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Sample records for airborne high spectral

  1. NASA Langley Airborne High Spectral Resolution Lidar Instrument Description

    NASA Technical Reports Server (NTRS)

    Harper, David B.; Cook, Anthony; Hostetler, Chris; Hair, John W.; Mack, Terry L.

    2006-01-01

    NASA Langley Research Center (LaRC) recently developed the LaRC Airborne High Spectral Resolution Lidar (HSRL) to make measurements of aerosol and cloud distribution and optical properties. The Airborne HSRL has undergone as series of test flights and was successfully deployed on the Megacity Initiative: Local and Global Research Observations (MILAGRO) field mission in March 2006 (see Hair et al. in these proceedings). This paper provides an overview of the design of the Airborne HSRL and descriptions of some key subsystems unique to this instrument.

  2. Airborne High Spectral Resolution Lidar Measurements of Atmospheric Aerosols

    NASA Astrophysics Data System (ADS)

    Ferrare, R.; Hostetler, C.; Hair, J.; Cook, A.; Harper, D.; Kleinman, L.; Clarke, A.; Russell, P.; Redemann, J.; Livingston, J.; Szykman, J.; Al-Saadi, J.

    2007-05-01

    NASA Langley Research Center (LaRC) recently developed an airborne High Spectral Resolution Lidar (HSRL) to measure aerosol distributions and optical properties. The HSRL technique takes advantage of the spectral distribution of the lidar return signal to discriminate aerosol and molecular signals and thereby measure aerosol extinction and backscatter independently. The LaRC instrument employs the HSRL technique to measure aerosol backscatter and extinction profiles at 532 nm and the standard backscatter lidar technique to measure aerosol backscatter profiles at 1064 nm. Depolarization profiles are measured at both wavelengths. Since March 2006, the airborne HSRL has acquired over 215 flight hours of data deployed on the NASA King Air B200 aircraft during several field experiments. Most of the flights were conducted during two major field experiments. The first major experiment was the joint Megacity Initiative: Local and Global Research Observations (MILAGRO) /Megacity Aerosol Experiment in Mexico City (MAX-MEX)/Intercontinental Chemical Transport Experiment-B (INTEX B) experiment that was conducted during March 2006 to investigate the evolution and transport of pollution from Mexico City. The second major experiment was the Texas Air Quality Study (TEXAQS)/Gulf of Mexico Atmospheric Composition and Climate Study (GoMACCS) that was conducted during August and September 2006 to investigate climate and air quality in the Houston/Gulf of Mexico region. Several flights were also conducted to help validate the Cloud-Aerosol LIdar with Orthogonal Polarization (CALIOP) lidar on board the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite (CALIPSO) satellite. In February 2007, several flights were carried out as part of an Environmental Protection Agency (EPA) experiment to assess air quality in central California. Airborne HSRL data acquired during these missions were used to quantify aerosol extinction and optical thickness contributed by various aerosol types

  3. Aerosol Classification using Airborne High Spectral Resolution Lidar Measurements

    NASA Astrophysics Data System (ADS)

    Burton, S. P.; Ferrare, R. A.; Hostetler, C. A.; Hair, J. W.; Obland, M. D.; Rogers, R.; Butler, C. F.; Cook, A.; Harper, D.; Froyd, K. D.

    2011-12-01

    The NASA Langley Research Center (LaRC) airborne High Spectral Resolution Lidar (HSRL) on the NASA B200 aircraft has acquired extensive datasets of aerosol extinction (532 nm), aerosol optical thickness (AOT) (532 nm), backscatter (532 and 1064 nm), and depolarization (532 and 1064 nm) profiles during 18 field missions that have been conducted over North America since 2006. The lidar measurements of aerosol intensive parameters (lidar ratio, depolarization, backscatter color ratio, spectral depolarization ratio) are shown to vary with location and aerosol type. A methodology based on observations of known aerosol types is used to qualitatively classify the extensive set of HSRL aerosol measurements into eight separate types. Several examples are presented showing how the aerosol intensive parameters vary with aerosol type and how these aerosols are classified according to this new methodology. The HSRL-based classification reveals vertical variability of aerosol types during the NASA ARCTAS field experiment conducted over Alaska and northwest Canada during 2008. In two examples derived from flights conducted during ARCTAS, the HSRL classification of biomass burning smoke is shown to be consistent with aerosol types derived from coincident airborne in situ measurements of particle size and composition. The HSRL retrievals of aerosol optical thickness and inferences of aerosol types are used to apportion aerosol optical thickness to aerosol type; results of this analysis are shown for several experiments.

  4. Aerosol Profile Measurements from the NASA Langley Research Center Airborne High Spectral Resolution Lidar

    NASA Technical Reports Server (NTRS)

    Obland, Michael D.; Hostetler, Chris A.; Ferrare, Richard A.; Hair, John W.; Roers, Raymond R.; Burton, Sharon P.; Cook, Anthony L.; Harper, David B.

    2008-01-01

    Since achieving first light in December of 2005, the NASA Langley Research Center (LaRC) Airborne High Spectral Resolution Lidar (HSRL) has been involved in seven field campaigns, accumulating over 450 hours of science data across more than 120 flights. Data from the instrument have been used in a variety of studies including validation and comparison with the Cloud- Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) satellite mission, aerosol property retrievals combining passive and active instrument measurements, aerosol type identification, aerosol-cloud interactions, and cloud top and planetary boundary layer (PBL) height determinations. Measurements and lessons learned from the HSRL are leading towards next-generation HSRL instrument designs that will enable even further studies of aerosol intensive and extensive parameters and the effects of aerosols on the climate system. This paper will highlight several of the areas in which the NASA Airborne HSRL is making contributions to climate science.

  5. Aerosol classification using airborne High Spectral Resolution Lidar measurements - methodology and examples

    NASA Astrophysics Data System (ADS)

    Burton, S. P.; Ferrare, R. A.; Hostetler, C. A.; Hair, J. W.; Rogers, R. R.; Obland, M. D.; Butler, C. F.; Cook, A. L.; Harper, D. B.; Froyd, K. D.

    2012-01-01

    The NASA Langley Research Center (LaRC) airborne High Spectral Resolution Lidar (HSRL) on the NASA B200 aircraft has acquired extensive datasets of aerosol extinction (532 nm), aerosol optical depth (AOD) (532 nm), backscatter (532 and 1064 nm), and depolarization (532 and 1064 nm) profiles during 18 field missions that have been conducted over North America since 2006. The lidar measurements of aerosol intensive parameters (lidar ratio, depolarization, backscatter color ratio, and spectral depolarization ratio) are shown to vary with location and aerosol type. A methodology based on observations of known aerosol types is used to qualitatively classify the extensive set of HSRL aerosol measurements into eight separate types. Several examples are presented showing how the aerosol intensive parameters vary with aerosol type and how these aerosols are classified according to this new methodology. The HSRL-based classification reveals vertical variability of aerosol types during the NASA ARCTAS field experiment conducted over Alaska and northwest Canada during 2008. In two examples derived from flights conducted during ARCTAS, the HSRL classification of biomass burning smoke is shown to be consistent with aerosol types derived from coincident airborne in situ measurements of particle size and composition. The HSRL retrievals of AOD and inferences of aerosol types are used to apportion AOD to aerosol type; results of this analysis are shown for several experiments.

  6. Aerosol classification using airborne High Spectral Resolution Lidar measurements - methodology and examples

    NASA Astrophysics Data System (ADS)

    Burton, S. P.; Ferrare, R. A.; Hostetler, C. A.; Hair, J. W.; Rogers, R. R.; Obland, M. D.; Butler, C. F.; Cook, A. L.; Harper, D. B.; Froyd, K. D.

    2011-09-01

    The NASA Langley Research Center (LaRC) airborne High Spectral Resolution Lidar (HSRL) on the NASA B200 aircraft has acquired extensive datasets of aerosol extinction (532 nm), aerosol optical thickness (AOT) (532 nm), backscatter (532 and 1064 nm), and depolarization (532 and 1064 nm) profiles during 18 field missions that have been conducted over North America since 2006. The lidar measurements of aerosol intensive parameters (lidar ratio, depolarization, backscatter color ratio, and spectral depolarization ratio) are shown to vary with location and aerosol type. A methodology based on observations of known aerosol types is used to qualitatively classify the extensive set of HSRL aerosol measurements into eight separate types. Several examples are presented showing how the aerosol intensive parameters vary with aerosol type and how these aerosols are classified according to this new methodology. The HSRL-based classification reveals vertical variability of aerosol types during the NASA ARCTAS field experiment conducted over Alaska and northwest Canada during 2008. In two examples derived from flights conducted during ARCTAS, the HSRL classification of biomass burning smoke is shown to be consistent with aerosol types derived from coincident airborne in situ measurements of particle size and composition. The HSRL retrievals of AOT and inferences of aerosol types are used to apportion AOT to aerosol type; results of this analysis are shown for several experiments.

  7. Airborne High Spectral Resolution Lidar Aerosol Measurements during MILAGRO and TEXAQS/GOMACCS

    NASA Technical Reports Server (NTRS)

    Ferrare, Richard; Hostetler, Chris; Hair, John; Cook Anthony; Harper, David; Burton, Sharon; Clayton, Marian; Clarke, Antony; Russell, Phil; Redemann, Jens

    2007-01-01

    Two1 field experiments conducted during 2006 provided opportunities to investigate the variability of aerosol properties near cities and the impacts of these aerosols on air quality and radiative transfer. The Megacity Initiative: Local and Global Research Observations (MILAGRO) /Megacity Aerosol Experiment in Mexico City (MAX-MEX)/Intercontinental Chemical Transport Experiment-B (INTEX-B) joint experiment conducted during March 2006 investigated the evolution and transport of pollution from Mexico City. The Texas Air Quality Study (TEXAQS)/Gulf of Mexico Atmospheric Composition and Climate Study (GoMACCS) (http://www.al.noaa.gov/2006/) conducted during August and September 2006 investigated climate and air quality in the Houston/Gulf of Mexico region. During both missions, the new NASA Langley airborne High Spectral Resolution Lidar (HSRL) was deployed on the NASA Langley B200 King Air aircraft and measured profiles of aerosol extinction, backscattering, and depolarization to: 1) characterize the spatial and vertical distributions of aerosols, 2) quantify aerosol extinction and optical thickness contributed by various aerosol types, 3) investigate aerosol variability near clouds, 4) evaluate model simulations of aerosol transport, and 5) assess aerosol optical properties derived from a combination of surface, airborne, and satellite measurements.

  8. Validation of CALIPSO Lidar Observations Using Data From the NASA Langley Airborne High Spectral Resolution Lidar

    NASA Technical Reports Server (NTRS)

    Hostetler, Chris; Hair, Johnathan; Liu, Zhaoyan; Ferrare, Rich; Harper, David; Cook, Anthony; Vaughan, Mark; Trepte, Chip; Winker, David

    2006-01-01

    This poster focuses on preliminary comparisons of data from the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) instrument on the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) spacecraft with data acquired by the NASA Langley Airborne High Spectral Resolution Lidar (HSRL). A series of 20 aircraft validation flights was conducted from 14 June through 27 September 2006, under both day and night lighting conditions and a variety of aerosol and cloud conditions. This poster presents comparisons of CALIOP measurements of attenuated backscatter at 532 and 1064 nm and depolarization at 532 nm with near coincident measurements from the Airborne HSRL as a preliminary assessment of CALIOP calibration accuracy. Note that the CALIOP data presented here are the pre-release version. These data have known artifacts in calibration which have been corrected in the December 8 CALIPSO data release which was not available at the time the comparisons were conducted for this poster. The HSRL data are also preliminary. No artifacts are known to exist; however, refinements in calibration and algorithms are likely to be implemented before validation comparisons are made final.

  9. Mixed Layer Heights Derived from the NASA Langley Research Center Airborne High Spectral Resolution Lidar

    NASA Technical Reports Server (NTRS)

    Scarino, Amy J.; Burton, Sharon P.; Ferrare, Rich A.; Hostetler, Chris A.; Hair, Johnathan W.; Obland, Michael D.; Rogers, Raymond R.; Cook, Anthony L.; Harper, David B.; Fast, Jerome; Dasilva, Arlindo; Benedetti, Angela

    2012-01-01

    The NASA airborne High Spectral Resolution Lidar (HSRL) has been deployed on board the NASA Langley Research Center's B200 aircraft to several locations in North America from 2006 to 2012 to aid in characterizing aerosol properties for over fourteen field missions. Measurements of aerosol extinction (532 nm), backscatter (532 and 1064 nm), and depolarization (532 and 1064 nm) during 349 science flights, many in coordination with other participating research aircraft, satellites, and ground sites, constitute a diverse data set for use in characterizing the spatial and temporal distribution of aerosols, as well as properties and variability of the Mixing Layer (ML) height. We describe the use of the HSRL data collected during these missions for computing ML heights and show how the HSRL data can be used to determine the fraction of aerosol optical thickness within and above the ML, which is important for air quality assessments. We describe the spatial and temporal variations in ML heights found in the diverse locations associated with these experiments. We also describe how the ML heights derived from HSRL have been used to help assess simulations of Planetary Boundary Layer (PBL) derived using various models, including the Weather Research and Forecasting Chemistry (WRF-Chem), NASA GEOS-5 model, and the ECMWF/MACC models.

  10. System for processing of airborne images of forest ecosystems using high spectral and spatial resolution data

    NASA Astrophysics Data System (ADS)

    Kozoderov, V. V.; Dmitriev, E. V.; Kamentsev, V. P.

    2014-12-01

    The developed hardware and software system for the recognition of natural and man-made objects based on the airborne hyperspectral sensing implements flight tasks on selected survey routes and computational procedures for solving applied problems that occur in data processing. The basics of object recognition based on obtained images of high spectral and spatial resolution in mathematical terms of sets of sites and labels and the basics of interrelations between separate resolution elements (pixels) for selected object classes are presented. Features of energy minimization of the processed scene are depicted as a target function of the optimization of computation and regularization of the solution of the considered problems as a theoretical basis for distinguishing between classes of objects in the presence of boundaries between them. Examples of the formation of information layers of recorded spectra for selected "pure species" of pine and birch forests are cited, with the separation of illuminated and shaded pixels, which increases the accuracy of object recognition in the processing of the images.

  11. Comparison of Aerosol Classification from Airborne High Spectral Resolution Lidar and the CALIPSO Vertical Feature Mask

    NASA Astrophysics Data System (ADS)

    Burton, S. P.; Ferrare, R. A.; Omar, A. H.; Hostetler, C. A.; Hair, J. W.; Rogers, R.; Obland, M. D.; Butler, C. F.; Cook, A. L.; Harper, D. B.

    2012-12-01

    The NASA Langley Research Center (LaRC) airborne High Spectral Resolution Lidar (HSRL-1) on the NASA B200 aircraft has acquired large datasets of aerosol extinction (532nm), backscatter (532 and 1064nm), and depolarization (532 and 1064nm) profiles during 349 science flights in 19 field missions across North America since 2006. The extinction-to-backscatter ratio ("lidar ratio"), aerosol depolarization ratios, and backscatter color ratio measurements from HSRL-1 are scale-invariant parameters that depend on aerosol type but not concentration. These four aerosol intensive parameters are combined to qualitatively classify HSRL aerosol measurements into eight separate composition types. The classification methodology uses models formed from "training cases" with known aerosol type. The remaining measurements are then compared with these models using the Mahalanobis distance. Aerosol products from the CALIPSO satellite include aerosol type information as well, which is used as input to the CALIPSO aerosol retrieval. CALIPSO aerosol types are inferred using a mix of aerosol loading-dependent parameters, estimated aerosol depolarization, and location, altitude, and surface type information. The HSRL instrument flies beneath the CALIPSO satellite orbit track, presenting the opportunity for comparisons between the HSRL aerosol typing and the CALIPSO Vertical Feature Mask Aerosol Subtype product, giving insight into the performance of the CALIPSO aerosol type algorithm. We find that the aerosol classification from the two instruments frequently agree for marine aerosols and pure dust, and somewhat less frequently for pollution and smoke. In addition, the comparison suggests that the CALIPSO polluted dust type is overly inclusive, encompassing cases of dust combined with marine aerosol as well as cases without much evidence of dust. Qualitative classification of aerosol type combined with quantitative profile measurements of aerosol backscatter and extinction has many useful

  12. A Nadir-adjusted Airborne Multi Spectral Imaging System (NAMSIS) for high-resolution remote sensing of carbon fluxes

    NASA Astrophysics Data System (ADS)

    Jiang, Z.; Scott, S.; Rahman, A. F.

    2012-12-01

    Satellite remote sensing is widely used in vegetation monitoring, water stress detection and carbon cycle modeling. However, image pixels from high temporal resolution satellite sensors (such as MODIS) have coarse spatial resolution, much larger than the canopies they are supposed to characterize. An alternative solution for on-demand high spatial resolution remote sensing is sensors onboard low-flying aircrafts. Airborne remote sensing has been traditionally used in crop management studies. In this presentation we demonstrate the application of a relatively low-cost airborne sensor system with customized spectral band combinations for studying forest carbon fluxes. Our team has developed an Inertia Measurement Unit (IMU) controlled automated system to detach aircraft movements (pitch and roll) and engine vibration from the six-band programmable imager, in order to maintain the sensor at nadir view at all times during the flight. Flight lines are configured by a GPS-controleld system to simulate MODIS pixels. A feature-based algorithm is used to automatically generate a mosaic of individual images along the flight lines. This algorithm eliminates the need to mosiac and georeference images manually. An empirical line method is used to calculate reflectance from the raw data. Images from this airborne system produce reflectance values that are comparable with MODIS reflectance product. These high spatial resolution (~0.5 m) images deliver detailed information about tree species and phenological conditions within each MODIS pixel, and thus permit a high resolution spatio-temporal assessment of forest carbon fluxes.

  13. Using Airborne High Spectral Resolution Lidar Data to Evaluate Combined Active Plus Passive Retrievals of Aerosol Extinction Profiles

    NASA Technical Reports Server (NTRS)

    Burton, S. P.; Ferrare, R. A.; Hostetler, C. A.; Hair, J. W.; Kittaka, C.; Vaughn, M. A.; Remer, L. A.

    2010-01-01

    We derive aerosol extinction profiles from airborne and space-based lidar backscatter signals by constraining the retrieval with column aerosol optical thickness (AOT), with no need to rely on assumptions about aerosol type or lidar ratio. The backscatter data were acquired by the NASA Langley Research Center airborne High Spectral Resolution Lidar (HSRL) and by the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) instrument on the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) satellite. The HSRL also simultaneously measures aerosol extinction coefficients independently using the high spectral resolution lidar technique, thereby providing an ideal data set for evaluating the retrieval. We retrieve aerosol extinction profiles from both HSRL and CALIOP attenuated backscatter data constrained with HSRL, Moderate-Resolution Imaging Spectroradiometer (MODIS), and Multiangle Imaging Spectroradiometer column AOT. The resulting profiles are compared with the aerosol extinction measured by HSRL. Retrievals are limited to cases where the column aerosol thickness is greater than 0.2 over land and 0.15 over water. In the case of large AOT, the results using the Aqua MODIS constraint over water are poorer than Aqua MODIS over land or Terra MODIS. The poorer results relate to an apparent bias in Aqua MODIS AOT over water observed in August 2007. This apparent bias is still under investigation. Finally, aerosol extinction coefficients are derived from CALIPSO backscatter data using AOT from Aqua MODIS for 28 profiles over land and 9 over water. They agree with coincident measurements by the airborne HSRL to within +/-0.016/km +/- 20% for at least two-thirds of land points and within +/-0.028/km +/- 20% for at least two-thirds of ocean points.

  14. A Compact Airborne High Spectral Resolution Lidar for Observations of Aerosol and Cloud Optical Properties

    NASA Technical Reports Server (NTRS)

    Hostetler, Chris A.; Hair, John W.; Cook, Anthony L.

    2002-01-01

    We are in the process of developing a nadir-viewing, aircraft-based high spectral resolution lidar (HSRL) at NASA Langley Research Center. The system is designed to measure backscatter and extinction of aerosols and tenuous clouds. The primary uses of the instrument will be to validate spaceborne aerosol and cloud observations, carry out regional process studies, and assess the predictions of chemical transport models. In this paper, we provide an overview of the instrument design and present the results of simulations showing the instrument's capability to accurately measure extinction and extinction-to-backscatter ratio.

  15. Use of high spectral resolution airborne visible/infrared imaging spectrometer data for geologic mapping: An overview

    NASA Technical Reports Server (NTRS)

    Carrere, Veronique

    1991-01-01

    Specific examples of the use of AVIRIS (Airborne Visible/Infrared Imaging Spectrometer) high spectral resolution data for mapping, alteration related to ore deposition and to hydrocarbon seepage, and alluvial fans are presented. Correction for atmospheric effects was performed using flat field correction, log residuals, and radiative transfer modeling. Minerals of interest (alunite, kaolinite, gypsum, carbonate iron oxides, etc.) were mapped based upon the wavelength position, depth and width of characteristic absorption features. Results were checked by comparing to existing maps, results from other sensors (Thematic Mapper (TM) and TIMS (Thermal Infrared Multispectral Scanner)), and laboratory spectra of samples collected in the field. Alteration minerals were identified and mapped. The signal to noise ratio of acquired AVIRIS data, long to 2.0 microns, was insufficient to map minerals of interest.

  16. 355-nm high spectral resolution airborne lidar LNG: system description and first results.

    PubMed

    Bruneau, D; Pelon, J; Blouzon, F; Spatazza, J; Genau, P; Buchholtz, G; Amarouche, N; Abchiche, A; Aouji, O

    2015-10-10

    A high spectral resolution (HSR) measurement capability in the ultraviolet has been added to the 3-wavelength-2-polarization-backscatter lidar LNG (lidar aerosols nouvelle génération) and tested during several flights. The system includes a Mach-Zehnder interferometer (MZI) as a spectral discriminator and does not require any frequency locking between the emitter and the interferometer. Results obtained during test flights show that the backscatter and extinction coefficients at 355 nm can be measured with a relative precision of 10% for 60 m and 240 m vertical resolution, respectively, in aerosol layers of 10-6  m-1 sr-1 backscatter coefficient with a 30-km horizontal resolution. The same relative precision is obtained in cirrus clouds of a 2×10-5  m-1 sr-1 backscatter coefficient for the same vertical resolution and a horizontal resolution reduced to 5 km. The capacity of the system to perform wind velocity measurements is also demonstrated with precisions in the range of 1 to 2  ms-1. Particle-to-total backscatter ratio and line-of-sight speed measurements have been performed on ground echoes; averaged data show biases less than 1% and 0.15  ms-1, respectively.

  17. Land cover classification based on object-oriented with airborne lidar and high spectral resolution remote sensing image

    NASA Astrophysics Data System (ADS)

    Li, Fangfang; Liu, Zhengjun; Xu, Qiangqiang; Ren, Haicheng; Zhou, Xingyu; Yuan, Yonghua

    2016-10-01

    In order to improve land cover classification accuracy of the coastal tidal wetland area in Dafeng, this paper take advantage of hyper-spectral remote sensing image with high spatial resolution airborne Lidar data. The introduction of feature extraction, band selection and nDSM models to reduce the dimension of the original image. After segmentation process that combining FNEA segmentation with spectral differences segmentation method, the paper finalize the study area through the establishment of the rule set classification of land cover classification. The results show that the proposed classification for land cover classification accuracy has improved significantly, including housing, shadow, water, vegetation classification of high precision. That is to say that the method can meet the needs of land cover classification of the coastal tidal wetland area in Dafeng. This innovation is the introduction of principal component analysis, and the use of characteristic index, shape and characteristics of various types of data extraction nDSM feature to improve the accuracy and speed of land cover classification.

  18. Comparison of Aerosol Classification From Airborne High Spectral Resolution Lidar and the CALIPSO Vertical Feature Mask

    NASA Technical Reports Server (NTRS)

    Burton, Sharon P.; Ferrare, Rich A.; Omar, Ali H.; Vaughan, Mark A.; Rogers, Raymond R.; Hostetler, Chris a.; Hair, Johnathan W.; Obland, Michael D.; Butler, Carolyn F.; Cook, Anthony L.; Harper, David B.

    2012-01-01

    Knowledge of aerosol composition and vertical distribution is crucial for assessing the impact of aerosols on climate. In addition, aerosol classification is a key input to CALIOP aerosol retrievals, since CALIOP requires an inference of the lidar ratio in order to estimate the effects of aerosol extinction and backscattering. In contrast, the NASA airborne HSRL-1 directly measures both aerosol extinction and backscatter, and therefore the lidar ratio (extinction-to-backscatter ratio). Four aerosol intensive properties from HSRL-1 are combined to infer aerosol type. Aerosol classification results from HSRL-1 are used here to validate the CALIOP aerosol type inferences.

  19. Combined Atmospheric and Ocean Profiling from an Airborne High Spectral Resolution Lidar

    NASA Astrophysics Data System (ADS)

    Hair, Johnathan; Hostetler, Chris; Hu, Yongxiang; Behrenfeld, Michael; Butler, Carolyn; Harper, David; Hare, Rich; Berkoff, Timothy; Cook, Antony; Collins, James; Stockley, Nicole; Twardowski, Michael; Cetinić, Ivona; Ferrare, Richard; Mack, Terry

    2016-06-01

    First of its kind combined atmospheric and ocean profile data were collected by the recently upgraded NASA Langley Research Center's (LaRC) High Spectral Resolution Lidar (HSRL-1) during the 17 July - 7 August 2014 Ship-Aircraft Bio-Optical Research Experiment (SABOR). This mission sampled over a region that covered the Gulf of Maine, open-ocean near Bermuda, and coastal waters from Virginia to Rhode Island. The HSRL-1 and the Research Scanning Polarimeter from NASA Goddard Institute for Space Studies collected data onboard the NASA LaRC King Air aircraft and flight operations were closely coordinated with the Research Vessel Endeavor that made in situ ocean optical measurements. The lidar measurements provided profiles of atmospheric backscatter and particulate depolarization at 532nm, 1064nm, and extinction (532nm) from approximately 9km altitude. In addition, for the first time HSRL seawater backscatter, depolarization, and diffuse attenuation data at 532nm were collected and compared to both the ship measurements and the Moderate Resolution Imaging Spectrometer (NASA MODIS-Aqua) satellite ocean retrievals.

  20. Object-based assessment of burn severity in diseased forests using high-spatial and high-spectral resolution MASTER airborne imagery

    NASA Astrophysics Data System (ADS)

    Chen, Gang; Metz, Margaret R.; Rizzo, David M.; Dillon, Whalen W.; Meentemeyer, Ross K.

    2015-04-01

    Forest ecosystems are subject to a variety of disturbances with increasing intensities and frequencies, which may permanently change the trajectories of forest recovery and disrupt the ecosystem services provided by trees. Fire and invasive species, especially exotic disease-causing pathogens and insects, are examples of disturbances that together could pose major threats to forest health. This study examines the impacts of fire and exotic disease (sudden oak death) on forests, with an emphasis on the assessment of post-fire burn severity in a forest where trees have experienced three stages of disease progression pre-fire: early-stage (trees retaining dried foliage and fine twigs), middle-stage (trees losing fine crown fuels), and late-stage (trees falling down). The research was conducted by applying Geographic Object-Based Image Analysis (GEOBIA) to MASTER airborne images that were acquired immediately following the fire for rapid assessment and contained both high-spatial (4 m) and high-spectral (50 bands) resolutions. Although GEOBIA has gradually become a standard tool for analyzing high-spatial resolution imagery, high-spectral resolution data (dozens to hundreds of bands) can dramatically reduce computation efficiency in the process of segmentation and object-based variable extraction, leading to complicated variable selection for succeeding modeling. Hence, we also assessed two widely used band reduction algorithms, PCA (principal component analysis) and MNF (minimum noise fraction), for the delineation of image objects and the subsequent performance of burn severity models using either PCA or MNF derived variables. To increase computation efficiency, only the top 5 PCA and MNF and top 10 PCA and MNF components were evaluated, which accounted for 10% and 20% of the total number of the original 50 spectral bands, respectively. Results show that if no band reduction was applied the models developed for the three stages of disease progression had relatively

  1. Using Airborne High Spectral Resolution Lidar Data to Evaluate Combined Active Plus Passive Retrievals of Aerosol Extinction Profiles

    NASA Technical Reports Server (NTRS)

    Burton, S. P.; Ferrare, R. A.; Kittaka, C.; Hostetler, C. A.; Hair, J. W.; Obland, M. D.; Rogers, R. R.; Cook, A. L.; Haper, D. B.

    2008-01-01

    Aerosol extinction profiles are derived from backscatter data by constraining the retrieval with column aerosol optical thickness (AOT), for example from coincident MODIS observations and without reliance on a priori assumptions about aerosol type or optical properties. The backscatter data were acquired with the NASA Langley High Spectral Resolution Lidar (HSRL). The HSRL also simultaneously measures extinction independently, thereby providing an ideal data set for evaluating the constrained retrieval of extinction from backscatter. We will show constrained extinction retrievals using various sources of column AOT, and examine comparisons with the HSRL extinction measurements and with a similar retrieval using data from the CALIOP lidar on the CALIPSO satellite.

  2. Thermal Infrared Spectral Imager for Airborne Science Applications

    NASA Technical Reports Server (NTRS)

    Johnson, William R.; Hook, Simon J.; Mouroulis, Pantazis; Wilson, Daniel W.; Gunapala, Sarath D.; Hill, Cory J.; Mumolo, Jason M.; Eng, Bjorn T.

    2009-01-01

    An airborne thermal hyperspectral imager is under development which utilizes the compact Dyson optical configuration and quantum well infrared photo detector (QWIP) focal plane array. The Dyson configuration uses a single monolithic prism-like grating design which allows for a high throughput instrument (F/1.6) with minimal ghosting, stray-light and large swath width. The configuration has the potential to be the optimal imaging spectroscopy solution for lighter-than-air (LTA) vehicles and unmanned aerial vehicles (UAV) due to its small form factor and relatively low power requirements. The planned instrument specifications are discussed as well as design trade-offs. Calibration testing results (noise equivalent temperature difference, spectral linearity and spectral bandwidth) and laboratory emissivity plots from samples are shown using an operational testbed unit which has similar specifications as the final airborne system. Field testing of the testbed unit was performed to acquire plots of apparent emissivity for various known standard minerals (such as quartz). A comparison is made using data from the ASTER spectral library.

  3. Assessment of the CALIPSO Lidar 532 nm Attenuated Backscatter Calibration Using the NASA LaRC Airborne High Spectral Resolution Lidar

    NASA Technical Reports Server (NTRS)

    Rogers, Raymond R.; Hostetler, Chris A.; Hair, Johnathan W.; Ferrare, Richard A.; Liu, Zhaoyan; Obland, Michael D.; Harper, David B.; Cook, Anthony L.; Powell, Kathleen A.; Vaughan, Mark A.; Winker, David M.

    2011-01-01

    The Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) instrument on the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) spacecraft has provided global, high-resolution vertical profiles of aerosols and clouds since it became operational on 13 June 2006. On 14 June 2006, the NASA Langley Research Center (LaRC) High Spectral Resolution Lidar (HSRL) was deployed aboard the NASA Langley B-200 aircraft for the first of a series of 86 underflights of the CALIPSO satellite to provide validation measurements for the CALIOP data products. To better assess the range of conditions under which CALIOP data products are produced, these validation flights were conducted under both daytime and nighttime lighting conditions, in multiple seasons, and over a large range of latitudes and aerosol and cloud conditions. This paper presents a quantitative assessment of the CALIOP 532 nm calibration (through the 532 nm total attenuated backscatter) using an internally calibrated airborne HSRL underflight data and is the most extensive study of CALIOP 532 nm calibration. Results show that average HSRL and CALIOP 532 nm total attenuated backscatter agree on average within 2.7% +/- 2.1% (CALIOP lower) at night and within 2.9 % +/- 3.9% (CALIOP lower) during the day., demonstrating the accuracy of the CALIOP 532 nm calibration algorithms. Additionally, comparisons with HSRL show consistency of the CALIOP calibration before and after the laser switch in 2009 as well as improvements in the daytime version 3 calibration scheme compared with the version 2 calibration scheme. Potential systematic uncertainties in the methodology relevant to validating satellite lidar measurements with an airborne lidar system are discussed and found to be less than 3.7% for this validation effort with HSRL. Results from this study are also compared to those from prior assessments of CALIOP calibration and attenuated backscatter.

  4. Comparison of Aerosol Classification Results from Airborne High Spectral Resolution Lidar (HSRL) Measurements and the Calipso Vertical Feature Mask

    NASA Technical Reports Server (NTRS)

    Burton, S. P.; Ferrare, R. A.; Hostetler, C. A.; Hair, J. W.; Rogers, R. R.; Obland, M. D.; Butler, C. F.; Cook, A. L.; Harper, D. B.; Froyd, K. D.; Omar, A.

    2012-01-01

    Knowledge of the vertical profile, composition, concentration, and size of aerosols is required for assessing the direct impact of aerosols on radiation, the indirect effects of aerosols on clouds and precipitation, and attributing these effects to natural and anthropogenic aerosols. Because anthropogenic aerosols are predominantly submicrometer, fine mode fraction (FMF) retrievals from satellite have been used as a tool for deriving anthropogenic aerosols. Although column and profile satellite retrievals of FMF have been performed over the ocean, such retrievals have not yet been been done over land. Consequently, uncertainty in satellite estimates of the anthropogenic component of the aerosol direct radiative forcing is greatest over land, due in large part to uncertainties in the FMF. Satellite measurements have been used to detect and evaluate aerosol impacts on clouds; however, such efforts have been hampered by the difficulty in retrieving vertically-resolved cloud condensation nuclei (CCN) concentration, which is the most direct parameter linking aerosol and clouds. Recent studies have shown correlations between average satellite derived column aerosol optical thickness (AOT) and in situ measured CCN. However, these same studies, as well as others that use detailed airborne in situ measurements have noted that vertical variability of the aerosol distribution, impacts of relative humidity, and the presence of coarse mode aerosols such as dust introduce large uncertainties in such relations.

  5. Planetary Boundary Layer (PBL) Heights Derived From NASA Langley Airborne High Spectral Resolution Lidar (HSRL) Data Acquired During TexAQS/GoMACCS, CHAPS, and MILAGRO

    NASA Astrophysics Data System (ADS)

    Burton, S. P.; Ferrare, R. A.; Hostetler, C. A.; Hair, J. W.; Cook, A.; Harper, D.; Obland, M. D.; Rogers, R. R.

    2007-12-01

    The NASA Langley Research Center airborne High Spectral Resolution Lidar (HSRL) was deployed on the NASA Langley B-200 King Air aircraft in the Mexico City metropolitan area during the Mega-city Initiative: Local and Global Research Observations (MILAGRO) campaign in March 2006; in the Houston metropolitan area during the Texas Air Quality Study (TexAQS)/Gulf of Mexico Atmospheric Composition and Climate Study (GoMACCS) in August and September 2006; and in the Oklahoma City area during Cumulus Humilis Aerosol Processing Study (CHAPS) in June 2007. The HSRL instrument measures profiles of aerosol extinction, backscatter and depolarization. The height of the Planetary Boundary Layer was derived by identifying sharp gradients in the HSRL 532-nm aerosol backscatter signal profiles using an automated technique based on Brooks (2003) [I.M. Brooks, Finding Boundary Layer Top: Application of Wavelet Covariance Transform to Lidar Backscatter Profiles. Journal of Atmospheric and Oceanic Technology 20, 1092-1105, 2003]. The technique uses a Haar wavelet covariance transform with multiple wavelet dilation values to adapt to non-ideal conditions where there can be gradients in the background signals and the boundary layer can be ill defined. The technique also identifies the top and bottom of the transition (i.e. entrainment) zone. We have further modified the algorithm to find PBL heights using HSRL backscatter data acquired during GoMACCS and MILAGRO, where complex terrain and overlying aerosol layers further complicate identifying the boundary layer. In addition, PBL heights are derived from HSRL backscatter data acquired during the CHAPS campaign, in another urban environment where the terrain is not as complex. We will describe the algorithm modifications we have made and show boundary layer heights and transition zone thicknesses for HSRL measurements over the Oklahoma City, Houston, and Mexico City areas during CHAPS, TexAQS/GoMACCS, and MILAGRO.

  6. Assessing Aerosol Mixed Layer Heights from the NASA Larc Airborne High Spectral Resolution Lidar (HSRL) during the Discover-AQ Field Campaigns

    NASA Astrophysics Data System (ADS)

    Scarino, A. J.; Ferrare, R. A.; Burton, S. P.; Hostetler, C. A.; Hair, J. W.; Rogers, R. R.; Berkoff, T.; Sawamura, P.; Collins, J. E., Jr.; Seaman, S. T.; Cook, A. L.; Harper, D. B.; Follette-Cook, M. B.; daSilva, A.; Randles, C. A.

    2014-12-01

    The first- and second-generation NASA airborne High Spectral Resolution Lidars (HSRL-1 and HSRL-2) have been deployed on board the NASA Langley Research Center King Air aircraft during the Deriving Information on Surface Conditions from Column and VERtically Resolved Observations Relevant to Air Quality (DISCOVER-AQ) field campaigns. These included deployments during July 2011 over Washington, D.C. and Baltimore, MD, during January and February 2013 over the San Joaquin Valley of California, during September 2013 over Houston, TX and during July and August 2014 over Denver, CO. Measurements of aerosol extinction, backscatter, and depolarization are available from both HSRL-1 and HSRL-2 in coordination with other participating research aircraft and ground sites. These measurements constitute a diverse data set for use in characterizing the spatial and temporal distribution of aerosols, aerosol optical thickness (AOT), as well as the mixed layer (ML) height. Analysis of the ML height at these four locations is presented, including temporal and horizontal variability and comparisons between land and water, including the Chesapeake Bay and Galveston Bay. Using the ML heights, the distribution of AOT relative to the ML heights is determined, which is relevant for assessing the long-range transport of aerosols. The ML heights are also used to help relate column AOT measurements and extinction profiles to surface PM2.5 concentrations. The HSRL ML heights are also used to evaluate the performance in simulating the temporal and spatial variability of ML heights from both chemical regional models and global forecast models.

