Does optimal estimation perform adequately for hyperspectral surface reflectance retrieval?

2020 ◽  
Author(s):  
Jouni Susiluoto ◽  
Michael Turmon ◽  
Nimrod Carmon ◽  
David Thompson
Keyword(s):  
Imaging Spectroscopy ◽  
Optimal Estimation ◽  
Full Potential ◽  
Surface Reflectance ◽  
Atmospheric Conditions ◽  
Bayesian Techniques ◽  
Posterior Mean ◽  
A Posteriori Estimate ◽  
Spectral Bands ◽  
Wide Range

<p>The current and coming imaging spectroscopy missions (EMIT, ECOSTRESS, AVIRIS-NG), and observables for potential future missions studying Surface Biology and Geology (SBG) observe a wide range of spectral bands, which can be used to infer about surface properties. The current state of the art approach for performing the retrieval of surface reflectance is optimal estimation (OE), which amounts to finding the maximum a posteriori estimate of the surface reflectance, after which the posterior covariance is approximated by linearizing the forward model (Rodgers, 2001). While this method has a principled basis and often performs well, with challenging atmospheres the optimization may fall into local minima, or the estimated posterior mean and covariance may be wrong.  Addressing these failures under realistic observing conditions is particularly important to realize the full potential of upcoming global observations.                                                                                                                                                                        </p><p><br>As a preparation to improving the quality of future retrievals, we evaluate the performance of OE against posteriors generated with advanced Bayesian techniques.  We present results from comparing the OE posterior mean and covariance to the true posterior, as computed by MCMC, for moderately challenging atmospheric conditions, and an instrument configuration consistent with AVIRIS-NG. </p>

scholarly journals Multiple wavelength retrieval of tropospheric aerosol optical properties from MAXDOAS measurements in Beijing

2010 ◽  
Vol 3 (4) ◽  
pp. 863-878 ◽  
Author(s):  
K. Clémer ◽  
M. Van Roozendael ◽  
C. Fayt ◽  
F. Hendrick ◽  
C. Hermans ◽  
...  
Keyword(s):  
Real Time ◽  
Optimal Estimation ◽  
Retrieval Algorithm ◽  
Aerosol Extinction ◽  
Vertical Profiles ◽  
Atmospheric Conditions ◽  
Multiple Wavelength ◽  
Tropospheric Aerosol ◽  
Wide Range ◽  
On Line

Abstract. We report on the retrieval of aerosol extinction profiles at four wavelengths from ground-based multi-axis differential absorption spectroscopy (MAXDOAS) measurements performed in Beijing, China. Measurements were made over a 10-month time period (June 2008 to April 2009) using a newly developed MAXDOAS instrument. A retrieval algorithm, based on an on-line implementation of the radiative transfer code LIDORT and the optimal estimation technique, has been designed to provide near real time information on aerosol extinction vertical profiles. The algorithm was applied to O4 measurements at four wavelengths (360, 477, 577, and 630 nm). The total aerosol optical depths (AODs) calculated from the retrieved profiles exhibit higher values in spring and summer and lower values in autumn and winter. Comparison of the retrieved total AODs with values from a co-located CIMEL sunphotometer revealed a good correlation. The best results are obtained for the UV region with a correlation coefficient (R) of 0.91 and a slope of the linear regression fit of 1.1. At the longest wavelength, R drops down to 0.67 and the slope increases to 1.5. The results confirm that good quality O4 slant column measurements are essential for the success of the retrievals. A method is presented to determine a correction factor to account for systematic errors. It is demonstrated that the algorithm is capable of reliably retrieving aerosol extinction profiles for a wide range of atmospheric conditions (total AODs at 360 nm ranging from about 0.1 to 3). The results open up new perspectives for the extension of the algorithm for the near real time retrieval of trace gas vertical profiles.

