Uso do satélite Landsat 8 na determinação da produtividade da água em bacia hidrográfica com predomínio do uso agrícola da cana-de-açúcar.

O estudo teve como objetivo analisar a distribuição espacial e temporal dos parâmetros da produtividade da água em microbacia ocupada pela cultura da cana de açúcar por meio da incorporação de dados agrometeorológicos e sensoriamento remoto, visando fornecer informações que permitem estabelecer relações de causa e efeito entre a produção de fitomassa dos agroecossistemas e as condições meteorológicas regionais para subsidiar o planejamento agrícola

Aplicação do algoritmo SAFER na determinação da evapotranspiração em condições de sazonalidade climática no noroeste paulista.

O presente estudo teve como objetivo estimar a variação espacial e temporal dos fluxos do balanço de energia da superfície terrestre via sensoriamento remoto em diferentes tipos de agroecossistemas, com aplicação do algoritmo SAFER em larga escala para a determinação da evapotranspiração em condições de sazonalidade climática na porção noroeste do Estado de São Paulo

Avaliação temporal e espacial do balanço de energia na microbacia do córrego do Ipê, no município de Ilha Solteira face a mudança de uso do solo.

O objetivo deste trabalho foi analisar a variação espacial e temporal dos componentes que compõem o balanço de energia na microbacia do Córrego do Ipê, ao longo do período de 2003 a 2011 para o período seco, buscando identificar interferências com a mudança de uso da terra ocorrida com a entrada da cultura da cana de açúcar

Evapotranspiração real para diferentes coberturas vegetais no noroeste paulista em período seco.

A determinação da evapotranspiração é de fundamental importância para o bom manejo da irrigação. No entanto, o uso de estações meteorológicas para se determinar a evapotranspiração muitas vezes pode comprometer a qualidade da informação, devido a distancia em relação às áreas de cultivo. Dentro dessas premissas, o uso do sensoriamento remoto através do algoritmo SEBAL vem apresentando bons resultados para a determinação da evapotranspiração. Dessa forma, este trabalho se propôs a utilizar o algoritmo para determinar a evapotranspiração real das culturas de cana de açúcar e pastagem e de uma área com mata nativa no noroeste paulista no período seco, com as áreas de pastagem apresentando os menores valores de evapotranspiração e os maiores valores de temperatura de superfíci

Large-scale radiation and energy balances with Landsat 8 images and agrometeorological data in the Brazilian semiarid region.

Aiming to subsidize the rational water resources management, four Landsat 8 (L8) images along different conditions of the year 2014 were used for modeling the radiation and energy balances in the mixed agroecosystems inside a Brazilian reference semiarid area. The SAFER algorithm was applied to calculate the latent heat flux (λE); net radiation (Rn) was acquired by the Slob equation; ground heat flux (G) was considered a fraction of Rn; and the sensible heat flux (H) was retrieved by residue in the energy balance equation. For classifying the vegetation, the surface resistance algorithm (SUREAL) was used to estimate the surface resistance to the water fluxes (rs) with threshold values for rs. Clearly, one could see higher λE values from irrigated crops (ICs) than those for natural vegetation (NV) with some situations of heat horizontal advection. The respective λE, H, and G average ratios to Rn for the ICs ecosystem were 64% to 79%, 18% to 28%, and 3%, respectively. For the NV ecosystem, the corresponding fractions were 4% to 37%, 60% to 94%, and 4%, respectively. The algorithms proved to have strong sensibility to quantifying the large-scale energy and mass exchanges by applying L8 images in mixed agroecosystems of semiarid environments