  7. Comparison of Mixed Layer Heights from Airborne High Spectral Resolution Lidar, Ground-based Measurements, and the WRP-Chem Model during CalNex and CARES

    SciTech Connect

    Scarino, Amy Jo; Obland, Michael; Fast, Jerome D.; Burton, S. P.; Ferrare, R. A.; Hostetler, Chris A.; Berg, Larry K.; Lefer, Barry; Haman, C.; Hair, John; Rogers, Ray; Butler, Carolyn; Cook, A. L.; Harper, David

    2014-06-05

    The California Research at the Nexus of Air Quality and Climate Change (CalNex) and Carbonaceous Aerosol and Radiative Effects Study (CARES) field campaigns during May and June 2010 provided a data set appropriate for studying characteristics of the planetary boundary layer (PBL). The NASA Langley Research Center (LaRC) airborne High Spectral Resolution Lidar (HSRL) was deployed to California onboard the NASA LaRC B-200 aircraft to aid incharacterizing aerosol properties during these two field campaigns. Measurements of aerosol extinction (532 nm), backscatter (532 and 1064 nm), and depolarization (532 and 1064 nm) profiles during 31 flights, many in coordination with other research aircraft and ground sites, constitute a diverse data set for use in characterizing the spatial and temporal distribution of aerosols, as well as the depth and variability of the daytime mixed layer (ML), which is a subset within the PBL. This work illustrates the temporal and spatial variability of the ML in the vicinity of Los Angeles and Sacramento, CA. ML heights derived from HSRL measurements are compared to PBL heights derived from radiosonde profiles, ML heights measured from ceilometers, and simulated PBL heights from the Weather Research and Forecasting Chemistry (WRF-Chem) community model. Comparisons between the HSRL ML heights and the radiosonde profiles in Sacramento result in a correlation coefficient value (R) of 0.93 (root7 mean-square (RMS) difference of 157 m and bias difference (HSRL radiosonde) of 5 m). HSRL ML heights compare well with those from the ceilometer in the LA Basin with an R of 0.89 (RMS difference of 108 m and bias difference (HSRL Ceilometer) of -9.7 m) for distances of up to 30 km between the B-200 flight track and the ceilometer site. Simulated PBL heights from WRF-Chem were compared with those obtained from all flights for each campaign, producing an R of 0.58 (RMS difference of 604 m and a bias difference (WRF-Chem HSRL) of -157 m) for CalNex and 0

  8. A13K-0336: Airborne Multi-Wavelength High Spectral Resolution Lidar for Process Studies and Assessment of Future Satellite Remote Sensing Concepts

    NASA Technical Reports Server (NTRS)

    Hostetler, Chris A.; Ferrare, Rich A.; Hair, Johnathan W.; Cook, Anthony L.; Harper, David B.; Mack, Terry L.; Hare, Richard J.; Cleckner, Craig S.; Rogers, Raymond R.; Muller, Detlef; Chemyakin, Eduard; Burton, Sharon P.; Obland, Michael D.; Scarino, Amy J.; Cairns, Brian; Russell, Phil; Redermann, Jens; Shinozuka, Y.; Schmid, Beat; Fast, Jerome; Berg, Larry; Flynn, Connor; Wagener, Rick; Gregory, Laurie

    2012-01-01

    NASA Langley recently developed the world's first airborne multi-wavelength high spectral resolution lidar (HSRL). This lidar employs the HSRL technique at 355 and 532 nm to make independent, unambiguous retrievals of aerosol extinction and backscatter. It also employs the standard backscatter technique at 1064 nm and is polarization-sensitive at all three wavelengths. This instrument, dubbed HSRL-2 (the secondgeneration HSRL developed by NASA Langley), is a prototype for the lidar on NASA's planned Aerosols- Clouds-Ecosystems (ACE) mission. HSRL-2 completed its first science mission in July 2012, the Two-Column Aerosol Project (TCAP) conducted by the Department of Energy (DOE) in Hyannis, MA. TCAP presents an excellent opportunity to assess some of the remote sensing concepts planned for ACE: HSRL-2 was deployed on the Langley King Air aircraft with another ACE-relevant instrument, the NASA GISS Research Scanning Polarimeter (RSP), and flights were closely coordinated with the DOE's Gulfstream-1 aircraft, which deployed a variety of in situ aerosol and trace gas instruments and the new Spectrometer for Sky-Scanning, Sun-Tracking Atmospheric Research (4STAR). The DOE also deployed their Atmospheric Radiation Measurement Mobile Facility and their Mobile Aerosol Observing System at a ground site located on the northeastern coast of Cape Cod for this mission. In this presentation we focus on the capabilities, data products, and applications of the new HSRL-2 instrument. Data products include aerosol extinction, backscatter, depolarization, and optical depth; aerosol type identification; mixed layer depth; and rangeresolved aerosol microphysical parameters (e.g., effective radius, index of refraction, single scatter albedo, and concentration). Applications include radiative closure studies, studies of aerosol direct and indirect effects, investigations of aerosol-cloud interactions, assessment of chemical transport models, air quality studies, present (e.g., CALIPSO

  9. Airborne Spectral Measurements of Ocean Directional Reflectance

    NASA Technical Reports Server (NTRS)

    Gatebe, Charles K.; King, Michael D.; Lyapustin, Alexei; Arnold, G. Thomas; Redemann, Jens

    2004-01-01

    During summer of 2001 NASA's Cloud Absorption Radiometer (CAR) obtained measurement of ocean angular distribution of reflected radiation or BRDF (bidirectional reflectance distribution function) aboard the University of Washington Convair CV-580 research aircraft under cloud-free conditions. The measurements took place aver the Atlantic Ocean off the eastern seaboard of the U.S. in the vicinity of the Chesapeake Light Tower and at nearby National Oceanic and Atmospheric Administration (NOAA) Buoy Stations. The measurements were in support of CLAMS, Chesapeake Lighthouse and Aircraft Measurements for Satellites, field campaign that was primarily designed to validate and improve NASA's Earth Observing System (EOS) satellite data products being derived from three sensors: MODIS (MODerate Resolution Imaging Spectro-Radiometer), MISR (Multi-angle Imaging Spectro-Radiometer) and CERES (Clouds and Earth s Radiant Energy System). Because of the high resolution of the CAR measurements and its high sensitivity to detect weak ocean signals against a noisy background, results of radiance field above the ocean are seen in unprecedented detail. The study also attempts to validate the widely used Cox-Munk model for predicting reflectance from a rough ocean surface.

  10. Forest tree species clssification based on airborne hyper-spectral imagery

    NASA Astrophysics Data System (ADS)

    Dian, Yuanyong; Li, Zengyuan; Pang, Yong

    2013-10-01

    Forest precision classification products were the basic data for surveying of forest resource, updating forest subplot information, logging and design of forest. However, due to the diversity of stand structure, complexity of the forest growth environment, it's difficult to discriminate forest tree species using multi-spectral image. The airborne hyperspectral images can achieve the high spatial and spectral resolution imagery of forest canopy, so it will good for tree species level classification. The aim of this paper was to test the effective of combining spatial and spectral features in airborne hyper-spectral image classification. The CASI hyper spectral image data were acquired from Liangshui natural reserves area. Firstly, we use the MNF (minimum noise fraction) transform method for to reduce the hyperspectral image dimensionality and highlighting variation. And secondly, we use the grey level co-occurrence matrix (GLCM) to extract the texture features of forest tree canopy from the hyper-spectral image, and thirdly we fused the texture and the spectral features of forest canopy to classify the trees species using support vector machine (SVM) with different kernel functions. The results showed that when using the SVM classifier, MNF and texture-based features combined with linear kernel function can achieve the best overall accuracy which was 85.92%. It was also confirm that combine the spatial and spectral information can improve the accuracy of tree species classification.

  11. FTIR-based airborne spectral imagery for target interrogation

    NASA Astrophysics Data System (ADS)

    Smithson, Tracy L.; St. Germain, Daniel; Nadeau, Denis

    2007-09-01

    DRDC Valcartier is continuing to developed infrared spectral imagery systems for a variety of military applications. Recently a hybrid airborne spectral imager / broadband imager system has been developed for ground target interrogation (AIRIS). This system employs a Fourier Transform Interferometer system coupled to two 8x8 element detector arrays to create spectral imagery in the region from 2.0 to 12 microns (830 to 5000 cm -1) at a spectral resolution of up to 1 cm -1. In addition, coupled to this sensor are three broadband imagers operating in the visible, mid-wave and long-wave infrared regions. AIRIS uses an on-board tracking capability to: dwell on a target, select multiple targets sequentially, or build a mosaic description of the environment around a specified target point. Currently AIRIS is being modified to include real-time spectral imagery calibration and application processing. In this paper the flexibility of the AIRIS system will be described, its concept of operation discussed and examples of measurements will be shown.

  12. Experimental feasibility of the airborne measurement of absolute oil fluorescence spectral conversion efficiency

    NASA Technical Reports Server (NTRS)

    Hoge, F. E.; Swift, R. N.

    1983-01-01

    Airborne lidar oil spill experiments carried out to determine the practicability of the AOFSCE (absolute oil fluorescence spectral conversion efficiency) computational model are described. The results reveal that the model is suitable over a considerable range of oil film thicknesses provided the fluorescence efficiency of the oil does not approach the minimum detection sensitivity limitations of the lidar system. Separate airborne lidar experiments to demonstrate measurement of the water column Raman conversion efficiency are also conducted to ascertain the ultimate feasibility of converting such relative oil fluorescence to absolute values. Whereas the AOFSCE model is seen as highly promising, further airborne water column Raman conversion efficiency experiments with improved temporal or depth-resolved waveform calibration and software deconvolution techniques are thought necessary for a final determination of suitability.

  13. Airborne Multiwavelength High-Spectral-Resolution Lidar (HSRL-2) Observations During TCAP 2012: Vertical Proles of Optical and Microphysical Properties of a Smoke/Urban Haze Plume Over the Northeastern Coast of the US

    SciTech Connect

    Muller, Detlef; Hostetler, Chris A.; Ferrare, R. A.; Burton, S. P.; Chemyakin, Eduard; Kolgotin, A.; Hair, John; Cook, A. L.; Harper, David; Rogers, R. R.; Hare, Rich; Cleckner, Craig; Obland, Michael; Tomlinson, Jason M.; Berg, Larry K.; Schmid, Beat

    2014-10-10

    We present rst measurements with the rst airborne multiwavelength High-Spectral Resolution Lidar (HSRL-2), developed by NASA Langley Research Center. The instrument was operated during the Department of Energy (DOE) Two-Column Aerosol Project (TCAP) in July 2012. We observed out ow of urban haze and fresh biomass burning smoke from the East Coast of the US out over the West Atlantic Ocean. Lidar ratios at 355 and 532 nm were ... sr indicating moderately absorbing aerosols. Extinctionrelated Angstrom exponents were 1.5{2 pointing at comparably small particles. Our novel automated, unsupervised data inversion algorithm retrieves particle e*ective radii of approximately 0.2 *m, which is in agreement with the large Angstrom exponents. We nd reasonable agreement to particle size parameters obtained from situ measurements carried out with the DOE G-1 aircraft that ew during the lidar observations.

  14. High spectral resolution remote sensing of canopy chemistry

    NASA Technical Reports Server (NTRS)

    Aber, John D.; Martin, Mary E.

    1995-01-01

    Near infrared laboratory spectra have been used for many years to determine nitrogen and lignin concentrations in plant materials. In recent years, similar high spectral resolution visible and infrared data have been available via airborne remote sensing instruments. Using data from NASA's Airborne visible/Infrared Imaging Spectrometer (AVIRIS) we attempt to identify spectral regions correlated with foliar chemistry at the canopy level in temperate forests.

  15. A Synergistic Approach to Atmospheric Compensation of Neon's Airborne Hyperspectral Imagery Utilizing an Airborne Solar Spectral Irradiance Radiometer

    NASA Astrophysics Data System (ADS)

    Wright, L.; Karpowicz, B. M.; Kindel, B. C.; Schmidt, S.; Leisso, N.; Kampe, T. U.; Pilewskie, P.

    2014-12-01

    A wide variety of critical information regarding bioclimate, biodiversity, and biogeochemistry is embedded in airborne hyperspectral imagery. Most, if not all of the primary signal relies upon first deriving the surface reflectance of land cover and vegetation from measured hyperspectral radiance. This places stringent requirements on terrain, and atmospheric compensation algorithms to accurately derive surface reflectance properties. An observatory designed to measure bioclimate, biodiversity, and biogeochemistry variables from surface reflectance must take great care in developing an approach which chooses algorithms with the highest accuracy, along with providing those algorithms with data necessary to describe the physical mechanisms that affect the measured at sensor radiance. The Airborne Observation Platform (AOP) part of the National Ecological Observatory Network (NEON) is developing such an approach. NEON is a continental-scale ecological observation platform designed to collect and disseminate data to enable the understanding and forecasting of the impacts of climate change, land use change, and invasive species on ecology. The instrumentation package used by the AOP includes a visible and shortwave infrared hyperspectral imager, waveform LiDAR, and high resolution (RGB) digital camera. In addition to airborne measurements, ground-based CIMEL sun photometers will be used to help characterize atmospheric aerosol loading, and ground validation measurements with field spectrometers will be made at select NEON sites. While the core instrumentation package provides critical information to derive surface reflectance of land surfaces and vegetation, the addition of a Solar Spectral Irradiance Radiometer (SSIR) is being investigated as an additional source of data to help identify and characterize atmospheric aerosol, and cloud contributions contributions to the radiance measured by the hyperspectral imager. The addition of the SSIR provides the opportunity to

  16. On the spectral combination of satellite gravity model, terrestrial and airborne gravity data for local gravimetric geoid computation

    NASA Astrophysics Data System (ADS)

    Jiang, Tao; Wang, Yan Ming

    2016-12-01

    One of the challenges for geoid determination is the combination of heterogeneous gravity data. Because of the distinctive spectral content of different data sets, spectral combination is a suitable candidate for its solution. The key to have a successful combination is to determine the proper spectral weights, or the error degree variances of each data set. In this paper, the error degree variances of terrestrial and airborne gravity data at low degrees are estimated by the aid of a satellite gravity model using harmonic analysis. For higher degrees, the error covariances are estimated from local gravity data first, and then used to compute the error degree variances. The white and colored noise models are also used to estimate the error degree variances of local gravity data for comparisons. Based on the error degree variances, the spectral weights of satellite gravity models, terrestrial and airborne gravity data are determined and applied for geoid computation in Texas area. The computed gravimetric geoid models are tested against an independent, highly accurate geoid profile of the Geoid Slope Validation Survey 2011 (GSVS11). The geoid computed by combining satellite gravity model GOCO03S and terrestrial (land and DTU13 altimetric) gravity data agrees with GSVS11 to ±1.1 cm in terms of standard deviation along a line of 325 km. After incorporating the airborne gravity data collected at 11 km altitude, the standard deviation is reduced to ±0.8 cm. Numerical tests demonstrate the feasibility of spectral combination in geoid computation and the contribution of airborne gravity in an area of high quality terrestrial gravity data. Using the GSVS11 data and the spectral combination, the degree of correctness of the error spectra and the quality of satellite gravity models can also be revealed.

  17. Highly Protable Airborne Multispectral Imaging System

    NASA Technical Reports Server (NTRS)

    Lehnemann, Robert; Mcnamee, Todd

    2001-01-01

    A portable instrumentation system is described that includes and airborne and a ground-based subsytem. It can acquire multispectral image data over swaths of terrain ranging in width from about 1.5 to 1 km. The system was developed especially for use in coastal environments and is well suited for performing remote sensing and general environmental monitoring. It includes a small,munpilotaed, remotely controlled airplance that carries a forward-looking camera for navigation, three downward-looking monochrome video cameras for imaging terrain in three spectral bands, a video transmitter, and a Global Positioning System (GPS) reciever.

  18. Final Technical Report for Interagency Agreement No. DE-SC0005453 “Characterizing Aerosol Distributions, Types, and Optical and Microphysical Properties using the NASA Airborne High Spectral Resolution Lidar (HSRL) and the Research Scanning Polarimeter (RSP)”

    SciTech Connect

    Hostetler, Chris; Ferrare, Richard

    2015-01-13

    Measurements of the vertical profile of atmospheric aerosols and aerosol optical and microphysical characteristics are required to: 1) determine aerosol direct and indirect radiative forcing, 2) compute radiative flux and heating rate profiles, 3) assess model simulations of aerosol distributions and types, and 4) establish the ability of surface and space-based remote sensors to measure the indirect effect. Consequently the ASR program calls for a combination of remote sensing and in situ measurements to determine aerosol properties and aerosol influences on clouds and radiation. As part of our previous DOE ASP project, we deployed the NASA Langley airborne High Spectral Resolution Lidar (HSRL) on the NASA B200 King Air aircraft during major field experiments in 2006 (MILAGRO and MaxTEX), 2007 (CHAPS), 2009 (RACORO), and 2010 (CalNex and CARES). The HSRL provided measurements of aerosol extinction (532 nm), backscatter (532 and 1064 nm), and depolarization (532 and 1064 nm). These measurements were typically made in close temporal and spatial coincidence with measurements made from DOE-funded and other participating aircraft and ground sites. On the RACORO, CARES, and CalNEX missions, we also deployed the NASA Goddard Institute for Space Studies (GISS) Research Scanning Polarimeter (RSP). RSP provided intensity and degree of linear polarization over a broad spectral and angular range enabling column-average retrievals of aerosol optical and microphysical properties. Under this project, we analyzed observations and model results from RACORO, CARES, and CalNex and accomplished the following objectives. 1. Identified aerosol types, characterize the vertical distribution of the aerosol types, and partition aerosol optical depth by type, for CARES and CalNex using HSRL data as we have done for previous missions. 2. Investigated aerosol microphysical and macrophysical properties using the RSP. 3. Used the aerosol backscatter and extinction profiles measured by the HSRL

  19. Image-Based Airborne Sensors: A Combined Approach for Spectral Signatures Classification through Deterministic Simulated Annealing

    PubMed Central

    Guijarro, María; Pajares, Gonzalo; Herrera, P. Javier

    2009-01-01

    The increasing technology of high-resolution image airborne sensors, including those on board Unmanned Aerial Vehicles, demands automatic solutions for processing, either on-line or off-line, the huge amountds of image data sensed during the flights. The classification of natural spectral signatures in images is one potential application. The actual tendency in classification is oriented towards the combination of simple classifiers. In this paper we propose a combined strategy based on the Deterministic Simulated Annealing (DSA) framework. The simple classifiers used are the well tested supervised parametric Bayesian estimator and the Fuzzy Clustering. The DSA is an optimization approach, which minimizes an energy function. The main contribution of DSA is its ability to avoid local minima during the optimization process thanks to the annealing scheme. It outperforms simple classifiers used for the combination and some combined strategies, including a scheme based on the fuzzy cognitive maps and an optimization approach based on the Hopfield neural network paradigm. PMID:22399989

  20. Evaluation of Various Spectral Inputs for Estimation of Forest Biochemical and Structural Properties from Airborne Imaging Spectroscopy Data

    NASA Astrophysics Data System (ADS)

    Homolová, L.; Janoutová, R.; Malenovský, Z.

    2016-06-01

    In this study we evaluated various spectral inputs for retrieval of forest chlorophyll content (Cab) and leaf area index (LAI) from high spectral and spatial resolution airborne imaging spectroscopy data collected for two forest study sites in the Czech Republic (beech forest at Štítná nad Vláří and spruce forest at Bílý Kříž). The retrieval algorithm was based on a machine learning method - support vector regression (SVR). Performance of the four spectral inputs used to train SVR was evaluated: a) all available hyperspectral bands, b) continuum removal (CR) 645 - 710 nm, c) CR 705 - 780 nm, and d) CR 680 - 800 nm. Spectral inputs and corresponding SVR models were first assessed at the level of spectral databases simulated by combined leaf-canopy radiative transfer models PROSPECT and DART. At this stage, SVR models using all spectral inputs provided good performance (RMSE for Cab < 10 μg cm-2 and for LAI < 1.5), with consistently better performance for beech over spruce site. Since application of trained SVRs on airborne hyperspectral images of the spruce site produced unacceptably overestimated values, only the beech site results were analysed. The best performance for the Cab estimation was found for CR bands in range of 645 - 710 nm, whereas CR bands in range of 680 - 800 nm were the most suitable for LAI retrieval. The CR transformation reduced the across-track bidirectional reflectance effect present in airborne images due to large sensor field of view.

  1. Airborne hyperspectral imaging in the visible-to-mid wave infrared spectral range by fusing three spectral sensors

    NASA Astrophysics Data System (ADS)

    Jakovels, Dainis; Filipovs, Jevgenijs; Erinš, Gatis; Taskovs, Juris

    2014-10-01

    Airborne hyperspectral imaging is widely used for remote sensing of environment. The choice of spectral region usually depends on the availability and cost of the sensor. Visible-to-near infrared (400-1100 nm) spectral range corresponds to spectral sensitivity of relatively cheap Si detectors therefore it is the most commonly used. The implementation of shortwave infrared (1100-3000 nm) requires more expensive solutions, but can provide valuable information about the composition of the substance. Mid wave infrared (3000-8000 nm) is rarely used for civilian applications, but it provides information on the thermal emission of materials. The fusion of different sensors allows spectral analysis of a wider spectral range combining and improving already existing algorithms for the analysis of chemical content and classification. Here we introduce our Airborne Surveillance and Environmental Monitoring System (ARSENAL) that was developed by fusing seven sensors. The first test results from the fusion of three hyperspectral imaging sensors in the visible-to-mid wave infrared (365-5000 nm) are demonstrated. Principal component analysis (PCA) is applied to test correlation between principal components (PCs) and common vegetation indices.

  2. High Resolution Airborne Digital Imagery for Precision Agriculture

    NASA Technical Reports Server (NTRS)

    Herwitz, Stanley R.

    1998-01-01

    The Environmental Research Aircraft and Sensor Technology (ERAST) program is a NASA initiative that seeks to demonstrate the application of cost-effective aircraft and sensor technology to private commercial ventures. In 1997-98, a series of flight-demonstrations and image acquisition efforts were conducted over the Hawaiian Islands using a remotely-piloted solar- powered platform (Pathfinder) and a fixed-wing piloted aircraft (Navajo) equipped with a Kodak DCS450 CIR (color infrared) digital camera. As an ERAST Science Team Member, I defined a set of flight lines over the largest coffee plantation in Hawaii: the Kauai Coffee Company's 4,000 acre Koloa Estate. Past studies have demonstrated the applications of airborne digital imaging to agricultural management. Few studies have examined the usefulness of high resolution airborne multispectral imagery with 10 cm pixel sizes. The Kodak digital camera integrated with ERAST's Airborne Real Time Imaging System (ARTIS) which generated multiband CCD images consisting of 6 x 106 pixel elements. At the designated flight altitude of 1,000 feet over the coffee plantation, pixel size was 10 cm. The study involved the analysis of imagery acquired on 5 March 1998 for the detection of anomalous reflectance values and for the definition of spectral signatures as indicators of tree vigor and treatment effectiveness (e.g., drip irrigation; fertilizer application).

  3. Airborne Spectral Measurements of Ocean Anisotropy during CLAMS

    NASA Technical Reports Server (NTRS)

    Gatebe, C. K.; King, M. D.; Arnold, G. T.; Lau, William K. M. (Technical Monitor)

    2002-01-01

    The Cloud Absorption Radiometer (CAR) aboard the University of Washington Convair CV-580 research aircraft obtained bidirectional reflectance-distribution function (BRDF) of Atlantic Ocean and Dismal Swamp between July 10 and August 2, 2001. The BRDF measurements (15 in total, 8 uncontaminated by clouds) obtained under a variety of sun angles and wind conditions, will be used to characterize ocean anisotropy in support of Chesapeake Lighthouse and Aircraft Measurements for Satellites (CLAMS) science objectives principally to validate products from NASA's EOS satellites, and to parameterize and validate BRDF models of the ocean. In this paper we present results of BRDF of the Ocean under different sun angles and wind conditions. The CAR is capable of measuring scattered light in fourteen spectral bands. The scan mirror, rotating at 100 rpm, directs the light into a Dall-Kirkham telescope where the beam is split into nine paths. Eight light beams pass through beam splitters, dichroics, and lenses to individual detectors (0.34-1.27 micron), and finally are registered by eight data channels. They are sampled simultaneously and continuously. The ninth beam passes through a spinning filter wheel to an InSb detector cooled by a Stirling cycle cooler. Signals registered by the ninth data channel are selected from among six spectral channels (1.55-2.30 micron). The filter wheel can either cycle through all six spectral bands at a prescribed interval (usually changing filter every fifth scan line), or lock onto any one of the six spectral bands and sample it continuously. To measure the BRF of the surface-atmosphere system, the University of Washington CV-580 had to fly in a circle about 3 km in diameter above the surface for roughly two minutes. Replicated observations (multiple circular orbits) were acquired over selected surfaces so that average BRF smooth out small-scale surface and atmospheric inhomogeneities. At an altitude of 600 m above the targeted surface area and

  4. Detection of hidden mineral deposits by airborne spectral analysis of forest canopies. [Spirit Lake, Washington; Catheart Mountain, Maine; Blacktail Mountain, Montana; and Cotter Basin, Montana

    NASA Technical Reports Server (NTRS)

    Collins, W.; Chang, S. H.; Kuo, J. T.

    1984-01-01

    Data from field surveys and biogeochemical tests conducted in Maine, Montana, and Washington strongly correlate with results obtained using high resolution airborne spectroradiometer which detects an anomalous spectral waveform that appears definitely associated with sulfide mineralization. The spectral region most affected by mineral stress is between 550 nm and 750 nm. Spectral variations observed in the field occur on the wings of the red chlorophyll band centered at about 690 nm. The metal-stress-induced variations on the absorption band wing are most successfully resolved in the high spectral resolution field data using a waveform analysis technique. The development of chlorophyll pigments was retarded in greenhouse plants doped with copper and zinc in the laboratory. The lowered chlorophyll production resulted in changes on the wings of the chlorophyll bands of reflectance spectra of the plants. The airborne spectroradiometer system and waveform analysis remains the most sensitive technique for biogeochemical surveys.

  5. Signature evaluation of natural targets using high spectral resolution techniques

    NASA Technical Reports Server (NTRS)

    Collins, W.; Chiu, H.-Y.

    1979-01-01

    The concept of 'spectral signature' identification has been applied to LANDSAT and other broad-band multi-spectral scanner data to classify various materials on the earth's surface. A large amount of the spectral information available is invisible, however, to the broad-band sensors. Although the natural targets of interest in remote sensing do not exhibit fine line features such as those associated with gaseous media, there is significant information to be extracted from smoothly varying spectral reflection functions of most natural targets. Subtle variations observed recently in the high resolution 'spectral signatures' of vegetation targets, in particular, promise to open new avenues of application using higher spectral and radiometric resolution techniques. This research was accomplished using a 500-band spectroradiometer system specially adapted to rapid airborne operations

  6. High Resolution Spectral Analysis

    DTIC Science & Technology

    2006-10-25

    filter - bank (one input many outputs) is then selected with a bandpass characteristic over the frequency range of interest. It consists of a dynamical...tailored to, disturbance isolation of a targeting system (e.g., laser) using input from a distributed array of 4 CHAPTER 1. ABSTRACT sensors. High...outstanding paper award from the IEEE Control Systems Society in 2003, and a U.S. patent [41] which was based on this and subsequent work. We mention that

  7. High Resolution Airborne Shallow Water Mapping

    NASA Astrophysics Data System (ADS)

    Steinbacher, F.; Pfennigbauer, M.; Aufleger, M.; Ullrich, A.

    2012-07-01

    In order to meet the requirements of the European Water Framework Directive (EU-WFD), authorities face the problem of repeatedly performing area-wide surveying of all kinds of inland waters. Especially for mid-sized or small rivers this is a considerable challenge imposing insurmountable logistical efforts and costs. It is therefore investigated if large-scale surveying of a river system on an operational basis is feasible by employing airborne hydrographic laser scanning. In cooperation with the Bavarian Water Authority (WWA Weilheim) a pilot project was initiated by the Unit of Hydraulic Engineering at the University of Innsbruck and RIEGL Laser Measurement Systems exploiting the possibilities of a new LIDAR measurement system with high spatial resolution and high measurement rate to capture about 70 km of riverbed and foreland for the river Loisach in Bavaria/Germany and the estuary and parts of the shoreline (about 40km in length) of lake Ammersee. The entire area surveyed was referenced to classic terrestrial cross-section surveys with the aim to derive products for the monitoring and managing needs of the inland water bodies forced by the EU-WFD. The survey was performed in July 2011 by helicopter and airplane and took 3 days in total. In addition, high resolution areal images were taken to provide an optical reference, offering a wide range of possibilities on further research, monitoring, and managing responsibilities. The operating altitude was about 500 m to maintain eye-safety, even for the aided eye, the airspeed was about 55 kts for the helicopter and 75 kts for the aircraft. The helicopter was used in the alpine regions while the fixed wing aircraft was used in the plains and the urban area, using appropriate scan rates to receive evenly distributed point clouds. The resulting point density ranged from 10 to 25 points per square meter. By carefully selecting days with optimum water quality, satisfactory penetration down to the river bed was achieved

  8. Airborne spectrometry: extraction of low energy γ-rays using two or three spectral windows.

    PubMed

    Martin-Burtart, Nicolas; Guillot, Ludovic; Nourreddine, Abdel-Mjid

    2012-08-01

    Airborne γ-ray spectrometry with NaI(Tl) is a recognized tool for emergency mapping. The maps produced usually look for natural isotopes ((40)K, (238)U, (232)Th) and (137)Cs due to the Chernobyl accident. Nowadays a new thematic emerges as nuclear materials tracking. Such materials emitting at low energies require new algorithms and a new method is presented here based on counts observed in two or three spectral windows. Since altitude is an important factor to be taken into account, an improvement is proposed to follow flight altitude changes. An extension to medium energies is proposed and compared to windows methods and to peak detection.

  9. Spectral aerosol direct radiative forcing from airborne radiative measurements during CalNex and ARCTAS

    NASA Astrophysics Data System (ADS)

    Leblanc, Samuel E.; Schmidt, K. S.; Pilewskie, P.; Redemann, J.; Hostetler, C.; Ferrare, R.; Hair, J.; Langridge, J. M.; Lack, D. A.

    2012-09-01

    This study presents the aerosol radiative forcing derived from airborne measurements of shortwave spectral irradiance during the 2010 Research at the Nexus of Air Quality and Climate Change (CalNex). Relative forcing efficiency, the radiative forcing normalized by aerosol optical thickness and incident irradiance, is a means of comparing the aerosol radiative forcing for different conditions. In this study, it is used to put the aerosol radiative effects of an air mass in the Los Angeles basin in context with case studies from three field missions that targeted other regions and aerosol types, including a case study from the Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS). For CalNex, we relied on irradiance measurements onboard the NOAA P-3 aircraft during a flight on 19 May 2010 over a ground station. CalNex presented a difficulty for determining forcing efficiency since one of the input parameters, optical thickness, was not available from the same aircraft. However, extinction profiles were available from a nearby aircraft. An existing retrieval algorithm was modified to use those measurements as initial estimate for the missing optical thickness. In addition, single scattering albedo and asymmetry parameter (secondary products of the method), were compared with CalNex in situ measurements. The CalNex relative forcing efficiency spectra agreed with earlier studies that found this parameter to be constrained at each wavelength within 20% per unit of aerosol optical thickness at 500 nm regardless of aerosol type and experiment, except for highly absorbing aerosols sampled near Mexico City. The diurnally averaged below-layer forcing efficiency integrated over the wavelength range of 350-700 nm for CalNex is estimated to be -58.6 ± 13.8 W/m2, whereas for the ARCTAS case it is -48.7 ± 11.5 W/m2.

  10. The development of a power spectral density processor for C and L band airborne radar scatterometer sensor systems

    NASA Technical Reports Server (NTRS)

    Harrison, D. A., III; Chladek, J. T.

    1983-01-01

    A real-time signal processor was developed for the NASA/JSC L-and C-band airborne radar scatterometer sensor systems. The purpose of the effort was to reduce ground data processing costs. Conversion of two quadrature channels of data (like and cross polarized) was made to obtain Power Spectral Density (PSD) values. A chirp-z transform (CZT) approach was used to filter the Doppler return signal and improved high frequency and angular resolution was realized. The processors have been tested with record signals and excellent results were obtained. CZT filtering can be readily applied to scatterometers operating at other wavelengths by altering the sample frequency. The design of the hardware and software and the results of the performance tests are described in detail.

  11. Forest Species Identification with High Spectral Resolution Data

    NASA Technical Reports Server (NTRS)

    Olson, C. E., Jr.; Zhu, Z.

    1985-01-01

    Data collected over the Sleeping Bear Sand Dunes Test Site and the Saginaw Forest Test Site (Michigan) with the JPL Airborne Imaging Spectrometer and the Collins' Airborne Spectroradiometer are being used for forest species identification. The linear discriminant function has provided higher identification accuracies than have principal components analyses. Highest identification accuracies are obtained in the 450 to 520 nm spectral region. Spectral bands near 1,300, 1,685 and 2,220 nm appear to be important, also.

  12. Spectral deconvolution and operational use of stripping ratios in airborne radiometrics.

    PubMed

    Allyson, J D; Sanderson, D C

    2001-01-01

    Spectral deconvolution using stripping ratios for a set of pre-defined energy windows is the simplest means of reducing the most important part of gamma-ray spectral information. In this way, the effective interferences between the measured peaks are removed, leading, through a calibration, to clear estimates of radionuclide inventory. While laboratory measurements of stripping ratios are relatively easy to acquire, with detectors placed above small-scale calibration pads of known radionuclide concentrations, the extrapolation to measurements at altitudes where airborne survey detectors are used bring difficulties such as air-path attenuation and greater uncertainties in knowing ground level inventories. Stripping ratios are altitude dependent, and laboratory measurements using various absorbers to simulate the air-path have been used with some success. Full-scale measurements from an aircraft require a suitable location where radionuclide concentrations vary little over the field of view of the detector (which may be hundreds of metres). Monte Carlo simulations offer the potential of full-scale reproduction of gamma-ray transport and detection mechanisms. Investigations have been made to evaluate stripping ratios using experimental and Monte Carlo methods.

  13. Airborne measurements of spectral direct aerosol radiative forcing in INTEX/ICARTT (2004) and comparisons to previous campaigns

    NASA Astrophysics Data System (ADS)

    Redemann, J.; Pilewskie, P.; Russell, P.; Livingston, J.; Howard, S.; Schmid, B.; Pommier, J.; Gore, W.; Eilers, J.; Wendisch, M.; Bush, B.; Valero, F.

    2005-12-01

    As part of the INTEX-NA (INtercontinental chemical Transport EXperiment-North America) and ITCT (Intercontinental Transport and Chemical Transformation of anthropogenic pollution) field studies, the NASA Ames 14-channel Airborne Tracking Sunphotometer (AATS-14) and a pair of Solar Spectral Flux Radiometers (SSFR) took measurements from aboard a Jetstream 31 (J31) aircraft during 19 science flights (~ 53 flight hours) over the Gulf of Maine between 12 July and 8 August 2004. AATS-14 measures the direct solar beam transmission at 14 discrete wavelengths (354-2138 nm), yielding aerosol optical depth (AOD) spectra, while the SSFR system yields down- and upwelling solar irradiance at a spectral resolution of ~ 8-12 nm over the wavelength range 300-1700 nm. The combination of simultaneous AATS and SSFR measurements yields plots of net spectral irradiance as a function of aerosol optical depth as measured along horizontal flight legs. From the slope of these plots we determine the instantaneous aerosol-induced change in net radiative flux per change in AOD. By normalization to an aerosol optical depth change of unity we derive the spectral aerosol radiative forcing efficiency [W m-2 nm-1]. Numerical integration of the irradiance measurements over a given spectral range yields the broadband aerosol radiative forcing efficiency [W m-2]. In INTEX/ITCT, we observed a total of 16 horizontal AOD gradients, with 10 gradients well suited for our analysis because of the small changes in solar zenith angle. Within the 10 case studies we found a high variability in the derived instantaneous aerosol forcing efficiencies for the visible wavelength range (350-700 nm), with a mean of -79.6 W m-2 and a standard deviation of 21.8 W m-2 (27%). The mean instantaneous forcing efficiency for the visible plus near-IR wavelength range (350-1670 nm) was derived to be 135.3 W m-2 with a standard deviation of 36.0 W m-2 (27%). An analytical conversion of the instantaneous forcing efficiencies to

  14. Airborne in-situ spectral characterization and concentration estimates of fluorescent organics as a function of depth

    NASA Technical Reports Server (NTRS)

    Tittle, R. A.

    1988-01-01

    The primary purpose of many in-situ airborne light scattering experiments in natural waters is to spectrally characterize the subsurface fluorescent organics and estimate their relative concentrations. This is often done by shining a laser beam into the water and monitoring its subsurface return signal. To do this with the proper interpretation, depth must be taken into account. If one disregards depth dependence when taking such estimates, both their spectral characteristics and their concentrations estimates can be rather ambiguous. A simple airborne lidar configuration is used to detect the subsurface return signal from a particular depth and wavelength. Underwater scatterometer were employed to show that in-situ subsurface organics are very sensitive to depth, but they also require the use of slow moving boats to cover large sample areas. Also, their very entry into the water disturbs the sample it is measuring. The method described is superior and simplest to any employed thus far.

  15. 137Cs measurement uncertainties and detection limits for airborne gamma spectrometry (AGS) data analysed using a spectral windows method.

    PubMed

    Cresswell, A J; Sanderson, D C W; White, D C

    2006-02-01

    The uncertainties associated with airborne gamma spectrometry (AGS) measurements analysed using a spectral windows method, and associated detection limits, have been investigated. For individual short measurements over buried 137Cs activity detection limits of 10 kBq m(-2) are achieved. These detection limits are reduced for superficial activity and longer integration times. For superficial activity, detection limits below 1 kBq m(-2) are achievable. A comparison is made with the detection limits for other data processing methods.

  16. Use of spectral vegetation indices derived from airborne hyperspectral imagery for detection of European corn borer infestation in Iowa corn plots

    EPA Science Inventory

    Eleven spectral vegetation indices that emphasize foliar plant pigments were calculated using airborne hyperspectral imagery and evaluated in 2004 and 2005 for their ability to detect experimental plots of corn manually inoculated with Ostrinia nubilalis (Hübner) neonate larvae. ...

  17. Field and airborne spectral characterization of suspected damage in red spruce (picea rubens) from Vermont

    NASA Technical Reports Server (NTRS)

    Rock, B. N.; Vogelmann, J. E.; Williams, D. L.

    1985-01-01

    The utilization of remote sensing to monitor forest damage due to acid deposition is investigated. Spectral and water measurements and aircraft radiance data of red spruce and balsam fir, collected in Camels Hump Mountain and Ripton, Vermont between August 13-20, 1984, are analyzed to evaluate the damage levels of the trees. Variations in reflectance features and canopy moisture content are studied. It is observed that damage correlates with elevation (greater damage at higher elevations); xylem water column tension is greater at higher damage sites; and a 'blue shift' is indicated in the spectral data at high damage sites.

  18. Integrated airborne lidar and multiple endmember spectral mixture analysis (MESMA) for plant species mapping across multiple functional groups

    NASA Astrophysics Data System (ADS)

    Dahlin, K.; Asner, G. P.