Optimal estimation of snow and ice surface parameters from imaging spectroscopy measurements

2021 ◽  
Author(s):  
Niklas Bohn ◽  
David Thompson ◽  
Nimrod Carmon ◽  
Jouni Susiluoto ◽  
Michael Turmon ◽  
...  
Keyword(s):  
Liquid Water ◽  
Imaging Spectroscopy ◽  
Greenland Ice Sheet ◽  
Optimal Estimation ◽  
Surface Reflectance ◽  
Mixing Ratio ◽  
Surface Parameters ◽  
Ice Surface ◽  
Orbital Imaging ◽  
Snow And Ice

<p>Snow and ice melt processes are key variables in Earth energy-balance and hydrological modeling. Their quantification facilitates predictions of meltwater runoff and distribution and availability of fresh water. Furthermore, they are indicators of climate change and control the balance of the Earth's ice sheets. These processes decrease the surface reflectance with unique spectral patterns due to the accumulation of liquid water and light absorbing particles (LAP), making imaging spectroscopy a powerful tool to measure and map this phenomenon. Here we present a new method to retrieve snow grain size, liquid water fraction, and LAP mass mixing ratio from airborne and space borne imaging spectroscopy acquisitions. This methodology is based on a simultaneous retrieval of atmospheric and surface parameters using optimal estimation (OE), a retrieval technique which leverages prior knowledge and measurement noise in the inversion and also produces uncertainty estimates. We exploit statistical relationships between surface reflectance spectra and snow and ice properties to estimate their most probable quantities given the reflectance. To test this new algorithm we conducted a sensitivity analysis based on simulated top-of-atmosphere radiance spectra using the upcoming EnMAP orbital imaging spectroscopy mission, demonstrating an accurate estimation performance of snow and ice surface properties. An additional validation experiment using in-situ measurements of glacier algae mass mixing ratio and surface reflectance from the Greenland Ice Sheet yields promising results. Finally, we evaluated the retrieval capacity for all snow and ice properties with an AVIRIS-NG acquisition from the Greenland Ice Sheet demonstrating this approach’s potential and suitability for upcoming orbital imaging spectroscopy missions.</p>

scholarly journals Multiple wavelength retrieval of tropospheric aerosol optical properties from MAXDOAS measurements in Beijing

2010 ◽  
Vol 3 (1) ◽  
pp. 111-145 ◽  
Author(s):  
K. Clémer ◽  
M. Van Roozendael ◽  
C. Fayt ◽  
F. Hendrick ◽  
C. Hermans ◽  
...  
Keyword(s):  
Real Time ◽  
Optimal Estimation ◽  
Retrieval Algorithm ◽  
Aerosol Extinction ◽  
Vertical Profiles ◽  
Atmospheric Conditions ◽  
Multiple Wavelength ◽  
Tropospheric Aerosol ◽  
Wide Range ◽  
On Line

Abstract. We report on the retrieval of aerosol extinction profiles at four wavelengths from ground-based multi-axis differential absorption spectroscopy (MAXDOAS) measurements performed in Beijing (N 39°58'37" E 116°22'51"), China. Measurements were made over a 10-month time period (June 2008 to April 2009) using a newly developed MAXDOAS instrument. A retrieval algorithm, based on an on-line implementation of the radiative transfer code LIDORT and the optimal estimation technique, has been designed to provide near real time information on aerosol extinction vertical profiles. The algorithm was applied to O4 measurements at four wavelengths (360, 477, 577, and 630 nm). The total aerosol optical depths (AODs) calculated from the retrieved profiles exhibit higher values in spring and summer and lower values in autumn and winter. Comparison of the retrieved total AODs with values from a co-located CIMEL sunphotometer revealed a good correlation. The best results are obtained for the UV region with a correlation coefficient (R) of 0.91 and a slope of the linear regression fit of 1.1. At the longest wavelength, R drops down to 0.67 and the slope increases to 1.5. The results indicate that good quality O4 slant column measurements are essential for the success of the retrievals. It is demonstrated that the algorithm is capable of reliably retrieving aerosol extinction profiles for a wide range of atmospheric conditions (total AODs at 360 nm ranging from about 0.1 to 3). The results open up new perspectives for the extension of the algorithm for the near real time retrieval of trace gas vertical profiles.

