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Sea Surface Temperature Derived From FY-4A/AGRI

IEEE JOURNAL OF SELECTED TOPICS IN APPLIED EARTH OBSERVATIONS AND REMOTE SENSING 2024年 17卷 14237-14247页

作者： Yang, Chang Guan, Lei Ocean Univ China Coll Marine Technol Fac Informat Sci & Engn Qingdao 266100 Peoples R China Qingdao Marine Sci & Technol Ctr Lab Reg Oceanog & Numer Modeling Qingdao 266071 Peoples R China Ocean Univ China Sanya Oceanog Inst Key Lab Ocean Observat & Informat Hainan Prov SANYA Oceanog Lab Sanya Peoples R China

In this study, we develop an improved algorithm for retrieving sea surface temperature (SST) from the Advanced Geosynchronous Radiation Imager (AGRI) on the Fengyun-4A satellite (FY-4A). First, we use a multichannel nonlinear SST algorithm that combines data from the 3.7, 8.5, 10.7, and 12 mu m channels during the nighttime, while during the daytime it combines data from the three long-wavelength bands centered at 8.5, 10.7, and 12 mu m. Second, to minimize the impact of water vapor and obtain more accurate SST, we provide different retrieval coefficients obtained from the in situ SST and the observed brightness temperature for different latitude regions and different time periods using two-thirds of the matchups from January 2019 to December 2021. We validate the retrieved FY-4A/AGRI SST and operational FY-4A/AGRI SST by comparing them with in situ SST using one-third of the matchups from January 2019 to December 2021. Compared with the in situ data, the full-disk retrieved AGRI SST has the bias, median, standard deviation (STD), robust standard deviation (RSD), and root mean square error (RMSE) of 0.01, 0.03, 0.59, 0.52, and 0.59 K in the daytime, respectively. In nighttime, the bias, median, STD, RSD, and RMSE are 0.02, 0.05, 0.63, 0.55, and 0.63 K, respectively. Our analyses of the results further demonstrate that the improved algorithm significantly improves the accuracy compared with the operational AGRI SST, correcting the large bias in the temporal and spatial scales and effectively accounting for the effect of water vapor and satellite zenith angle.

关键词： Satellite broadcasting Brightness temperature Radiometry Orbits Clouds Atmospheric modeling Approximation algorithms Advanced Geosynchronous Radiation Imager (AGRI) Fengyun-4A latitude segmentation multichannel algorithm retrieval coefficients sea surface temperature (SST)

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Monte Carlo uncertainty analysis of dose estimates in radiochromic film dosimetry with single-channel and multichannel algorithms

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PHYSICA MEDICA-EUROPEAN JOURNAL OF MEDICAL PHYSICS 2018年 47卷 23-33页

作者： Vera-Sanchez, Juan Antonio Ruiz-Morales, Carmen Gonzalez-Lopez, Antonio Hosp Univ St Joan de Reus Serv Fis Med Reus Tarragona Spain Univ Granada PhD Programme Phys & Space Sci Granada Spain Hosp Univ Virgen de la Arrixaca El Palmar Murcia Spain

Purpose: To provide a multi-stage model to calculate uncertainty in radiochromic film dosimetry with Monte-Carlo techniques. This new approach is applied to single-channel and multichannel algorithms. Material and methods: Two lots of Gafchromic EBT3 are exposed in two different Varian linacs. They are read with an EPSON V800 flatbed scanner. The Monte-Carlo techniques in uncertainty analysis provide a numerical representation of the probability density functions of the output magnitudes. From this numerical representation, traditional parameters of uncertainty analysis as the standard deviations and bias are calculated. Moreover, these numerical representations are used to investigate the shape of the probability density functions of the output magnitudes. Also, another calibration film is read in four EPSON scanners (two V800 and two 10000XL) and the uncertainty analysis is carried out with the four images. Results: The dose estimates of single-channel and multichannel algorithms show a Gaussian behavior and low bias. The multichannel algorithms lead to less uncertainty in the final dose estimates when the EPSON V800 is employed as reading device. In the case of the EPSON 10000XL, the single-channel algorithms provide less uncertainty in the dose estimates for doses higher than four Gy. Conclusion: A multi-stage model has been presented. With the aid of this model and the use of the Monte-Carlo techniques, the uncertainty of dose estimates for single-channel and multichannel algorithms are estimated. The application of the model together with Monte-Carlo techniques leads to a complete characterization of the uncertainties in radiochromic film dosimetry.