    2010-12-01

    The ability to map plant species distributions has long been one of the key goals of terrestrial remote sensing. Achieving this goal has been challenging, however, due to technical constraints and the difficulty in relating remote observations to ground measurements. Advances in both the types of data that can be collected remotely and in available analytical tools like multiple endmember spectral mixture analysis (MESMA) are allowing for rapid improvements in this field. In 2007 the Carnegie Airborne Observatory (CAO) acquired high resolution lidar and hyperspectral imagery of Jasper Ridge Biological Preserve (Woodside, California). The site contains a mosaic of vegetation types, from grassland to chaparral to evergreen forest. To build a spectral library, 415 GPS points were collected in the field, made up of 44 plant species, six plant categories (for nonphotosynthetic vegetation), and four substrate types. Using the lidar data to select the most illuminated pixels as seen from the aircraft (based on canopy shape and viewing angle), we then reduced the spectral library to only the most fully lit pixels. To identify individual plant species in the imagery, first the hyperspectral data was used to calculate the normalized difference vegetation index (NDVI), and then pixels with an NDVI less than 0.15 were removed from further analysis. The remaining image was stratified into five classes based on vegetation height derived from the lidar data. For each class, a suite of possible endmembers was identified and then three endmember selection procedures (endmember average RMS, minimum average spectral angle, and count based endmember selection) were employed to select the most representative endmembers from each species in each class. Two and three endmember models were then applied and each pixel was assigned a species or plant category based on the highest endmember fraction. To validate the approach, an independent set of 200 points was collected throughout the

  19. High Speed Video for Airborne Instrumentation Application

    NASA Technical Reports Server (NTRS)

    Tseng, Ting; Reaves, Matthew; Mauldin, Kendall

    2006-01-01

    A flight-worthy high speed color video system has been developed. Extensive system development and ground and environmental. testing hes yielded a flight qualified High Speed Video System (HSVS), This HSVS was initially used on the F-15B #836 for the Lifting Insulating Foam Trajectory (LIFT) project.

  20. Automatic Extraction of Optimal Endmembers from Airborne Hyperspectral Imagery Using Iterative Error Analysis (IEA) and Spectral Discrimination Measurements

    PubMed Central

    Song, Ahram; Chang, Anjin; Choi, Jaewan; Choi, Seokkeun; Kim, Yongil

    2015-01-01

    Pure surface materials denoted by endmembers play an important role in hyperspectral processing in various fields. Many endmember extraction algorithms (EEAs) have been proposed to find appropriate endmember sets. Most studies involving the automatic extraction of appropriate endmembers without a priori information have focused on N-FINDR. Although there are many different versions of N-FINDR algorithms, computational complexity issues still remain and these algorithms cannot consider the case where spectrally mixed materials are extracted as final endmembers. A sequential endmember extraction-based algorithm may be more effective when the number of endmembers to be extracted is unknown. In this study, we propose a simple but accurate method to automatically determine the optimal endmembers using such a method. The proposed method consists of three steps for determining the proper number of endmembers and for removing endmembers that are repeated or contain mixed signatures using the Root Mean Square Error (RMSE) images obtained from Iterative Error Analysis (IEA) and spectral discrimination measurements. A synthetic hyperpsectral image and two different airborne images such as Airborne Imaging Spectrometer for Application (AISA) and Compact Airborne Spectrographic Imager (CASI) data were tested using the proposed method, and our experimental results indicate that the final endmember set contained all of the distinct signatures without redundant endmembers and errors from mixed materials. PMID:25625907

  1. Automatic extraction of optimal endmembers from airborne hyperspectral imagery using iterative error analysis (IEA) and spectral discrimination measurements.

    PubMed

    Song, Ahram; Chang, Anjin; Choi, Jaewan; Choi, Seokkeun; Kim, Yongil

    2015-01-23

    Pure surface materials denoted by endmembers play an important role in hyperspectral processing in various fields. Many endmember extraction algorithms (EEAs) have been proposed to find appropriate endmember sets. Most studies involving the automatic extraction of appropriate endmembers without a priori information have focused on N-FINDR. Although there are many different versions of N-FINDR algorithms, computational complexity issues still remain and these algorithms cannot consider the case where spectrally mixed materials are extracted as final endmembers. A sequential endmember extraction-based algorithm may be more effective when the number of endmembers to be extracted is unknown. In this study, we propose a simple but accurate method to automatically determine the optimal endmembers using such a method. The proposed method consists of three steps for determining the proper number of endmembers and for removing endmembers that are repeated or contain mixed signatures using the Root Mean Square Error (RMSE) images obtained from Iterative Error Analysis (IEA) and spectral discrimination measurements. A synthetic hyperpsectral image and two different airborne images such as Airborne Imaging Spectrometer for Application (AISA) and Compact Airborne Spectrographic Imager (CASI) data were tested using the proposed method, and our experimental results indicate that the final endmember set contained all of the distinct signatures without redundant endmembers and errors from mixed materials.

  2. Aerosol Classification from High Spectral Resolution Lidar Measurements

    NASA Astrophysics Data System (ADS)

    Burton, S. P.; Hair, J. W.; Ferrare, R. A.; Hostetler, C. A.; Kahnert, M.; Vaughan, M. A.; Cook, A. L.; Harper, D. B.; Berkoff, T.; Seaman, S. T.; Collins, J. E., Jr.; Fenn, M. A.; Rogers, R. R.

    2015-12-01

    The NASA Langley airborne High Spectral Resolution Lidars, HSRL-1 and HSRL-2, have acquired large datasets of vertically resolved aerosol extinction, backscatter, and depolarization during >30 airborne field missions since 2006. The lidar measurements of aerosol intensive parameters like lidar ratio and color ratio embed information about intrinsic aerosol properties, and are combined to qualitatively classify HSRL aerosol measurements into aerosol types. Knowledge of aerosol type is important for assessing aerosol radiative forcing, and can provide useful information for source attribution studies. However, atmospheric aerosol is frequently not a single pure type, but instead is a mixture, which affects the optical and radiative properties of the aerosol. We show that aerosol intensive parameters measured by lidar can be understood using mixing rules for cases of external mixing. Beyond coarse classification and mixing between classes, variations in the lidar aerosol intensive parameters provide additional insight into aerosol processes and composition. This is illustrated by depolarization measurements at three wavelengths, 355 nm, 532 nm, and 1064 nm, made by HSRL-2. Particle depolarization ratio is an indicator of non-spherical particles. Three cases each have a significantly different spectral dependence of the depolarization ratio, related to the size of the depolarizing particles. For two dust cases, large non-spherical particles account for the depolarization of the lidar light. The spectral dependence reflects the size distribution of these particles and reveals differences in the transport histories of the two plumes. For a smoke case, the depolarization is inferred to be due to the presence of small coated soot aggregates. Interestingly, the depolarization at 355 nm is similar for this smoke case compared to the dust cases, having potential implications for the upcoming EarthCARE satellite, which will measure particle depolarization ratio only at 355 nm.

  3. High Voltage Design Guide for Airborne Equipment

    DTIC Science & Technology

    1976-06-01

    500 380 210 140 50 800 770 530 500 360 210 140 85 780 670 530 480 360 220 140 125 870 630 560 520 350 220 140 114 4.1.2 High Voltage Cable. At high...radioactive source of ionizing radiation such as polonium sHould be placed near the equipment under test in the altitude chamber to insure a supply of...electrons in the critical gap volumcs. Polonium is recommenoed because it’is not as hard to handle as other gari~na sources like cobalt 60. 6.1

  4. High-performance computing for airborne applications

    SciTech Connect

    Quinn, Heather M; Manuzzato, Andrea; Fairbanks, Tom; Dallmann, Nicholas; Desgeorges, Rose

    2010-06-28

    Recently, there has been attempts to move common satellite tasks to unmanned aerial vehicles (UAVs). UAVs are significantly cheaper to buy than satellites and easier to deploy on an as-needed basis. The more benign radiation environment also allows for an aggressive adoption of state-of-the-art commercial computational devices, which increases the amount of data that can be collected. There are a number of commercial computing devices currently available that are well-suited to high-performance computing. These devices range from specialized computational devices, such as field-programmable gate arrays (FPGAs) and digital signal processors (DSPs), to traditional computing platforms, such as microprocessors. Even though the radiation environment is relatively benign, these devices could be susceptible to single-event effects. In this paper, we will present radiation data for high-performance computing devices in a accelerated neutron environment. These devices include a multi-core digital signal processor, two field-programmable gate arrays, and a microprocessor. From these results, we found that all of these devices are suitable for many airplane environments without reliability problems.

  5. Spectral characterization of coastal sediments using Field Spectral Libraries, Airborne Hyperspectral Images and Topographic LiDAR Data (FHyL)

    NASA Astrophysics Data System (ADS)

    Manzo, Ciro; Valentini, Emiliana; Taramelli, Andrea; Filipponi, Federico; Disperati, Leonardo

    2015-04-01

    Beach dune systems are important for coastal zone ecosystems as they provide natural sea defences that dissipate wave energy. Geomorphological models of this near-shore topography require site-specific sediment composition, grain size and moisture content as inputs. Hyperspectral, field radiometry and LiDAR remote sensing can be used as tools by providing synoptic maps of these properties. However, multi-remote sensing of near-shore beach images can only be interpreted if there are adequate bio-geophysical or empirical models for information extraction. Our aim was thus to model the effects of varying sediment properties on the reflectance in both field and laboratory conditions within the FHyL (Field Spectral Libraries, Airborne Hyperspectral Images and Topographic LiDAR) procedure, using a multisource dataset (airborne Hyperspectral - MIVIS and topographic LiDAR - Hawk-eye II and field radiometry). The methodology consisted of (i) acquisition of simultaneous multi-source datasets (airborne Hyperspectral - MIVIS and topographic LiDAR - Hawk-eye) (ii) hyperspectral measurements of sediment mixtures with varying physical characteristics (moisture, grain size and minerals) in field and laboratory conditions, (iii) determination and quantification of specific absorption features, and (iv) correlation between the absorption features and physical parameters cited above. Results showed the potential of hyperspectral signals to assess the effect of moisture, grain-size and mineral composition on sediment properties.

  6. Urban Building Collapse Detection Using Very High Resolution Imagery and Airborne LIDAR Data

    NASA Astrophysics Data System (ADS)

    Wang, X.; Li, P.

    2013-07-01

    The increasing availability of very high resolution (VHR) remotely sensed images makes it possible to detect and assess urban building damages in the aftermath of earthquake disasters by using these data. However, the accuracy obtained using spectral features from VHR data alone is comparatively low, since both undamaged and collapsed buildings are spectrally similar. The height information provided by airborne LiDAR (Light Detection And Ranging) data is complementary to VHR imagery. Thus, combination of these two datasets will be beneficial to the automatic and accurate extraction of building collapse. In this study, a hierarchical multi-level method of building collapse detection using bi-temporal (pre- and post-earthquake) VHR images and postevent airborne LiDAR data was proposed. First, buildings, bare ground, vegetation and shadows were extracted using post-event image and LiDAR data and masked out. Then building collapse was extracted using the bi-temporal VHR images of the remaining area with a one-class classifier. The proposed method was evaluated using bi-temporal VHR images and LiDAR data of Port au Prince, Haiti, which was heavily hit by an earthquake in January 2010. The method was also compared with some existing methods. The results showed that the method proposed in this study significantly outperformed the existing methods, with improvement range of 47.6% in kappa coefficient. The proposed method provided a fast and reliable way of detecting urban building collapse, which can also be applied to relevant applications.

  7. Fiber-coupled high resolution infrared array spectrometer for the Kuiper Airborne Observatory

    NASA Technical Reports Server (NTRS)

    Glenar, D. A.; Reuter, D.; Mumma, M. J.; Chin, G.; Wiedemann, G.; Jennings, D.

    1990-01-01

    A novel cryogenic grating spectrometer (FCAS) is being designed for observations of volatiles in cometary and planetary atmospheres, and in newly forming planetary systems. The instrument features two-dimensional detector arrays coupled to a high-dispersion echelle by infrared fibers, and will achieve a spectral resolving power of about 40,000. The primary observational platform for this instrument will be the Kuiper Airborne Observatory, but it will also be configured for use at ground-based observatories. Initially, the spectrometer will use a 58 x 62, 1- to 5-micron InSb array. Larger-format IR arrays and arrays of different composition, will later be incorporated as they become available. The instrument will be used in two modes. The first uses a large format IR array in the spectral image plane for the customary one-dimensional spectral-one-dimensional spatial coverage. In the second mode, a massive, coherent bundle of infrared transmitting ZrF4 fibers will be installed after the dispersive element, to reformat the two-dimensional array into an elongated one-dimensional array for wide spectral coverage, allowing multiple lines to be measured in a single integration with high sensitivity. The overall instrument design is discussed, and the system sensitivity is estimated.

  8. Fiber-coupled high resolution infrared array spectrometer for the Kuiper Airborne Observatory

    NASA Astrophysics Data System (ADS)

    Glenar, D. A.; Reuter, D.; Mumma, M. J.; Chin, G.; Wiedemann, G.; Jennings, D.

    1990-07-01

    A novel cryogenic grating spectrometer (FCAS) is being designed for observations of volatiles in cometary and planetary atmospheres, and in newly forming planetary systems. The instrument features two-dimensional detector arrays coupled to a high-dispersion echelle by infrared fibers, and will achieve a spectral resolving power of about 40,000. The primary observational platform for this instrument will be the Kuiper Airborne Observatory, but it will also be configured for use at ground-based observatories. Initially, the spectrometer will use a 58 x 62, 1- to 5-micron InSb array. Larger-format IR arrays and arrays of different composition, will later be incorporated as they become available. The instrument will be used in two modes. The first uses a large format IR array in the spectral image plane for the customary one-dimensional spectral-one-dimensional spatial coverage. In the second mode, a massive, coherent bundle of infrared transmitting ZrF4 fibers will be installed after the dispersive element, to reformat the two-dimensional array into an elongated one-dimensional array for wide spectral coverage, allowing multiple lines to be measured in a single integration with high sensitivity. The overall instrument design is discussed, and the system sensitivity is estimated.

  9. Airborne prototype instrument suite test flight of a low-light high-dynamic range imager and visible spectrometer

    NASA Astrophysics Data System (ADS)

    Kuester, Michele A.; Lasnik, James K.; Ramond, Tanya; Lin, Tony; Johnson, Brian; Kaptchen, Paul; Good, William

    2007-09-01

    The Airborne Sensors Initiative (ASI) at Ball Aerospace and Technologies Corp. (BATC) specializes in airborne demonstration of internally-developed instrument concepts and innovative remote sensing technologies. In December 2006, ASI flew an environmental remote sensing suite consisting of the Low Light Imager (LLI) and Prototype Airborne Visible Imaging Spectrometer (PAVIS), both of which are operated using a pushbroom approach. LLI is designed for nighttime or high dynamic range imaging. It is capable of yielding 10 7 dynamic range and offers quality images amid illumination extending from a 1/ 4 moon to full sunlight and with autonomous operation. PAVIS is an imaging spectrometer based on the Dyson design and exhibits a 200 nm spectral bandwidth tunable within 400 - 850 nm. Developed internally to demonstrate promising remote sensing capabilities, these small, low-mass and low-power instruments are prepared for aircraft flight and are currently being used in the field to acquire scientific data. The LLI/PAVIS instrument suite has been utilized to collect airborne urban and rural imagery, as well as spectral information about the Great Salt Lake area, western Colorado, and ancient lava flows in southern Idaho. Highlights of the instrument design and ensuing data from previous flights are presented herein.

  10. Oceanic radiance model development and validation: application of airborne active-passive ocean color spectral measurements.

    PubMed

    Hoge, F E; Swift, R; Yungel, J

    1995-06-20

    It is shown that airborne active-passive (laser-solar) ocean color data can be used to develop and validate oceanic radiance models. The two principal inputs to the oceanic radiance model, chlorophyll pigment and incident solar irradiance, are obtained from a nadir-viewing laser-induced fluorescence spectrometer and a zenith-viewing radiometer, respectively. The computed water-leaving radiances are validated by comparison with the calibrated output of a separate nadir-viewing radiometer subsystem. In the North Atlantic Ocean, the calculated and the observed airborne radiances are found to compare very favorably for the 443-, 520-, and 550-nm wavelengths over an ∼ 170-km flight track east of St. John's, Newfoundland. The results further suggest that the semianalytical radiance model of ocean color, the airborne active (laser) fluorescence spectrometer, and the passive (solar) radiometric instrumentation are all remarkably precise.

  11. Technology for the detection of airborne intruders approaching the high-security high-value asset

    NASA Astrophysics Data System (ADS)

    Greneker, Eugene F., III

    1995-05-01

    Security plans to protect high-value assets usually concentrate on stopping potential ground intruders before they reach the asset. Barriers, such as fences, are the first line of defense against the found intruder, providing a delay mechanism. The sight of 10 to 12 foot high fencing topped with razor wire, guard towers, and roving patrols also serves as a psychological deterrent to the potential ground intrusion sensors between an outer and an inner barrier. This visible 'hardness' of a high-value asset makes airborne penetration more attractive, even though the airborne intruder may require training in the use of an aircraft or other airborne conveyance system. Certain airborne intrusion scenarios allow an adversary to penetrate much deeper and faster through delay and defense systems designed to deter the ground intruder. Since an airborne intruder can quickly reach the high-value asset, early detection critical to asset defense. Early detection of the airborne intruder also ensures appropriate use of the deadly force doctrine because the guard force has time to coordinate the response.

  12. Spectral control of an alexandrite laser for an airborne water-vapor differential absorption lidar system

    NASA Technical Reports Server (NTRS)

    Ponsardin, Patrick; Grossmann, Benoist E.; Browell, Edward V.

    1994-01-01

    A narrow-linewidth pulsed alexandrite laser has been greatly modified for improved spectral stability in an aircraft environment, and its operation has been evaluated in the laboratory for making water-vapor differential absorption lidar measurements. An alignment technique is described to achieve the optimum free spectral range ratio for the two etalons inserted in the alexandrite laser cavity, and the sensitivity of this ratio is analyzed. This technique drastically decreases the occurrence of mode hopping, which is commonly observed in a tunable, two-intracavity-etalon laser system. High spectral purity (greater than 99.85%) at 730 nm is demonstrated by the use of a water-vapor absorption line as a notch filter. The effective cross sections of 760-nm oxygen and 730-nm water-vapor absorption lines are measured at different pressures by using this laser, which has a finite linewidth of 0.02 cm(exp -1) (FWHM). It is found that for water-vapor absorption linewidths greater than 0.04 cm(exp -1) (HWHM), or for altitudes below 10 km, the laser line can be considered monochromatic because the measured effective absorption cross section is within 1% of the calculated monochromatic cross section. An analysis of the environmental sensitivity of the two intracavity etalons is presented, and a closed-loop computer control for active stabilization of the two intracavity etalons in the alexandrite laser is described. Using a water-vapor absorption line as a wavelength reference, we measure a long-term frequency drift (approximately 1.5 h) of less than 0.7 pm in the laboratory.

  13. Spectral difference analysis and airborne imaging classification for citrus greening infected trees

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Citrus greening, also called Huanglongbing (HLB), became a devastating disease spread through citrus groves in Florida, since it was first found in 2005. Multispectral (MS) and hyperspectral (HS) airborne images of citrus groves in Florida were acquired to detect citrus greening infected trees in 20...

  14. Airborne Spectral Measurements of Surface-Atmosphere Anisotropy for Arctic Sea Ice and Tundra

    NASA Technical Reports Server (NTRS)

    Arnold, G. Thomas; Tsay, Si-Chee; King, Michael D.; Li, Jason Y.; Soulen, Peter F.

    1999-01-01

    Angular distributions of spectral reflectance for four common arctic surfaces: snow-covered sea ice, melt-season sea ice, snow-covered tundra, and tundra shortly after snowmelt were measured using an aircraft based, high angular resolution (1-degree) multispectral radiometer. Results indicate bidirectional reflectance is higher for snow-covered sea ice than melt-season sea ice at all wavelengths between 0.47 and 2.3 pm, with the difference increasing with wavelength. Bidirectional reflectance of snow-covered tundra is higher than for snow-free tundra for measurements less than 1.64 pm, with the difference decreasing with wavelength. Bidirectional reflectance patterns of all measured surfaces show maximum reflectance in the forward scattering direction of the principal plane, with identifiable specular reflection for the melt-season sea ice and snow-free tundra cases. The snow-free tundra had the most significant backscatter, and the melt-season sea ice the least. For sea ice, bidirectional reflectance changes due to snowmelt were more significant than differences among the different types of melt-season sea ice. Also the spectral-hemispherical (plane) albedo of each measured arctic surface was computed. Comparing measured nadir reflectance to albedo for sea ice and snow-covered tundra shows albedo underestimated 5-40%, with the largest bias at wavelengths beyond 1 pm. For snow-free tundra, nadir reflectance underestimates plane albedo by about 30-50%.

  15. Infrared airborne spectroradiometer survey results in the western Nevada area

    NASA Technical Reports Server (NTRS)

    Collins, W.; Chang, S. H.; Kuo, J. T.

    1982-01-01

    The Mark II airborne spectroradiometer system was flown over several geologic test sites in western Nevada. The infrared mineral absorption bands were observed and recorded for the first time using an airborne system with high spectral resolution in the 2.0 to 2.5 micron region. The data show that the hydrothermal alteration zone minerals, carbonates, and other minerals are clearly visible in the airborne survey mode. The finer spectral features that distinguish the various minerals with infrared bands are also clearly visible in the airborne survey data. Using specialized computer pattern recognition methods, it is possible to identify mineralogy and map alteration zones and lithologies by airborne spectroradiometer survey techniques.

  16. Airborne measurements of spectral direct aerosol radiative forcing in the Intercontinental chemical Transport Experiment/Intercontinental Transport and Chemical Transformation of anthropogenic pollution, 2004

    NASA Astrophysics Data System (ADS)

    Redemann, Jens; Pilewskie, Peter; Russell, Philip B.; Livingston, John M.; Howard, Steve; Schmid, Beat; Pommier, John; Gore, Warren; Eilers, James; Wendisch, Manfred

    2006-07-01

    As part of the INTEX-NA (Intercontinental chemical Transport Experiment-North America) and ITCT (Intercontinental Transport and Chemical Transformation of anthropogenic pollution) field studies, the NASA Ames 14-channel Airborne Tracking Sunphotometer (AATS-14) and a pair of Solar Spectral Flux Radiometers (SSFR) took measurements from aboard a Sky Research Jet stream 31 (J31) aircraft during 19 science flights over the Gulf of Maine during 12 July to 8 August 2004. The combination of coincident AATS-14 and SSFR measurements yields plots of net (downwelling minus upwelling) spectral irradiance as a function of aerosol optical depth (AOD) as measured along horizontal flight legs. By definition, the slope of these plots yields the instantaneous change in net irradiance per unit AOD change and is referred to as the instantaneous spectral aerosol radiative forcing efficiency, Ei (W m-2 nm-1). Numerical integration over a given spectral range yields the instantaneous broadband aerosol radiative forcing efficiency (W m-2). This technique for deriving Ei is called the aerosol gradient method. Within 10 case studies considered suitable for our analysis we found a high variability in the derived instantaneous aerosol forcing efficiencies for the visible wavelength range (350-700 nm), with a mean of -79.6 W m-2 and a standard deviation of 21.8 W m-2 (27%). An analytical conversion of the instantaneous forcing efficiencies to 24-hour-average values yielded -45.8 ± 13.1 W m-2 (mean ± std). We present spectrally resolved aerosol forcing efficiencies between 350 and 1670 nm, estimates of the midvisible aerosol single scattering albedo and a comparison of observed broadband forcing efficiencies to previously reported values.

  17. High-Resolution Broadband Spectral Interferometry

    SciTech Connect

    Erskine, D J; Edelstein, J

    2002-08-09

    We demonstrate solar spectra from a novel interferometric method for compact broadband high-resolution spectroscopy. The spectral interferometer (SI) is a hybrid instrument that uses a spectrometer to externally disperse the output of a fixed-delay interferometer. It also has been called an externally dispersed interferometer (EDI). The interferometer can be used with linear spectrometers for imaging spectroscopy or with echelle spectrometers for very broad-band coverage. EDI's heterodyning technique enhances the spectrometer's response to high spectral-density features, increasing the effective resolution by factors of several while retaining its bandwidth. The method is extremely robust to instrumental insults such as focal spot size or displacement. The EDI uses no moving parts, such as purely interferometric FTS spectrometers, and can cover a much wider simultaneous bandpass than other internally dispersed interferometers (e.g. HHS or SHS).

  18. Airborne and Ground-Based Measurements Using a High-Performance Raman Lidar

    NASA Technical Reports Server (NTRS)

    Whiteman, David N.; Rush, Kurt; Rabenhorst, Scott; Welch, Wayne; Cadirola, Martin; McIntire, Gerry; Russo, Felicita; Adam, Mariana; Venable, Demetrius; Connell, Rasheen; Veselovskii, Igor; Forno, Ricardo; Mielke, Bernd; Stein, Bernhard; Leblanc, Thierry; McDermid, Stuart; Voemel, Holger

    2010-01-01

    -II measurements, along with numerical simulation, were used to determine that the likely reason for the suboptimal airborne aerosol extinction performance during theWAVES_2007 campaign was amisaligned interference filter. With full laser power and a properly tuned interference filter,RASL is shown to be capable ofmeasuring themain water vapor and aerosol parameters with temporal resolutions of between 2 and 45 s and spatial resolutions ranging from 30 to 330 m from a flight altitude of 8 km with precision of generally less than 10%, providing performance that is competitive with some airborne Differential Absorption Lidar (DIAL) water vapor and High Spectral Resolution Lidar (HSRL) aerosol instruments. The use of diode-pumped laser technology would improve the performance of an airborne Raman lidar and permit additional instrumentation to be carried on board a small research aircraft. The combined airborne and ground-based measurements presented here demonstrate a level of versatility in Raman lidar that may be impossible to duplicate with any other single lidar technique.

  19. Compact Highly Sensitive Multi-species Airborne Mid-IR Spectrometer

    SciTech Connect

    Richter, Dirk; Weibring, P.; Walega, J.; Fried, Alan; Spuler, Scott M.; Taubman, Matthew S.

    2015-02-01

    We report on the development and airborne field deployment of a mid-IR laser based spectrometer. The instrument was configured for the simultaneous in-situ detection of formaldehyde (CH2O) and ethane (C2H6). Numerous mechanical, optical, electronic, and software improvements over a previous instrument design resulted in reliable highly sensitive airborne operation with long stability times yielding 90% airborne measurement coverage during the recent air quality study over the Colorado front range, FRAPPÉ 2014. Airborne detection sensitivities of ~ 15 pptv (C2H6) and ~40 pptv (CH2O) were generally obtained for 1 s of averaging for simultaneous detection.

  20. High Spectral Resolution Lidar: System Calibration

    NASA Astrophysics Data System (ADS)

    Vivek Vivekanandan, J.; Morley, Bruce; Spuler, Scott; Eloranta, Edwin

    2015-04-01

    One of the unique features of the high spectral resolution lidar (HSRL) is simultaneous measurements of backscatter and extinction of atmosphere. It separates molecular scattering from aerosol and cloud particle backscatter based on their Doppler spectrum width. Scattering from aerosol and cloud particle are referred as Mie scattering. Molecular or Rayleigh scattering is used as a reference for estimating aerosol extinction and backscatter cross-section. Absolute accuracy of the backscattered signals and their separation into Rayleigh and Mie scattering depends on spectral purity of the transmitted signals, accurate measurement of transmit power, and precise performance of filters. Internal calibration is used to characterize optical subsystems Descriptions of high spectral resolution lidar system and its measurement technique can be found in Eloronta (2005) and Hair et al.(2001). Four photon counting detectors are used to measure the backscatter from the combined Rayleigh and molecular scattering (high and low gain), molecular scattering and cross-polarized signal. All of the detectors are sensitive to crosstalk or leakage through the optical filters used to separate the received signals and special data files are used to remove these effects as much as possible. Received signals are normalized with respect to the combined channel response to Mie and Rayleigh scattering. The laser transmit frequency is continually monitored and tuned to the 1109 Iodine absorption line. Aerosol backscatter cross-section is measured by referencing the aerosol return signal to the molecular return signal. Extinction measurements are calculated based on the differences between the expected (theoretical) and actual change in the molecular return. In this paper an overview of calibration of the HSRL is presented. References: Eloranta, E. W., High Spectral Resolution Lidar in Lidar: Range-Resolved Optical Remote Sensing of the Atmosphere, Klaus Weitkamp editor, Springer Series in Optical

  1. Real time orthorectification of high resolution airborne pushbroom imagery

    NASA Astrophysics Data System (ADS)

    Reguera-Salgado, Javier; Martin-Herrero, Julio

    2011-11-01

    Advanced architectures have been proposed for efficient orthorectification of digital airborne camera images, including a system based on GPU processing and distributed computing able to geocorrect three digital still aerial photographs per second. Here, we address the computationally harder problem of geocorrecting image data from airborne pushbroom sensors, where each individual image line has associated its own camera attitude and position parameters. Using OpenGL and CUDA interoperability and projective texture techniques, originally developed for fast shadow rendering, image data is projected onto a Digital Terrain Model (DTM) as if by a slide projector placed and rotated in accordance with GPS position and inertial navigation (IMU) data. Each line is sequentially projected onto the DTM to generate an intermediate frame, consisting of a unique projected line shaped by the DTM relief. The frames are then merged into a geometrically corrected georeferenced orthoimage. To target hyperband systems, avoiding the high dimensional overhead, we deal with an orthoimage of pixel placeholders pointing to the raw image data, which are then combined as needed for visualization or processing tasks. We achieved faster than real-time performance in a hyperspectral pushbroom system working at a line rate of 30 Hz with 200 bands and 1280 pixel wide swath over a 1 m grid DTM, reaching a minimum processing speed of 356 lines per second (up to 511 lps), over eleven (up to seventeen) times the acquisition rate. Our method also allows the correction of systematic GPS and/or IMU biases by means of 3D user interactive navigation.

  2. Spectral combination of land-based, airborne, shipborne and altimeter-derived gravity values: examples in Taiwan and Tahiti

    NASA Astrophysics Data System (ADS)

    Hwang, Cheinway

    2016-04-01

    Taiwan and Tahiti are bordered by seas and are islands with mountain ranges up to 4000 m height. The gravity fields here are rough due to the geodynamic processes that create the islands. On and around the two islands, gravity data have been collected by land gravimeters in relative gravity networks (point-wise), by airborne and shipborne (along-track) methods and by transformations from sea surface heights (altimeter-derived). Typically, network-adjusted land gravity values have accuracies of few tens of micro gals and contain the full gravity spectrum. Airborne gravity values are obtained by filtering original one-HZ along-track gravity values collected at varying flight altitudes that are affected by aircraft dynamics, GPS positioning error and gravimeter error. At a 5000-m flight height, along-track airborne gravity has a typical spatial resolution of 4 km and an accuracy of few mgal. Shipborne gravity is similar to airborne gravity, but with higher spatial resolutions because of ship's lower speed. Altimeter-derived gravity has varying spatial resolutions and accuracies, depending on altimeter data, processing method and extent of waveform interference. Using the latest versions of Geosat/GM, ERS-1/GM, ENVISAT, Jason-1/GM, Cryosat-2 and SARAL altimeter data, one can achieve accuracies at few mgal. The synergy of the four kinds of gravity datasets is made by the band-limited least-squares collocation, which best integrates datasets of different accuracies and spatial resolutions. The method uses the best contributions from a DEM, a global gravity model, available gravity datasets to form an optimal gravity grid. We experiment with different optimal spherical harmonic degrees of EGM08 for use around the two islands. For Tahiti, the optimal degree is 1500. New high-resolution gravity and geoid grids are constructed for the two islands and can be used in future geophysical and geodetic studies.

  3. Superconducting Quantum Interference Devices for the Detection of Magnetic Flux and Application to Airborne High Frequency Direction Finding

    DTIC Science & Technology

    2015-03-26

    SUPERCONDUCTING QUANTUM INTERFERENCE DEVICES FOR THE DETECTION OF MAGNETIC FLUX AND APPLICATION TO AIRBORNE HIGH FREQUENCY DIRECTION FINDING THESIS...SUPERCONDUCTING QUANTUM INTERFERENCE DEVICES FOR THE DETECTION OF MAGNETIC FLUX AND APPLICATION TO AIRBORNE HIGH FREQUENCY DIRECTION FINDING THESIS Presented to the...SUPERCONDUCTING QUANTUM INTERFERENCE DEVICES FOR THE DETECTION OF MAGNETIC FLUX AND APPLICATION TO AIRBORNE HIGH FREQUENCY DIRECTION FINDING THESIS Travis

  4. Building detection by fusion of airborne laser scanner data and multi-spectral images: Performance evaluation and sensitivity analysis

    NASA Astrophysics Data System (ADS)

    Rottensteiner, Franz; Trinder, John; Clode, Simon; Kubik, Kurt

    In this paper, we describe the evaluation of a method for building detection by the Dempster-Shafer fusion of airborne laser scanner (ALS) data and multi-spectral images. For this purpose, ground truth was digitised for two test sites with quite different characteristics. Using these data sets, the heuristic models for the probability mass assignments are validated and improved, and rules for tuning the parameters are discussed. The sensitivity of the results to the most important control parameters of the method is assessed. Further we evaluate the contributions of the individual cues used in the classification process to determine the quality of the results. Applying our method with a standard set of parameters on two different ALS data sets with a spacing of about 1 point/m 2, 95% of all buildings larger than 70 m 2 could be detected and 95% of all detected buildings larger than 70 m 2 were correct in both cases. Buildings smaller than 30 m 2 could not be detected. The parameters used in the method have to be appropriately defined, but all except one (which must be determined in a training phase) can be determined from meaningful physical entities. Our research also shows that adding the multi-spectral images to the classification process improves the correctness of the results for small residential buildings by up to 20%.

  5. Applying spectral unmixing and support vector machine to airborne hyperspectral imagery for detecting giant reed

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This study evaluated linear spectral unmixing (LSU), mixture tuned matched filtering (MTMF) and support vector machine (SVM) techniques for detecting and mapping giant reed (Arundo donax L.), an invasive weed that presents a severe threat to agroecosystems and riparian areas throughout the southern ...

  6. Aerosol Spectral Radiative Forcing Efficiency from Airborne Measurements During Multiple Field Missions

    NASA Astrophysics Data System (ADS)

    Schmidt, S.; Leblanc, S. E.; Pilewskie, P.; Redemann, J.; Hostetler, C. A.; Ferrare, R. A.; Hair, J. W.

    2012-12-01

    Measurements of shortwave spectral irradiance in conjunction with measurements of aerosol optical depth are used to determine the direct aerosol radiative forcing for various different regions and missions. To better compare cases with different air masses and solar geometry, we use the concept of top-of-layer and bottom-of-layer relative forcing efficiency. The aerosol layers were sampled from aircraft during several field campaigns, including the Megacity Initiative: Local and Global Research Observations (MILAGRO, Mexico, 2006); the Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS, Alaska and Alberta, 2008), Research at the Nexus of Air Quality and Climate Change (CalNex, California, 2010); and the Deep Convective Clouds and Chemistry Experiment (DC3, central US, 2012). We show that the spectral shape of the relative forcing efficiency is similar for these aerosol layers regardless of the aerosol type. The spectral relative forcing efficiency at any one wavelength for the majority of the cases is constrained within a span of 20% per unit of midvisible aerosol optical depth. Single scattering albedo, asymmetry parameter, and surface albedo are secondary products for the various methods used to determine aerosol radiative forcing. Using these, we determine the diurnally averaged spectral and broadband top-of-atmosphere and surface radiative forcing efficiency for the various different aerosol types and surface conditions.

  7. On the retrieval of water-related canopy biochemistry from airborne hyperspectral data and its comparison to MODIS spectral response

    NASA Astrophysics Data System (ADS)

    Casas Planes; Riaño, D.; Ustin, S.; Dennison, P. E.; Salas, J.

    2013-12-01

    Quantification of states and rates of water content in vegetation is critical in plant ecology. This work aims to assess the performance of a wide range of methodologies for the retrieval of vegetation biochemical and biophysical properties related to water, including: (i) foliar water content (FWC, cm), (ii) canopy water content (CWC, cm), (iii) fuel moisture content (FMC) and several interrelated variables: (iv) leaf mass per area (LMA, g/cm2), (v) foliar biomass (FB, g/m2), and (vi) leaf area index (LAI, m2/m2). Methods are applied to Airborne Visible Infrared Imaging Spectrometer (AVIRIS) data collected over Stanford University's Jasper Ridge Biological Preserve, California, USA, and derived Moderate Resolution Imaging Spectrometer (MODIS)-like data, within a multitemporal frame and stratified by cover type (i.e. grassland, shrubland and forest). Assessed methods are: (i) spectral fitting techniques applied to AVIRIS data, ii) the use of standard and recently designed indices, iii) AVIRIS PROSAIL and MODIS CWC PROSAIL inversion; and iv) the estimation of best band combination indices calibrated with the experimental dataset. This work shows how CWC retrieved from spectral fitting techniques proved relatively inaccurate. RTM simulations were significantly improved with the incorporation of a soil spectrum particularly in the case of grasslands and only for LAI in forests. Spectral indices provided higher accuracy; however, the most accurate index differed by variable and by cover types. Empirical calibration of indices improved the retrievals significantly in the case of FMC, LMA and FB using bands in the longer wavelength SWIR region.

  8. Maximum-likelihood spectral estimation and adaptive filtering techniques with application to airborne Doppler weather radar. Thesis Technical Report No. 20

    NASA Technical Reports Server (NTRS)

    Lai, Jonathan Y.

    1994-01-01

    This dissertation focuses on the signal processing problems associated with the detection of hazardous windshears using airborne Doppler radar when weak weather returns are in the presence of strong clutter returns. In light of the frequent inadequacy of spectral-processing oriented clutter suppression methods, we model a clutter signal as multiple sinusoids plus Gaussian noise, and propose adaptive filtering approaches that better capture the temporal characteristics of the signal process. This idea leads to two research topics in signal processing: (1) signal modeling and parameter estimation, and (2) adaptive filtering in this particular signal environment. A high-resolution, low SNR threshold maximum likelihood (ML) frequency estimation and signal modeling algorithm is devised and proves capable of delineating both the spectral and temporal nature of the clutter return. Furthermore, the Least Mean Square (LMS) -based adaptive filter's performance for the proposed signal model is investigated, and promising simulation results have testified to its potential for clutter rejection leading to more accurate estimation of windspeed thus obtaining a better assessment of the windshear hazard.

  9. Optimal attributes for the object based detection of giant reed in riparian habitats: A comparative study between Airborne High Spatial Resolution and WorldView-2 imagery

    NASA Astrophysics Data System (ADS)

    Fernandes, Maria Rosário; Aguiar, Francisca C.; Silva, João M. N.; Ferreira, Maria Teresa; Pereira, José M. C.