Recent Applications of High Resolution Electron Microscopy to Crystalline Arrays of Virus Particles

1978 ◽  
Vol 36 (3) ◽  
pp. 470-482 ◽  
Author(s):  
R.W. Horne
Keyword(s):  
Electron Microscopy ◽  
Image Processing ◽  
Analytical Techniques ◽  
Staining Technique ◽  
High Resolution Electron Microscopy ◽  
Optical Diffraction ◽  
Full Potential ◽  
Virus Particles ◽  
Resolution Electron ◽  
Wide Range

The technique of surrounding virus particles with a neutralised electron dense stain was described at the Fourth International Congress on Electron Microscopy, Berlin 1958 (see Home & Brenner, 1960, p. 625). For many years the negative staining technique in one form or another, has been applied to a wide range of biological materials. However, the full potential of the method has only recently been explored following the development and applications of optical diffraction and computer image analytical techniques to electron micrographs (cf. De Hosier & Klug, 1968; Markham 1968; Crowther et al., 1970; Home & Markham, 1973; Klug & Berger, 1974; Crowther & Klug, 1975). These image processing procedures have allowed a more precise and quantitative approach to be made concerning the interpretation, measurement and reconstruction of repeating features in certain biological systems.

scholarly journals Enhanced Bilosomal Properties Resulted in Optimum Pharmacological Effects by Increased Acidification Pathways

Pharmaceutics ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1184
Author(s):  
Armin Mooranian ◽  
Thomas Foster ◽  
Corina M Ionescu ◽  
Daniel Walker ◽  
Melissa Jones ◽  
...  
Keyword(s):  
Bile Acids ◽  
Biological Effects ◽  
Cellular Respiration ◽  
Full Potential ◽  
Protective Effects ◽  
Pharmacological Effects ◽  
Β Cells ◽  
Positive Effects ◽  
Wide Range ◽  
Anti Inflammatory

Introduction: Recent studies in our laboratory have shown that some bile acids, such as chenodeoxycholic acid (CDCA), can exert cellular protective effects when encapsulated with viable β-cells via anti-inflammatory and anti-oxidative stress mechanisms. However, to explore their full potential, formulating such bile acids (that are intrinsically lipophilic) can be challenging, particularly if larger doses are required for optimal pharmacological effects. One promising approach is the development of nano gels. Accordingly, this study aimed to examine biological effects of various concentrations of CDCA using various solubilising nano gel systems on encapsulated β-cells. Methods: Using our established cellular encapsulation system, the Ionic Gelation Vibrational Jet Flow technology, a wide range of CDCA β-cell capsules were produced and examined for morphological, biological, and inflammatory profiles. Results and Conclusion: Capsules’ morphology and topographic characteristics remained similar, regardless of CDCA or nano gel concentrations. The best pharmacological, anti-inflammatory, and cellular respiration, metabolism, and energy production effects were observed at high CDCA and nano gel concentrations, suggesting dose-dependent cellular protective and positive effects of CDCA when incorporated with high loading nano gel.

scholarly journals Mineral Physicochemistry Underlying Feature-Based Extraction of Mineral Abundance and Composition from Shortwave, Mid and Thermal Infrared Reflectance Spectra

Minerals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 347
Author(s):  
Carsten Laukamp ◽  
Andrew Rodger ◽  
Monica LeGras ◽  
Heta Lampinen ◽  
Ian C. Lau ◽  
...  
Keyword(s):  
Mineral Exploration ◽  
Relevant Information ◽  
Ore Deposits ◽  
Reflectance Spectra ◽  
Full Potential ◽  
Infrared Reflectance ◽  
Vibrational Modes ◽  
Diagnostic Features ◽  
Wide Range ◽  
Mineral Assemblages