关键词： Uncertainty analysis Radiochromic film Monte-Carlo multichannel algorithm

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multichannel algorithms for seismic reflectivity inversion

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JOURNAL OF GEOPHYSICS AND ENGINEERING 2017年第1期14卷 41-50页

作者： Wang, Ruo Wang, Yanghua China Geol Survey Oil & Gas Survey Key Lab Unconvent Oil & Gas Geol 10 Haoyuan Beijing 100029 Peoples R China Imperial Coll London Dept Earth Sci & Engn Ctr Reservoir Geophys London SW7 2BP England

Seismic reflectivity inversion is a deconvolution process for quantitatively extracting the reflectivity series and depicting the layered subsurface structure. The conventional method is a single channel inversion and cannot clearly characterise stratified structures, especially from seismic data with low signal-to-noise ratio. Because it is implemented on a traceby- trace basis, the continuity along reflections in the original seismic data is deteriorated in the inversion results. We propose here multichannel inversion algorithms that apply the information of adjacent traces during seismic reflectivity inversion. Explicitly, we incorporate a spatial prediction filter into the conventional Cauchy-constrained inversion method. We verify the validity and feasibility of the method using field data experiments and find an improved lateral continuity and clearer structures achieved by the multichannel algorithms. Finally, we compare the performance of three multichannel algorithms and merit the effectiveness based on the lateral coherency and structure characterisation of the inverted reflectivity profiles, and the residual energy of the seismic data at the same time.

关键词： reflectivity inversion Cauchy-constrained inversion multichannel algorithm spatial prediction filter

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FOURIER EXPANSION OF HAMMERSTEIN MODELS FOR NONLINEAR ACOUSTIC SYSTEM IDENTIFICATION

FOURIER EXPANSION OF HAMMERSTEIN MODELS FOR NONLINEAR ACOUST...

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IEEE International Conference on Acoustics, Speech, and Signal Processing (ICASSP)

作者： Malik, Sarmad Enzner, Gerald Ruhr Univ Bochum Inst Commun Acoust Bochum Germany

ISBN: (纸本)9781457705397

We consider the task of acoustic system identification, where the input signal undergoes a memoryless nonlinear transformation before convolving with an unknown linear system. We focus on the possibility of modeling the nonlinearity with different basis functions, namely the established power series and the proposed Fourier expansion. In this work the unknown coefficients of generic basis functions are merged with the unknown linear system to obtain an equivalent multichannel structure. We use a multichannel DFT-domain algorithm for learning the underlying coefficients of both types of basis functions. We show that the Fourier modeling achieves faster convergence and better learning of the underlying nonlinearity than the polynomial basis.

关键词： Memoryless nonlinearity polynomial expansion Fourier series multichannel algorithm

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FOURIER EXPANSION OF HAMMERSTEIN MODELS FOR NONLINEAR ACOUSTIC SYSTEM IDENTIFICATION

FOURIER EXPANSION OF HAMMERSTEIN MODELS FOR NONLINEAR ACOUST...

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IEEE International Conference on Acoustics, Speech and Signal Processing

作者： Sarmad Malik Gerald Enzner Institute of Communication Acoustics Ruhr-Universitat Bochum Germany

ISBN: (纸本)9781457705380

关键词： Memoryless nonlinearity polynomial expansion Fourier series multichannel algorithm

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Accurate atmospheric correction of ASTER thermal infrared imagery using the WVS method

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IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING 2005年第12期43卷 2778-2792页

作者： Tonooka, H Ibaraki Univ Ibaraki 3168511 Japan

The water vapor scaling (WVS) method involves an atmospheric correction algorithm for thermal infrared (TIR) multispectral data, designed mainly for the five TIR spectral bands of the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on the Terra satellite. First, this method is improved for better applicability to ASTER/TIR imagery. The major improvement is the determination of a water vapor scaling factor on a band-by-band basis, which can reduce most of the errors induced by various factors such as algorithm assumptions. Next, the WVS method is validated by assessing the surface temperature and emissivity retrieved for a global-based simulation model (416 448 conditions), 183 ASTER scenes selected globally, and ASTER scenes from two test sites, Hawaii Island and Tokyo Bay. In situ lake surface temperatures measured in 13 vicarious calibration experiments, Moderate Resolution Imaging Spectroradiometer sea surface temperature products, and a climatic lake temperature are also used in validation. All the results indicate that although the ASTER/TIR standard atmospheric correction algorithm performs less well in humid conditions, the WVS method will provide more accurate retrieval of surface temperature and emissivity in most conditions including notably humid conditions. The expected root mean square error is about 0.6 K in temperature. Since the WVS method will be degraded by errors in gray pixel selection and cloud detection, these processing steps should be applied accurately.

关键词： global data assimilation system (GDAS) gray pixel MODTRAN multichannel algorithm radiative transfer surface emissivity surface temperature validation

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