    2014-10-01

    Giant reed is an aggressive invasive plant of riparian ecosystems in many sub-tropical and warm-temperate regions, including Mediterranean Europe. In this study we tested a set of geometric, spectral and textural attributes in an object based image analysis (OBIA) approach to map giant reed invasions in riparian habitats. Bagging Classification and Regression Tree were used to select the optimal attributes and to build the classification rules sets. Mapping accuracy was performed using landscape metrics and the Kappa coefficient to compare the topographical and geometric similarity between the giant reed patches obtained with the OBIA map and with a validation map derived from on-screen digitizing. The methodology was applied in two high spatial resolution images: an airborne multispectral imagery and the newly WorldView-2 imagery. A temporal coverage of the airborne multispectral images was radiometrically calibrated with the IR-Mad transformation and used to assess the influence of the phenological variability of the invader. We found that optimal attributes for giant reed OBIA detection are a combination of spectral, geometric and textural information, with different scoring selection depending on the spectral and spatial characteristics of the imagery. WorldView-2 showed higher mapping accuracy (Kappa coefficient of 77%) and spectral attributes, including the newly yellow band, were preferentially selected, although a tendency to overestimate the total invaded area, due to the low spatial resolution (2 m of pixel size vs. 50 cm) was observed. When airborne images were used, geometric attributes were primarily selected and a higher spatial detail of the invasive patches was obtained, due to the higher spatial resolution. However, in highly heterogeneous landscapes, the low spectral resolution of the airborne images (4 bands instead of the 8 of WorldView-2) reduces the capability to detect giant reed patches. Giant reed displays peculiar spectral and geometric

  10. Mangrove species mapping in Kuala Sepetang Mangrove Forest, Perak using high resolution airborne data

    NASA Astrophysics Data System (ADS)

    Beh, B. C.; MatJafri, M. Z.; Lim, H. S.

    2015-10-01

    Mangrove vegetation is widely employed and studied as it is a unique ecosystem which is able to provide plenty of goods and applications to our country. In this paper, high resolution airborne image data obtained the flight mission on Kuala Sepetang Mangrove Forest Reserve, Perak, Malaysia will be used for mangrove species mapping. Supervised classification using the retrieved surface reflectance will be performed to classify the airborne data using Geomatica 2013 software package. The ground truth data will be used to validate the classification accuracy. High correlation of R2=0.873 was achieved in this study indicate that high resolution airborne data is reliable and suitable used for mangrove species mapping.

  11. Simple method for measuring vibration amplitude of high power airborne ultrasonic transducer: using thermo-couple.

    PubMed

    Saffar, Saber; Abdullah, Amir

    2014-03-01

    Vibration amplitude of transducer's elements is the influential parameters in the performance of high power airborne ultrasonic transducers to control the optimum vibration without material yielding. The vibration amplitude of elements of provided high power airborne transducer was determined by measuring temperature of the provided high power airborne transducer transducer's elements. The results showed that simple thermocouples can be used both to measure the vibration amplitude of transducer's element and an indicator to power transmission to the air. To verify our approach, the power transmission to the air has been investigated by other common method experimentally. The experimental results displayed good agreement with presented approach.

  12. Spectral optical layer properties of cirrus from collocated airborne measurements and simulations

    NASA Astrophysics Data System (ADS)

    Finger, Fanny; Werner, Frank; Klingebiel, Marcus; Ehrlich, André; Jäkel, Evelyn; Voigt, Matthias; Borrmann, Stephan; Spichtinger, Peter; Wendisch, Manfred

    2016-06-01

    Spectral upward and downward solar irradiances from vertically collocated measurements above and below a cirrus layer are used to derive cirrus optical layer properties such as spectral transmissivity, absorptivity, reflectivity, and cloud top albedo. The radiation measurements are complemented by in situ cirrus crystal size distribution measurements and radiative transfer simulations based on the microphysical data. The close collocation of the radiative and microphysical measurements, above, beneath, and inside the cirrus, is accomplished by using a research aircraft (Learjet 35A) in tandem with the towed sensor platform AIRTOSS (AIRcraft TOwed Sensor Shuttle). AIRTOSS can be released from and retracted back to the research aircraft by means of a cable up to a distance of 4 km. Data were collected from two field campaigns over the North Sea and the Baltic Sea in spring and late summer 2013. One measurement flight over the North Sea proved to be exemplary, and as such the results are used to illustrate the benefits of collocated sampling. The radiative transfer simulations were applied to quantify the impact of cloud particle properties such as crystal shape, effective radius reff, and optical thickness τ on cirrus spectral optical layer properties. Furthermore, the radiative effects of low-level, liquid water (warm) clouds as frequently observed beneath the cirrus are evaluated. They may cause changes in the radiative forcing of the cirrus by a factor of 2. When low-level clouds below the cirrus are not taken into account, the radiative cooling effect (caused by reflection of solar radiation) due to the cirrus in the solar (shortwave) spectral range is significantly overestimated.

  13. Sunglint effects on the characterization of optically active substances in high spatial resolution airborne hyperspectral images

    NASA Astrophysics Data System (ADS)

    Streher, A. S.; Faria Barbosa, C. Clemente; Soares Galvão, L.; Goodman, J. A.; Silva, T. S.

    2013-05-01

    Sunglint, also known as the specular reflection of light from water surfaces, is a component of sensor-received radiance that represents a confounding factor on the characterization of water bodies by remote sensing. In airborne remote sensing images, the effect of sunglint can be minimized by optimizing the flight paths, directing the sensor towards or away from the Sun, and by keeping solar zenith angles between 30° and 60°. However, these guidelines cannot always be applied, often due to the irregular spatial pattern of lakes, estuaries and coastlines. The present study assessed the impact of sunglint on the relationship between the optically active substances (OAS) concentration, in optically complex waters, and the spectral information provided by an airborne high spatial resolution hyperspectral sensor (SpecTIR). The Ibitinga reservoir, located in southeastern Brazil (state of São Paulo), was selected as the study area because of its meandering shape. As a result, there is demanding constant changes in data acquisition geometry to achieve complete coverage, therefore not allowing sunglint conditions to be minimized during image acquisition. Field data collection was carried out on October 23 and 24, 2011. During these two days, 15 water stations along the reservoir were sampled, concurrently with the SpecTIR image acquisition in 357 bands (398-2455 nm) and at 3 m spatial resolution. Chlorophyll, pheophytin, total suspended solids, organic and inorganic suspended solids and colored dissolved matter were determined in laboratory. The images were corrected for the atmospheric effects using the Fast Line-of-sight Atmospheric Analysis of Spectral Hypercubes (FLAASH) algorithm and then geometrically corrected. In order to evaluate the sunglint effects on the OAS characterization, the images were corrected for such effects using the deglint algorithm from Goodman et al. (2008). The SpecTIR 662-nm band reflectance was selected to be correlated to the OAS due to

  14. High spectral resolution reflectance spectroscopy of minerals

    NASA Technical Reports Server (NTRS)

    Clark, Roger N.; King, Trude V. V.; Klejwa, Matthew; Swayze, Gregg A.; Vergo, Norma

    1990-01-01

    The reflectance spectra of minerals are studied as a function of spectral resolution in the range from 0.2 to 3.0 microns. Selected absorption bands were studied at resolving powers as high as 2240. At resolving powers of approximately 1000, many OH-bearing minerals show diagnostic sharp absorptions at the resolution limit. At low resolution, some minerals may not be distinguishable, but as the resolution is increased, most can be easily identified. As the resolution is increased, many minerals show fine structure, particularly in the OH-stretching overtone region near 1.4 micron. The fine structure can enhance the ability to discriminate between minerals, and in some cases the fine structure can be used to determine elemental composition.

  15. Generalized high-spectral-resolution lidar technique with a multimode laser for aerosol remote sensing.

    PubMed

    Cheng, Zhongtao; Liu, Dong; Zhang, Yupeng; Liu, Chong; Bai, Jian; Wang, Dan; Wang, Nanchao; Zhou, Yudi; Luo, Jing; Yang, Yongying; Shen, Yibing; Su, Lin; Yang, Liming

    2017-01-23

    High-spectral-resolution lidar (HSRL) is a powerful tool for atmospheric aerosol remote sensing. The current HSRL technique often requires a single longitudinal mode laser as the transmitter to accomplish the spectral discrimination of the aerosol and molecular scattering conveniently. However, single-mode laser is cumbersome and has very strict requirements for ambient stability, making the HSRL instrument not so robust in many cases. In this paper, a new HSRL concept, called generalized HSRL technique with a multimode laser (MML-gHSRL), is proposed, which can work using a multimode laser. The MML-gHSRL takes advantage of the period characteristic of the spectral function of the interferometric spectral discrimination filter (ISDF) thoroughly. By matching the free spectral range of the ISDF with the mode interval of the multimode laser, fine spectral discrimination for the lidar return from each longitudinal mode can be realized. Two common ISDFs, i.e., the Fabry-Perot interferometer (FPI) and field-widened Michelson interferometer (FWMI), are introduced to develop the MML-gHSRL, and their performance is quantitatively analyzed and compared. The MML-gHSRL is a natural but significant generalization for the current HSRL technique based on the IDSF. It is potential that this technique would be a good entrance to future HSRL developments, especially in airborne and satellite-borne aerosol remote sensing applications.

  16. High Resolution Airborne Laser Scanning and Hyperspectral Imaging with a Small Uav Platform

    NASA Astrophysics Data System (ADS)

    Gallay, Michal; Eck, Christoph; Zgraggen, Carlo; Kaňuk, Ján; Dvorný, Eduard

    2016-06-01

    The capabilities of unmanned airborne systems (UAS) have become diverse with the recent development of lightweight remote sensing instruments. In this paper, we demonstrate our custom integration of the state-of-the-art technologies within an unmanned aerial platform capable of high-resolution and high-accuracy laser scanning, hyperspectral imaging, and photographic imaging. The technological solution comprises the latest development of a completely autonomous, unmanned helicopter by Aeroscout, the Scout B1-100 UAV helicopter. The helicopter is powered by a gasoline two-stroke engine and it allows for integrating 18 kg of a customized payload unit. The whole system is modular providing flexibility of payload options, which comprises the main advantage of the UAS. The UAS integrates two kinds of payloads which can be altered. Both payloads integrate a GPS/IMU with a dual GPS antenna configuration provided by OXTS for accurate navigation and position measurements during the data acquisition. The first payload comprises a VUX-1 laser scanner by RIEGL and a Sony A6000 E-Mount photo camera. The second payload for hyperspectral scanning integrates a push-broom imager AISA KESTREL 10 by SPECIM. The UAS was designed for research of various aspects of landscape dynamics (landslides, erosion, flooding, or phenology) in high spectral and spatial resolution.

  17. High spectral resolution reflectance spectroscopy of minerals

    USGS Publications Warehouse

    Clark, R.N.; King, T.V.V.; Klejwa, M.; Swayze, G.A.; Vergo, N.

    1990-01-01

    The reflectance spectra of minerals are studied as a function of spectral resolution in the range from 0.2 to 3.0 ??m. Selected absorption bands were studied at resolving powers (??/????) as high as 2240. At resolving powers of approximately 1000, many OH-bearing minerals show diagnostic sharp absorptions at the resolution limit. At low resolution, some minerals may not be distinguishable, but as the resolution is increased, most can be easily identified. As the resolution is increased, many minerals show fine structure, particularly in the OH-stretching overtone region near 1.4 ??m. The fine structure can enhance the ability to discriminate between minerals, and in some cases the fine structure can be used to determine elemental composition. The study shows that high-resolution reflectance spectroscopy of minerals may prove to be a very important tool in the laboratory, in the field using field-portable spectrometers, from aircraft, and from satellites looking at Earth or other planetary surfaces. -from Authors

  18. High spectral resolution image of Barnacle Bill

    NASA Technical Reports Server (NTRS)

    1997-01-01

    The rover Sojourner's first target for measurement by the Alpha-Proton-Xray Spectrometer (APXS) was the rock named Barnacle Bill, located close to the ramp down which the rover made its egress from the lander. The full spectral capability of the Imager for Mars Pathfinder (IMP), consisting of 13 wavelength filters, was used to characterize the rock's surface. The measured area is relatively dark, and is shown in blue. Nearby on the rock surface, soil material is trapped in pits (shown in red).

    Mars Pathfinder is the second in NASA's Discovery program of low-cost spacecraft with highly focused science goals. The Jet Propulsion Laboratory, Pasadena, CA, developed and manages the Mars Pathfinder mission for NASA's Office of Space Science, Washington, D.C. The Imager for Mars Pathfinder (IMP) was developed by the University of Arizona Lunar and Planetary Laboratory under contract to JPL. Peter Smith is the Principal Investigator. JPL is an operating division of the California Institute of Technology (Caltech).

  19. A synthetic high fidelity, high cadence spectral Earth database

    NASA Astrophysics Data System (ADS)

    Schwieterman, Edward; Meadows, Victoria; Robinson, Tyler D.; Lustig-Yaeger, Jacob; Sparks, William B.; Cracraft, Misty

    2016-10-01

    Earth is currently our only, and will always be our best, example of a living planet. While Earth data model comparisons have been effectively used in recent years to validate spectral models, observations by interplanetary spacecraft are limited to "snapshots" in terms of viewing geometry and Earth's dynamic surface and atmosphere state. We use the well-validated Virtual Planetary Laboratory 3D spectral Earth model to generate both simulated disk-averaged spectra and high resolution, spatially resolved spectral data cubes of Earth at a viewing geometry consistent with Lunar viewing angles at wavelengths from the far UV (0.1 μm) the to the far IR (200 μm). The database includes disk-averaged spectra from dates 03/19/2008 to 04/23/2008 at one-hour cadence and fully spectral data cubes for a subset of those times. These spectral products have a wide range of applications including calibration of spacecraft instrumentation (Robinson et al. 2014), modeling the radiation environment of permanently shadowed Lunar craters due to Earthshine (Glenar et al., in prep), and testing the detectability of atmospheric and surface features of an Earth-like planet orbiting a distant star with a large space-based telescope mission concepts such as LUVOIR. These data include the phase and time-dependent changes in spectral biosignatures (O2, O3, CH4, VRE) and habitability markers (N2, H2O, CO2, ocean glint). The advantages of the VPL Earth model data products over 1D spectra traditionally used for testing instrument architectures include accurate modeling of Earth's surface inhomogeneity (continental distribution and ice caps), cloud cover and variability, pole to equator temperature gradients, obliquity, phase-dependent scattering effects, and rotation. We present a subset of this spectral data including anticipated signal-to-noise calculations of an exoEarth twin at different phases using a coronagraph instrument model (Robinson et al. 2015). We also calculate time

  20. Detection of harvested trees in forests from repeated high density airborne laser scanning

    NASA Astrophysics Data System (ADS)

    Pietrzyk, P. J.; Lindenbergh, R. C.

    2014-05-01

    Identification of harvested and fallen trees is a prerequisite for the detection and measurement of changes in forests. This paper presents a three step approach to monitor harvested and fallen trees based on direct comparison of repeated high density airborne LIDAR data. In a first step differences between data sets are obtained from a point to point comparison, such that the data can be reduced to the deviating points only. Secondly, the resulting points are clustered into spatially connected regions using region growing. Finally, individual trees are extracted from the clusters by analysing their relative proximity and by analysing geometric properties of points in the clusters. Two data sets, acquired at a four year interval and covering a forest with mainly deciduous trees, are compared. First results show that most points relating to a change can be extracted and that clustering of these with region growing enables us to efficiently separate harvested and fallen trees from the remaining trees. Grouped harvested trees could not be separated using the region growing approach due to touching crowns. Segmentation of these using spectral clustering however identified individual regions well, but the results depend mainly on the pre-defined number of clusters. Crowns of grouped trees can be therefore separated if the number of trees is known.

  1. Automated processing of high resolution airborne images for earthquake damage assessment

    NASA Astrophysics Data System (ADS)

    Nex, F.; Rupnik, E.; Toschi, I.; Remondino, F.

    2014-11-01

    Emergency response ought to be rapid, reliable and efficient in terms of bringing the necessary help to sites where it is actually needed. Although the remote sensing techniques require minimum fieldwork and allow for continuous coverage, the established approaches rely on a vast manual work and visual assessment thus are time-consuming and imprecise. Automated processes with little possible interaction are in demand. This paper attempts to address the aforementioned issues by employing an unsupervised classification approach to identify building areas affected by an earthquake event. The classification task is formulated in the Markov Random Fields (MRF) framework and only post-event airborne high-resolution images serve as the input. The generated photogrammetric Digital Surface Model (DSM) and a true orthophoto provide height and spectral information to characterize the urban scene through a set of features. The classification proceeds in two phases, one for distinguishing the buildings out of an urban context (urban classification), and the other for identifying the damaged structures (building classification). The algorithms are evaluated on a dataset consisting of aerial images (7 cm GSD) taken after the Emilia-Romagna (Italy) earthquake in 2012.

  2. Advanced High-Power Generator for Airborne Applications

    DTIC Science & Technology

    1983-06-01

    Generators 40 AOSTRACT (Con, ..... ..rn e d.., &.#d it ^.*.C..4 aIdef.tll by 4101414h n .umbf. This report summarizes the work accomplished through Phase ...II of a four- phase prcgram to design and build the stator and housing for a 5-Mw generator and test the complete 5-Mw generator. The PM rotor for this...airborne electrical power supply technology. Phases I and II encompassed a 10-ironth period from April 1981 to January 1982. DDJN7 1473 EDITION OF Nov5 -o

  3. New, Flexible Applications with the Multi-Spectral Titan Airborne Lidar

    NASA Astrophysics Data System (ADS)

    Swirski, A.; LaRocque, D. P.; Shaker, A.; Smith, B.

    2015-12-01

    Traditional lidar designs have been restricted to using a single laser channel operating at one particular wavelength. Single-channel systems excel at collecting high-precision spatial (XYZ) data, with accuracies down to a few centimeters. However, target classification is difficult with spatial data alone, and single-wavelength systems are limited to the strengths and weaknesses of the wavelength they use. To resolve these limitations in lidar design, Teledyne Optech developed the Titan, the world's first multispectral lidar system, which uses three independent laser channels operating at 532, 1064, and 1550 nm. Since Titan collects 12 bit intensity returns for each wavelength separately, users can compare how strongly targets in the survey area reflect each wavelength. Materials such as soil, rock and foliage all reflect the wavelengths differently, enabling post-processing algorithms to identify the material of targets easily and automatically. Based on field tests in Canada, automated classification algorithms have combined this with elevation data to classify targets into six basic types with 78% accuracy. Even greater accuracy is possible with further algorithm enhancement and the use of an in-sensor passive imager such as a thermal, multispectral, CIR or RGB camera. Titan therefore presents an important new tool for applications such as land-cover classification and environmental modeling while maintaining lidar's traditional strengths: high 3D accuracy and day/night operation. Multispectral channels also enable a single lidar to handle both topographic and bathymetric surveying efficiently, which previously required separate specialized lidar systems operating at different wavelengths. On land, Titan can survey efficiently from 2000 m AGL with a 900 kHz PRF (300 kHz per channel), or up to 2500 m if only the infrared 1064 and 1550 nm channels are used. Over water, the 532 nm green channel penetrates water to collect seafloor returns while the infrared

  4. Application of spectral and spatial indices for specific class identification in Airborne Prism EXperiment (APEX) imaging spectrometer data for improved land cover classification

    NASA Astrophysics Data System (ADS)

    Kallepalli, Akhil; Kumar, Anil; Khoshelham, Kourosh; James, David B.

    2016-10-01

    Hyperspectral remote sensing's ability to capture spectral information of targets in very narrow bandwidths gives rise to many intrinsic applications. However, the major limiting disadvantage to its applicability is its dimensionality, known as the Hughes Phenomenon. Traditional classification and image processing approaches fail to process data along many contiguous bands due to inadequate training samples. Another challenge of successful classification is to deal with the real world scenario of mixed pixels i.e. presence of more than one class within a single pixel. An attempt has been made to deal with the problems of dimensionality and mixed pixels, with an objective to improve the accuracy of class identification. In this paper, we discuss the application of indices to cope with the disadvantage of the dimensionality of the Airborne Prism EXperiment (APEX) hyperspectral Open Science Dataset (OSD) and to improve the classification accuracy using the Possibilistic c-Means (PCM) algorithm. This was used for the formulation of spectral and spatial indices to describe the information in the dataset in a lesser dimensionality. This reduced dimensionality is used for classification, attempting to improve the accuracy of determination of specific classes. Spectral indices are compiled from the spectral signatures of the target and spatial indices have been defined using texture analysis over defined neighbourhoods. The classification of 20 classes of varying spatial distributions was considered in order to evaluate the applicability of spectral and spatial indices in the extraction of specific class information. The classification of the dataset was performed in two stages; spectral and a combination of spectral and spatial indices individually as input for the PCM classifier. In addition to the reduction of entropy, while considering a spectral-spatial indices approach, an overall classification accuracy of 80.50% was achieved, against 65% (spectral indices only) and

  5. Applying spectral mixture analysis (SMA) for soil information extraction on the airborne visible/infrared imaging spectrometer (AVIRIS) data

    NASA Astrophysics Data System (ADS)

    Accioly, Luciano Jose De Oliveira

    1997-11-01

    The research objectives of this study were formulated to produce the soil spectral maps using spectral mixture analysis on the AVIRIS data of the Walnut Gulch Experimental Watershed, Tombstone, Arizona. To accomplish this objective the spectral characteristics of eight soils of this Watershed were determined considering the effect of the source of illumination/sensor viewing geometry, degree of wetness (dry vs wet), surface roughness, and the source of the spectra (field, sieved samples and lab) on the selection of image and reference endmembers. The scale effect of the source of spectra was also studied in connection with AVIRIS spectral response. The soils presented anisotropic behavior which varied inversely with the wavelength, and it was reduced under wet conditions. Loss of information occurred when moving from large scale data set (lab, sieved sample, and field spectra) to small scale data (AVIRIS). Cluster analysis and factor analysis were used to extract information about how soil reference endmembers are grouped in relation to viewing angles, degree of wetness and the source of the spectra. Factor analysis was applied to identify the key set of bands that carried most of the information. Soil spectral classes varied as a result of scale effects, soil conditions (wet or dry), and viewing angles. Factor analysis showed that with four unique bands (located at 0.410, 1.310, 0.650, and 2.400 mum) it was possible to reconstruct the four basic soil spectral curves (Epitaph, Graham, McAllister, and Baboquivari) from the lab data set. AVIRIS image was modeled using mixture analysis on the basis of image endmembers and reference endmembers. Based on the four dimensions of the AVIRIS data image endmembers were defined by three soil spectra (McAllister, Stronghold-3, and Graham) and by one spectra of green vegetation. The shade fractions were separated from dark soils (Graham and Epitaph) on the basis of the spatial context. The target test identified at least seven

  6. High-Rate Wireless Airborne Network Demonstration (HiWAND) Flight Test Results

    NASA Technical Reports Server (NTRS)

    Franz, Russell

    2008-01-01

    An increasing number of flight research and airborne science experiments now contain network-ready systems that could benefit from a high-rate bidirectional air-to-ground network link. A prototype system, the High-Rate Wireless Airborne Network Demonstration, was developed from commercial off-the-shelf components while leveraging the existing telemetry infrastructure on the Western Aeronautical Test Range. This approach resulted in a cost-effective, long-range, line-of-sight network link over the S and the L frequency bands using both frequency modulation and shaped-offset quadrature phase-shift keying modulation. This report discusses system configuration and the flight test results.

  7. High-Rate Wireless Airborne Network Demonstration (HiWAND) Flight Test Results

    NASA Technical Reports Server (NTRS)

    Franz, Russell

    2007-01-01

    An increasing number of flight research and airborne science experiments now contain network-ready systems that could benefit from a high-rate bidirectional air-to-ground network link. A prototype system, the High-Rate Wireless Airborne Network Demonstration, was developed from commercial off-the-shelf components while leveraging the existing telemetry infrastructure on the Western Aeronautical Test Range. This approach resulted in a cost-effective, long-range, line-of-sight network link over the S and the L frequency bands using both frequency modulation and shaped-offset quadrature phase-shift keying modulation. This paper discusses system configuration and the flight test results.

  8. Comprehensive view of high-spectral-resolution lidar technique from the perspective of spectral discrimination

    NASA Astrophysics Data System (ADS)

    Cheng, Zhongtao; Liu, Dong; Yang, Yongying; Luo, Jing; Zhang, Yupeng; Zhou, Yudi; Bai, Jian; Liu, Chong; Shen, Yibing

    2016-05-01

    As already known commonly, high-spectral-resolution lidar technique (HSRL) employs a narrowband spectroscopic filter to separate the elastic backscattered aerosol signal from the thermal Doppler broadened molecular backscattered contribution. This paper presents a new and comprehensive view of HSRL technique from the perspective of spectral discrimination, without concretizing the analysis into a specific spectral discrimination filter. Based on a general HSRL layout with three-channel configuration, a theoretical model of retrieval error evaluation is introduced. In this model, we only take the error sources related to the spectral discrimination parameters into account, and ignore other error sources not associated with these focused parameters. This theoretical model is subsequently verified by Monte Carlo (MC) simulations. Both the model and MC simulations demonstrate that a large molecular transmittance and a large spectral discrimination ratio (SDR, i.e., ratio of the molecular transmittance to the aerosol transmittance) are beneficial to reduce the retrieval error. Moreover, we find that the signal-to-noise ratio (SNR) and SDR of the lidar system are often tradeoffs, and we suggest considering a suitable SDR for higher molecular transmittance (thus higher SNR) instead of using unnecessarily high SDR when designing the spectral discrimination filter. This view interprets the function of the narrowband spectroscopic filter in HSRL system essentially, and will provide some general guidelines for the reasonable design of the spectral discrimination filter for HSRL community.

  9. Using High-Resolution Airborne Remote Sensing to Study Aerosol Near Clouds

    NASA Technical Reports Server (NTRS)

    Levy, Robert; Munchak, Leigh; Mattoo, Shana; Marshak, Alexander; Wilcox, Eric; Gao, Lan; Yorks, John; Platnick, Steven

    2016-01-01

    The horizontal space in between clear and cloudy air is very complex. This so-called twilight zone includes activated aerosols that are not quite clouds, thin cloud fragments that are not easily observable, and dying clouds that have not quite disappeared. This is a huge challenge for satellite remote sensing, specifically for retrieval of aerosol properties. Identifying what is cloud versus what is not cloud is critically important for attributing radiative effects and forcings to aerosols. At the same time, the radiative interactions between clouds and the surrounding media (molecules, surface and aerosols themselves) will contaminate retrieval of aerosol properties, even in clear skies. Most studies on aerosol cloud interactions are relevant to moderate resolution imagery (e.g. 500 m) from sensors such as MODIS. Since standard aerosol retrieval algorithms tend to keep a distance (e.g. 1 km) from the nearest detected cloud, it is impossible to evaluate what happens closer to the cloud. During Studies of Emissions, Atmospheric Composition, Clouds and Climate Coupling by Regional Surveys (SEAC4RS), the NASA ER-2 flew with the enhanced MODIS Airborne Simulator (eMAS), providing MODIS-like spectral observations at high (50 m) spatial resolution. We have applied MODIS-like aerosol retrieval for the eMAS data, providing new detail to characterization of aerosol near clouds. Interpretation and evaluation of these eMAS aerosol retrievals is aided by independent MODIS-like cloud retrievals, as well as profiles from the co-flying Cloud Physics Lidar (CPL). Understanding aerosolcloud retrieval at high resolution will lead to better characterization and interpretation of long-term, global products from lower resolution (e.g.MODIS) satellite retrievals.

  10. Use of spectral vegetation indices derived from airborne hyperspectral imagery for detection of European corn borer infestation in Iowa corn plots.

    PubMed

    Carroll, Matthew W; Glaser, John A; Hellmich, Richard L; Hunt, Thomas E; Sappington, Thomas W; Calvin, Dennis; Copenhaver, Ken; Fridgen, John

    2008-10-01

    Eleven spectral vegetation indices that emphasize foliar plant pigments were calculated using airborne hyperspectral imagery and evaluated in 2004 and 2005 for their ability to detect experimental plots of corn manually inoculated with Ostrinia nubilalis (Hübner) neonate larvae. Manual inoculations were timed to simulate infestation of corn, Zea mays L., by first and second flights of adult O. nubilalis. The ability of spectral vegetation indices to detect O. nubilalis-inoculated plots improved as the growing season progressed, with multiple spectral vegetation indices able to identify infested plots in late August and early September. Our findings also indicate that for detecting O. nubilalis-related plant stress in corn, spectral vegetation indices targeting carotenoid and anthocyanin pigments are not as effective as those targeting chlorophyll. Analysis of image data suggests that feeding and stem boring by O. nubilalis larvae may increase the rate of plant senescence causing detectable differences in plant biomass and vigor when compared with control plots. Further, we identified an approximate time frame of 5-6 wk postinoculation, when spectral differences of manually inoculated "second" generation O. nubilalis plots seem to peak.

  11. A high-resolution airborne four-camera imaging system for agricultural remote sensing

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This paper describes the design and testing of an airborne multispectral digital imaging system for remote sensing applications. The system consists of four high resolution charge coupled device (CCD) digital cameras and a ruggedized PC equipped with a frame grabber and image acquisition software. T...

  12. Spectral Analysis in High Radiation Space Backgrounds with Robust Fitting

    NASA Technical Reports Server (NTRS)

    Lasche, G. P.; Coldwell, R. L.; Nobel, L. A.; Rester, A. C.; Trombka, J. I.

    1997-01-01

    Spectral analysis software is tested for its ability to fit spectra from space. The approach, which emphasizes the background shape function, is uniquely suited to the identification of weak-strength nuclides in high-radiation background environments.

  13. 1/f noise and very high spectral rigidity

    NASA Astrophysics Data System (ADS)

    Relaño, A.; Retamosa, J.; Faleiro, E.; Molina, R. A.; Zuker, A. P.

    2006-02-01

    It was recently pointed out that the spectral fluctuations of quantum systems are formally analogous to discrete time series, and therefore their structure can be characterized by the power spectrum of the signal. Moreover, it is found that the power spectrum of chaotic spectra displays a 1/f behavior, while that of regular systems follows a 1/f2 law. This analogy provides a link between the concepts of spectral rigidity and antipersistence. Trying to get a deeper understanding of this relationship, we have studied the correlation structure of spectra with high spectral rigidity. Using an appropriate family of random Hamiltonians, we increase the spectral rigidity up to hindering completely the spectral fluctuations. Analyzing the long range correlation structure a neat power law 1/f has been found for all the spectra, along the whole process. Therefore, 1/f noise is the characteristic fingerprint of a transition that, preserving the scale-free correlation structure, hinders completely the fluctuations of the spectrum.

  14. Spectral/spatial data fusion and neural networks for vegetation understory information extraction from hyperspectral airborne images

    NASA Astrophysics Data System (ADS)

    Binaghi, Elisabetta; Gallo, Ignazio; Boschetti, Mirco; Brivio, Pietro A.

    2004-02-01

    In this paper, we propose a method able to fuse spectral information with spatial contextual information in order to solve "operationally" classification problem. The salient aspect of the method is the integration of heterogeneous data within a Multi-Layer Perceptron model. Spatial and spectral relationships are not explicitly formalized in an attempt to limit design and computational complexity; raw data are instead presented directly as input to the neural network classifier. The method in particular addresses new open problems in processing hyperspectral and high resolution data finding solution for multisource analysis. Experimental results in real domain show this fusing approach is able to produce accurate classification. The method in fact is able to handle the problem of a volumetric mixture typical of natural forest ecosystems identifying the different surfaces present under the tree canopy. The understory map, produced by the neural classification method, was used as input to the inversion of radiative transfer models that show a significant increase in the retrieval of important biophysical vegetation parameter.

  15. Application of spectral phase shaping to high resolution CARS spectroscopy.

    PubMed

    Postma, S; van Rhijn, A C W; Korterik, J P; Gross, P; Herek, J L; Offerhaus, H L

    2008-05-26

    By spectral phase shaping of both the pump and probe pulses in coherent anti-Stokes Raman scattering (CARS) spectroscopy we demonstrate the extraction of the frequencies, bandwidths and relative cross sections of vibrational lines. We employ a tunable broadband Ti:Sapphire laser synchronized to a ps-Nd:YVO mode locked laser. A high resolution spectral phase shaper allows for spectroscopy with a precision better than 1 cm(-1) in the high frequency region around 3000 cm(-1). We also demonstrate how new spectral phase shaping strategies can amplify the resonant features of isolated vibrations to such an extent that spectroscopy and microscopy can be done at high resolution, on the integrated spectral response without the need for a spectrograph.

  16. High Energy 2-Micron Solid-State Laser Transmitter for NASA's Airborne CO2 Measurements

    NASA Technical Reports Server (NTRS)

    Singh, Upendra N.; Yu, Jirong; Petros, Mulugeta; Bai, Yingxin

    2012-01-01

    A 2-micron pulsed, Integrated Path Differential Absorption (IPDA) lidar instrument for ground and airborne atmospheric CO2 concentration measurements via direct detection method is being developed at NASA Langley Research Center. This instrument will provide an alternate approach to measure atmospheric CO2 concentrations with significant advantages. A high energy pulsed approach provides high-precision measurement capability by having high signal-to-noise level and unambiguously eliminates the contamination from aerosols and clouds that can bias the IPDA measurement.

  17. Similarity and Complementarity of Airborne and Terrestrial LiDAR Data in High Mountain Regions

    NASA Astrophysics Data System (ADS)

    Kamp, Nicole; Glira, Philipp; Pfeifer, Norbert

    2013-04-01

    Glacier melt and a consequential increased sediment transport (erosion, transportation and accumulation) in high mountain regions are causing a frequent occurrence of geomorphic processes such as landslides and other natural hazards. These effects are investigated at the Gepatschferner (Kaunertal, Oetztal Alps, Tyrol), the second largest glacier in Austria, in the PROSA project (Catholic University Eichstätt - Ingolstadt, Vienna University of Technology, Friedrich Alexander University Erlangen-Nürnberg, Martin-Luther-University Halle-Wittenberg, University of Innsbruck, Munich University of Technology). To monitor these geomorphic processes, data with a very high spatial and very high temporally accuracy and resolution are needed. For this purpose multi-temporal terrestrial and aerial laser scanning data are acquired, processed and analysed. Airborne LiDAR data are collected with a density of 10 points/m² over the whole study area of the glacier and its foreland. Terrestrial LiDAR data are gathered to complement and improve the airborne LiDAR data. The different viewing geometry results in differences between airborne and terrestrial data. Very steep slopes and rock faces (around 90°, depending on the viewing direction) are not visible from the airborne view point. On the other hand, terrestrial viewpoints exhibit shadows for areas above the scanner position and in viewing direction behind vertical or steep faces. In addition, the density of terrestrial data is varying strongly, but has for most of the covered area a much higher level of detail than the airborne dataset. A small temporal baseline is also inevitable and may cause differences between acquisition of airborne and terrestrial data. The goal of this research work is to develop a method for merging airborne and terrestrial LiDAR data. One prerequisite for merging is the identification of areas which are measurements of the same physical surface in either data set. This allows a transformation of the

  18. Remote sensing cloud properties from high spectral resolution infrared observations

    NASA Technical Reports Server (NTRS)

    Smith, William L.; Ma, Xia L.; Ackerman, Steven A.; Revercomb, H. E.; Knuteson, R. O.

    1993-01-01

    A technique for estimating cloud radiative properties (spectral emissivity and reflectivity) in the IR is developed based on observations at a spectral resolution of approximately 0.5/cm. The algorithm uses spectral radiance observations and theoretical calculations of the IR spectra for clear and cloudy conditions along with lidar-determined cloud-base and cloud-top pressure. An advantage of the high spectral resolution observations is that the absorption effects of atmospheric gases are minimized by analyzing between gaseous absorption lines. The technique is applicable to both ground-based and aircraft-based platforms and derives the effective particle size and associated cloud water content required to satisfy, theoretically, the observed cloud IR spectra. The algorithm is tested using theoretical simulations and applied to observations made with the University of Wisconsin's ground-based and NASA ER-2 aircraft High-Resolution Infrared Spectrometer instruments.

  19. Minimum High Fire Temperatures Detected in AVIRIS Spectral Measurements from Brazil in 1995

    NASA Technical Reports Server (NTRS)

    Green, Robert O.

    1998-01-01

    In August and September of 1995 the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) was deployed to Brazil as part of the NASA Smoke Cloud Aerosol and Radiation experiment in Brazil (SCAR-B). AVIRIS measures spectra from 400 to 2500 nm at 10-nm intervals. These spectra are acquired as images with dimensions of 11 by up to 800 km with 20-m spatial resolution. Spectral images measured by AVIRIS are spectrally, radiometrically, and spatially calibrated. During the SCAR-B deployment, AVIRIS measured more than 300 million spectra of regions of Brazil. A portion of these spectra were acquired over areas of actively burning fires. Actively burning fires emit radiance in the AVIRIS spectral range as a function of temperature. This emitted radiance is expressed from the 2500-nm end of the AVIRIS spectrum to shorter wavelengths as a function of intensity and modeled by the Planck function. The objective of this research and analysis was to use spectroscopic methods to determine the minimum high temperature of the most intense fires measured in the SCAR-B AVIRIS data set. Spectra measured by AVIRIS with hot sources have been previously examined for volcanic lava.

  20. High spatial resolution imaging of methane and other trace gases with the airborne Hyperspectral Thermal Emission Spectrometer (HyTES)

    NASA Astrophysics Data System (ADS)

    Hulley, Glynn C.; Duren, Riley M.; Hopkins, Francesca M.; Hook, Simon J.; Vance, Nick; Guillevic, Pierre; Johnson, William R.; Eng, Bjorn T.; Mihaly, Jonathan M.; Jovanovic, Veljko M.; Chazanoff, Seth L.; Staniszewski, Zak K.; Kuai, Le; Worden, John; Frankenberg, Christian; Rivera, Gerardo; Aubrey, Andrew D.; Miller, Charles E.; Malakar, Nabin K.; Sánchez Tomás, Juan M.; Holmes, Kendall T.

    2016-06-01

    Currently large uncertainties exist associated with the attribution and quantification of fugitive emissions of criteria pollutants and greenhouse gases such as methane across large regions and key economic sectors. In this study, data from the airborne Hyperspectral Thermal Emission Spectrometer (HyTES) have been used to develop robust and reliable techniques for the detection and wide-area mapping of emission plumes of methane and other atmospheric trace gas species over challenging and diverse environmental conditions with high spatial resolution that permits direct attribution to sources. HyTES is a pushbroom imaging spectrometer with high spectral resolution (256 bands from 7.5 to 12 µm), wide swath (1-2 km), and high spatial resolution (˜ 2 m at 1 km altitude) that incorporates new thermal infrared (TIR) remote sensing technologies. In this study we introduce a hybrid clutter matched filter (CMF) and plume dilation algorithm applied to HyTES observations to efficiently detect and characterize the spatial structures of individual plumes of CH4, H2S, NH3, NO2, and SO2 emitters. The sensitivity and field of regard of HyTES allows rapid and frequent airborne surveys of large areas including facilities not readily accessible from the surface. The HyTES CMF algorithm produces plume intensity images of methane and other gases from strong emission sources. The combination of high spatial resolution and multi-species imaging capability provides source attribution in complex environments. The CMF-based detection of strong emission sources over large areas is a fast and powerful tool needed to focus on more computationally intensive retrieval algorithms to quantify emissions with error estimates, and is useful for expediting mitigation efforts and addressing critical science questions.