Reflectance spectroscopy allows cost-effective and rapid mineral characterisation, addressing mineral exploration and mining challenges. Shortwave (SWIR), mid (MIR) and thermal (TIR) infrared reflectance spectra are collected in a wide range of environments and scales, with instrumentation ranging from spaceborne, airborne, field and drill core sensors to IR microscopy. However, interpretation of reflectance spectra is, due to the abundance of potential vibrational modes in mineral assemblages, non-trivial and requires a thorough understanding of the potential factors contributing to the reflectance spectra. In order to close the gap between understanding mineral-diagnostic absorption features and efficient interpretation of reflectance spectra, an up-to-date overview of major vibrational modes of rock-forming minerals in the SWIR, MIR and TIR is provided. A series of scripts are proposed that allow the extraction of the relative intensity or wavelength position of single absorption and other mineral-diagnostic features. Binary discrimination diagrams can assist in rapidly evaluating mineral assemblages, and relative abundance and chemical composition of key vector minerals, in hydrothermal ore deposits. The aim of this contribution is to make geologically relevant information more easily extractable from reflectance spectra, enabling the mineral resources and geoscience communities to realise the full potential of hyperspectral sensing technologies.

scholarly journals Industrial Plume Properties Retrieved by Optimal Estimation Using Combined Hyperspectral and Sentinel-2 Data

2021 ◽  
Vol 13 (10) ◽  
pp. 1865
Author(s):  
Gabriel Calassou ◽  
Pierre-Yves Foucher ◽  
Jean-François Léon
Keyword(s):  
Matched Filter ◽  
Estimation Method ◽  
Optimal Estimation ◽  
Model Parameters ◽  
Surface Reflectance ◽  
Sequential Method ◽  
Modal Radius ◽  
Sentinel 2

Stack emissions from the industrial sector are a subject of concern for air quality. However, the characterization of the stack emission plume properties from in situ observations remains a challenging task. This paper focuses on the characterization of the aerosol properties of a steel plant stack plume through the use of hyperspectral (HS) airborne remote sensing imagery. We propose a new method, based on the combination of HS airborne acquisition and surface reflectance imagery derived from the Sentinel-2 Multi-Spectral Instrument (MSI). The proposed method detects the plume footprint and estimates the surface reflectance under the plume, the aerosol optical thickness (AOT), and the modal radius of the plume. Hyperspectral surface reflectances are estimated using the coupled non-negative matrix factorization (CNMF) method combining HS and MSI data. The CNMF reduces the error associated with estimating the surface reflectance below the plume, particularly for heterogeneous classes. The AOT and modal radius are retrieved using an optimal estimation method (OEM), based on the forward model and allowing for uncertainties in the observations and in the model parameters. The a priori state vector is provided by a sequential method using the root mean square error (RMSE) metric, which outperforms the previously used cluster tuned matched filter (CTMF). The OEM degrees of freedom are then analysed, in order to refine the mask plume and to enhance the quality of the retrieval. The retrieved mean radii of aerosol particles in the plume is 0.125 μμm, with an uncertainty of 0.05 μμm. These results are close to the ultra-fine mode (modal radius around 0.1 μμm) observed from in situ measurements within metallurgical plant plumes from previous studies. The retrieved AOT values vary between 0.07 (near the source point) and 0.01, with uncertainties of 0.005 for the darkest surfaces and above 0.010 for the brightest surfaces.

Molecular markers and antioxidant activity in berry crops: Genetic diversity analysis

2012 ◽  
Vol 92 (6) ◽  
pp. 1121-1133 ◽  
Author(s):  
S. C. Debnath ◽  
Y. L. Siow ◽  
J. Petkau ◽  
D. An ◽  
N. V. Bykova
Keyword(s):  
Genetic Diversity ◽  
Antioxidant Activity ◽  
Molecular Markers ◽  
Molecular Techniques ◽  
Diversity Analysis ◽  
Full Potential ◽  
Genetic Diversity Analysis ◽  
Wide Range ◽  
Berry Crops ◽  
Improvement Programs

