estimates from the S-SEBI model. In contrast, the instantaneous energy balance components are more affected. The strong seasonality impacts the evaporative fraction, which is more evident in late summer and autumn and may compromise the performance of the model in the biome. The effects in the daily ET are lower when in situ data without EBC are considered as ground truth. However, they are less correlated with the remote sensing-based estimates. These insights are useful to monitor water and energy fluxes from local to regional scale and provide the opportunity to capture ET trends over the natural grasslands of the Pampa

Brown seaweed meal to nile tilapia fingerlings

This work evaluated the effects of increasing levels of the brown seaweed Ascophyllum nodosum meal (BSM) in the feed given to Nile tilapia Oreochromis niloticus fingerlings. The completely randomized design experiment lasted 42 days. Nile tilapia fingerlings (n=75) with an average age of 30 days and average weight of 0.43 ± 0.02 g were assigned to 25 plastic tanks and submitted to five treatments in five repetitions. The treatments were increasing levels of BSM (5, 10, 15, and 20 g kg -1 of feed) and a control feed (no BSM). Each experimental unit was made up of a 36 L plastic tank with three fingerlings. The parameters studied were final average weight, percentage of weight gain, apparent feed conversion ratio, total length and carcass yield with and without head. The final average weight, percentage of weight gain, and total length were not affected by the treatments (p>0.05). The apparent feed conversion ratio improved linearly (p<0.01) and carcass yield increased linearly (p<0.01) as the BSM in feeds increased. BSM is an additive with potential use in Nile tilapia feed at the level of 20 g kg -1 because it does not result in growth loss and improves the feed conversion ratio and carcass yield in Nile tilapia during the fingerling period.Este trabalho avaliou os efeitos de níveis crescentes da farinha de alga marrom Ascophyllum nodosum (FAM) nas rações para alevinos de tilápia do Nilo Oreochromis niloticus. O experi- mento, com delineamento inteiramente casua- lizado, durou 42 dias. Foram utilizados alevinos de tilápia do Nilo (n= 75) com idade média de 30 dias e peso médio de 0,43 ± 0,02 g, distribuídos em 25 tanques plásticos submetidos à cinco tratamentos e cinco repetições. Os tratamentos foram níveis crescentes de farinha de alga marrom (5, 10, 15 e 20 g kg -1 de ração) e uma ração controle (sem FAM). Cada unidade experimental foi composta por um tanque plástico de 36 L com três alevinos. Foram estudados os parâmetros médios de peso final, percentagem de ganho de peso, taxa de conversão alimentar aparente, comprimento total e rendimento de carcaça, com e sem cabeça. As médias de peso final, percentagem de ganho de peso e comprimento total não foram influenciadas pelos tratamentos (p>0,05). Os valores da taxa de conversão alimentar aparente melhoraram linearmente (p<0,01) e os valores de rendimento de carcaça aumentaram linearmente (p<0,01) à medida que se aumentaram os níveis de FAM nas rações. A farinha de alga marrom é um aditivo com potencial utilização em rações de tilápia do Nilo no nível de 20 g kg -1 , pois não diminui o crescimento e promove melhora da taxa de conversão alimen- tar e do rendimento de carcaça de alevinos de tilápia do Nilo

Assessing uncertainties in estimating surface energy fluxes from remote sensing over natural grasslands in Brazil

Evapotranspiration (ET) is one of the main fluxes in the global water cycle. As the Brazilian Pampa biome carries a rich biodiversity, accurate information on the ET dynamics is essential to support its proper monitoring and establish conservation strategies. In this context, we assessed an operational methodology based on the Simplified Surface Energy Balance Index (S-SEBI) model to estimate energy fluxes over the natural grasslands of the Pampa between 2014 and 2019. The S-SEBI is an ET model that requires a minimum of meteorological inputs and has demonstrated reasonable accuracy worldwide. Therefore, we investigated the model performance considering radiation data from both ERA5 reanalysis and Eddy Covariance measurements from a flux tower. Furthermore, comparisons from satellite-based estimates with in situ measurements were performed with and without energy balance closure (EBC). Results indicated that the meteorological inputs have low sensitivity on daily ET estimates from the S-SEBI model. In contrast, the instantaneous energy balance components are more affected. The strong seasonality impacts the evaporative fraction, which is more evident in late summer and autumn and may compromise the performance of the model in the biome. The effects in the daily ET are lower when in situ data without EBC are considered as ground truth. However, they are less correlated with the remote sensing-based estimates. These insights are useful to monitor water and energy fluxes from local to regional scale and provide the opportunity to capture ET trends over the natural grasslands of the Pampa