  1. Use of a new high-speed digital data acquisition system in airborne ice-sounding

    USGS Publications Warehouse

    Wright, David L.; Bradley, Jerry A.; Hodge, Steven M.

    1989-01-01

    A high-speed digital data acquisition and signal averaging system for borehole, surface, and airborne radio-frequency geophysical measurements was designed and built by the US Geological Survey. The system permits signal averaging at rates high enough to achieve significant signal-to-noise enhancement in profiling, even in airborne applications. The first field use of the system took place in Greenland in 1987 for recording data on a 150 by 150-km grid centered on the summit of the Greenland ice sheet. About 6000-line km were flown and recorded using the new system. The data can be used to aid in siting a proposed scientific corehole through the ice sheet.

  2. Airborne infrared mineral mapping survey of Marysvale, Utah

    NASA Technical Reports Server (NTRS)

    Collins, W.; Chang, S. H.

    1982-01-01

    Infrared spectroradiometer survey results from flights over the Marysvale, Utah district show that hydrothermal alteration mineralogy can be mapped using very rapid and effective airborne techniques. The system detects alteration mineral absorption band intensities in the infrared spectral region with high sensitivity. The higher resolution spectral features and high spectral differences characteristic of the various clay and carbonate minerals are also readily identified by the instrument allowing the mineralogy to be mapped as well as the mineralization intensity.

  3. The EUV dayglow at high spectral resolution

    SciTech Connect

    Morrison, M.D.; Bowers, C.W.; Feldman, P.D. ); Meier, R.R. )

    1990-04-01

    Rocket observations of the dayglow spectrum of the terrestrial atmosphere between 840 {angstrom} and 1860 {angstrom} at 2 {angstrom} resolution were obtained with a sounding rocket payload flown on January 17, 1985. Additionally, spectra were also obtained using a 0.125-m focal length scanning Ebert-Fastie monochromator covering the wavelength interval of 1150-1550 {angstrom} at 7 {angstrom} resolution on this flight and on a sounding rocket flight on August 29, 1983, under similar viewing geometries and solar zenith angles. Three bands of the N{sub 2} c{prime}{sub 4} system are seen clearly resolved in the dayglow. Analysis of high-resolution N{sub 2} Lyman-Birge-Hopfield data shows no anomalous vibrational distribution as has been reported from other observations. The altitude profiles of the observed O and N{sub 2} emissions demonstrate that the MSIS-83 model O and N{sub 2} densities are appropriate for the conditions of both the 1983 and 1985 rocket flights. A reduction of a factor of 2 in the model O{sub 2} density is required for both flights to reproduce the low-altitude atomic oxygen emission profiles. The volume excitation rates calculated using the Hinteregger et al. (1981) SC{number sign}21REFW solar reference spectrum and the photoelectron flux model of Strickland and Meier (1982) need to be scaled upward by a factor of 1.4 for both fights to match the observations.

  4. Measurement and Analysis of Atmospheric Spectral Optical Depths with NASA Ames Airborne Sunphotometers During TARFOX and ACE-2

    NASA Technical Reports Server (NTRS)

    Livingston, John M.

    1997-01-01

    In accordance with the scope of work of this contract, the following tasks were undertaken and completed during the course of the contract: (1) Participation in the design and development of the 14-channel Ames Airborne Tracking Sunphotometer (AATS-14), including the development and implementation of Visual Basic software for real-time data processing and display and post-acquisition data reduction and analysis. (2) Operation of the six-channel Ames Airborne Tracking Sunphotometer (AATS-6) aboard the University of Washington C-131A during TARFOX and in-field analysis and presentation of data acquired with the AATS-6. (3) Post-mission analysis of data acquired during TARFOX with the AATS-6 and the AATS-14. (4) Pre-TARFOX calibration of the AATS-6 at Mauna Loa Observatory in May 1996, and post-TARFOX calibration of the AATS-6 and AATS- 14 at Zugspitze, Germany in October 1996, including analyses of all data sets. (5) Analysis of AATS-14 airborne calibration data acquired on 17 November 1996 during a late afternoon Pelican flight over the central California coast. (6) Operational training, instrument preparation, field coordination, and analysis of shipboard measurements of aerosol optical depth with the AATS-6 during ACE-2. (7) Coordination of data acquisition with the AATS-14 aboard the Pelican during ACE-2 and in-field preliminary data analysis and presentation. (8) Calibration of the AATS-6 and AATS-14 in April/May 1997 at Mauna Loa prior to ACE-2, and post-mission calibration of the AATS-6 at Mauna Loa in August 1997.

  5. Airborne Multispectral LIDAR Data for Land-Cover Classification and Land/water Mapping Using Different Spectral Indexes

    NASA Astrophysics Data System (ADS)

    Morsy, S.; Shaker, A.; El-Rabbany, A.; LaRocque, P. E.

    2016-06-01

    Airborne Light Detection And Ranging (LiDAR) data is widely used in remote sensing applications, such as topographic and landwater mapping. Recently, airborne multispectral LiDAR sensors, which acquire data at different wavelengths, are available, thus allows recording a diversity of intensity values from different land features. In this study, three normalized difference feature indexes (NDFI), for vegetation, water, and built-up area mapping, were evaluated. The NDFIs namely, NDFIG-NIR, NDFIG-MIR, and NDFINIR-MIR were calculated using data collected at three wavelengths; green: 532 nm, near-infrared (NIR): 1064 nm, and mid-infrared (MIR): 1550 nm by the world's first airborne multispectral LiDAR sensor "Optech Titan". The Jenks natural breaks optimization method was used to determine the threshold values for each NDFI, in order to cluster the 3D point data into two classes (water and land or vegetation and built-up area). Two sites at Scarborough, Ontario, Canada were tested to evaluate the performance of the NDFIs for land-water, vegetation, and built-up area mapping. The use of the three NDFIs succeeded to discriminate vegetation from built-up areas with an overall accuracy of 92.51%. Based on the classification results, it is suggested to use NDFIG-MIR and NDFINIR-MIR for vegetation and built-up areas extraction, respectively. The clustering results show that the direct use of NDFIs for land-water mapping has low performance. Therefore, the clustered classes, based on the NDFIs, are constrained by the recorded number of returns from different wavelengths, thus the overall accuracy is improved to 96.98%.

  6. High resolution mapping of the tropospheric NO2 distribution in three Belgian cities based on airborne APEX remote sensing

    NASA Astrophysics Data System (ADS)

    Tack, Frederik; Merlaud, Alexis; Fayt, Caroline; Danckaert, Thomas; Iordache, Daniel; Meuleman, Koen; Deutsch, Felix; Adriaenssens, Sandy; Fierens, Frans; Van Roozendael, Michel

    2015-04-01

    An approach is presented to retrieve tropospheric nitrogen dioxide (NO2) vertical column densities (VCDs) and to map the NO2 two dimensional distribution at high resolution, based on Airborne Prism EXperiment (APEX) observations. APEX, developed by a Swiss-Belgian consortium on behalf of ESA (European Space Agency), is a pushbroom hyperspectral imager with a high spatial (approximately 3 m at 5000 m ASL), spectral (413 to 2421 nm in 533 narrow, contiguous spectral bands) and radiometric (14-bit) resolution. VCDs are derived, following a similar approach as described in the pioneering work of Popp et al. (2012), based on (1) spectral calibration and spatial binning of the observed radiance spectra in order to improve the spectral resolution and signal-to-noise ratio, (2) Differential Optical Absorption Spectroscopy (DOAS) analysis of the pre-processed spectra in the visible wavelength region, with a reference spectrum containing low NO2 absorption, in order to quantify the abundance of NO2 along the light path, based on its molecular absorption structures and (3) radiative transfer modeling for air mass factor calculation in order to convert slant to vertical columns. This study will be done in the framework of the BUMBA (Belgian Urban NO2 Monitoring Based on APEX hyperspectral data) project. Dedicated flights with APEX mounted in a Dornier DO-228 airplane, operated by Deutsches Zentrum für Luft- und Raumfahrt (DLR), are planned to be performed in Spring 2015 above the three largest and most heavily polluted Belgian cities, i.e. Brussels, Antwerp and Liège. The retrieved VCDs will be validated by comparison with correlative ground-based and car-based DOAS observations. Main objectives are (1) to assess the operational capabilities of APEX to map the NO2 field over an urban area at high spatial and spectral resolution in a relatively short time and cost-effective way, and to characterise all aspects of the retrieval approach; (2) to use the APEX NO2 measurements

  7. Novel Airborne Imaging Polarimeter Undergoes High-Altitude Flight Testing

    NASA Technical Reports Server (NTRS)

    Diner, David J.; Pingree, Paula J.; Chipman, Russell A.

    2015-01-01

    Optical and signal processing technologies for high-accuracy polarimetric imaging, aimed at studying the impact of atmospheric haze and clouds on Earth's climate, have been demonstrated on checkout flights aboard NASA's ER-2 aircraft.

  8. Spectrally high performing quantum cascade lasers

    NASA Astrophysics Data System (ADS)

    Toor, Fatima

    emits at lambda = 10.8 mum for positive and lambda = 8.6 mum for negative polarity current with microsecond time delay is presented. Such a system is the first demonstration of a time and wavelength multiplexed system that uses a single QC laser. Fourth, work on the design and fabrication of a single-mode distributed feedback (DFB) QC laser emitting at lambda ≈ 7.7 mum to be used in a QC laser based photoacoustic sensor is presented. The DFB QC laser had a temperature tuning co-efficient of 0.45 nm/K for a temperature range of 80 K to 320 K, and a side mode suppression ratio of greater than 30 dB. Finally, study on the lateral mode patterns of wide ridge QC lasers is presented. The results include the observation of degenerate and non-degenerate lateral modes in wide ridge QC lasers emitting at lambda ≈ 5.0 mum. This study was conducted with the end goal of using wide ridge QC lasers in a novel technique to spatiospectrally combine multiple transverse modes to obtain an ultra high power single spot QC laser beam.

  9. Characterizing Aerosol Distributions and Optical Properties Using the NASA Langley High Spectral Resolution Lidar

    SciTech Connect

    Hostetler, Chris; Ferrare, Richard

    2013-02-14

    The objective of this project was to provide vertically and horizontally resolved data on aerosol optical properties to assess and ultimately improve how models represent these aerosol properties and their impacts on atmospheric radiation. The approach was to deploy the NASA Langley Airborne High Spectral Resolution Lidar (HSRL) and other synergistic remote sensors on DOE Atmospheric Science Research (ASR) sponsored airborne field campaigns and synergistic field campaigns sponsored by other agencies to remotely measure aerosol backscattering, extinction, and optical thickness profiles. Synergistic sensors included a nadir-viewing digital camera for context imagery, and, later in the project, the NASA Goddard Institute for Space Studies (GISS) Research Scanning Polarimeter (RSP). The information from the remote sensing instruments was used to map the horizontal and vertical distribution of aerosol properties and type. The retrieved lidar parameters include profiles of aerosol extinction, backscatter, depolarization, and optical depth. Products produced in subsequent analyses included aerosol mixed layer height, aerosol type, and the partition of aerosol optical depth by type. The lidar products provided vertical context for in situ and remote sensing measurements from other airborne and ground-based platforms employed in the field campaigns and was used to assess the predictions of transport models. Also, the measurements provide a data base for future evaluation of techniques to combine active (lidar) and passive (polarimeter) measurements in advanced retrieval schemes to remotely characterize aerosol microphysical properties. The project was initiated as a 3-year project starting 1 January 2005. It was later awarded continuation funding for another 3 years (i.e., through 31 December 2010) followed by a 1-year no-cost extension (through 31 December 2011). This project supported logistical and flight costs of the NASA sensors on a dedicated aircraft, the subsequent

  10. An Examination of Corrections for High Altitude, High Speed Airborne Gravimetry

    NASA Astrophysics Data System (ADS)

    Preaux, S. A.; Diehl, T. M.; Childers, V. A.

    2009-12-01

    Standard corrections for airborne gravimetry are optimized for low altitude, low speed surveys. They are shown to have multi-mgal errors at the high altitude and high speed of the surveys for the GRAV-D project. Higher order methods for computing the Eötvös, free air and off-level corrections are investigated. The first and second order approximations for the Eötvös correction from Harlan (1968) have differences up to 6 mgal, depending on latitude, and include assumptions about Earth shape that are undesirable in a geodetic application. Similarly, first and second order approximations for the free air correction (Hackney and Featherstone 2003) differ by up to 20 mgal and contain assumptions about Earth shape. Including more sophisticated downward continuation when incorporating data into a geoid model may be preferable to applying a free air correction. Finally, an exact analytical method of correcting for aircraft motion and orientation is proposed which takes advantage of the GPS reference system to avoid Earth shape assumptions, eliminate approximations and yield vector gravity.

  11. Airborne Hydromapping - How high-resolution bathymetric surveys will change the research and work focused on waterbody-related topics

    NASA Astrophysics Data System (ADS)

    Steinbacher, Frank; Baran, Ramona; Dobler, Wolfgang; Aufleger, Markus

    2013-04-01

    Repetitive surveying of inshore waters and coastal zones is becoming more and more essential in order to evaluate water-level dynamics, structural and zonal variations of rivers and riparian areas, river degradation, water flow, reservoir sedimentation, delta growth, as well as coastal processes. This can only be achieved in an effective manner by employing hydrographic airborne laser scanning (hydromapping). A new laser scanner is introduced, which has been specifically designed for the acquisition of high-resolution hydrographic data in order to survey and monitor inland waters and shallow coastal zones. Recently, this scanner has been developed within the framework of an Austrian research cooperation between Riegl LMS and the Unit of Hydraulic Engineering at the University of Innsbruck. We present exemplary measurement results obtained with the compact airborne laser-scanning system during our project work. Along the Baltic Sea coast northeast of Kiel city, northern Germany, we obtained measurement depths up to 8 m under clear-water conditions. Moreover, we detect underwater dune-structures and the accumulation of sediment within groin structures. In contrast, under turbid water conditions we obtained depths of approximately 3 m along the Rhine River at Rheinfelden, German-Swiss border east of Basel city. Nevertheless, we were able to map small-scale and complex morphologic features within a fish ramp or bedrock cliffs. The laser data had been combined with sonar measurements displaying the bathymetry at depths of ca. 2-25 m in order to document comprehensively the actual hydrographic setting after the new construction of the hydropower plant Rheinfelden. In summary, a high-resolution spatial view on the ground of various waterbodies is now possible for the first time with point densities in the usual range of approximately 10-20 points/m². However, the combination of these data with high-resolution aerial (approximately < 5 cm/pixel) or spectral images offers

  12. [Winter wheat growth spatial variation study based on temporal airborne high-spectrum images].

    PubMed

    Song, Xiao-yu; Wang, Ji-hua; Yan, Guang-jian; Huang, Wen-jiang; Liu, Liang-yun

    2010-07-01

    Precision agriculture technology is defined as an information-and technology-based agriculture management system to identify, analyze and manage crop spatial and temporal variation within fields for optimum profitability, sustainability and protection of the environment. In the present study, push-broom hyperspectral image sensor (PHI) image was used to investigate the spatial variance of winter wheat growth. The variable-rate fertilization contrast experiment was carried out on the National Experimental Station for Precision Agriculture of China during 2001-2002. Three airborne PHI images were acquired during the wheat growth season of 2002. Then contrast analysis about the wheat growth spatial variation was applied to the variable-rate fertilization area and uniformity fertilization area. The results showed that the spectral reflectance standard deviation increased significantly in red edge and short infrared wave band for all images. The wheat milky stage spectral reflectance has the maximum standard deviation in short infrared wave band, then the wheat jointing stage and wheat filling stage. Then six spectrum parameters that sensitive to wheat growth variation were defined and analyzed. The results indicate that parameters spatial variation coefficient for variable-rate experiment area was higher than that of contrast area in jointing stage. However, it decreased after the variable-rate fertilization application. The parameters spatial variation coefficient for variable-rate area was lower than that of contrast area in filling and milking stages. In addition, the yield spatial variation coefficient for variable-rate area was lower than that of contrast area. However, the yield mean value for variable-rate area was lower than that of contrast area. The study showed that the crop growth spatial variance information can be acquired through airborne remote sensing images timely and exactly. Remote sensing technology has provided powerful analytical tools for

  13. The pulse-pair algorithm as a robust estimator of turbulent weather spectral parameters using airborne pulse Doppler radar

    NASA Technical Reports Server (NTRS)

    Baxa, Ernest G., Jr.; Lee, Jonggil

    1991-01-01

    The pulse pair method for spectrum parameter estimation is commonly used in pulse Doppler weather radar signal processing since it is economical to implement and can be shown to be a maximum likelihood estimator. With the use of airborne weather radar for windshear detection, the turbulent weather and strong ground clutter return spectrum differs from that assumed in its derivation, so the performance robustness of the pulse pair technique must be understood. Here, the effect of radar system pulse to pulse phase jitter and signal spectrum skew on the pulse pair algorithm performance is discussed. Phase jitter effect may be significant when the weather return signal to clutter ratio is very low and clutter rejection filtering is attempted. The analysis can be used to develop design specifications for airborne radar system phase stability. It is also shown that the weather return spectrum skew can cause a significant bias in the pulse pair mean windspeed estimates, and that the poly pulse pair algorithm can reduce this bias. It is suggested that use of a spectrum mode estimator may be more appropriate in characterizing the windspeed within a radar range resolution cell for detection of hazardous windspeed gradients.

  14. A new high spectral resolution lidar technique for direct retrievals of cloud and aerosol extinction

    NASA Astrophysics Data System (ADS)

    Yorks, J. E.; McGill, M. J.; Hlavka, D. L.

    2014-12-01

    The Airborne Cloud-Aerosol Transport System (ACATS) is a Doppler lidar system and high spectral resolution lidar (HSRL) recently developed at NASA Goddard Space Flight Center (GSFC). ACATS passes the returned atmospheric backscatter through a single etalon and divides the transmitted signal into several channels (wavelength intervals), which are measured simultaneously and independently (Figure 1). Both the particulate and molecular scattered signal can be directly and unambiguously measured, allowing for direct retrievals of particle extinction. The broad Rayleigh-scattered spectrum is imaged as a nearly flat background, illustrated in Figure 1c. The integral of the particulate backscattered spectrum is analogous to the aerosol measurement from the typical absorption filter HSRL technique in that the molecular and particulate backscatter components can be separated (Figure 1c and 1d). The main difference between HSRL systems that use the iodine filter technique and the multichannel etalon technique used in the ACATS instrument is that the latter directly measures the spectral broadening of the particulate backscatter using the etalon to filter out all backscattered light with the exception of a narrow wavelength interval (1.5 picometers for ACATS) that contains the particulate spectrum (grey, Figure 1a). This study outlines the method and retrieval algorithms for ACATS data products, focusing on the HSRL derived cloud and aerosol properties. While previous ground-based multi-channel etalon systems have been built and operated for wind retrievals, there has been no airborne demonstration of the technique and the method has not been used to derive HSRL cloud and aerosol properties. ACATS has flown on the NASA ER-2 during flights over Alaska in July 2014 and as part of the Wallops Airborne Vegetation Experiment (WAVE) in September 2012. This study will focus on the HSRL aspect of the ACATS instrument, since the method and retrieval algorithms have direct application

  15. Comparison of High and Low Density Airborne LIDAR Data for Forest Road Quality Assessment

    NASA Astrophysics Data System (ADS)

    Kiss, K.; Malinen, J.; Tokola, T.

    2016-06-01

    Good quality forest roads are important for forest management. Airborne laser scanning data can help create automatized road quality detection, thus avoiding field visits. Two different pulse density datasets have been used to assess road quality: high-density airborne laser scanning data from Kiihtelysvaara and low-density data from Tuusniemi, Finland. The field inventory mainly focused on the surface wear condition, structural condition, flatness, road side vegetation and drying of the road. Observations were divided into poor, satisfactory and good categories based on the current Finnish quality standards used for forest roads. Digital Elevation Models were derived from the laser point cloud, and indices were calculated to determine road quality. The calculated indices assessed the topographic differences on the road surface and road sides. The topographic position index works well in flat terrain only, while the standardized elevation index described the road surface better if the differences are bigger. Both indices require at least a 1 metre resolution. High-density data is necessary for analysis of the road surface, and the indices relate mostly to the surface wear and flatness. The classification was more precise (31-92%) than on low-density data (25-40%). However, ditch detection and classification can be carried out using the sparse dataset as well (with a success rate of 69%). The use of airborne laser scanning data can provide quality information on forest roads.

  16. Short Pulse Switches for Airborne High Power Supplies

    DTIC Science & Technology

    1973-10-01

    must be small and lightweight and must operate reliably for 50.000 cycles. All of these design goals can be met utilizing the vacuum interrupter... reliability and to significantly reduce development and future manufacturing costs. Where necessary, modifications have been made to these components in...Westlnghouse proprietary material utilized In our current vacuum Interrupter product line. In order to Insure highly reliable lightweight actuation of

  17. A high gain antenna system for airborne satellite communication applications

    NASA Technical Reports Server (NTRS)

    Maritan, M.; Borgford, M.

    1990-01-01

    A high gain antenna for commercial aviation satellites communication is discussed. Electromagnetic and practical design considerations as well as candidate systems implementation are presented. An evaluation of these implementation schemes is given, resulting in the selection of a simple top mounted aerodynamic phased array antenna with a remotely located beam steering unit. This concept has been developed into a popular product known as the Canadian Marconi Company CMA-2100. A description of the technical details is followed by a summary of results from the first production antennas.

  18. Short Pulse Switches for Airborne High Power Supplies

    DTIC Science & Technology

    1973-10-01

    high voltage direct current interrupter tube is patterned after interrupters built by Hughes for HVDC circuit breaker service. These tubes have been...tested at the 100 kV, 2 kA, 2 kV/fisec level. This tube is the only known component inherently capable of HVDC interruption (i. e. , without...GE No. ZR 7512). The pulser circuit is shown in Fig. 11-26. The battery represents the (3 kV) HVDC supply. The total stored energy is

  19. Unusual spectral weight transfer in high temperature Bi-superconductors

    NASA Astrophysics Data System (ADS)

    Graf, Jeff; Gweon, Gey-Hong; Zhou, Shuyun; Rotenberg, Eli; Eisaki, Hiroshi; Lanzara, Alessandra

    2005-03-01

    High resolution angle resolved photoemission spectroscopy (ARPES) studies of the electronic structure of single layer (Bi2Sr2CuO6+δ) and double layer (Bi2Sr2CaCuO8+δ) Bi-compound are reported. A detailed study of the quasiparticle spectral function as a function of momentum, temperature and doping is presented. Unusual spectral weight transfer is observed in both systems and discussed in terms of a strong interplay between the electron-lattice and electron-electron interaction in these materials.

  20. High-Energy Spectral Signatures in Gamma-Ray Bursts

    NASA Technical Reports Server (NTRS)

    Baring, Matthew D.

    1999-01-01

    One of the principal results obtained by the EGRET experiment aboard the Compton Gamma-Ray Observatory (CGRO) was the detection of several gamma-ray bursts (GRBs) above 100 MeV. The broad-band spectra obtained for these bursts gave no indication of any high-energy spectral attenuation that might preclude detection of bursts by ground-based Cerenkov telescopes (ACTs), thus motivating several TeV observational programs. This paper explores the expectations for the spectral properties in the TeV and sub-TeV bands for bursts, in particular how attenuation of photons by pair creation internal to the source modifies the spectrum to produce distinctive spectral signatures. The energy of spectral breaks and the associated spectral indices provide valuable information that can constrain the bulk Lorentz factor of the GRB outflow at a given time. These characteristics define palpable observational goals for ACT programs, and strongly impact the observability of bursts in the TeV band.

  1. High-Energy Spectral Signatures in Gamma-Ray Bursts

    NASA Technical Reports Server (NTRS)

    Baring, Matthew G.

    2000-01-01

    One of the principal results obtained by the EGRET experiment aboard the Compton Gamma-Ray Observatory (CGRO) was the detection of several gamma-ray bursts (GRBs) above 100 MeV. The broad-band spectra obtained for these bursts gave no indication of any high energy spectral attenuation that might preclude detection of bursts by ground-based Cerenkov telescopes (ACTs), thus motivating several TeV observational programs. This paper explores the expectations for the spectral properties in the TeV and sub-TeV bands for bursts, in particular how attenuation of photons by pair creation internal to the source modifies the spectrum to produce distinctive spectral signatures. The energy of spectral breaks and the associated spectral indices provide valuable information that can constrain the bulk Lorentz factor of the GRB outflow at a given time. These characteristics define palpable observational goals for ACT programs, and strongly impact the observability of bursts in the TeV band.

  2. A comparison of LOWTRAN-7 corrected Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) data with ground spectral measurements

    NASA Technical Reports Server (NTRS)

    Xu, Peng-Yang; Greeley, Ronald

    1992-01-01

    Atmospheric correction of imaging spectroscopy data is required for quantitative analysis. Different models were proposed for atmospheric correction of these data. LOWTRAN-7 is a low-resolution model and computer code for predicting atmospheric transmittance and background radiance from 0 to 50,00 cm(sup -1) which was developed by the Air Force Geophysics Laboratory. The Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) data used are radiometrically calibrated and include the 28 Sep. 1989 Providence Fan flight line segment 07, California. It includes a dark gravel surface defined as a calibration site by the Geologic Remote Sensing Field Experiment (GRSFE). Several ground measurements of portable spectrometer DAEDALUS AA440 Spectrafax were taken during the GRSFE, July 1989 field campaign. Comparisons of the LOWTRAN-7 corrected AVIRIS data with the ground spectrometer measurement were made.

  3. Multimodal microscopy with high resolution spectral focusing CARS

    NASA Astrophysics Data System (ADS)

    Baldacchini, Tommaso; Zadoyan, Ruben

    2014-02-01

    In this work we describe a device that extends capabilities of multiphoton microscopes based on dual wavelength output femtosecond laser sources. CARS with 17cm-1 spectral resolution is experimentally demonstrated. Our approach is based on spectral focusing CARS. For pulse shaping of the pump and Stokes beams we utilize transmission gratings based stretcher. It allows the dispersion of the stretcher to be continuously adjusted in wide range. The best spectral resolution is achieved when the chirp rates in both pump and Stokes beam are matched. The device is automated. Any change in the beam path lengths due to the stretcher adjustment or wavelength tuning is compensated by the delay line. We incorporated into the device a computer controlled beam pointing stabilization system that compensates the beam pointing deviation due to dispersion in the system. High level of automation and computer control makes the operation of the device easy. We present CARS images of several samples that demonstrate high spectral resolution, high contrast and chemical selectivity.

  4. Alternative techniques for high-resolution spectral estimation of spectrally encoded endoscopy

    NASA Astrophysics Data System (ADS)

    Mousavi, Mahta; Duan, Lian; Javidi, Tara; Ellerbee, Audrey K.

    2015-09-01

    Spectrally encoded endoscopy (SEE) is a minimally invasive optical imaging modality capable of fast confocal imaging of internal tissue structures. Modern SEE systems use coherent sources to image deep within the tissue and data are processed similar to optical coherence tomography (OCT); however, standard processing of SEE data via the Fast Fourier Transform (FFT) leads to degradation of the axial resolution as the bandwidth of the source shrinks, resulting in a well-known trade-off between speed and axial resolution. Recognizing the limitation of FFT as a general spectral estimation algorithm to only take into account samples collected by the detector, in this work we investigate alternative high-resolution spectral estimation algorithms that exploit information such as sparsity and the general region position of the bulk sample to improve the axial resolution of processed SEE data. We validate the performance of these algorithms using bothMATLAB simulations and analysis of experimental results generated from a home-built OCT system to simulate an SEE system with variable scan rates. Our results open a new door towards using non-FFT algorithms to generate higher quality (i.e., higher resolution) SEE images at correspondingly fast scan rates, resulting in systems that are more accurate and more comfortable for patients due to the reduced image time.

  5. Universal spectral weight transfer in high temperature superconductors

    NASA Astrophysics Data System (ADS)

    Graf, Jeff; Gweon, G.-H.; McElroy, K.; Zhou, S. Y.; Jozwiak, C.; Rotenberg, E.; Bill, A.; Sasagawa, T.; Eisaki, H.; Uchida, S.; Takagi, H.; Lee, D.-H.; Lanzara, A.

    2006-03-01

    High resolution angle resolved photoemission spectroscopy (ARPES) studies of the electronic structure of several cuprate families, over the entire phase diagram, from undoped to highly overdoped regime are reported. A detailed study of the one-electron dynamics as a function of momentum, temperature and doping is presented. A universal spectral weight transfer is observed for all systems and discussed in terms of a strong interplay between the electron-lattice and electron-electron interaction in these materials.

  6. Universal spectral weight transfer in high temperature superconductors

    NASA Astrophysics Data System (ADS)

    Graf, Jeff; Gweon, Gey-Hong; McElroy, Kyle; Zhou, Shuyun; Jozwiak, Chris; Rotenberg, Eli; Bill, Andreas; Sasagawa, T.; Eisaki, H.; Uchida, S.; Takagi, H.; Lee, Dung-Hai; Lanzara, Alessandra

    2007-03-01

    High resolution angle resolved photoemission spectroscopy (ARPES) studies of the electronic structure of several cuprate families, over the entire phase diagram, from undoped to highly overdoped regime are reported. A detailed study of the one-electron dynamics as a function of momentum, temperature and doping is presented. A universal spectral weight transfer is observed for all systems and discussed in terms of a strong interplay between the electron-lattice and electron-electron interaction in these materials.

  7. Spectral feature design in high dimensional multispectral data

    NASA Technical Reports Server (NTRS)

    Chen, Chih-Chien Thomas; Landgrebe, David A.

    1988-01-01

    The High resolution Imaging Spectrometer (HIRIS) is designed to acquire images simultaneously in 192 spectral bands in the 0.4 to 2.5 micrometers wavelength region. It will make possible the collection of essentially continuous reflectance spectra at a spectral resolution sufficient to extract significantly enhanced amounts of information from return signals as compared to existing systems. The advantages of such high dimensional data come at a cost of increased system and data complexity. For example, since the finer the spectral resolution, the higher the data rate, it becomes impractical to design the sensor to be operated continuously. It is essential to find new ways to preprocess the data which reduce the data rate while at the same time maintaining the information content of the high dimensional signal produced. Four spectral feature design techniques are developed from the Weighted Karhunen-Loeve Transforms: (1) non-overlapping band feature selection algorithm; (2) overlapping band feature selection algorithm; (3) Walsh function approach; and (4) infinite clipped optimal function approach. The infinite clipped optimal function approach is chosen since the features are easiest to find and their classification performance is the best. After the preprocessed data has been received at the ground station, canonical analysis is further used to find the best set of features under the criterion that maximal class separability is achieved. Both 100 dimensional vegetation data and 200 dimensional soil data were used to test the spectral feature design system. It was shown that the infinite clipped versions of the first 16 optimal features had excellent classification performance. The overall probability of correct classification is over 90 percent while providing for a reduced downlink data rate by a factor of 10.

  8. International Symposium on Airborne Geophysics

    NASA Astrophysics Data System (ADS)

    Mogi, Toru; Ito, Hisatoshi; Kaieda, Hideshi; Kusunoki, Kenichiro; Saltus, Richard W.; Fitterman, David V.; Okuma, Shigeo; Nakatsuka, Tadashi

    2006-05-01

    Airborne geophysics can be defined as the measurement of Earth properties from sensors in the sky. The airborne measurement platform is usually a traditional fixed-wing airplane or helicopter, but could also include lighter-than-air craft, unmanned drones, or other specialty craft. The earliest history of airborne geophysics includes kite and hot-air balloon experiments. However, modern airborne geophysics dates from the mid-1940s when military submarine-hunting magnetometers were first used to map variations in the Earth's magnetic field. The current gamut of airborne geophysical techniques spans a broad range, including potential fields (both gravity and magnetics), electromagnetics (EM), radiometrics, spectral imaging, and thermal imaging.

  9. Ultra-High Temperature Ceramics for solar receivers: spectral and high-temperature emittance characterization

    NASA Astrophysics Data System (ADS)

    Sani, E.; Mercatelli, L.; Jafrancesco, D.; Sans, J. L.; Sciti, D.

    2012-12-01

    We report on the preparation, room temperature spectral reflectance and high-temperature thermal emittance characterization of different boride and carbide Ultra-High Temperature Ceramics (UHTCs). The investigated samples are compared with a reference material for solar absorber applications, i.e. silicon carbide. We show that spectral and thermal emittance properties of UHTCs are promising for novel solar receivers.

  10. High-energy, efficient, 30-Hz ultraviolet laser sources for airborne ozone-lidar systems.

    PubMed

    Elsayed, Khaled A; Chen, Songsheng; Petway, Larry B; Meadows, Byron L; Marsh, Waverly D; Edwards, William C; Barnes, James C; DeYoung, Russell J

    2002-05-20

    Two compact, high-pulse-energy, injection-seeded, 30-Hz frequency-doubled Nd:YAG-laser-pumped Ti: sapphire lasers were developed and operated at infrared wavelengths of 867 and 900 nm. Beams with laser pulse energy >30 mJ at ultraviolet wavelengths of 289 and 300 nm were generated through a tripling of the frequencies of these Ti:sapphire lasers. This work is directed at the replacement of dye lasers for use in an airborne ozone differential absorption lidar system. The ultraviolet pulse energy at 289 and 300 nm had 27% and 31% absolute optical energy conversion efficiencies from input pulse energies at 867 and 900 nm, respectively.

  11. Development and Utilization of High Precision Digital Elevation Data taken by Airborne Laser Scanner

    NASA Astrophysics Data System (ADS)

    Akutsu, Osamu; Ohta, Masataka; Isobe, Tamio; Ando, Hisamitsu, Noguchi, Takahiro; Shimizu, Masayuki

    2005-03-01

    Disasters caused by heavy rain in urban areas bring a damage such as chaos in the road and railway transport systems, power failure, breakdown of the telephone system and submersion of built up areas, subways and underground shopping arcades, etc. It is important to obtain high precision elevation data which shows the detailed landform because a slight height difference affects damages by flood very considerably. Therefore, The Geographical Survey Institute (GSI) is preparing 5m grid digital terrain model (DTM) based on precise ground elevation data taken by using airborne laser scanner. This paper describes the process and an example of the use of a 5m grid digital data set.

  12. Performance Analysis of the AeroTP Transport Protocol for Highly-Dynamic Airborne Telemetry Networks

    DTIC Science & Technology

    2011-06-03

    Acknowledgment Options.” RFC 2018 (Proposed Standard ), Oct. 1996. [11] “The ns- 3 network simulator.” http://www.nsnam.org, July 2009. [12] M. AL-Enazi, S. A. Gogi...AFFTC-PA- 11146 Performance Analysis of the AeroTP Transport Protocol for Highly-Dynamic Airborne Telemetry Networks James P.G. Sterbenz...Kamakshi Sirisha Pathapati, Truc Anh N. Nguyen, Justin P. Rohrer AIR FORCE FLIGHT TEST CENTER EDWARDS AFB, CA JUNE 3 , 2011 A F F T C

  13. Survival of Airborne Bacteria in a High Urban Concentration of Carbon Monoxide1

    PubMed Central

    Lighthart, Bruce

    1973-01-01

    Vegetative cells of Serratia marcescens 8UK, Sarcina lutea, and spores of Bacillus subtilus var. niger were held in aerosols, with and without an urban concentration of CO (85 μliters per liter or ppm), for up to 6 hr at 15 C and a relative humidity (RH) of approximately 0, 25, 50, 75, and 95%. It was found that CO enhanced the death rate of S. marcescens 8UK at least four- to sevenfold at low RH (ca. 1 to 25%), but protected the cells at high RH (ca. 90%). Death rates of S. lutea, with or without added CO, were comparatively low over the entire RH range. However, in the first hour, airborne S. lutea held in CO-containing air were more stable than those in air without added CO (i.e., CO protection). A marked increase in the death rate (up to 70-fold) occurred in the subsequent 5 hr within the RH range of approximately 0 to 75%. Statistical analysis indicated that aerosol decay rates of B. subtilus var. niger spores decreased significantly, when held in a CO-containing as compared to a non-CO-containing atmosphere, in the 0 to 85% RH range. Thus, the data presented indicate that CO in the urban environment may have a protective or lethal effect on airborne bacteria, dependent upon at least the microbial species, aerosol age, and relative humidity. A mechanism for CO death enhancement and protection of airborne S. marcescens 8UK is suggested to involve CO uncoupling of an energy-requiring death mechanism and an energy-requiring maintenance mechanism at high and low RH, respectively. PMID:4631439

  14. Disaster phenomena of Wenchuan earthquake in high resolution airborne synthetic aperture radar images

    NASA Astrophysics Data System (ADS)

    Wang, Chao; Zhang, Hong; Wu, Fan; Zhang, Bo; Tang, Yixian; Wu, Hongan; Wen, Xiaoyang; Yan, Dongmei

    2009-05-01

    The devastating Wenchuan Earthquake occurred in Sichuan Province, Southwestern China, with a magnitude of 8.0 on May 12, 2008. Most buildings along the seismic zone were ruined, resulting in infrastructure damage to factories, traffic facilities and power supplies. The earthquake also triggered geological disasters, such as landslides, debris flow, landslide lakes, etc. During the rescue campaign the remote sensing aircrafts of the Chinese Academy of Sciences (CAS), equipped with synthetic aperture radar (SAR) and optical sensors, flew over the disaster area and acquired many high resolution airborne SAR images. We first describe the basic characteristics of SAR imagery. The SAR images of buildings are simulated, and the backscattering mechanism of the buildings is analyzed. Finally, the various disaster phenomena are described and analyzed in the high resolution airborne SAR images. It is shown that certain phenomena of ruins could be identified clearly in high resolution SAR images in proper imaging conditions, while the functional destruction is quite difficult to detect. With calibrated data, the polarmetric SAR interferometry could be used to analyze the scattering mechanism and 3D distribution of the scattering center, which are redound to earthquake damage assessment.

  15. Aerosol, surface, and cloud optical parameters derived from airborne spectral actinic flux: measurement comparison with other methods

    NASA Astrophysics Data System (ADS)

    Stark, H.; Bierwirth, E.; Schmidt, S.; Kindel, B. C.; Pilewskie, P.; Lack, D. A.; Madronich, S.; Parrish, D. D.