Debnath, S. C., Siow, Y. L., Petkau, J., An, D. and Bykova, N. V. 2012. Molecular markers and antioxidant activity in berry crops: Genetic diversity analysis. Can. J. Plant Sci. 92: 1121–1133. An improved understanding of important roles of dietary fruits in maintaining human health has led to a dramatic increase of global berry crop production. Berry fruits contain relatively high levels of vitamin C, cellulose and pectin, and produce anthocyanins, which have important therapeutic values, including antitumor, antiulcer, antioxidant and anti-inflammatory activities. There is a need to develop reliable methods to identify berry germplasm and assess genetic diversity/relatedness for dietary properties in berry genotypes for practical breeding purposes through genotype selection in a breeding program for cultivar development, and proprietary-rights protection. The introduction of molecular biology techniques, such as DNA-based markers, allows direct comparison of different genetic materials independent of environmental influences. Significant progress has been made in diversity analysis of wild cranberry, lowbush blueberry, lingonberry and cloudberry germplasm, and in strawberry and raspberry cultivars and advanced breeding lines developed in Canada. Inter simple sequence repeat (ISSR) markers detected an adequate degree of polymorphism to differentiate among berry genotypes, making this technology valuable for cultivar identification and for the more efficient choice of parents in the current berry improvement programs. Although multiple factors affect antioxidant activity, a wide range of genetic diversity has been reported in wild and cultivated berry crops. Diversity analysis based on molecular markers did not agree with those from antioxidant activity. The paper also discusses the issues that still need to be addressed to utilize the full potential of molecular techniques including expressed sequence tag-polymerase chain reaction (EST-PCR) analysis to develop improved environment-friendly berry cultivars suited to the changing needs of growers and consumers.

Layered Manufacturing: Challenges and Opportunities

2002 ◽  
Vol 758 ◽  
Author(s):  
Khershed P. Cooper
Keyword(s):  
Science Research ◽  
Scientific Activity ◽  
Layered Manufacturing ◽  
Full Potential ◽  
Local Composition ◽  
Photosensitive Polymers ◽  
Wide Range ◽  
Challenges And Opportunities ◽  
Future Direction

ABSTRACTLayered Manufacturing (LM) refers to computer-aided manufacturing processes in which parts are made in sequential layers relatively quickly. Parts that are produced by LM can be formed from a wide range of materials such as photosensitive polymers, metals and ceramics in sizes from a centimeter to a few meters with sub-millimeter feature resolutions. LM has found use in diverse areas including biomedical engineering, pharmaceuticals, aerospace, defense, electronics and design engineering. The promise of LM is the capability to make customized complex-shaped functional parts without specialized tooling and without assembly. LM is still a few years away from fully realizing its promise but its potential for manufacturing remains high. A few of the fundamental challenges in materials processing confronting the community are improving the quality of the surface finish, eliminating residual stress, controlling local composition and microstructure, achieving fine feature size and dimensional tolerance and accelerating processing speed. Until these challenges are met, the applicability of LM and its commercialization will be restricted. Sustained scientific activity in LM has advanced over the past decade into many different areas of manufacturing and has enabled exploration of novel processes and development of hybrid processes. The research community of today has the opportunity to shape the future direction of science research to realize the full potential of LM.

SiC Semiconductor Applications - An Air Force Perspective

1996 ◽  
Vol 423 ◽  
Author(s):  
L. S. Rea
Keyword(s):  
Air Force ◽  
Device Performance ◽  
Full Potential ◽  
Materials Development ◽  
Device Development ◽  
Performance Requirements ◽  
Wide Range ◽  
The Status ◽  
Performance Results ◽  
High Temperature Electronic

AbstractThe Department of Defense (DoD) is investing in the development of Silicon Carbide (SiC) for a wide range of applications. Over the past year, SiC technology has demonstrated excellent device performance results for power devices, high temperature electronic devices and microwave devices. The materials growth and processing technology for SiC is now at a level of sufficient maturity to support substantial device development efforts. While there is still considerable materials and device research required for SiC to achieve it's full potential, the fundamental technology has been proven for several critical applications. A perspective on some Air Force device performance requirements will be presented. The status of SiC materials development, material limits to advances in device performance and issues relating to supporting technology will also be discussed.

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