Phytotoxic and dissuasive activity of Chihuahua desert plants

With the purpose of finding plant compounds with the potential use as herbicides and insecticides, a research was realized with the objective of evaluate the phytotoxic and dissuasive activity of four Chihuahua desert plants. The phytotoxic activity evaluation was tested on Lactuca sativa and Lolium perenne, while the dissuasive activity was realized on three species of phytophagous insects: Myzus persicae, Rhopalosiphum padi and Spodoptera littoralis. Raw extracts were used, the solvents hexane, methanol and ethanol of different plants’ organs (root, steam, leaf and flower) of four species: Fouquieria splendens (ocotillo), Larrea tridentate (governor), Astragalus mollissimus (wild grass) and Pachycereus pecten-aboriginum (echo), by the establishment of in vitro bioassays at a concentration of 10 mg/ml extract/solvent. In the toxicity bioassay, the percentage of germination, root and leaf length were measured. The results showed that the leaf extract of L. tridentata had phytotoxic activity for L. sativa, while for L. perenne the phytotoxicity was observed within the ocotillo, governor and echo extracts. In the dissuasive bioassay, each treatment had 20 repetitions with 10 adult insects per repetition. The methanolic extracts of F. splendens leaf and root, ethanolic extract of A. mollisimus sheet and the ethanolic extract of P. pecten-aboriginum stems showed moderate dissuasive response of feeding against M. persicae, presenting a settlement inhibition index of 53.53, 54.35, 60.00 and 48.84% respectively. Nevertheless, the results indicated that none of the 10 extracts tested on S. littoralis showed significant dissuasive properties for this Lepidoptera, while for R. padi all the tested extracts presented dissuasive properties. The treatments of the four vegetable species evaluated showed defensive or dissuasive properties of moderate to strong feeding against the insects M. persicae and R. padi, presenting interesting potential for being used as insecticides, while the tested extracts that presented phytotoxicity for both lettuce and ryegrass present possibilities for the realization of herbicides

Water productivity mapping using Landsat 8 satellite together with weather stations.

The main goal of this research was to determine the spatial-temporal agro-ecological indicators of water productivity in watersheds with diferent types of land use and occupation, using Landsat 8 images, agro-meteorological stations and application of Monteithand SAFER (Simple Algorithm for Retrieving Evapotranspiration) models to estimate the production biomass (BIO) and the actual evapotranspiration (ET), respectively. Incident global solar radiation (RS↓) is observed seasonality of radiation during the year

JWST Detects Neon Line Variability in a Protoplanetary Disk

We report the first detection of variability in the mid-infrared neon line emission of a protoplanetary disk by comparing a JWST MIRI MRS spectrum of SZ Cha taken in 2023 with a Spitzer IRS SH spectrum of this object from 2008. We measure the [Ne III]-to-[Ne II] line flux ratio, which is a diagnostic of the high-energy radiation field, to distinguish between the dominance of EUV- or X-ray-driven disk photoevaporation. We find that the [Ne III]-to-[Ne II] line flux ratio changes significantly from $\sim1.4$ in 2008 to $\sim0.2$ in 2023. This points to a switch from EUV-dominated to X-ray-dominated photoevaporation of the disk. We present contemporaneous ground-based optical spectra of the Halpha emission line that show the presence of a strong wind in 2023. We propose that this strong wind prevents EUV radiation from reaching the disk surface while the X-rays permeate the wind and irradiate the disk. We speculate that at the time of the Spitzer observations, the wind was suppressed and EUV radiation reached the disk. These observations confirm that the MIR neon emission lines are sensitive to changes in high-energy radiation reaching the disk surface. This highlights the [Ne III]-to-[Ne II] line flux ratio as a tool to gauge the efficiency of disk photoevaporation in order to provide constraints on the planet-formation timescale. However, multiwavelength observations are crucial to interpret the observations and properly consider the star-disk connection.Comment: Accepted to ApJ

The Truncated Disk of CoKu Tau/4

We present a model of a dusty disk with an inner hole which accounts for the Spitzer Space Telescope Infrared Spectrograph observations of the low-mass pre-main sequence star CoKu Tau/4. We have modeled the mid-IR spectrum (between 8 and 25 mic) as arising from the inner wall of a disk. Our model disk has an evacuated inner zone of radius ~ 10 AU, with a dusty inner ``wall'', of half-height ~ 2 AU, that is illuminated at normal incidence by the central star. The radiative equilibrium temperature decreases from the inner disk edge outward through the optically-thick disk; this temperature gradient is responsible for the emission of the silicate bands at 10 and 20 mic. The observed spectrum is consistent with being produced by Fe-Mg amorphous glassy olivine and/or pyroxene, with no evidence of a crystalline component. The mid-infrared spectrum of CoKu Tau/4 is reminiscent of that of the much older star TW Hya, where it has been suggested that the significant clearing of its inner disk is due to planet formation. However, no inner disk remains in CoKu Tau/4, consistent with the star being a weak-emission (non-accreting) T Tauri star. The relative youth of CoKu Tau/4 (~ 1 Myr) may indicate much more rapid planet formation than typically assumed.Comment: 32 pages, 9 figures, accepted in Ap