    2009-12-01

    Optical parameters of aerosols, surfaces, and clouds are essential for an accurate description of Earth’s radiative balance. We will present values for such parameters derived from spectral actinic flux measured on board the NOAA WP-3D aircraft during the Aerosol, Radiation, and Cloud Processes affecting Arctic Climate (ARCPAC) study in April 2008. We will compare these measurements to results obtained from other instruments on board the same aircraft, such as the Solar Spectral Flux Radiometer (SSFR) for irradiance measurements and aerosol extinction and absorption measurements by cavity ring-down and Particle Soot Absorption Photometer (PSAP). Actinic flux is sensitive to these parameters and can be used to measure them directly in the atmosphere without in-situ sampling methods required. We will describe the specifics of the actinic flux measurements, show advantages and disadvantages of this measurement technique, and compare results with other techniques. Furthermore, we will compare our measurements with model calculations from radiative transfer models such as the Tropospheric Ultraviolet and Visible (TUV) radiation model, the widely used library of radiative transfer (libradtran) model, and a Monte-Carlo radiation model (GRIMALDI). Also, we will investigate satellite measurements to constrain the radiation measurements to general radiation conditions in the arctic and to compare the results to aerosol optical depth retrievals. In particular, we will show results for surface albedo of the Arctic Ocean ice surface, extinction and absorption of Arctic haze layers, and optical thickness and albedo measurements of clouds.

  16. Accuracy assessment of airborne photogrammetrically derived high-resolution digital elevation models in a high mountain environment

    NASA Astrophysics Data System (ADS)

    Müller, Johann; Gärtner-Roer, Isabelle; Thee, Patrick; Ginzler, Christian

    2014-12-01

    High-resolution digital elevation models (DEMs) generated by airborne remote sensing are frequently used to analyze landform structures (monotemporal) and geomorphological processes (multitemporal) in remote areas or areas of extreme terrain. In order to assess and quantify such structures and processes it is necessary to know the absolute accuracy of the available DEMs. This study assesses the absolute vertical accuracy of DEMs generated by the High Resolution Stereo Camera-Airborne (HRSC-A), the Leica Airborne Digital Sensors 40/80 (ADS40 and ADS80) and the analogue camera system RC30. The study area is located in the Turtmann valley, Valais, Switzerland, a glacially and periglacially formed hanging valley stretching from 2400 m to 3300 m a.s.l. The photogrammetrically derived DEMs are evaluated against geodetic field measurements and an airborne laser scan (ALS). Traditional and robust global and local accuracy measurements are used to describe the vertical quality of the DEMs, which show a non Gaussian distribution of errors. The results show that all four sensor systems produce DEMs with similar accuracy despite their different setups and generations. The ADS40 and ADS80 (both with a ground sampling distance of 0.50 m) generate the most accurate DEMs in complex high mountain areas with a RMSE of 0.8 m and NMAD of 0.6 m They also show the highest accuracy relating to flying height (0.14‰). The pushbroom scanning system HRSC-A produces a RMSE of 1.03 m and a NMAD of 0.83 m (0.21‰ accuracy of the flying height and 10 times the ground sampling distance). The analogue camera system RC30 produces DEMs with a vertical accuracy of 1.30 m RMSE and 0.83 m NMAD (0.17‰ accuracy of the flying height and two times the ground sampling distance). It is also shown that the performance of the DEMs strongly depends on the inclination of the terrain. The RMSE of areas up to an inclination <40° is better than 1 m. In more inclined areas the error and outlier occurrence

  17. Detecting Climate Signatures with High Spectral Resolution Infrared Satellite Measurements

    NASA Astrophysics Data System (ADS)

    Deslover, D. H.; Tobin, D.; Knuteson, R. O.; Revercomb, H. E.

    2013-12-01

    Upwelling atmospheric infrared radiances can be accurately monitored from high spectral resolution satellite observations. The high spectral resolution nature of these measurements affords the ability to track various climate relevant parameters such as window channels sensitive to surface temperature and clouds, channels with higher sensitivity to trace gases including CO2, CH4, SO2, HNO3, as well as channels sensitive only to upper tropospheric or lower stratospheric temperature. NASA's Atmospheric Infrared Sounder (AIRS) provides a data record that extends from its 2002 launch to the present. The Infrared Atmospheric Sounding Interferometer (IASI) onboard Metop- (A launched in 2006, B in 2012), as well as the Joint Polar Satellite System (JPSS) Cross-track Infrared Sounder (CrIS) launched in 2011, complement this data record. Future infrared sounders with similar capabilities will augment these measurements into the distant future. We have created a global data set from the aforementioned satellite observations. Our analysis yields a channel dependent approach that can be further constrained in terms of diurnal, seasonal and geographic limits, with measurement accuracies of better than a few tenths of degree Kelvin. In this study, we have applied this concept to obtain a better understanding of long-term stratospheric temperature trends. We will present a survey of temperature trends for spectral channels that were chosen to be sensitive to stratospheric emission. Results will be shown for tropical, mid-latitude and polar stratospheric observations.

  18. High spectral resolution measurements for the ARM Program

    SciTech Connect

    Revercomb, H.E.

    1992-05-22

    This report focuses on the design and fabrication of high spectral resolution FTIR (Fourier Transform Infrared) instrumentation for the CART sites of the Atmospheric Radiation Measurement (ARM) Program. The ultimate objective of this grant is to develop three different types of instruments, named the AERI, AERI-X, and SORT. The Atmospheric Emitted Radiance Interferometer (AERI) is the simplest. It will be available for early deployment at the first ARM site and will be deployable at several locations in the extended network to give horizontal coverage. The AERI will be an 0.5 cm{sup {minus}1} resolution instrument, which measures accurately calibrated radiance spectra for radiation studies and for remote sensing of atmospheric state variables. The AERI-X and the SORTI are higher spectral resolution instruments for obtaining the highest practical resolution for spectroscopy at the ARM central sites. The AERI-X, like the AERI will measure atmospheric emitted radiance, but with resolutions as high as 0.1 cm{sup {minus}1}. The Solar Radiance Transmission Interferometer will measure the total transmission of the atmosphere by tracking the sun through changes in atmospheric air mass. The large solar signal makes it practical for this instrument to offer the ultimate in spectral resolution, about 0.002 cm{sup {minus}1}.

  19. System optimization of a field-widened Michelson interferometric spectral filter for high spectral resolution lidar

    NASA Astrophysics Data System (ADS)

    Liu, Dong; Miller, Ian; Hostetler, Chris; Cook, Anthony; Hair, Johnathan

    2011-06-01

    High spectral resolution lidars (HSRLs) have recently shown great value in aerosol measurements form aircraft and are being called for in future space-based aerosol remote sensing applications. A quasi-monolithic field-widened, off-axis Michelson interferometer had been developed as the spectral discrimination filter for an HSRL currently under development at NASA Langley Research Center (LaRC). The Michelson filter consists of a cubic beam splitter, a solid arm and an air arm. The input light is injected at 1.5° off-axis to provide two output channels: standard Michelson output and the reflected complementary signal. Piezo packs connect the air arm mirror to the main part of the filter that allows it to be tuned within a small range. In this paper, analyses of the throughput wavephase, locking error, AR coating, and tilt angle of the interferometer are described. The transmission ratio for monochromatic light at the transmitted wavelength is used as a figure of merit for assessing each of these parameters.

  20. Field-widened Michelson interferometer for spectral discrimination in high-spectral-resolution lidar: practical development.

    PubMed

    Cheng, Zhongtao; Liu, Dong; Zhang, Yupeng; Yang, Yongying; Zhou, Yudi; Luo, Jing; Bai, Jian; Shen, Yibing; Wang, Kaiwei; Liu, Chong; Su, Lin; Yang, Liming

    2016-04-04

    A field-widened Michelson interferometer (FWMI), which is intended as the spectroscopic discriminator in ground-based high-spectral-resolution lidar (HSRL) for atmospheric aerosol detection, is described in this paper. The structure, specifications and design of the developed prototype FWMI are introduced, and an experimental approach is proposed to optimize the FWMI assembly and evaluate its comprehensive characteristic simultaneously. Experimental results show that, after optimization process, the peak-to-valley (PV) value and root-mean-square (RMS) value of measured OPD variation for the FWMI are 0.04λ and 0.008λ respectively among the half divergent angle range of 1.5 degree. Through an active locking technique, the frequency of the FWMI can be locked to the laser transmitter with accuracy of 27 MHz for more than one hour. The practical spectral discrimination ratio (SDR) for the developed FWMI is evaluated to be larger than 86 if the divergent angle of incident beam is smaller than 0.5 degree. All these results demonstrate the great potential of the developed FWMI as the spectroscopic discriminator for HSRLs, as well as the feasibility of the proposed design and optimization process. This paper is expected to provide a good entrance for the lidar community in future HSRL developments using the FWMI technique.

  1. Field-widened Michelson interferometer for spectral discrimination in high-spectral-resolution lidar: theoretical framework.

    PubMed

    Cheng, Zhongtao; Liu, Dong; Luo, Jing; Yang, Yongying; Zhou, Yudi; Zhang, Yupeng; Duan, Lulin; Su, Lin; Yang, Liming; Shen, Yibing; Wang, Kaiwei; Bai, Jian

    2015-05-04

    A field-widened Michelson interferometer (FWMI) is developed to act as the spectral discriminator in high-spectral-resolution lidar (HSRL). This realization is motivated by the wide-angle Michelson interferometer (WAMI) which has been used broadly in the atmospheric wind and temperature detection. This paper describes an independent theoretical framework about the application of the FWMI in HSRL for the first time. In the framework, the operation principles and application requirements of the FWMI are discussed in comparison with that of the WAMI. Theoretical foundations for designing this type of interferometer are introduced based on these comparisons. Moreover, a general performance estimation model for the FWMI is established, which can provide common guidelines for the performance budget and evaluation of the FWMI in the both design and operation stages. Examples incorporating many practical imperfections or conditions that may degrade the performance of the FWMI are given to illustrate the implementation of the modeling. This theoretical framework presents a complete and powerful tool for solving most of theoretical or engineering problems encountered in the FWMI application, including the designing, parameter calibration, prior performance budget, posterior performance estimation, and so on. It will be a valuable contribution to the lidar community to develop a new generation of HSRLs based on the FWMI spectroscopic filter.

  2. Advances toward high spectral resolution quantum X-ray calorimetry

    NASA Technical Reports Server (NTRS)

    Moseley, S. H.; Kelley, R. L.; Schoelkopf, R. J.; Szymkowiak, A. E.; Mccammon, D.

    1988-01-01

    Thermal detectors for X-ray spectroscopy combining high spectral resolution and quantum efficiency have been developed. These microcalorimeters measure the energy released in the absorption of a single photon by sensing the rise in temperature of a small absorbing structure. The ultimate energy resolution of such a device is limited by the thermodynamic power fluctuations in the thermal link between the calorimeter and isothermal bath and can in principle be made as low as 1 eV. The performance of a real device is degraded due to noise contributions such as excess 1/f noise in the thermistor and incomplete conversion of energy into phonons. The authors report some recent advances in thermometry, X-ray absorption and thermalization, fabrication techniques, and detector optimization in the presence of noise. These improvements have resulted in a device with a spectral resolution of 17 eV FWHM, measured at 6 keV.

  3. Distance measurement to high remote targets based on the airborne chaotic laser

    NASA Astrophysics Data System (ADS)

    Kou, Renke; Wang, Haiyan; Wu, Xueming

    2016-10-01

    According to the characteristics of chaotic laser, which has ability of novel anti-jamming, high bandwidth and detecting distance of the movement target to the millimeter precision, a modeling method of using airborne chaotic laser system to detect distance of high remote targets is proposed for the first time. The characteristics of chaotic laser and principle of interferometry distance were analyzed and the model of airborne chaotic laser ranging is established. Meanwhile, the influence of detection accuracy, which inducted by the main peak width of chaotic laser and the jamming signal is analyzed. According to the results of simulation analysis, we can get conclusions that the main factors of affecting the distance measurement are transmitted power, receiving sensitivity, and various losses of transmission medium. Autocorrelation characteristic of chaotic signal can also affect the dynamic range of the whole system. The main peak width of chaotic laser is the main factor of influencing the accuracy of measurement. However, the jamming signal affect distance measuring range and accuracy of measurement little. Finally, the model's effectiveness is proved by comparing the experience data and simulation data.

  4. Airborne ultrasonic transducer using polymer-based elastomer with high output-to-weight ratio

    NASA Astrophysics Data System (ADS)

    Wu, Jiang; Mizuno, Yosuke; Tabaru, Marie; Nakamura, Kentaro

    2015-08-01

    With the properties of low density, low elastic modulus, and low mechanical loss, poly(phenylene sulfide) (PPS) is a suitable material as the elastomer in an airborne ultrasonic transducer for generating large vibration velocity. In this study, we design and fabricate a transducer composed of a PPS-based longitudinal vibrator and a PPS-based disk of 0.3 mm thickness to obtain high-intensity ultrasound. The rated sound pressure at a distance of 300 mm reached 38.9 Pa (125 dB, 0 dB re. 0.02 mPa) when the frequency and voltage were 58.90 kHz and 20 V. The weight of this transducer is 6.3 g. The ratio of the sound pressure to the weight of the prototype transducer is 1.8 times larger than that of the commercial transducer. The experimental results indicate that PPS is a good substitute for metal as the elastomer for manufacturing airborne ultrasonic transducers with a high output-to-weight ratio.

  5. Real-time Data Processing and Visualization for the Airborne Scanning High-resolution Interferometer Sounder (S-HIS)

    NASA Astrophysics Data System (ADS)

    Taylor, J. K.; Revercomb, H. E.; Hoese, D.; Garcia, R. K.; Smith, W. L.; Weisz, E.; Tobin, D. C.; Best, F. A.; Knuteson, R. O.; Sullivan, D. V.; Barnes, C. M.; Van Gilst, D. P.

    2015-12-01

    The Hurricane and Severe Storm Sentinel (HS3) is a five-year NASA mission targeted to enhance the understanding of the formation and evolution of hurricanes in the Atlantic basin. Measurements were made from two NASA Global Hawk Unmanned Aircraft Systems (UAS) during the 2012 through 2014 hurricane seasons, with flights conducted from the NASA Wallops Flight Facility. The Global Hawk aircraft are capable of high altitude flights with durations of up to 30 hours, which allow extensive observations over distant storms, not typically possible with manned aircraft. The two NASA Global Hawks were equipped with instrument suites to study the storm environment, and inner core structure and processes, respectively. The Scanning High-resolution Interferometer Sounder (S-HIS), designed and built by the University of Wisconsin (UW) Space Science and Engineering Center (SSEC), measures emitted thermal radiation at high spectral resolution between 3.3 and 18 microns. The radiance measurements are used to obtain temperature and water vapor profiles of the Earth's atmosphere. The S-HIS spatial resolution is 2 km at nadir, across a 40 km ground swath from a nominal altitude of 20 kilometers. Since 1998, the S-HIS has participated in 33 field campaigns and has proven to be extremely dependable, effective, and highly accurate. It has flown on the NASA ER-2, DC-8, Proteus, WB-57, and Global Hawk airborne platforms. The UW S-HIS infrared sounder instrument is equipped with a real-time ground data processing system capable of delivering atmospheric profiles, radiance data, and engineering status to mission support scientists - all within less than one minute from the time of observation. This ground data processing system was assembled by a small team using existing software and proven practical techniques similar to a satellite ground system architecture. This summary outlines the design overview for the system and illustrates the data path, content, and outcomes.

  6. Evaluation of eelgrass beds mapping using a high-resolution airborne multispectral scanner

    USGS Publications Warehouse

    Su, H.; Karna, D.; Fraim, E.; Fitzgerald, M.; Dominguez, R.; Myers, J.S.; Coffland, B.; Handley, L.R.; Mace, T.

    2006-01-01

    Eelgrass (Zostera marina) can provide vital ecological functions in stabilizing sediments, influencing current dynamics, and contributing significant amounts of biomass to numerous food webs in coastal ecosystems. Mapping eelgrass beds is important for coastal water and nearshore estuarine monitoring, management, and planning. This study demonstrated the possible use of high spatial (approximately 5 m) and temporal (maximum low tide) resolution airborne multispectral scanner on mapping eelgrass beds in Northern Puget Sound, Washington. A combination of supervised and unsupervised classification approaches were performed on the multispectral scanner imagery. A normalized difference vegetation index (NDVI) derived from the red and near-infrared bands and ancillary spatial information, were used to extract and mask eelgrass beds and other submerged aquatic vegetation (SAV) in the study area. We evaluated the resulting thematic map (geocoded, classified image) against a conventional aerial photograph interpretation using 260 point locations randomly stratified over five defined classes from the thematic map. We achieved an overall accuracy of 92 percent with 0.92 Kappa Coefficient in the study area. This study demonstrates that the airborne multispectral scanner can be useful for mapping eelgrass beds in a local or regional scale, especially in regions for which optical remote sensing from space is constrained by climatic and tidal conditions. ?? 2006 American Society for Photogrammetry and Remote Sensing.

  7. Improved method for estimating tree crown diameter using high-resolution airborne data

    NASA Astrophysics Data System (ADS)

    Brovkina, Olga; Latypov, Iscander Sh.; Cienciala, Emil; Fabianek, Tomas

    2016-04-01

    Automatic mapping of tree crown size (radius, diameter, or width) from remote sensing can provide a major benefit for practical and scientific purposes, but requires the development of accurate methods. This study presents an improved method for average tree crown diameter estimation at a forest plot level from high-resolution airborne data. The improved method consists of the combination of a window binarization procedure and a granulometric algorithm, and avoids the complicated crown delineation procedure that is currently used to estimate crown size. The systematic error in average crown diameter estimates is corrected with the improved method. The improved method is tested with coniferous, beech, and mixed-species forest plots based on airborne images of various spatial resolutions. The absolute (quantitative) accuracy of the improved crown diameter estimates is comparable or higher for both monospecies plots and mixed-species plots than the current methods. The ability of the improved method to produce good estimates for average crown diameters for monoculture and mixed species, to use remote sensing data of various spatial resolution and to operate in automatic mode promisingly suggests its applicability to a wide range of forest systems.

  8. ATLAS: an airborne active linescan system for high-resolution topographic mapping

    NASA Astrophysics Data System (ADS)

    Willetts, David V.; Kightley, Peter J.; Mole, S. G.; Pearson, Guy N.; Pearson, P.; Coffey, Adrian S.; Stokes, Tim J.; Tapster, Paul R.; Westwood, M.

    2004-12-01

    High resolution ground mapping is of interest for survey and management of long linear features such as roads, railways and pipelines, and for georeferencing of areas such as flood plains for hydrological purposes. ATLAS (Airborne Topographic Laser System) is an active linescan system operating at the eyesafe wavelength of 1.5μm. Built for airborne survey, it is currently certified for use on a Twin Squirrel helicopter for operation from low levels to heights above 500 feet allowing commercial survey in built up areas. The system operates at a pulse repetition frequency of 56kHz with a line completed in 15ms, giving 36 points/m2 at the surface at the design flight speed. At each point the range to the ground is measured together with the scan angle of the system. This data is combined with a system attitude measurement from an integrated inertial navigation system and with system position derived from differential GPS data aboard the platform. A recording system captures the data with a synchronised time-stamp to enable post-processed reconstruction of a cloud of data points that will give a three-dimensional representation of the terrain, allowing the points to be located with respect to absolute Earth referenced coordinates to a precision of 5cm in three axes. This paper summarises the design, harmonisation, evaluation and performance of the system, and shows examples of survey data.

  9. Linear array transducer for high-power airborne ultrasound using flextensional structure

    NASA Astrophysics Data System (ADS)

    Yamamoto, Jun; Mizuno, Yosuke; Tabaru, Marie; Nakamura, Kentaro

    2015-07-01

    To change the direction of ultrasonic irradiation without moving a transducer, a high-power airborne ultrasonic transducer for a one-dimensional phased array system was designed and tested. A flextensional element transducer with higher-mode bending vibration was fabricated to obtain a high vibration amplitude over a wide aperture, where a phase-compensating stepped structure was employed. The width of the main lobe at half maximum and the sidelobe level were measured to be 14.3 deg and 0.78, respectively. The maximal sound pressure of 132 dB (0 dB re. 0.02 mPa) was obtained under the applied voltage of 4.0 V. The beam steering characteristics of a phased array using eight elements were compared with the simple theory.

  10. High spatial resolution observations of 137Cs in northern Britain and Ireland from airborne geophysical survey.

    PubMed

    Scheib, Cathy; Beamish, David

    2010-09-01

    This study reports the (137)Cs data derived from three regional and national scale High Resolution Airborne Resource and Environmental Surveys (HiRES) in northern Britain and Ireland. The detailed spatial resolution, combined with the large areas these surveys collectively cover, gives insight into large-scale deposition patterns and possible subsequent re-distribution of (137)Cs on a level that was previously not possible. The largest survey area considered covers the whole of Northern Ireland. All three data sets display some clustering of higher (137)Cs activities on high ground together with regional scale NNW-SSE and NW-SE banding features. We interpret these as representing a series of rainfall interceptions of the repeated passage of the Chernobyl plume. Our observations, obtained at 200 m flight line intervals, appear to provide significant detail in relation to existing knowledge of large scale along-wind deposition of (137)Cs.

  11. Spectral fingerprinting of polycyclic aromatic hydrocarbons in high-volume ambient air samples by constant energy synchronous luminescence spectroscopy

    USGS Publications Warehouse

    Kerkhoff, M.J.; Lee, T.M.; Allen, E.R.; Lundgren, D.A.; Winefordner, J.D.

    1985-01-01

    A high-volume sampler fitted with a glass-fiber filter and backed by polyurethane foam (PUF) was employed to collect airborne particulate and gas-phase polycylic aromatic hydrocarbons (PAHs) in ambient air. Samples were collected from four sources representing a range of environmental conditions: gasoline engine exhaust, diesel engine exhaust, air near a heavily traveled interstate site, and air from a moderately polluted urban site. Spectral fingerprints of the unseparated particulate and gas-phase samples were obtained by constant energy synchronous luminescence spectroscopy (CESLS). Five major PAHs in the gas-phase extracts were characterized and estimated. The compatibility of a high-volume sampling method using polyurethane foam coupled with CESLS detection is explored for use as a screening technique for PAHs in ambient air. ?? 1985 American Chemical Society.

  12. High-Accuracy Elevation Data at Large Scales from Airborne Single-Pass SAR Interferometry

    NASA Astrophysics Data System (ADS)

    Schumann, Guy; Moller, Delwyn; Mentgen, Felix

    2015-12-01

    Digital elevation models (DEMs) are essential data sets for disaster risk management and humanitarian relief services as well as many environmental process models. At present, on the hand, globally available DEMs only meet the basic requirements and for many services and modeling studies are not of high enough spatial resolution and lack accuracy in the vertical. On the other hand, LiDAR-DEMs are of very high spatial resolution and great vertical accuracy but acquisition operations can be very costly for spatial scales larger than a couple of hundred square km and also have severe limitations in wetland areas and under cloudy and rainy conditions. The ideal situation would thus be to have a DEM technology that allows larger spatial coverage than LiDAR but without compromising resolution and vertical accuracy and still performing under some adverse weather conditions and at a reasonable cost. In this paper, we present a novel single pass In-SAR technology for airborne vehicles that is cost-effective and can generate DEMs with a vertical error of around 0.3 m for an average spatial resolution of 3 m. To demonstrate this capability, we compare a sample single-pass In-SAR Ka-band DEM of the California Central Valley from the NASA/JPL airborne GLISTIN-A to a high-resolution LiDAR DEM. We also perform a simple sensitivity analysis to floodplain inundation. Based on the findings of our analysis, we argue that this type of technology can and should be used to replace large regions of globally available lower resolution DEMs, particularly in coastal, delta and floodplain areas where a high number of assets, habitats and lives are at risk from natural disasters. We conclude with a discussion on requirements, advantages and caveats in terms of instrument and data processing.

  13. Glaciotectonic structures mapped by GPR, geoelectrical, high-resolution seismic and airborne transient electromagnetic methods

    NASA Astrophysics Data System (ADS)

    Høyer, Anne-Sophie; Møller, Ingelise; Jørgensen, Flemming

    2013-04-01

    Glaciotectonic structures have traditionally been recognized through observations in the landscape or exposures like cliffs. However, mapping of these structures can highly benefit from geophysical data, which can give information on buried glaciotectonic complexes. In the current study, we focus on the appearance of glaciotectonic structures in data from four commonly used geophysical methods: Ground penetrating radar (GPR), geoelectrical, high-resolution seismic and airborne transient electromagnetic (SkyTEM). The data are collected within a study area that covers 100 km2 and is located in the western part of Denmark. The study area is characterized by a highly heterogeneous geological setting, which has been influenced by multiple glacial deformation phases resulting in a buried glaciotectonic complex. The glaciotectonic structures appear as folds and faults and are recognizable at all scales. As a consequence of the different resolution capabilities of the methods, different degrees of detail are observed: Large-scale structures are recognized based on the seismic and airborne transient electromagnetic data, whereas small-scale structures are interpreted based on the GPR and geoelectrical data. At the same time, the nature of the methods results in different types of information from the data: The GPR and the seismic data generally provide detailed structural information, whereas the electric and electromagnetic data provide a more 'blurred' resistivity image of the subsurface. In order to recognize geological structures on the electric and electromagnetic data, the structures therefore need to influence sediments with contrasting resistivities to the surroundings. The structures are recognizable on all the different data sets, but the understanding and thus, the interpretation, of the geological environment strongly benefits from the combined observations from the different types of data.

  14. A high performance spectral code for nonlinear MHD stability

    SciTech Connect

    Taylor, M.

    1992-09-01

    A new spectral code, NSTAB, has been developed to do nonlinear stability and equilibrium calculations for the magnetohydrodynamic (MHD) equations in three dimensional toroidal geometries. The code has the resolution to test nonlinear stability by calculating bifurcated equilibria directly. These equilibria consist of weak solutions with current sheets near rational surfaces and other less localized modes. Bifurcated equilibria with a pronounced current sheet where the rotational transform crosses unity are calculated for the International Thermonuclear Experimental Reactor (ITER). Bifurcated solutions with broader resonances are found for the LHD stellarator currently being built in Japan and an optimized configuration like the Wendelstein VII-X proposed for construction in Germany. The code is able to handle the many harmonics required to capture the high mode number of these instabilities. NSTAB builds on the highly successful BETAS code, which applies the spectral method to a flux coordinate formulation of the variational principle associated with the MHD equilibrium equations. However, a new residue condition for the location of the magnetic axis has been developed and implemented. This condition is based on the weak formulation of the equations and imposes no constraints on the inner flux surfaces.

  15. High-energy spectral breaks in gamma-ray bursts

    NASA Technical Reports Server (NTRS)

    Schaefer, Bradley E.; Teegarden, Bonnard J.; Cline, Thomas L.; Fishman, Gerald J.; Meegan, Charles A.; Wilson, Robert B.; Paciesas, William S.; Pendleton, Geoffrey N.; Matteson, James L.; Band, David L.

    1992-01-01

    Model fits are presented for 18 gamma-ray burst spectra from 100 keV to 27 MeV made with the BATSE spectroscopy detectors on the Compton Gamma Ray Observatory. Most of the bursts are well fitted as power laws with spectral indices between -1.36 and -2.29; however, five bursts show definite departures from a simple power-law fit at high energies. Three of these bursts are well fitted with broken power-law spectra and break energies of from 400 to 690 keV, such as might arise from photon-photon interactions. If so, then the source compactness and hence distance will be sharply constrained. Two of the bursts have spectra with sharply confined slope changes and are well fitted with broken power-law spectra with break energies of 1.2 and 1.6 MeV at peak, such as might arise from photon-magnetic field interactions. If so, then these spectral breaks provide strong evidence for the existence of high magnetic fields in the burst emission region.

  16. Laser measurement of extinction coefficients of highly absorbing liquids. [airborne oil spill monitoring application

    NASA Technical Reports Server (NTRS)

    Hoge, F. E.; Kincaid, J. S.

    1980-01-01

    A coaxial dual-channel laser system has been developed for the measurement of extinction coefficients of highly absorbing liquids. An empty wedge-shaped sample cell is first translated laterally through a He-Ne laser beam to measure the differential thickness using interference fringes in reflection. The wedge cell is carefully filled with the oil sample and translated through the coaxially positioned dye laser beam for the differential attenuation or extinction measurement. Optional use of the instrumentation as a single-channel extinction measurement system and also as a refractometer is detailed. The system and calibration techniques were applied to the measurement of two crude oils whose extinction values were required to complete the analysis of airborne laser data gathered over four controlled spills.

  17. Airborne ROWS data report for the high resolution experiment, June 1993

    NASA Technical Reports Server (NTRS)

    Vandemark, D.; Hines, D.; Bailey, S.; Stewart, K.

    1994-01-01

    Airborne radar ocean wave spectrometer (ROWS) data collected during the Office of Naval Research's High Resolution Remote Sensing Experiment of June 1993 are presented. This data summary covers six flights made using NASA's T-39 aircraft over a region of the North Atlantic off the coast of North Carolina and includes multiple crossings of the gulf stream. The Ku-band ROWS was operated in a configuration which continuously switched between an altimeter and a spectrometer channel. Data derived from the two channels include altimeter radar cross section, altimeter-derived sea surface mean square slope and wind speed, and directional and nondirectional longwave spectra. Discussion is provided for several events of particular interest.

  18. Automated planimetric quality control in high accuracy airborne laser scanning surveys

    NASA Astrophysics Data System (ADS)

    Vosselman, George

    2012-11-01

    With the increasing point densities of airborne laser scanning surveys, the applications of the generated point clouds have evolved from the production of digital terrain models to 3D modelling of a wide variety of objects. Likewise in quality control procedures criteria for height accuracy are extended with measures to describe the planimetric accuracy. This paper introduces a measure for the potential accuracy of outlining objects in a point cloud. It describes how this accuracy can be verified with the use of ridge lines of gable roofs in strip overlaps. Because of the high accuracy of modern laser scanning surveys, the influence of roof tiles onto the estimation of ridge lines is explicitly modelled. New selection criteria are introduced that allow an automated, reliable and accurate extraction of ridge lines from point clouds. The applicability of the procedure is demonstrated in a pilot project in an area covering 100,000 ha with around 20 billion points.

  19. High-resolution airborne gravity imaging over James Ross Island (West Antarctica)

    USGS Publications Warehouse

    Jordan, T.A.; Ferraccioli, F.; Jones, P.C.; Smellie, J.L.; Ghidella, M.; Corr, H. F. J.; Zakrajsek, A.F.

    2007-01-01

    James Ross Island (JRI) exposes a Miocene-Recent alkaline basaltic volcanic complex that developed in a back-arc, east of the northern Antarctic Peninsula. JRI has been the focus of several geological studies because it provides a window on Neogene magmatic processes and paleoenvironments. However, little is known about its internal structure. New airborne gravity data were collected as part of the first high-resolution aerogeophysical survey flown over the island and reveal a prominent negative Bouguer gravity anomaly over Mt Haddington. This is intriguing as basaltic volcanoes are typically associated with positive Bouguer anomalies, linked to underlying mafic intrusions. The negative Bouguer anomaly may be associated with a hitherto unrecognised low-density sub-surface body, such as a breccia-filled caldera, or a partially molten magma chamber.

  20. The WEIZMASS spectral library for high-confidence metabolite identification

    NASA Astrophysics Data System (ADS)

    Shahaf, Nir; Rogachev, Ilana; Heinig, Uwe; Meir, Sagit; Malitsky, Sergey; Battat, Maor; Wyner, Hilary; Zheng, Shuning; Wehrens, Ron; Aharoni, Asaph

    2016-08-01

    Annotation of metabolites is an essential, yet problematic, aspect of mass spectrometry (MS)-based metabolomics assays. The current repertoire of definitive annotations of metabolite spectra in public MS databases is limited and suffers from lack of chemical and taxonomic diversity. Furthermore, the heterogeneity of the data prevents the development of universally applicable metabolite annotation tools. Here we present a combined experimental and computational platform to advance this key issue in metabolomics. WEIZMASS is a unique reference metabolite spectral library developed from high-resolution MS data acquired from a structurally diverse set of 3,540 plant metabolites. We also present MatchWeiz, a multi-module strategy using a probabilistic approach to match library and experimental data. This strategy allows efficient and high-confidence identification of dozens of metabolites in model and exotic plants, including metabolites not previously reported in plants or found in few plant species to date.

  1. The WEIZMASS spectral library for high-confidence metabolite identification

    PubMed Central

    Shahaf, Nir; Rogachev, Ilana; Heinig, Uwe; Meir, Sagit; Malitsky, Sergey; Battat, Maor; Wyner, Hilary; Zheng, Shuning; Wehrens, Ron; Aharoni, Asaph

    2016-01-01

    Annotation of metabolites is an essential, yet problematic, aspect of mass spectrometry (MS)-based metabolomics assays. The current repertoire of definitive annotations of metabolite spectra in public MS databases is limited and suffers from lack of chemical and taxonomic diversity. Furthermore, the heterogeneity of the data prevents the development of universally applicable metabolite annotation tools. Here we present a combined experimental and computational platform to advance this key issue in metabolomics. WEIZMASS is a unique reference metabolite spectral library developed from high-resolution MS data acquired from a structurally diverse set of 3,540 plant metabolites. We also present MatchWeiz, a multi-module strategy using a probabilistic approach to match library and experimental data. This strategy allows efficient and high-confidence identification of dozens of metabolites in model and exotic plants, including metabolites not previously reported in plants or found in few plant species to date. PMID:27571918

  2. High performance computing with a conservative spectral Boltzmann solver

    NASA Astrophysics Data System (ADS)

    Haack, Jeffrey R.; Gamba, Irene M.

    2012-11-01

    We present new results building on the conservative deterministic spectral method for the space inhomogeneous Boltzmann equation developed by Gamba and Tharkabhushaman. This approach is a two-step process that acts on the weak form of the Boltzmann equation, and uses the machinery of the Fourier transform to reformulate the collisional integral into a weighted convolution in Fourier space. A constrained optimization problem is solved to preserve the mass, momentum, and energy of the resulting distribution. We extend this method to second order accuracy in space and time, and explore how to leverage the structure of the collisional formulation for high performance computing environments. The locality in space of the collisional term provides a straightforward memory decomposition, and we perform some initial scaling tests on high performance computing resources. We also use the improved computational power of this method to investigate a boundary-layer generated shock problem that cannot be described by classical hydrodynamics.

  3. Breast density estimation from high spectral and spatial resolution MRI.

    PubMed

    Li, Hui; Weiss, William A; Medved, Milica; Abe, Hiroyuki; Newstead, Gillian M; Karczmar, Gregory S; Giger, Maryellen L

    2016-10-01

    A three-dimensional breast density estimation method is presented for high spectral and spatial resolution (HiSS) MR imaging. Twenty-two patients were recruited (under an Institutional Review Board--approved Health Insurance Portability and Accountability Act-compliant protocol) for high-risk breast cancer screening. Each patient received standard-of-care clinical digital x-ray mammograms and MR scans, as well as HiSS scans. The algorithm for breast density estimation includes breast mask generating, breast skin removal, and breast percentage density calculation. The inter- and intra-user variabilities of the HiSS-based density estimation were determined using correlation analysis and limits of agreement. Correlation analysis was also performed between the HiSS-based density estimation and radiologists' breast imaging-reporting and data system (BI-RADS) density ratings. A correlation coefficient of 0.91 ([Formula: see text]) was obtained between left and right breast density estimations. An interclass correlation coefficient of 0.99 ([Formula: see text]) indicated high reliability for the inter-user variability of the HiSS-based breast density estimations. A moderate correlation coefficient of 0.55 ([Formula: see text]) was observed between HiSS-based breast density estimations and radiologists' BI-RADS. In summary, an objective density estimation method using HiSS spectral data from breast MRI was developed. The high reproducibility with low inter- and low intra-user variabilities shown in this preliminary study suggest that such a HiSS-based density metric may be potentially beneficial in programs requiring breast density such as in breast cancer risk assessment and monitoring effects of therapy.

  4. Airborne Differential Absorption and High Spectral Resolution Lidar Measurements for Cirrus Cloud Studies

    NASA Astrophysics Data System (ADS)

    Gross, Silke; Schaefler, Andreas; Wirth, Martin; Fix, Andreas

    2016-06-01

    Aerosol and water vapor measurements were performed with the lidar system WALES of the German Aerospace Center (DLR) onboard the German research aircraft G550-HALO during the HALO Techno-Mission in October and November 2010 and during the ML-Cirrus mission in March and April 2014 over Central Europe and the North Atlantic region. Curtains composed of lidar profiles beneath the aircraft show the water vapor mixing ratio and the backscatter ratio. Temperature data from ECMWF model analysis are used to calculate the relative humidity above ice (RHi) in the 2-D field along the flight track to study the RHi distribution inside and outside of cirrus clouds at different stages of cloud evolution.

  5. Multipurpose Spectral Imager

    NASA Astrophysics Data System (ADS)

    Sigernes, Fred; Lorentzen, Dag Arne; Heia, Karsten; Svenøe, Trond

    2000-06-01

    A small spectral imaging system is presented that images static or moving objects simultaneously as a function of wavelength. The main physical principle is outlined and demonstrated. The instrument is capable of resolving both spectral and spatial information from targets throughout the entire visible region. The spectral domain has a bandpass of 12 . One can achieve the spatial domain by rotating the system s front mirror with a high-resolution stepper motor. The spatial resolution range from millimeters to several meters depends mainly on the front optics used and whether the target is fixed (static) or movable relative to the instrument. Different applications and examples are explored, including outdoor landscapes, industrial fish-related targets, and ground-level objects observed in the more traditional way from an airborne carrier (remote sensing). Through the examples, we found that the instrument correctly classifies whether a shrimp is peeled and whether it can disclose the spectral and spatial microcharacteristics of targets such as a fish nematode (parasite). In the macroregime, we were able to distinguish a marine vessel from the surrounding sea and sky. A study of the directional spectral albedo from clouds, mountains, snow cover, and vegetation has also been included. With the airborne experiment, the imager successfully classified snow cover, leads, and new and rafted ice, as seen from 10.000 ft (3.048 m).

  6. High-spectral-resolution lidar for ocean ecosystem studies

    NASA Astrophysics Data System (ADS)

    Liu, Dong; Zhou, Yudi; Yang, Yongying; Cheng, Zhongtao; Luo, Jing; Zhang, Yupeng; Shen, Yibing; Wang, Kaiwei; Liu, Chong; Bai, Jian

    2016-05-01

    The research and protection of the ocean ecosystem are key works to maintain the marine status and develop marine functions. However, human's knowledge about the ocean is greatly limited. Now, in situ, acoustic and remote sensing methods have been applied in the research to understand and explore the ocean. Especially, the lidar is one outstanding remote sensing method for its high spatial and temporal resolution as well as the ability of the vertical detection. Highspectral- resolution lidar (HSRL) employs an ultra-narrow spectral filter to distinguish scattering signals between particles and water molecules without assuming a lidar ratio and obtains optical properties of the ocean with a high accuracy. Nevertheless, the complexity of the seawater causes variable marine optical properties, which gives huge potentiality to develop a HSRL working at different wavelengths in order to promote the inversion accuracy and increase the detection depth. The field-widened Michelson interferometer (FWMI), whose central transmittance can be tuned to any wavelength and field of view is large, can be employed as the HSRL spectral filter and solves problems that the operating wavelength of the iodine filter is fixed and the field of view of Fabry-Perot interferometer is small. The principle of the HSRL based on the FWMI designing for the ocean remote sensing will be presented in detail. In addition, the availability of the application of the FWMI influenced by the disturbance of the states of Brillouin scattering is analyzed and the preliminary theory shows that the HSRL instrument basing on FWMI could be employed in the marine remote sensing with a high accuracy.

