Continental-scale surface reflectance product from CBERS-4 MUX data: Assessment of atmospheric correction method using coincident Landsat observations

A practical atmospheric correction algorithm, called Coupled Moderate Products for Atmospheric Correction (CMPAC), was developed and implemented for the Multispectral Camera (MUX) on-board the China-Brazil Earth Resources Satellite (CBERS-4). This algorithm uses a scene-based processing and sliding window technique to derive MUX surface reflectance (SR) at continental scale. Unlike other optical sensors, MUX instrument imposes constraints for atmospheric correction due to the absence of spectral bands for aerosol estimation from imagery itself. To overcome this limitation, the proposed algorithm performs a further processing of atmospheric products from Moderate Resolution Imaging Spectroradiometer (MODIS) and Visible Infrared Imaging Radiometer Suite (VIIRS) sensors as input parameters for radiative transfer calculations. The success of CMPAC algorithm was fully assessed and confirmed by comparison of MUX SR data with the Landsat-8 OLI Level-2 and Aerosol Robotic Network (AERONET)-derived SR products. The spectral adjustment was performed to compensate for the differences of relative spectral response between MUX and OLI sensors. The results show that MUX SR values are fairly similar to operational Landsat-8 SR products (mean difference \u3c 0.0062, expressed in reflectance). There is a slight underestimation of MUX SR compared to OLI product (except the NIR band), but the error metrics are typically low and scattered points are around the line 1:1. These results suggest the potential of combining these datasets (MUX and OLI) for quantitative studies. Further, the robust agreement of MUX and AERONET-derived SR values emphasizes the quality of moderate atmospheric products as input parameters in this application, with root-mean-square deviation lower than 0.0047. These findings confirm that (i) CMPAC is a suitable tool for estimating surface reflectance of CBERS MUX data, and (ii) ancillary products support the application of atmospheric correction by filling the gap of atmospheric information. The uncertainties of atmospheric products, negligence of the bidirectional effects, and two aerosol models were also identified as a limitation. Finally, this study presents a framework basis for atmospheric correction of CBERS-4 MUX images. The utility of CBERS data comes from its use, and this new product enables the quantitative remote sensing for land monitoring and environmental assessment at 20 m spatial resolution

Photography-based taxonomy is inadequate, unnecessary, and potentially harmful for biological sciences

The question whether taxonomic descriptions naming new animal species without type specimen(s) deposited in collections should be accepted for publication by scientific journals and allowed by the Code has already been discussed in Zootaxa (Dubois & Nemésio 2007; Donegan 2008, 2009; Nemésio 2009a–b; Dubois 2009; Gentile & Snell 2009; Minelli 2009; Cianferoni & Bartolozzi 2016; Amorim et al. 2016). This question was again raised in a letter supported by 35 signatories published in the journal Nature (Pape et al. 2016) on 15 September 2016. On 25 September 2016, the following rebuttal (strictly limited to 300 words as per the editorial rules of Nature) was submitted to Nature, which on 18 October 2016 refused to publish it. As we think this problem is a very important one for zoological taxonomy, this text is published here exactly as submitted to Nature, followed by the list of the 493 taxonomists and collection-based researchers who signed it in the short time span from 20 September to 6 October 2016

Vicarious Calibration – Let the Data Do All the Work!

Radiometric Calibration of optical satellite systems has been a key aspect of satellite remote sensing since the launch of the first Landsat sensor in 1972. Initially the approach to achieve this goal was based in on-board systems using lamps. In more recent years on–board diffuser systems have also been used. In a parallel path, vicarious calibration techniques have also emerged and proven themselves to be valuable additions to the calibration toolkit. In this workshop we explore the current state of the art of vicarious calibration techniques, compare them to on-board calibration capabilities, and build the case that vicarious techniques can provide the primary basis for calibration of most optical sensor systems

Spectral and Atmospheric Characterization of a Site at Atacama Desert for Earth Observation Sensor Calibration

Made available in DSpace on 2019-09-12T16:53:51Z (GMT). No. of bitstreams: 0 Previous issue date: 2015Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Fondecyt-Initial (CONICYT) [11130359]The application of Earth observation sensor data in quantitative approaches calls on the conversion of original digital numbers to radiometric quantities such as radiance or reflectance. This conversion depends on the sensor absolute calibration. One of the postlaunch methods adopted to calibrate orbital sensors is the reflectance-based approach. According to this method, a reference surface with specifics characteristics is required. The main objective of this work is to evaluate the suitability of a specific surface located at Atacama Desert in Chile to be used as a reference surface for calibration of Earth observation sensor purposes. A field campaign was carried out from August 19 to 22, 2014, when radiometric measurements were performed to spectrally characterize the reference surface and to evaluate the atmospheric characteristics of the study area. The average reference surface reflectance factor in the spectral region from 350 to 2500 nm ranged from 0.1 to 0.3, and its spatial uniformity was within 2%-4%. The amount of atmospheric aerosols was low, with an aerosol optical depth at 550 nm between 0.08 and 0.11 during the fieldwork period. The climate is hyperarid, and the water column abundance was lower than 0.43 g/cm(2). The results demonstrated that a reference surface at Atacama Desert could be effectively used for calibration of either airborne or orbital electrooptical sensors, providing an excellent surface in South America.[Pinto, Cibele T.; Ponzoni, Flavio J.] Natl Inst Space Res INPE, Div Remote Sensing, Sao Jose Dos Campos, Brazil[Barrientos, C.] Chile Air Force, Aerial Photogrammetr Serv, Santiago, Chile[Mattar, C.; Santamaria-Artigas, A.] Univ Chile, Dept Environm Sci & Renewable Nat Resources, Lab Anal Biosphere, Santiago 1058, Chile[Castro, Ruy M.] Inst Adv Studies IEAv CTA, Div Geointelligence EGI, BR-12231970 Sao Jose Dos Campos, Brazil[Castro, Ruy M.] Universidade de Taubaté (Unitau) , Div Math & Phys, BR-12201970 Taubate, Brazi