  7. Methodology for High-Throughput Field Phenotyping of Canopy Temperature Using Airborne Thermography.

    PubMed

    Deery, David M; Rebetzke, Greg J; Jimenez-Berni, Jose A; James, Richard A; Condon, Anthony G; Bovill, William D; Hutchinson, Paul; Scarrow, Jamie; Davy, Robert; Furbank, Robert T

    2016-01-01

    Lower canopy temperature (CT), resulting from increased stomatal conductance, has been associated with increased yield in wheat. Historically, CT has been measured with hand-held infrared thermometers. Using the hand-held CT method on large field trials is problematic, mostly because measurements are confounded by temporal weather changes during the time required to measure all plots. The hand-held CT method is laborious and yet the resulting heritability low, thereby reducing confidence in selection in large scale breeding endeavors. We have developed a reliable and scalable crop phenotyping method for assessing CT in large field experiments. The method involves airborne thermography from a manned helicopter using a radiometrically-calibrated thermal camera. Thermal image data is acquired from large experiments in the order of seconds, thereby enabling simultaneous measurement of CT on potentially 1000s of plots. Effects of temporal weather variation when phenotyping large experiments using hand-held infrared thermometers are therefore reduced. The method is designed for cost-effective and large-scale use by the non-technical user and includes custom-developed software for data processing to obtain CT data on a single-plot basis for analysis. Broad-sense heritability was routinely >0.50, and as high as 0.79, for airborne thermography CT measured near anthesis on a wheat experiment comprising 768 plots of size 2 × 6 m. Image analysis based on the frequency distribution of temperature pixels to remove the possible influence of background soil did not improve broad-sense heritability. Total image acquisition and processing time was ca. 25 min and required only one person (excluding the helicopter pilot). The results indicate the potential to phenotype CT on large populations in genetics studies or for selection within a plant breeding program.

  8. Methodology for High-Throughput Field Phenotyping of Canopy Temperature Using Airborne Thermography

    PubMed Central

    Deery, David M.; Rebetzke, Greg J.; Jimenez-Berni, Jose A.; James, Richard A.; Condon, Anthony G.; Bovill, William D.; Hutchinson, Paul; Scarrow, Jamie; Davy, Robert; Furbank, Robert T.

    2016-01-01

    Lower canopy temperature (CT), resulting from increased stomatal conductance, has been associated with increased yield in wheat. Historically, CT has been measured with hand-held infrared thermometers. Using the hand-held CT method on large field trials is problematic, mostly because measurements are confounded by temporal weather changes during the time required to measure all plots. The hand-held CT method is laborious and yet the resulting heritability low, thereby reducing confidence in selection in large scale breeding endeavors. We have developed a reliable and scalable crop phenotyping method for assessing CT in large field experiments. The method involves airborne thermography from a manned helicopter using a radiometrically-calibrated thermal camera. Thermal image data is acquired from large experiments in the order of seconds, thereby enabling simultaneous measurement of CT on potentially 1000s of plots. Effects of temporal weather variation when phenotyping large experiments using hand-held infrared thermometers are therefore reduced. The method is designed for cost-effective and large-scale use by the non-technical user and includes custom-developed software for data processing to obtain CT data on a single-plot basis for analysis. Broad-sense heritability was routinely >0.50, and as high as 0.79, for airborne thermography CT measured near anthesis on a wheat experiment comprising 768 plots of size 2 × 6 m. Image analysis based on the frequency distribution of temperature pixels to remove the possible influence of background soil did not improve broad-sense heritability. Total image acquisition and processing time was ca. 25 min and required only one person (excluding the helicopter pilot). The results indicate the potential to phenotype CT on large populations in genetics studies or for selection within a plant breeding program. PMID:27999580

  9. Atmospheric Temperature Profile Measurements Using Mobile High Spectral Resolution Lidar

    NASA Astrophysics Data System (ADS)

    Razenkov, Ilya I.; Eloranta, Edwin W.

    2016-06-01

    The High Spectral Resolution Lidar (HSRL) designed at the University of Wisconsin-Madison discriminates between Mie and Rayleigh backscattering [1]. It exploits the Doppler effect caused by thermal motion of molecules, which broadens the spectrum of the transmitted laser light. That allows for absolute calibration of the lidar and measurements of the aerosol volume backscatter coefficient. Two iodine absorption filters with different absorption line widths (a regular iodine vapor filter and Argon buffered iodine filter) allow for atmospheric temperature profile measurements. The sensitivity of the measured signal-to-air temperature ratio is around 0.14%/K. The instrument uses a shared telescope transmitter-receiver design and operates in eyesafe mode (the product of laser average power and telescope aperture equals 0.1 Wm2 at 532 nm).

  10. High-speed spectral tuning CARS microscopy using AOTF laser

    NASA Astrophysics Data System (ADS)

    Hashimoto, Mamoru; Iwatsuka, Junichi; Niioka, Hirohiko; Araki, Tsutomu

    2012-03-01

    We have developed a high speed spectral tuning CARS microscopy system using a mode-locked Ti:Sapphire laser with an acousto-optic tunable filter (AOTF) in the cavity. Since the wavelength of the laser is tunable with the applied radio frequency to the AOTF, the wavelength is electrically tunable.The pulse duration of the laser is about 10 ps, tunable range is 800 nm to 930 nm, and the tuning speed is ms order. The laser is synchronized with another mode-locked Ti:Sapphire laser laser our own method using a balance cross-correlator and phase lock loop technique. The synchronized lasers are used for light source of multi-focus CARS microscopy system using a microlens array scanner, and the hyperspectral imaging of adipocyte cells is demonstrated.

  11. A High Spectral Resolution Lidar Based on Absorption Filter

    NASA Technical Reports Server (NTRS)

    Piironen, Paivi

    1996-01-01

    A High Spectral Resolution Lidar (HSRL) that uses an iodine absorption filter and a tunable, narrow bandwidth Nd:YAG laser is demonstrated. The iodine absorption filter provides better performance than the Fabry-Perot etalon that it replaces. This study presents an instrument design that can be used a the basis for a design of a simple and robust lidar for the measurement of the optical properties of the atmosphere. The HSRL provides calibrated measurements of the optical properties of the atmospheric aerosols. These observations include measurements of aerosol backscatter cross sections, optical depth, backscatter phase function depolarization, and multiple scattering. The errors in the HSRL data are discussed and the effects of different errors on the measured optical parameters are shown.

  12. Characterization of high density through silicon vias with spectral reflectometry.

    PubMed

    Ku, Yi-Sha; Huang, Kuo Cheng; Hsu, Weite

    2011-03-28

    Measurement and control is an important step for production-worthy through silicon vias etch. We demonstrate the use and enhancement of an existing wafer metrology tool, spectral reflectometer by implementing novel theoretical model and measurement algorithm for high density through-silicon via (HDTSV) inspection. It is capable of measuring depth and depth variations of array vias by Discrete Fourier Transform (DFT) analysis in one shot measurement. Surface roughness of via bottom can also be extracted by scattering model fitting. Our non-destructive solution can measure TSV profile diameters as small as 5 μm and aspect ratios greater than 13:1. The measurement precision is in the range of 0.02 μm. Metrology results from actual 3D interconnect processing wafers are presented.

  13. High spectral resolution remote sensing detection system for atmosphere greenhouse gas

    NASA Astrophysics Data System (ADS)

    Zhang, Da; Zheng, Yuquan

    2016-10-01

    Space-borne high signal-to-noise ratio (SNR) and high spectral resolution spectral detection system with high detection accuracy (1-4ppm) is demonstrated under the application background of the detection of atmospheric carbon dioxide as the main component of greenhouse gases. According to greenhouse gas concentrations detection accuracy requirements and simulation of different spectral absorption spectrum of carbon dioxide, the reasonable spectral channel center wavelength, spectral bandwidth and spectral resolution is determined of the high spectral resolution carbon dioxide remote sensing system. Grating spectral imaging system using large area diffractive grating spectral as a core splitting element is to achieve fine spectrum splitting. By the application of large area array detector push-broom mode, the hyperspectral greenhouse gas detection system is developed with the spectrum center wavelength of 0.76um, 1.61um and 2.06um, spectral resolution indicators better than 0.047nm, 0.142nm and 0.182nm actually. The system components and working principle are described. Important parts involved in the system design such as spectral imaging system, large-array CCD visible-light detector, large-array HgCdTe infrared detectors, high SNR and low temperature drift imaging electronics, etc. are discussed. SNR indicators of three spectral ranges are estimated based on system parameters, in order to analyzing realizability of high detection accuracy of XCO2. The system performances are tested by taking fine spectral calibration and radiometric calibration methods in the laboratory. Spectral calibration results showed that: three spectral channels mean spectral resolutions of hyperspectral detection of greenhouse gases are better than 0.042 nm, 0.128nm and 0.17nm, three spectral channels average SNRs are up to 53dB, 48dB and 45dB respectively under the typical operating conditions of system. Development of this system successfully filled greenhouse gas detection systems

  14. Power spectral density specifications for high-power laser systems

    SciTech Connect

    Lawson, J.K.; Aikens, D.A.; English, R.E. Jr.; Wolfe, C.R.

    1996-04-22

    This paper describes the use of Fourier techniques to characterize the transmitted and reflected wavefront of optical components. Specifically, a power spectral density, (PSD), approach is used. High power solid-state lasers exhibit non-linear amplification of specific spatial frequencies. Thus, specifications that limit the amplitude of these spatial frequencies are necessary in the design of these systems. Further, NIF optical components have square, rectangular or irregularly shaped apertures with major dimensions up-to 800 mm. Components with non-circular apertures can not be analyzed correctly with Zernicke polynomials since these functions are an orthogonal set for circular apertures only. A more complete and powerful representation of the optical wavefront can be obtained by Fourier analysis in 1 or 2 dimensions. The PSD is obtained from the amplitude of frequency components present in the Fourier spectrum. The shape of a resultant wavefront or the focal spot of a complex multicomponent laser system can be calculated and optimized using PSDs of the individual optical components which comprise the system. Surface roughness can be calculated over a range of spatial scale-lengths by integrating the PSD. Finally, since the optical transfer function (OTF) of the instruments used to measure the wavefront degrades at high spatial frequencies, the PSD of an optical component is underestimated. We can correct for this error by modifying the PSD function to restore high spatial frequency information. The strengths of PSD analysis are leading us to develop optical specifications incorporating this function for the planned National Ignition Facility (NIF).

  15. COLLECTION OF AIRBORNE PARTICLES BY A HIGH-GRADIENT PERMANENT MAGNETIC METHOD

    SciTech Connect

    Cheng, Mengdawn; Allman, Steve L; Ludtka, Gerard Michael; Avens, Larry R

    2014-01-01

    We report on the use of magnetic force in collection of airborne particles by a high- gradient permanent magnetic separation (HGPMS) device. Three aerosol particles of different magnetic susceptibility (NaCl, CuO, and Fe2O3) were generated in the electrical mobility size range of 10 to 200 nm and were used to study HGPMS collection. One HGPMS matrix element, made of stainless steel wool, was used in the device configuration. Three flow rates were selected to simulate the environmental wind speeds of interest to the study. Magnetic force was found to exhibit an insignificant effect on the separation of NaCl particles, even in the HGPMS configuration. Diffusion was a major mechanism in the removal of the diamagnetic particles; however, diffusion is insignificant under the influence of a high-gradient magnetic field for paramagnetic or ferromagnetic particles. The HGPMS showed high-performance collection (> 99%) of paramagnetic CuO and ferromagnetic Fe2O3 particles for particle sizes greater than or equal to 60 nm. As the wind speed increases, the influence of the magnetic force weakens, and the capability to remove particles from the gas stream diminishes. The results suggest that the HGPMS principle could be explored for development of an advanced miniaturized passive aerosol collector.

  16. High-speed high-precision and ultralong-range complex spectral domain dimensional metrology.

    PubMed

    Bao, Wen; Shen, Yi; Chen, Tao; Li, Peng; Ding, Zhihua

    2015-05-04

    A precise, nondestructive dimensional metrological system is crucial to manufacturing and packaging of multi-component optical system. To this end, an orthogonal dispersive spectrometer based complex spectral domain interferometric system for high-speed high-precision and ultralong-range dimensional metrology is developed. An improved complex method based on actual spectral phase shift is proposed to achieve ultrahigh suppression of artifacts. Suppression ratios of 80 dB for DC and 60 dB for mirror images are realized, the highest ratios among existing complex methods. To ensure high-precision in distance determination, an averaged spectral phase measurement algorithm is adopted. A precision of 60 nm within a measurement range of 200 mm without axial movement of the sample is demonstrated. The measurement range is readily extendable if axial movement of the sample and range cascading are involved. The system holds potential applications in various areas for real-time nondestructive testing and evaluation.

  17. High resolution atomic coherent control via spectral phase manipulation of an optical frequency comb.

    PubMed

    Stowe, Matthew C; Cruz, Flavio C; Marian, Adela; Ye, Jun

    2006-04-21

    We demonstrate high resolution coherent control of cold atomic rubidium utilizing spectral phase manipulation of a femtosecond optical frequency comb. Transient coherent accumulation is directly manifested by the enhancement of signal amplitude and spectral resolution via the pulse number. The combination of frequency comb technology and spectral phase manipulation enables coherent control techniques to enter a new regime with natural linewidth resolution.

  18. High Resolution Atomic Coherent Control via Spectral Phase Manipulation of an Optical Frequency Comb

    SciTech Connect

    Stowe, Matthew C.; Cruz, Flavio C.; Marian, Adela; Ye Jun

    2006-04-21

    We demonstrate high resolution coherent control of cold atomic rubidium utilizing spectral phase manipulation of a femtosecond optical frequency comb. Transient coherent accumulation is directly manifested by the enhancement of signal amplitude and spectral resolution via the pulse number. The combination of frequency comb technology and spectral phase manipulation enables coherent control techniques to enter a new regime with natural linewidth resolution.

  19. An Airborne Observing Campaign of an Announced Small Asteroid Impact for High Fidelity Impact Modeling Validation

    NASA Astrophysics Data System (ADS)

    Jenniskens, P. M. M.; Grinstead, J. H.

    2015-12-01

    High fidelity modeling of an asteroid impact requires a known size, mass, shape, entry orientation, entry speed, entry angle, time and location of entry, and material properties of the impacting asteroid. Much of that information can be gathered from small asteroids on an impact trajectory with Earth while they are on approach, given sufficient warning time. That makes small asteroid impacts uniquely suited for collecting data to validate such models. One-meter sized asteroids impact Earth about once a week, 4-meter sized asteroids impact once a year. So far, only asteroid 2008 TC3 was observed in space, characterized prior to impact, and then recovered in part as meteorites on the ground. The next TC3-like impact could provide more warming time to study the impact in detail. Close to 70 percent of all asteroid impacts on Earth occur over the ocean. Hence, small asteroid impact observations require an instrumented airborne platform to take a multi-disciplined research team to the right location at the right time. From a safe 100-km distance, the impact would be observed low enough in the sky to study the process of fragmentation that dictates at which altitude the kinetic energy is deposited that can cause an airburst. Constraints on radiative heating, ablation rate, and fragmentation processes can be obtained from measuring the air plasma emission escaping the shock, elemental atom line emissions and excitation conditions, pressure broadening, and deceleration in the plane of the known trajectory. It is also possible to measure wake, lightcurve and air plasma emission line intensities early in flight that can be used to evaluate the presence of regolith and the internal cohesion of asteroids. The main element abundance (asteroid composition) can be measured for individual fragments, while CN-band emission can point to the presence of organic matter. Such information will help constrain the meteorite type if no meteorites can be recovered in an over

  20. High Spatial Resolution Airborne Multispectral Thermal Infrared Remote Sensing Data for Analysis of Urban Landscape Characteristics

    NASA Technical Reports Server (NTRS)

    Quattrochi, Dale A.; Luvall, Jeffrey C.; Estes, Maurice G., Jr.; Arnold, James E. (Technical Monitor)

    2000-01-01

    We have used airborne multispectral thermal infrared (TIR) remote sensing data collected at a high spatial resolution (i.e., 10m) over several cities in the United States to study thermal energy characteristics of the urban landscape. These TIR data provide a unique opportunity to quantify thermal responses from discrete surfaces typical of the urban landscape and to identify both the spatial arrangement and patterns of thermal processes across the city. The information obtained from these data is critical to understanding how urban surfaces drive or force development of the Urban Heat Island (UHI) effect, which exists as a dome of elevated air temperatures that presides over cities in contrast to surrounding non-urbanized areas. The UHI is most pronounced in the summertime where urban surfaces, such as rooftops and pavement, store solar radiation throughout the day, and release this stored energy slowly after sunset creating air temperatures over the city that are in excess of 2-4'C warmer in contrast with non-urban or rural air temperatures. The UHI can also exist as a daytime phenomenon with surface temperatures in downtown areas of cities exceeding 38'C. The implications of the UHI are significant, particularly as an additive source of thermal energy input that exacerbates the overall production of ground level ozone over cities. We have used the Airborne Thermal and Land Applications Sensor (ATLAS), flown onboard a Lear 23 jet aircraft from the NASA Stennis Space Center, to acquire high spatial resolution multispectral TIR data (i.e., 6 bandwidths between 8.2-12.2 (um) over Huntsville, Alabama, Atlanta, Georgia, Baton Rouge, Louisiana, Salt Lake City, Utah, and Sacramento, California. These TIR data have been used to produce maps and other products, showing the spatial distribution of heating and cooling patterns over these cities to better understand how the morphology of the urban landscape affects development of the UHI. In turn, these data have been used

  1. X-ray spectral evolution of high redshift quasars

    NASA Technical Reports Server (NTRS)

    Bechtold, Jill; Elvis, Martin; Fiore, Fabrizio; Kuhn, Olga; Cutri, Roc M.; Mcdowell, Jonathan C.; Rieke, Marcia; Siemiginowska, Aneta; Wilkes, Belinda J.

    1994-01-01

    At z approx. equals 3, the x-ray spectra of radio-loud and radio-quiet quasars are different. High-redshift radio-quiet quasars either have large absorbing columns, N(sub H), and steeper power law spectral indices, alpha(sub epsilon), than low redshift quasars, or no absorption and similar alpha(sub epsilon)'s. In contrast, the radio-loud quasars at high redshift have substantial absorption and similar alpha(sub epsilon)'s to low redshift quasars. Implications for the interpretation of the evolution of the luminosity function of quasars are discussed. If the absorption arises outside the central engine for both radio-loud and radio-quiet quasars, then radio-quiet quasars differ from the radio-loud quasars in that their emitted power law spectrum has evolved with redshift. We argue that this favors models where quasars are numerous and short-lived, rather than rare and long-lived.

  2. Diagnostics of Ellerman bombs with high-resolution spectral data

    NASA Astrophysics Data System (ADS)

    Li, Zhen; Fang, Cheng; Guo, Yang; Chen, Peng-Fei; Xu, Zhi; Cao, Wen-Da

    2015-09-01

    Ellerman bombs (EBs) are tiny brightenings often observed near sunspots. The most impressive characteristic of EB spectra is the two emission bumps in both wings of the Hα and Ca II 8542Å lines. High-resolution spectral data of three small EBs were obtained on 2013 June 6 with the largest solar telescope, the 1.6 m New Solar Telescope at the Big Bear Solar Observatory. The characteristics of these EBs are analyzed. The sizes of the EBs are in the range of 0.3‧ - 0.8‧ and their durations are only 3-5 min. Our semi-empirical atmospheric models indicate that the heating occurs around the temperature minimum region with a temperature increase of 2700-3000 K, which is surprisingly higher than previously thought. The radiative and kinetic energies are estimated to be as high as 5 × 1025 - 3.0 × 1026 erg despite the small size of these EBs. Observations of the magnetic field show that the EBs just appeared in a parasitic region with mixed polarities and were accompanied by mass motions. Nonlinear force-free field extrapolation reveals that the three EBs are connected with a series of magnetic field lines associated with bald patches, which strongly implies that these EBs should be produced by magnetic reconnection in the solar lower atmosphere. According to the lightcurves and the estimated magnetic reconnection rate, we propose that there is a three phase process in EBs: pre-heating, flaring and cooling phases.

  3. Development of the NASA High-Altitude Imaging Wind and Rain Airborne Profiler

    NASA Technical Reports Server (NTRS)

    Li, Lihua; Heymsfield, Gerald; Carswell, James; Schaubert, Dan; McLinden, Matthew; Vega, Manuel; Perrine, Martin

    2011-01-01

    The scope of this paper is the development and recent field deployments of the High-Altitude Imaging Wind and Rain Airborne Profiler (HIWRAP), which was funded under the NASA Instrument Incubator Program (IIP) [1]. HIWRAP is a dual-frequency (Ka- and Ku-band), dual-beam (300 and 400 incidence angles), conical scanning, Doppler radar system designed for operation on the NASA high-altitude (65,000 ft) Global Hawk Unmanned Aerial System (UAS). It utilizes solid state transmitters along with a novel pulse compression scheme that results in a system with compact size, light weight, less power consumption, and low cost compared to radars currently in use for precipitation and Doppler wind measurements. By combining measurements at Ku- and Ka-band, HIWRAP is able to image winds through measuring volume backscattering from clouds and precipitation. In addition, HIWRAP is also capable of measuring surface winds in an approach similar to SeaWinds on QuikScat. To this end, HIWRAP hardware and software development has been completed. It was installed on the NASA WB57 for instrument test flights in March, 2010 and then deployed on the NASA Global Hawk for supporting the Genesis and Rapid Intensification Processes (GRIP) field campaign in August-September, 2010. This paper describes the scientific motivations of the development of HIWRAP as well as system hardware, aircraft integration and flight missions. Preliminary data from GRIP science flights is also presented.

  4. RADI's Airborne X-SAR with High Resolution: Performance, Characterization and Verification

    NASA Astrophysics Data System (ADS)

    Shen, T.; Li, J.; Wang, Z. R.; Huang, L.

    2016-11-01

    X-SAR is an airborne multi-mode synthetic aperture radar (SAR) system with high- resolution, interferometer and full-polarization, developed by the Institute of Remote Sensing and Digital Earth (RADI), Chinese Academy of Sciences (CAS), funded by the CAS Large Research Infrastructures. Since 2009, the first developed stage of X-SAR system was successfully implemented to an operational SAR with high resolution (up to 0.5 meter). In May 2013, the imaging verification on flights test was carried out. The data calibration on the laboratory measurements were completed at the end of 2015. Many valuable results of imaging verification and data calibration have emphasized the quantitative microwave measurement capabilities. This paper presents the results of X-SAR system performance, characterization, optimization, and verification as carried out during the flight trials and laboratory measurement. The system performance and calibration parameters are presented such as transmitter amplitude accuracy, phase noise, system gain change with temperature variation, long-term radiometric stability. The imaging verification of the key performance parameters is discussed, including target-response function, target pairs discrimination, image noise and radiometric resolution. The example imagery of radiometric enhanced products for intensity change detection is also described.

  5. Vibration amplitude and induced temperature limitation of high power air-borne ultrasonic transducers.

    PubMed

    Saffar, Saber; Abdullah, Amir

    2014-01-01

    The acoustic impedances of matching layers, their internal loss and vibration amplitude are the most important and influential parameters in the performance of high power airborne ultrasonic transducers. In this paper, the optimum acoustic impedances of the transducer matching layers were determined by using a genetic algorithm, the powerful tool for optimizating domain. The analytical results showed that the vibration amplitude increases significantly for low acoustic impedance matching layers. This enhancement is maximum and approximately 200 times higher for the last matching layer where it has the same interface with the air than the vibration amplitude of the source, lead zirconate titanate-pizo electric while transferring the 1 kW is desirable. This large amplitude increases both mechanical failure and temperature of the matching layers due to the internal loss of the matching layers. It has analytically shown that the temperature in last matching layer with having the maximum vibration amplitude is high enough to melt or burn the matching layers. To verify suggested approach, the effect of the amplitude of vibration on the induced temperature has been investigated experimentally. The experimental results displayed good agreement with the theoretical predictions.

  6. Spectral Knowledge (SK-UTALCA): Software for Exploratory Analysis of High-Resolution Spectral Reflectance Data on Plant Breeding.

    PubMed

    Lobos, Gustavo A; Poblete-Echeverría, Carlos

    2016-01-01

    This article describes public, free software that provides efficient exploratory analysis of high-resolution spectral reflectance data. Spectral reflectance data can suffer from problems such as poor signal to noise ratios in various wavebands or invalid measurements due to changes in incoming solar radiation or operator fatigue leading to poor orientation of sensors. Thus, exploratory data analysis is essential to identify appropriate data for further analyses. This software overcomes the problem that analysis tools such as Excel are cumbersome to use for the high number of wavelengths and samples typically acquired in these studies. The software, Spectral Knowledge (SK-UTALCA), was initially developed for plant breeding, but it is also suitable for other studies such as precision agriculture, crop protection, ecophysiology plant nutrition, and soil fertility. Various spectral reflectance indices (SRIs) are often used to relate crop characteristics to spectral data and the software is loaded with 255 SRIs which can be applied quickly to the data. This article describes the architecture and functions of SK-UTALCA and the features of the data that led to the development of each of its modules.

  7. Spectral Knowledge (SK-UTALCA): Software for Exploratory Analysis of High-Resolution Spectral Reflectance Data on Plant Breeding

    PubMed Central

    Lobos, Gustavo A.; Poblete-Echeverría, Carlos

    2017-01-01

    This article describes public, free software that provides efficient exploratory analysis of high-resolution spectral reflectance data. Spectral reflectance data can suffer from problems such as poor signal to noise ratios in various wavebands or invalid measurements due to changes in incoming solar radiation or operator fatigue leading to poor orientation of sensors. Thus, exploratory data analysis is essential to identify appropriate data for further analyses. This software overcomes the problem that analysis tools such as Excel are cumbersome to use for the high number of wavelengths and samples typically acquired in these studies. The software, Spectral Knowledge (SK-UTALCA), was initially developed for plant breeding, but it is also suitable for other studies such as precision agriculture, crop protection, ecophysiology plant nutrition, and soil fertility. Various spectral reflectance indices (SRIs) are often used to relate crop characteristics to spectral data and the software is loaded with 255 SRIs which can be applied quickly to the data. This article describes the architecture and functions of SK-UTALCA and the features of the data that led to the development of each of its modules. PMID:28119705

  8. Spatial and Spectral Brightness Enhancement of High Power Semiconductor Lasers

    NASA Astrophysics Data System (ADS)

    Leidner, Jordan Palmer

    The performance of high-power broad-area diode lasers is inhibited by beam filamentation induced by free-carrier-based self-focusing. The resulting beam degradation limits their usage in high-brightness, high-power applications such as pumping fiber lasers, and laser cutting, welding, or marking. Finite-difference propagation method simulations via RSoft's BeamPROP commercial simulation suite and a custom-built MATLAB code were used for the study and design of laser cavities that suppress or avoid filamentation. BeamPROP was used to design a tapered, passive, multi-mode interference cavity for the creation of a self-phase-locking laser array, which is comprised of many single-mode gain elements coupled to a wide output coupler to avoid damage from local high optical intensities. MATLAB simulations were used to study the effects of longitudinal and lateral cavity confinement on lateral beam quality in conventional broad-area lasers. This simulation was expanded to design a laser with lateral gain and index prescription that is predicted to operate at or above state-of-the-art powers while being efficiently coupled to conventional telecom single-mode optical fibers. Experimentally, a commercial broad-area laser was coupled in the far-field to a single-mode fiber Bragg grating to provide grating-stabilized single-mode laser feedback resulting in measured spectral narrowing for efficient pump absorption. Additionally a 19 GHz-span, spatially resolved, self-heterodyne measurement was made of a broad-area laser to study the evolution/devolution of the mode content of the emitted laser beam with increasing power levels.

  9. Airborne fungi in low and high allergic prevalence child care centers

    NASA Astrophysics Data System (ADS)

    Zuraimi, M. S.; Fang, L.; Tan, T. K.; Chew, F. T.; Tham, K. W.

    Fungi exposure has been linked to asthma and allergies among children. To determine the association between fungal exposure and wheeze and rhinitis symptoms, we examined concentrations of culturable indoor and outdoor fungi of various aerodynamic sizes in low and high allergic prevalence child care centers (CCCs) in Singapore. Environmental parameters were also performed for air temperature, relative humidity and ventilation rates, while information on CCC characteristics was collected via an inspection. Most commonly recovered fungi were Penicillium, Aspergillus, Geotrichum, Cladosporium and sterile mycelia with Geotrichum and sterile mycelia amounting to an average of 71.5% of the total airborne culturable fungi studied. Indoor and outdoor total culturable fungi concentrations and those in the size range of 1.1-3.3 μm were significantly higher in high allergic prevalence CCCs. When fungal types/genera were compared, indoor and outdoor Geotrichum and sterile mycelia of aerodynamic sizes 1.1-3.3 μm were found to be significantly elevated in high allergic prevalence CCCs. Indeed, average geometric mean diameters ( Dg, ave) of indoor and outdoor culturable fungi were consistently smaller in CCCs with high prevalence of allergies than those with low prevalence. We found significant associations of higher fungal concentrations, especially those with smaller aerodynamic sizes in CCCs situated near parks. There were no differences in fungal levels between CCCs with respect to their dampness profile mainly due to high CCC ventilation rates. Since particle size is a factor that determines where a fungi particle deposits in the respiratory tract, this study provides useful information in the etiology of wheeze and rhinitis symptoms among the CCC attending children.

  10. Characterization of airborne particles at a high-btu coal-gasification pilot plant.

    PubMed

    Davidson, C I; Santhanam, S; Stetter, J R; Flotard, R D; Gebert, E

    1982-12-01

    Airborne particles in fugitive emissions have been measured at a slagging fixed-bed coal-gasification pilot plant using lignite. Sampling was conducted during shutdown operations and opening of the gasifier following an aborted startup. Aerosol collected with a Sierra high-volume impactor was subjected to analysis by gas chromatography, mass spectrometry, and scanning electron microscopy; aerosol collected with an Andersen low-volume impactor was subjected to flameless atomic absorption analysis. The data show that the bulk of the trace organic material is associated with small particles: these data are similar to data on ambient air reported in the literature. Particle morphologies resemble those of fly ash from coal combustion, including smooth spheres, vesicular spheres, and crystalline material. Trace element size distributions are bimodal and resemble data for ambient air. Pb-containing particles are generally submicron, while particles containing Al, Fe, and other crustal species are mostly of supermicron size. Aluminum-based aerosol enrichment factors calculated from the lignite composition show that the composition of the aerosol resembles that of the coal, with the exception of modest enrichments of Mg, Na, As, and Pb in the submicron size range. Aerosol enrichment factors based on the earth's crustal composition are somewhat greater than those based on coal composition for several elements, suggesting potential errors in using crustal enrichment data to investigate chemical fractionation during aerosol formation.

  11. High-resolution NO2 observations from the Airborne Compact Atmospheric Mapper: Retrieval and validation

    NASA Astrophysics Data System (ADS)

    Lamsal, L. N.; Janz, S. J.; Krotkov, N. A.; Pickering, K. E.; Spurr, R. J. D.; Kowalewski, M. G.; Loughner, C. P.; Crawford, J. H.; Swartz, W. H.; Herman, J. R.

    2017-02-01

    Nitrogen dioxide (NO2) is a short-lived atmospheric pollutant that serves as an air quality indicator and is itself a health concern. The Airborne Compact Atmospheric Mapper (ACAM) was flown on board the NASA UC-12 aircraft during the Deriving Information on Surface Conditions from Column and Vertically Resolved Observations Relevant to Air Quality Maryland field campaign in July 2011. The instrument collected hyperspectral remote sensing measurements in the 304-910 nm range, allowing daytime observations of several tropospheric pollutants, including nitrogen dioxide (NO2), at an unprecedented spatial resolution of 1.5 × 1.1 km2. Retrievals of slant column abundance are based on the differential optical absorption spectroscopy method. For the air mass factor computations needed to convert these retrievals to vertical column abundance, we include high-resolution information for the surface reflectivity by using bidirectional reflectance distribution function data from the Moderate Resolution Imaging Spectroradiometer. We use high-resolution simulated vertical distributions of NO2 from the Community Multiscale Air Quality and Global Modeling Initiative models to account for the temporal variation in atmospheric NO2 to retrieve middle and lower tropospheric NO2 columns (NO2 below the aircraft). We compare NO2 derived from ACAM measurements with in situ observations from NASA's P-3B research aircraft, total column observations from the ground-based Pandora spectrometers, and tropospheric column observations from the space-based Ozone Monitoring Instrument. The high-resolution ACAM measurements not only give new insights into our understanding of atmospheric composition and chemistry through observation of subsampling variability in typical satellite and model resolutions, but they also provide opportunities for testing algorithm improvements for forthcoming geostationary air quality missions.

  12. Forest Stand Segmentation Using Airborne LIDAR Data and Very High Resolution Multispectral Imagery

    NASA Astrophysics Data System (ADS)

    Dechesne, Clément; Mallet, Clément; Le Bris, Arnaud; Gouet, Valérie; Hervieu, Alexandre

    2016-06-01

    Forest stands are the basic units for forest inventory and mapping. Stands are large forested areas (e.g., ≥ 2 ha) of homogeneous tree species composition. The accurate delineation of forest stands is usually performed by visual analysis of human operators on very high resolution (VHR) optical images. This work is highly time consuming and should be automated for scalability purposes. In this paper, a method based on the fusion of airborne laser scanning data (or lidar) and very high resolution multispectral imagery for automatic forest stand delineation and forest land-cover database update is proposed. The multispectral images give access to the tree species whereas 3D lidar point clouds provide geometric information on the trees. Therefore, multi-modal features are computed, both at pixel and object levels. The objects are individual trees extracted from lidar data. A supervised classification is performed at the object level on the computed features in order to coarsely discriminate the existing tree species in the area of interest. The analysis at tree level is particularly relevant since it significantly improves the tree species classification. A probability map is generated through the tree species classification and inserted with the pixel-based features map in an energetical framework. The proposed energy is then minimized using a standard graph-cut method (namely QPBO with α-expansion) in order to produce a segmentation map with a controlled level of details. Comparison with an existing forest land cover database shows that our method provides satisfactory results both in terms of stand labelling and delineation (matching ranges between 94% and 99%).

  13. Marine fluorescence from high spectrally resolved satellite measurements

    NASA Astrophysics Data System (ADS)

    Wolanin, Aleksandra; Dinter, Tilman; Rozanov, Vladimir; Noël, Stefan; Vountas, Marco; Burrows, John P.; Bracher, Astrid

    2014-05-01

    When chlorophyll molecules absorb light, most of this energy is transformed into chemical energy in a process of photosynthesis. However, a fraction of the energy absorbed is reemitted as fluorescence. As a result of its relationship to photosynthetic e?ciency, information about chlorophyll fluorescence can be used to assess the physiological state of phytoplankton (Falkowski and Kolber,1995). In-situ measurements of chlorophyll fluorescence are widespread in physiological and ecophysiological studies. When retrieved from space, chlorophyll fluorescence can improve our knowledge of global biogeochemical cycles and phytoplankton productivity (Behrenfeld et al., 2009; Huot et al., 2013) by providing high coverage and periodicity. So far, the only satellite retrieval of sun-induced marine fluorescence, Fluorescence Line Height (FLH), was designed for MODIS (Abbott and Letelier, 1999), and later also applied to the similar sensor MERIS (Gower et al., 2004). However, it could so far not be evaluated on global scale. Here, we present a different approach to observe marine chlorophyll fluorescence, based on the Differential Optical Absorption Spectroscopy (DOAS) technique (Perner and Platt, 1979) applied to the hyperspectral data from Scanning Imaging Absorption Spectrometer for Atmospheric Chartography (SCIAMACHY) and Global Ozone Monitoring Experiment-2 (GOME-2). Since fluorescence, as a trans-spectral process, leads to the shift of the wavelength of the radiation, it can be observed in the filling-in of Fraunhofer lines. In our retrieval, we evaluate the filling-in of the Zeeman triplet Fraunhofer line FeI at 684.3 nm, which is located very close to the emission peak of marine fluorescence (~685 nm). In order to conduct the chlorophyll fluorescence retrieval with the DOAS method, we calculated the reference spectra for chlorophyll fluorescence, based on simulations performed with the coupled ocean-atmosphere radiative transfer model SCIATRAN (Rozanov et al., 2014

  14. Airborne infrared hyperspectral imager for intelligence, surveillance and reconnaissance applications

    NASA Astrophysics Data System (ADS)

    Lagueux, Philippe; Puckrin, Eldon; Turcotte, Caroline S.; Gagnon, Marc-André; Bastedo, John; Farley, Vincent; Chamberland, Martin

    2012-09-01

    Persistent surveillance and collection of airborne intelligence, surveillance and reconnaissance information is critical in today's warfare against terrorism. High resolution imagery in visible and infrared bands provides valuable detection capabilities based on target shapes and temperatures. However, the spectral resolution provided by a hyperspectral imager adds a spectral dimension to the measurements, leading to additional tools for detection and identification of targets, based on their spectral signature. The Telops Hyper-Cam sensor is an interferometer-based imaging system that enables the spatial and spectral analysis of targets using a single sensor. It is based on the Fourier-transform technology yielding high spectral resolution and enabling high accuracy radiometric calibration. It provides datacubes of up to 320×256 pixels at spectral resolutions as fine as 0.25 cm-1. The LWIR version covers the 8.0 to 11.8 μm spectral range. The Hyper-Cam has been recently used for the first time in two compact airborne platforms: a bellymounted gyro-stabilized platform and a gyro-stabilized gimbal ball. Both platforms are described in this paper, and successful results of high-altitude detection and identification of targets, including industrial plumes, and chemical spills are presented.

  15. Airborne infrared hyperspectral imager for intelligence, surveillance, and reconnaissance applications

    NASA Astrophysics Data System (ADS)

    Puckrin, Eldon; Turcotte, Caroline S.; Gagnon, Marc-André; Bastedo, John; Farley, Vincent; Chamberland, Martin

    2012-06-01

    Persistent surveillance and collection of airborne intelligence, surveillance and reconnaissance information is critical in today's warfare against terrorism. High resolution imagery in visible and infrared bands provides valuable detection capabilities based on target shapes and temperatures. However, the spectral resolution provided by a hyperspectral imager adds a spectral dimension to the measurements, leading to additional tools for detection and identification of targets, based on their spectral signature. The Telops Hyper-Cam sensor is an interferometer-based imaging system that enables the spatial and spectral analysis of targets using a single sensor. It is based on the Fourier-transform technology yielding high spectral resolution and enabling high accuracy radiometric calibration. It provides datacubes of up to 320×256 pixels at spectral resolutions as fine as 0.25 cm-1. The LWIR version covers the 8.0 to 11.8 μm spectral range. The Hyper-Cam has been recently used for the first time in two compact airborne platforms: a belly-mounted gyro-stabilized platform and a gyro-stabilized gimbal ball. Both platforms are described in this paper, and successful results of high-altitude detection and identification of targets, including industrial plumes, and chemical spills are presented.