Evaluation of the uncertainty in the spectral band adjustment factor (SBAF) for cross-calibration using Monte Carlo simulation

Made available in DSpace on 2019-09-12T16:53:47Z (GMT). No. of bitstreams: 0 Previous issue date: 2016Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Cross-calibration is one of the various methods applied for Earth Observation Satellites sensor calibration. In the cross-calibration procedure, one sensor is calibrated against another sensor, in which the radiometric calibration is better known, via near-simultaneous imaging of a common ground target. One of the most important steps during the cross-calibration is the Spectral Band Adjustment Factor (SBAF) assessment. The SBAF is used to compensate the differences in the spectral responses of the sensors, avoiding large uncertainties in cross-calibration results. The investigation described in this work focussed on the evaluation of the SBAF's inherent uncertainties using Monte Carlo Simulation method. Basically, the Monte Carlo approach is based on calculating multiple integral by random sampling. The SBAFs were developed for analogous Landsat 8 Operational Land Imager and CBERS 4 Multispectral Camera spectral bands. The Hyperion hyperspectral sensor on-board Earth Observing-1 was utilized to understand the spectral profile of the target and to derive the SBAF. This study was performed over two pseudo invariant calibration sites: Algodones Dunes and Libya-4. The spectral uncertainty of the SBAFs using Monte Carlo was found to be within 0.01-1.79%. The results suggested that the uncertainty of the SBAFs is dependent on the correlation between the input variables: the higher the correlation, the lowest is the SBAF uncertainty.[Pinto, Cibele T.; Ponzoni, Flavio J.] Natl Inst Space Res, Div Remote Sensing, Sao Jose Dos Campos, Brazil[Castro, Ruy M.] Inst Adv Studies, Div Geointelligence, Sao Jose Dos Campos, Brazil[Castro, Ruy M.] Universidade de Taubaté (Unitau), Div Math & Phys[Leigh, Larry; Kaewmanee, Morakot; Aaron, David; Helder, Dennis] S Dakota State Univ, Coll Engn, Off Engn Res, Brookings, SD 57007 US

Structure–activity relationships for the interactions of 2`- and 3`-(O)-(N-methyl)anthraniloyl-substituted purine and pyrimidine nucleotides with mammalian adenylyl cyclases

Membranous adenylyl cyclases (ACs) play a key role in signal transduction and are promising drug targets. In previous studies we showed that 2',3'-(O)-(N-methylanthraniloyl) (MANT)-substituted nucleotides are potent AC inhibitors. The aim of this study was to provide systematic structure-activity relationships for 21 (M)ANT-substituted nucleotides at the purified catalytic AC subunit heterodimer VC1:IIC2, the VC1:VC1 homodimer and recombinant ACs 1, 2 and 5. (M)ANT-nucleotides inhibited fully activated VC1:IIC2 in the order of affinity for bases hypoxanthine>uracil>cytosine>adenine∼guanine≫xanthine. Omission of a hydroxyl group at the 2' or 3'-position reduced inhibitor potency as did introduction of a γ-thiophosphate group or omission of the γ-phosphate group. Substitution of the MANT-group by an ANT-group had little effect on affinity. Although all nucleotides bound to VC1:IIC2 similarly according to the tripartite pharmacophore model with a site for the base, the ribose, and the phosphate chain, nucleotides exhibited subtle differences in their binding modes as revealed by fluorescence spectroscopy and molecular modelling. MANT-nucleotides also differentially interacted with the VC1:VC1 homodimer as assessed by fluorescence spectroscopy and modelling. Similar structure-activity relationships as for VC1:IIC2 were obtained for recombinant ACs 1, 2 and 5, with AC2 being the least sensitive AC isoform in terms of inhibition. Overall, ACs possess a broad base-specificity with no preference for the "cognate" base adenine as verified by enzyme inhibition, fluorescence spectroscopy and molecular modelling. These properties of ACs are indicative for ligand-specific conformational landscapes that extend to the VC1:VC1 homodimer and should facilitate development of non-nucleotide inhibitors