  16. New confocal microscopy hyperspectral imager for NIR-emitting bioprobes: high spectral resolution for a wide spectral range (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Marcet, Stéphane; Benayas, Antonio; Quintanilla, Marta; Mangiarini, Francesca; Verhaegen, Marc; Vetrone, Fiorenzo; Blais-Ouellette, Sébastien

    2016-03-01

    Functional nanoscale materials are being extensively investigated for applications in biology and medicine and are ready to make significant contributions in the realization of exciting advancements in diverse areas of diagnostics and therapeutics. Aiming for more accurate, efficient, non-invasive and fast diagnostic tools, the use of near-infrared (NIR) light in the range of the 1st and 2nd biological window (NIR-I: 0.70-0.95 µm; NIR-II: 1.00-1.35 µm) provides deeper penetration depth into biological tissue, better image contrast, reduced phototoxicity and photobleaching. Consequently, NIR-based bioimaging became a quickly emerging field and manifold new NIR-emitting bioprobes have been reported. Since commercially available microscopes are not optimized for this kind of NPs, a new microscopy hyperspectral confocal imager has been developed to cover a broad spectral range (400 to 1700 nm) with high spectral resolution. The smallest spectral variation can be easily monitored thanks to the high spectral resolution (as low as 0.2 nm). This is possible thanks to a combination of an EMCCD and an InGaAs camera with a high resolution spectrometer. An extended number of NPs can be excited with a Ti:Sapphire laser, which provides tunable illumination within 690-1040 nm. Cells and tissues can be mapped in less than 100 ms, allowing in-vivo imaging. As a proof of concept, here we present the preliminary results of the spatial distribution of the fluorescence signal intensity from lanthanide doped nanoparticles incorporated into a system of biological interest. The temperature sub-mm gradient - analyzing the spectral features so gathered through an all-optical route is also thoroughly discussed.

  17. High-accuracy continuous airborne measurements of greenhouse gases (CO2 and CH4) during BARCA

    NASA Astrophysics Data System (ADS)

    Chen, H.; Winderlich, J.; Gerbig, C.; Hoefer, A.; Rella, C. W.; Crosson, E. R.; van Pelt, A. D.; Steinbach, J.; Kolle, O.; Beck, V.; Daube, B. C.; Gottlieb, E. W.; Chow, V. Y.; Santoni, G. W.; Wofsy, S. C.

    2009-12-01

    High-accuracy continuous measurements of greenhouse gases (CO2 and CH4) during the BARCA (Balanço Atmosférico Regional de Carbono na Amazônia) phase B campaign in Brazil in May 2009 were accomplished using a newly available analyzer based on the cavity ring-down spectroscopy (CRDS) technique. This analyzer was flown without a drying system or any in-flight calibration gases. Water vapor corrections associated with dilution and pressure-broadening effects for CO2 and CH4 were derived from laboratory experiments employing measurements of water vapor by the CRDS analyzer. Before the campaign, the stability of the analyzer was assessed by laboratory tests under simulated flight conditions. During the campaign, a comparison of CO2 measurements between the CRDS analyzer and a nondispersive infrared (NDIR) analyzer on board the same aircraft showed a mean difference of 0.22±0.09 ppm for all flights over the Amazon rain forest. At the end of the campaign, CO2 concentrations of the synthetic calibration gases used by the NDIR analyzer were determined by the CRDS analyzer. After correcting for the isotope and the pressure-broadening effects that resulted from changes of the composition of synthetic vs. ambient air, and applying those concentrations as calibrated values of the calibration gases to reprocess the CO2 measurements made by the NDIR, the mean difference between the CRDS and the NDIR during BARCA was reduced to 0.05±0.09 ppm, with the mean standard deviation of 0.23±0.05 ppm. The results clearly show that the CRDS is sufficiently stable to be used in flight without drying the air or calibrating in flight and the water corrections are fully adequate for high-accuracy continuous airborne measurements of CO2 and CH4.

  18. The NASA Airborne Tropical TRopopause EXperiment (ATTREX):High-Altitude Aircraft Measurements in the Tropical Western Pacific

    NASA Technical Reports Server (NTRS)

    Jensen, E. J.; Pfister, L.; Jordan, D. E.; Bui, T. V.; Ueyama, R.; Singh, H. B.; Lawson, P.; Thornberry, T.; Diskin, G.; McGill, M.; Pittman, J.; Atlas, E.; Kim, J.

    2016-01-01

    The February through March 2014 deployment of the NASA Airborne Tropical TRopopause EXperiment (ATTREX) provided unique in situ measurements in the western Pacific Tropical Tropopause Layer (TTL). Six flights were conducted from Guam with the long-range, high-altitude, unmanned Global Hawk aircraft. The ATTREX Global Hawk payload provided measurements of water vapor, meteorological conditions, cloud properties, tracer and chemical radical concentrations, and radiative fluxes. The campaign was partially coincident with the CONTRAST and CAST airborne campaigns based in Guam using lower-altitude aircraft The ATTREX dataset is being used for investigations of TTL cloud, transport, dynamical, and chemical processes as well as for evaluation and improvement of global-model representations of TTL processes.

  19. Comprehensive x-ray spectral code for high energy astrophysics

    SciTech Connect

    Liedahl, D A; Fournier, K B; Mauche, C W

    2000-08-18

    The aim of this project has been to develop a spectral analysis tool with a level of quality and completeness commensurate to that expected in data from the current generation of X-ray observatories. The code is called LXSS (Livermore X-Ray Spectral Synthesizer). X-ray-emitting astrophysical plasmas are rarely, if ever, in LTE, so they have adopted the detailed level accounting approach, in which rates for processes that populate or depopulate atomic energy levels are treated explicitly. This entails the generation of a large quantity of atomic data, most of which is calculated using ''in-house'' computer codes. Calculations are benchmarked against laboratory data, and spectral models have been used to provide first-time interpretations of astrophysical X-ray spectra. The design of a versatile graphical user interface that allows access to and manipulation of the atomic database comprises the second major part of the project.

  20. Imaging and radiometric performance simulation for a new high-performance dual-band airborne reconnaissance camera

    NASA Astrophysics Data System (ADS)

    Seong, Sehyun; Yu, Jinhee; Ryu, Dongok; Hong, Jinsuk; Yoon, Jee-Yeon; Kim, Sug-Whan; Lee, Jun-Ho; Shin, Myung-Jin

    2009-05-01

    In recent years, high performance visible and IR cameras have been used widely for tactical airborne reconnaissance. The process improvement for efficient discrimination and analysis of complex target information from active battlefields requires for simultaneous multi-band measurement from airborne platforms at various altitudes. We report a new dual band airborne camera designed for simultaneous registration of both visible and IR imagery from mid-altitude ranges. The camera design uses a common front end optical telescope of around 0.3m in entrance aperture and several relay optical sub-systems capable of delivering both high spatial resolution visible and IR images to the detectors. The camera design is benefited from the use of several optical channels packaged in a compact space and the associated freedom to choose between wide (~3 degrees) and narrow (~1 degree) field of view. In order to investigate both imaging and radiometric performances of the camera, we generated an array of target scenes with optical properties such as reflection, refraction, scattering, transmission and emission. We then combined the target scenes and the camera optical system into the integrated ray tracing simulation environment utilizing Monte Carlo computation technique. Taking realistic atmospheric radiative transfer characteristics into account, both imaging and radiometric performances were then investigated. The simulation results demonstrate successfully that the camera design satisfies NIIRS 7 detection criterion. The camera concept, details of performance simulation computation, the resulting performances are discussed together with future development plan.

  1. Characterization of Airborne Microbial Communities at a High-Elevation Site and Their Potential To Act as Atmospheric Ice Nuclei▿

    PubMed Central

    Bowers, Robert M.; Lauber, Christian L.; Wiedinmyer, Christine; Hamady, Micah; Hallar, Anna G.; Fall, Ray; Knight, Rob; Fierer, Noah

    2009-01-01

    Bacteria and fungi are ubiquitous in the atmosphere. The diversity and abundance of airborne microbes may be strongly influenced by atmospheric conditions or even influence atmospheric conditions themselves by acting as ice nucleators. However, few comprehensive studies have described the diversity and dynamics of airborne bacteria and fungi based on culture-independent techniques. We document atmospheric microbial abundance, community composition, and ice nucleation at a high-elevation site in northwestern Colorado. We used a standard small-subunit rRNA gene Sanger sequencing approach for total microbial community analysis and a bacteria-specific 16S rRNA bar-coded pyrosequencing approach (4,864 sequences total). During the 2-week collection period, total microbial abundances were relatively constant, ranging from 9.6 × 105 to 6.6 × 106 cells m−3 of air, and the diversity and composition of the airborne microbial communities were also relatively static. Bacteria and fungi were nearly equivalent, and members of the proteobacterial groups Burkholderiales and Moraxellaceae (particularly the genus Psychrobacter) were dominant. These taxa were not always the most abundant in freshly fallen snow samples collected at this site. Although there was minimal variability in microbial abundances and composition within the atmosphere, the number of biological ice nuclei increased significantly during periods of high relative humidity. However, these changes in ice nuclei numbers were not associated with changes in the relative abundances of the most commonly studied ice-nucleating bacteria. PMID:19502432

  2. Adjusting Spectral Indices for Spectral Response Function Differences of Very High Spatial Resolution Sensors Simulated from Field Spectra

    PubMed Central

    Cundill, Sharon L.; van der Werff, Harald M. A.; van der Meijde, Mark

    2015-01-01

    The use of data from multiple sensors is often required to ensure data coverage and continuity, but differences in the spectral characteristics of sensors result in spectral index values being different. This study investigates spectral response function effects on 48 spectral indices for cultivated grasslands using simulated data of 10 very high spatial resolution sensors, convolved from field reflectance spectra of a grass covered dike (with varying vegetation condition). Index values for 48 indices were calculated for original narrow-band spectra and convolved data sets, and then compared. The indices Difference Vegetation Index (DVI), Global Environmental Monitoring Index (GEMI), Enhanced Vegetation Index (EVI), Modified Soil-Adjusted Vegetation Index (MSAVI2) and Soil-Adjusted Vegetation Index (SAVI), which include the difference between the near-infrared and red bands, have values most similar to those of the original spectra across all 10 sensors (1:1 line mean 1:1R2 > 0.960 and linear trend mean ccR2 > 0.997). Additionally, relationships between the indices’ values and two quality indicators for grass covered dikes were compared to those of the original spectra. For the soil moisture indicator, indices that ratio bands performed better across sensors than those that difference bands, while for the dike cover quality indicator, both the choice of bands and their formulation are important. PMID:25781511

  3. Semi-automated structural analysis of high resolution magnetic and gamma-ray spectrometry airborne surveys

    NASA Astrophysics Data System (ADS)

    Debeglia, N.; Martelet, G.; Perrin, J.; Truffert, C.; Ledru, P.; Tourlière, B.

    2005-08-01

    A user-controlled procedure was implemented for the structural analysis of geophysical maps. Local edge segments are first extracted using a suitable edge detector function, then linked into straight discontinuities and, finally, organised in complex boundary lines best delineating geophysical features. Final boundary lines may be attributed by a geologist to lithological contacts and/or structural geological features. Tests of some edge detectors, (i) horizontal gradient magnitude (HGM), (ii) various orders of the analytic signal ( An), reduced to the pole or not, (iii) enhanced horizontal derivative (EHD), (iv) composite analytic signal (CAS), were performed on synthetic magnetic data (with and without noise). As a result of these comparisons, the horizontal gradient appears to remain the best operator for the analysis of magnetic data. Computation of gradients in the frequency domain, including filtering and upward continuation of noisy data, is well-suited to the extraction of magnetic gradients associated to deep sources, while space-domain smoothing and differentiation techniques is generally preferable in the case of shallow magnetic sources, or for gamma-ray spectrometry analysis. Algorithms for edge extraction, segment linking, and line following can be controlled by choosing adequate edge detector and processing parameters which allows adaptation to a desired scale of interpretation. Tests on synthetic and real case data demonstrate the adaptability of the procedure and its ability to produce basic layer for multi-data analysis. The method was applied to the interpretation of high-resolution airborne magnetic and gamma-ray spectrometry data collected in northern Namibia. It allowed the delineation of dyke networks concealed by superficial weathering and demonstrated the presence of lithological variations in alluvial flows. The output from the structural analysis procedure are compatible with standard GIS softwares and enable the geologist to (i) compare

  4. An Improved High-Sensitivity Airborne Transient Electromagnetic Sensor for Deep Penetration

    PubMed Central

    Chen, Shudong; Guo, Shuxu; Wang, Haofeng; He, Miao; Liu, Xiaoyan; Qiu, Yu; Zhang, Shuang; Yuan, Zhiwen; Zhang, Haiyang; Fang, Dong; Zhu, Jun

    2017-01-01

    The investigation depth of transient electromagnetic sensors can be effectively increased by reducing the system noise, which is mainly composed of sensor internal noise, electromagnetic interference (EMI), and environmental noise, etc. A high-sensitivity airborne transient electromagnetic (AEM) sensor with low sensor internal noise and good shielding effectiveness is of great importance for deep penetration. In this article, the design and optimization of such an AEM sensor is described in detail. To reduce sensor internal noise, a noise model with both a damping resistor and a preamplifier is established and analyzed. The results indicate that a sensor with a large diameter, low resonant frequency, and low sampling rate will have lower sensor internal noise. To improve the electromagnetic compatibility of the sensor, an electromagnetic shielding model for a central-tapped coil is established and discussed in detail. Previous studies have shown that unclosed shields with multiple layers and center grounding can effectively suppress EMI and eddy currents. According to these studies, an improved differential AEM sensor is constructed with a diameter, resultant effective area, resonant frequency, and normalized equivalent input noise of 1.1 m, 114 m2, 35.6 kHz, and 13.3 nV/m2, respectively. The accuracy of the noise model and the shielding effectiveness of the sensor have been verified experimentally. The results show a good agreement between calculated and measured results for the sensor internal noise. Additionally, over 20 dB shielding effectiveness is achieved in a complex electromagnetic environment. All of these results show a great improvement in sensor internal noise and shielding effectiveness. PMID:28106718

  5. An Improved High-Sensitivity Airborne Transient Electromagnetic Sensor for Deep Penetration.

    PubMed

    Chen, Shudong; Guo, Shuxu; Wang, Haofeng; He, Miao; Liu, Xiaoyan; Qiu, Yu; Zhang, Shuang; Yuan, Zhiwen; Zhang, Haiyang; Fang, Dong; Zhu, Jun

    2017-01-17

    The investigation depth of transient electromagnetic sensors can be effectively increased by reducing the system noise, which is mainly composed of sensor internal noise, electromagnetic interference (EMI), and environmental noise, etc. A high-sensitivity airborne transient electromagnetic (AEM) sensor with low sensor internal noise and good shielding effectiveness is of great importance for deep penetration. In this article, the design and optimization of such an AEM sensor is described in detail. To reduce sensor internal noise, a noise model with both a damping resistor and a preamplifier is established and analyzed. The results indicate that a sensor with a large diameter, low resonant frequency, and low sampling rate will have lower sensor internal noise. To improve the electromagnetic compatibility of the sensor, an electromagnetic shielding model for a central-tapped coil is established and discussed in detail. Previous studies have shown that unclosed shields with multiple layers and center grounding can effectively suppress EMI and eddy currents. According to these studies, an improved differential AEM sensor is constructed with a diameter, resultant effective area, resonant frequency, and normalized equivalent input noise of 1.1 m, 114 m², 35.6 kHz, and 13.3 nV/m², respectively. The accuracy of the noise model and the shielding effectiveness of the sensor have been verified experimentally. The results show a good agreement between calculated and measured results for the sensor internal noise. Additionally, over 20 dB shielding effectiveness is achieved in a complex electromagnetic environment. All of these results show a great improvement in sensor internal noise and shielding effectiveness.

  6. Airborne gravity is here

    SciTech Connect

    Hammer, S.

    1982-01-11

    After 20 years of development efforts, the airborne gravity survey has finally become a practical exploration method. Besides gravity data, the airborne survey can also collect simultaneous, continuous records of high-precision magneticfield data as well as terrain clearance; these provide a topographic contour map useful in calculating terrain conditions and in subsequent planning and engineering. Compared with a seismic survey, the airborne gravity method can cover the same area much more quickly and cheaply; a seismograph could then detail the interesting spots.

  7. Spectral properties of gaseous uranium hexafluoride at high temperature

    NASA Technical Reports Server (NTRS)

    Krascella, N. L.

    1980-01-01

    A study to determine relative spectral emission and spectral absorption data for UF6-argon mixtures at elevated temperatures is discussed. These spectral data are required to assist in the theoretical analysis of radiation transport in the nuclear fuel-buffer gas region of a plasma core reactor. Relative emission measurements were made for UF6-argon mixtures over a range of temperatures from 650 to 1900 K and in the wavelength range from 600 to 5000 nanometers. All emission results were determined for a total pressure of 1.0 atm. Uranium hexafluoride partial pressures varied from about 3.5 to 12.7 mm Hg. Absorption measurements were attempted at 600, 625, 650 and 675 nanometers for a temperature of 1000 K. The uranium partial pressure for these determinations was 25 mm Hg. The results exhibit appreciable emission for hot UF6-argon mixtures at wavelengths between 600 and 1800 nanometers and no measurable absorption. The equipment used to evaluate the spectral properties of the UF6-argon mixtures included a plasma torch-optical plenum assembly, the monochromator, and the UF6 transfer system. Each is described.

  8. High-performance spectral element algorithms and implementations.

    SciTech Connect

    Fischer, P. F.; Tufo, H. M.

    1999-08-28

    We describe the development and implementation of a spectral element code for multimillion gridpoint simulations of incompressible flows in general two- and three-dimensional domains. Parallel performance is present on up to 2048 nodes of the Intel ASCI-Red machine at Sandia.

  9. Spectral reflectance inversion with high accuracy on green target

    NASA Astrophysics Data System (ADS)

    Jiang, Le; Yuan, Jinping; Li, Yong; Bai, Tingzhu; Liu, Shuoqiong; Jin, Jianzhou; Shen, Jiyun

    2016-09-01

    Using Landsat-7 ETM remote sensing data, the inversion of spectral reflectance of green wheat in visible and near infrared waveband in Yingke, China is studied. In order to solve the problem of lower inversion accuracy, custom atmospheric conditions method based on moderate resolution transmission model (MODTRAN) is put forward. Real atmospheric parameters are considered when adopting this method. The atmospheric radiative transfer theory to calculate atmospheric parameters is introduced first and then the inversion process of spectral reflectance is illustrated in detail. At last the inversion result is compared with simulated atmospheric conditions method which was a widely used method by previous researchers. The comparison shows that the inversion accuracy of this paper's method is higher in all inversion bands; the inversed spectral reflectance curve by this paper's method is more similar to the measured reflectance curve of wheat and better reflects the spectral reflectance characteristics of green plant which is very different from green artificial target. Thus, whether a green target is a plant or artificial target can be judged by reflectance inversion based on remote sensing image. This paper's research is helpful for the judgment of green artificial target hidden in the greenery, which has a great significance on the precise strike of green camouflaged weapons in military field.

  10. High-Rate Data-Capture for an Airborne Lidar System

    NASA Technical Reports Server (NTRS)

    Valett, Susan; Hicks, Edward; Dabney, Philip; Harding, David

    2012-01-01

    A high-rate data system was required to capture the data for an airborne lidar system. A data system was developed that achieved up to 22 million (64-bit) events per second sustained data rate (1408 million bits per second), as well as short bursts (less than 4 s) at higher rates. All hardware used for the system was off the shelf, but carefully selected to achieve these rates. The system was used to capture laser fire, single-photon detection, and GPS data for the Slope Imaging Multi-polarization Photo-counting Lidar (SIMPL). However, the system has applications for other laser altimeter systems (waveform-recording), mass spectroscopy, xray radiometry imaging, high-background- rate ranging lidar, and other similar areas where very high-speed data capture is needed. The data capture software was used for the SIMPL instrument that employs a micropulse, single-photon ranging measurement approach and has 16 data channels. The detected single photons are from two sources those reflected from the target and solar background photons. The instrument is non-gated, so background photons are acquired for a range window of 13 km and can comprise many times the number of target photons. The highest background rate occurs when the atmosphere is clear, the Sun is high, and the target is a highly reflective surface such as snow. Under these conditions, the total data rate for the 16 channels combined is expected to be approximately 22 million events per second. For each photon detection event, the data capture software reads the relative time of receipt, with respect to a one-per-second absolute time pulse from a GPS receiver, from an event timer card with 0.1-ns precision, and records that information to a RAID (Redundant Array of Independent Disks) storage device. The relative time of laser pulse firings must also be read and recorded with the same precision. Each of the four event timer cards handles the throughput from four of the channels. For each detection event, a flag is

  11. High Frequency Direction Finding Using Structurally Integrated Antennas on a Large Airborne Platform

    DTIC Science & Technology

    2011-03-24

    signal processing techniques, including superresolution techniques, as a possible way to extend the airborne DF capability to the HF band. Structurally...electrically or mechan- ically scanned beams has been diminished by array processing techniques [4]. The implementation of superresolution algorithms

  12. High diversity of airborne fungi in the hospital environment as revealed by meta-sequencing-based microbiome analysis

    PubMed Central

    Tong, Xunliang; Xu, Hongtao; Zou, Lihui; Cai, Meng; Xu, Xuefeng; Zhao, Zuotao; Xiao, Fei; Li, Yanming

    2017-01-01

    Invasive fungal infections acquired in the hospital have progressively emerged as an important cause of life-threatening infection. In particular, airborne fungi in hospitals are considered critical pathogens of hospital-associated infections. To identify the causative airborne microorganisms, high-volume air samplers were utilized for collection, and species identification was performed using a culture-based method and DNA sequencing analysis with the Illumina MiSeq and HiSeq 2000 sequencing systems. Few bacteria were grown after cultivation in blood agar. However, using microbiome sequencing, the relative abundance of fungi, Archaea species, bacteria and viruses was determined. The distribution characteristics of fungi were investigated using heat map analysis of four departments, including the Respiratory Intensive Care Unit, Intensive Care Unit, Emergency Room and Outpatient Department. The prevalence of Aspergillus among fungi was the highest at the species level, approximately 17% to 61%, and the prevalence of Aspergillus fumigatus among Aspergillus species was from 34% to 50% in the four departments. Draft genomes of microorganisms isolated from the hospital environment were obtained by sequence analysis, indicating that investigation into the diversity of airborne fungi may provide reliable results for hospital infection control and surveillance. PMID:28045065

  13. Combined High Spectral Resolution Lidar and Radar Measurement of Drizzle

    NASA Astrophysics Data System (ADS)

    Eloranta, Edwin

    2015-04-01

    Marine stratus clouds are an important feature of the global climate system. Cloud lifetime is sensitive to drizzle rates. Drizzle not only removes water from the cloud but it's evaporation cools the sub-cloud layer acting to suppress convection. Accurate measurements of drizzle rates will improve our understanding of cloud maintenance. Simultaneous lidar measurements of extinction and radar backscatter allow determination of drizzle droplet particle size, liquid water content, fall velocity and water flux. However, drizzle measurements with conventional lidar are hampered by: 1)changes in the transmission of the output window caused by water accumulation on the lidar output window, 2)the difficulty of correcting the backscatter signal for atmospheric extinction and, 3)the effects of multiple scattering. High spectral resolution lidar avoids problems with window transmission and atmospheric attenuation because the backscatter is referenced to the known molecular scattering cross section at each point in the profile. Although multiple scattering degrades the direct measurement of extinction with the HSRL, it has little effect the HSRL measurement of backscatter cross section. We have developed an iterative solution that begins by estimating the extinction cross in drizzle using an assumed lidar ratio and the backscatter measurement. This is combined with the radar backscatter to make a first estimate of the particle size distribution. Mie scattering theory is then used to compute an improved lidar ratio for this particle size distribution and the new lidar ratio provides an improved extinction cross section. The calculation assumes a modified gamma distribution of sizes. The mode diameter of the distribution is fixed by the lidar-radar cross section ratio, while the width of the distribution is determined by matching the computed fall velocity of the drizzle with the observed radar Doppler velocity. The strengths and limitations of the this approach are examined

  14. Design of the interferometric spectral discrimination filters for a three-wavelength high-spectral-resolution lidar.

    PubMed

    Luo, Jing; Liu, Dong; Zhang, Yupeng; Cheng, Zhongtao; Liu, Chong; Bai, Jian; Shen, Yibing; Yang, Yongying; Zhou, Yudi; Tang, Peijun; Liu, Qun; Xu, Peituo; Su, Lin; Zhang, Xiaoyu; Yang, Liming

    2016-11-28

    We address design of the interferometric spectral discrimination (ISD) filters for a specific three-wavelength high-spectral-resolution lidar (HSRL) in this paper. Taking into account the strong dependence of the transmittance of the ISD filters on the incident angle of light ray, the optical path of the receiving channel with an ISD filter in HSRL is analyzed. We derive the lidar equation with the angular distribution of backscatter signal, through which Monte Carlo (MC) simulations are then carried out to obtain the optimal parameters of the ISD filters for the HSRL at 1064 nm, 532 nm and 355 nm, respectively. Comparing the retrieval errors of the MC simulations based on different ISD filters, the configuration and parameters of the best ISD filter at each wavelength are determined. This paper can be employed as a theoretical guidance during the design of a three-wavelength HSRL with ISD filters.

  15. Preliminary assessment of airborne imaging spectrometer and airborne thematic mapper data acquired for forest decline areas in the Federal Republic of Germany

    NASA Technical Reports Server (NTRS)

    Herrmann, Karin; Ammer, Ulrich; Rock, Barrett; Paley, Helen N.

    1988-01-01

    This study evaluated the utility of data collected by the high-spectral resolution airborne imaging spectrometer (AIS-2, tree mode, spectral range 0.8-2.2 microns) and the broad-band Daedalus airborne thematic mapper (ATM, spectral range 0.42-13.0 micron) in assessing forest decline damage at a predominantly Scotch pine forest in the FRG. Analysis of spectral radiance values from the ATM and raw digital number values from AIS-2 showed that higher reflectance in the near infrared was characteristic of high damage (heavy chlorosis, limited needle loss) in Scotch pine canopies. A classification image of a portion of the AIS-2 flight line agreed very well with a damage assessment map produced by standard aerial photointerpretation techniques.

  16. Fiber-Coupled Planar Light-Wave Circuit for Seed Laser Control in High Spectral Resolution Lidar Systems

    NASA Technical Reports Server (NTRS)

    Cook, Anthony; McNeil, Shirley; Switzer, Gregg; Battle, Philip

    2010-01-01

    Precise laser remote sensing of aerosol extinction and backscatter in the atmosphere requires a high-power, pulsed, frequency doubled Nd:YAG laser that is wavelength- stabilized to a narrow absorption line such as found in iodine vapor. One method for precise wavelength control is to injection seed the Nd:YAG laser with a low-power CW laser that is stabilized by frequency converting a fraction of the beam to 532 nm, and to actively frequency-lock it to an iodine vapor absorption line. While the feasibility of this approach has been demonstrated using bulk optics in NASA Langley s Airborne High Spectral Resolution Lidar (HSRL) program, an ideal, lower cost solution is to develop an all-waveguide, frequency-locked seed laser in a compact, robust package that will withstand the temperature, shock, and vibration levels associated with airborne and space-based remote sensing platforms. A key technology leading to this miniaturization is the integration of an efficient waveguide frequency doubling element, and a low-voltage phase modulation element into a single, monolithic, planar light-wave circuit (PLC). The PLC concept advances NASA's future lidar systems due to its compact, efficient and reliable design, thus enabling use on small aircraft and satellites. The immediate application for this technology is targeted for NASA Langley's HSRL system for aerosol and cloud characterization. This Phase I effort proposes the development of a potassium titanyl phosphate (KTP) waveguide phase modulator for future integration into a PLC. For this innovation, the proposed device is the integration of a waveguide-based frequency doubler and phase modulator in a single, fiber pigtail device that will be capable of efficient second harmonic generation of 1,064-nm light and subsequent phase modulation of the 532 nm light at 250 MHz, providing a properly spectrally formatted beam for HSRL s seed laser locking system. Fabrication of the integrated PLC chip for NASA Langley, planned for

  17. High altitude airborne remote sensing mission using the advanced microwave precipitation radiometer (AMPR)

    NASA Technical Reports Server (NTRS)

    Galliano, J.; Platt, R. H.; Spencer, Roy; Hood, Robbie

    1991-01-01

    The advanced microwave precipitation radiometer (AMPR) is an airborne multichannel imaging radiometer used to better understand how the earth's climate structure works. Airborne data results from the October 1990 Florida thunderstorm mission in Jacksonville, FL, are described. AMPR data on atmospheric precipitation in mesoscale storms were retrieved at 10.7, 19.35, 37.1, and 85.5 GHz onboard the ER-2 aircraft at an altitude of 20 km. AMPR's three higher-frequency data channels were selected to operate at the same frequencies as the spaceborne special sensor microwave/imager (SSM/I) presently in orbit. AMPR uses two antennas to receive the four frequencies: the lowest frequency channel uses a 9.7-in aperture lens antennas, while the three higher-frequency channels share a separate 5.3-in aperture lens antenna. The radiometer's temperature resolution performance is summarized.

  18. Chlorophyll content in eucalypt vegetation at the leaf and canopy scales as derived from high resolution spectral data.

    PubMed

    Coops, Nicholas C; Stone, Christine; Culvenor, Darius S; Chisholm, Laurie A; Merton, Ray N

    2003-01-01

    The physiological status of forest canopy foliage is influenced by a range of factors that affect leaf pigment content and function. Recently, several indices have been developed from remotely sensed data that attempt to provide robust estimates of leaf chlorophyll content. These indices have been developed from either hand-held spectroradiometer spectra or high spectral resolution (or hyperspectral) imagery. We determined if two previously published indices (Datt 1999), which were specifically developed to predict chlorophyll content in eucalypt vegetation by remote sensing at the leaf scale, can be extrapolated accurately to the canopy. We derived the two indices from hand-held spectroradiometer data of eucalypt leaves exhibiting a range of insect damage symptoms. We also derived the indices from spectra obtained from high spectral and spatial resolution Compact Airborne Spectrographic Imager 2 (CASI-2) imagery to determine if reasonable estimates at a scale of < 1 m can be achieved. One of the indices (R 850/R 710 index, where R is reflectance) derived from hand-held spectroradiometer data showed a moderate correlation with relative leaf chlorophyll content (r = 0.59, P < 0.05) for all dominant eucalypt species in the study area. The R (850)/R (710) index derived from CASI-2 imagery yielded slightly lower correlations over the entire data set (r = 0.42, P < 0.05), but correlations for individual species were high (r = 0.77, P < 0.05). A scaling analysis indicated that the R (850)/R (710) index was strongly affected by soil and water cover types when pixels were mixed, but appeared to be invariant to changes in proportions of understory, which may limit its application.

  19. High Spectral Resolution Infrared and Raman Lidar Observations for the ARM Program: Clear and Cloudy Sky Applications

    SciTech Connect

    Revercomb, Henry; Tobin, David; Knuteson, Robert; Borg, Lori; Moy, Leslie

    2009-06-17

    This grant began with the development of the Atmospheric Emitted Radiance Interferometer (AERI) for ARM. The AERI has provided highly accurate and reliable observations of downwelling spectral radiance (Knuteson et al. 2004a, 2004b) for application to radiative transfer, remote sensing of boundary layer temperature and water vapor, and cloud characterization. One of the major contributions of the ARM program has been its success in improving radiation calculation capabilities for models and remote sensing that evolved from the multi-year, clear-sky spectral radiance comparisons between AERI radiances and line-by-line calculations (Turner et al. 2004). This effort also spurred us to play a central role in improving the accuracy of water vapor measurements, again helping ARM lead the way in the community (Turner et al. 2003a, Revercomb et al. 2003). In order to add high-altitude downlooking AERI-like observations over the ARM sites, we began the development of an airborne AERI instrument that has become known as the Scanning High-resolution Interferometer Sounder (Scanning-HIS). This instrument has become an integral part of the ARM Unmanned Aerospace Vehicle (ARM-UAV) program. It provides both a cross-track mapping view of the earth and an uplooking view from the 12-15 km altitude of the Scaled Composites Proteus aircraft when flown over the ARM sites for IOPs. It has successfully participated in the first two legs of the “grand tour” of the ARM sites (SGP and NSA), resulting in a very good comparison with AIRS observations in 2002 and in an especially interesting data set from the arctic during the Mixed-Phase Cloud Experiment (M-PACE) in 2004.

  20. Thermal management of closed computer modules utilizing high density circuitry. [in Airborne Information Management System

    NASA Technical Reports Server (NTRS)

    Hoadley, A. W.; Porter, A. J.

    1990-01-01

    This paper presents data on a preliminary analysis of the thermal dynamic characteristics of the Airborne Information Management System (AIMS), which is a continuing design project at NASA Dryden. The analysis established the methods which will be applied to the actual AIMS boards as they become available. The paper also describes the AIMS liquid cooling system design and presents a thermodynamic computer model of the AIMS cooling system, together with an experimental validation of this model.

  1. Estimating forest canopy attributes via airborne, high-resolution, multispectral imagery in midwest forest types

    NASA Astrophysics Data System (ADS)

    Gatziolis, Demetrios

    An investigation of the utility of high spatial resolution (sub-meter), 16-bit, multispectral, airborne digital imagery for forest land cover mapping in the heterogeneous and structurally complex forested landscapes of northern Michigan is presented. Imagery frame registration and georeferencing issues are presented and a novel approach for bi-directional reflectance distribution function (BRDF) effects correction and between-frame brightness normalization is introduced. Maximum likelihood classification of five cover type classes is performed over various geographic aggregates of 34 plots established in the study area that were designed according to the Forest Inventory and Analysis protocol. Classification accuracy estimates show that although band registration and BRDF corrections and brightness normalization provide an approximately 5% improvement over the raw imagery data, overall classification accuracy remains relatively low, barely exceeding 50%. Computed kappa coefficients reveal no statistical differences among classification trials. Classification results appear to be independent of geographic aggregations of sampling plots. Estimation of forest stand canopy parameter parameters (stem density, canopy closure, and mean crown diameter) is based on quantifying the spatial autocorrelation among pixel digital numbers (DN) using variogram analysis and slope break analysis, an alternative non-parametric approach. Parameter estimation and cover type classification proceed from the identification of tree apexes. Parameter accuracy assessment is evaluated via value comparison with a spatially precise set of field observations. In general, slope-break-based parameter estimates are superior to those obtained using variograms. Estimated root mean square errors at the plot level for the former average 6.5% for stem density, 3.5% for canopy closure and 2.5% for mean crown diameter, which are less than or equal to error rates obtained via traditional forest stand

  2. Toward high performance radioisotope thermophotovoltaic systems using spectral control

    NASA Astrophysics Data System (ADS)

    Wang, Xiawa; Chan, Walker; Stelmakh, Veronika; Celanovic, Ivan; Fisher, Peter

    2016-12-01

    This work describes RTPV-PhC-1, an initial prototype for a radioisotope thermophotovoltaic (RTPV) system using a two-dimensional photonic crystal emitter and low bandgap thermophotovoltaic (TPV) cell to realize spectral control. We validated a system simulation using the measurements of RTPV-PhC-1 and its comparison setup RTPV-FlatTa-1 with the same configuration except a polished tantalum emitter. The emitter of RTPV-PhC-1 powered by an electric heater providing energy equivalent to one plutonia fuel pellet reached 950 °C with 52 W of thermal input power and produced 208 mW output power from 1 cm2 TPV cell. We compared the system performance using a photonic crystal emitter to a polished flat tantalum emitter and found that spectral control with the photonic crystal was four times more efficient. Based on the simulation, with more cell areas, better TPV cells, and improved insulation design, the system powered by a fuel pellet equivalent heat source is expected to reach an efficiency of 7.8%.

  3. Airborne and Ground-Based Measurements Using a High-Performance Raman Lidar. Part 2; Ground Based

    NASA Technical Reports Server (NTRS)

    Whiteman, David N.; Cadirola, Martin; Venable, Demetrius; Connell, Rasheen; Rush, Kurt; Leblanc, Thierry; McDermid, Stuart

    2009-01-01

    The same RASL hardware as described in part I was installed in a ground-based mobile trailer and used in a water vapor lidar intercomparison campaign, hosted at Table Mountain, CA, under the auspices of the Network for the Detection of Atmospheric Composition Change (NDACC). The converted RASL hardware demonstrated high sensitivity to lower stratospheric water vapor indicating that profiling water vapor at those altitudes with sufficient accuracy to monitor climate change is possible. The measurements from Table Mountain also were used to explain the reason, and correct , for sub-optimal airborne aerosol extinction performance during the flight campaign.

  4. A High-Order Finite Spectral Volume Method for Conservation Laws on Unstructured Grids

    NASA Technical Reports Server (NTRS)

    Wang, Z. J.; Liu, Yen; Kwak, Dochan (Technical Monitor)

    2001-01-01

    A time accurate, high-order, conservative, yet efficient method named Finite Spectral Volume (FSV) is developed for conservation laws on unstructured grids. The concept of a 'spectral volume' is introduced to achieve high-order accuracy in an efficient manner similar to spectral element and multi-domain spectral methods. In addition, each spectral volume is further sub-divided into control volumes (CVs), and cell-averaged data from these control volumes is used to reconstruct a high-order approximation in the spectral volume. Riemann solvers are used to compute the fluxes at spectral volume boundaries. Then cell-averaged state variables in the control volumes are updated independently. Furthermore, TVD (Total Variation Diminishing) and TVB (Total Variation Bounded) limiters are introduced in the FSV method to remove/reduce spurious oscillations near discontinuities. A very desirable feature of the FSV method is that the reconstruction is carried out only once, and analytically, and is the same for all cells of the same type, and that the reconstruction stencil is always non-singular, in contrast to the memory and CPU-intensive reconstruction in a high-order finite volume (FV) method. Discussions are made concerning why the FSV method is significantly more efficient than high-order finite volume and the Discontinuous Galerkin (DG) methods. Fundamental properties of the FSV method are studied and high-order accuracy is demonstrated for several model problems with and without discontinuities.

  5. Time-resolved High Spectral Resolution Observation of 2MASSW J0746425+200032AB

    NASA Astrophysics Data System (ADS)

    Wang, Ji; Prato, Lisa; Mawet, Dimitri

    2017-03-01

    Many brown dwarfs (BDs) exhibit photometric variability at levels from tenths to tens of percents. The photometric variability is related to magnetic activity or patchy cloud coverage, characteristic of BDs near the L–T transition. Time-resolved spectral monitoring of BDs provides diagnostics of cloud distribution and condensate properties. However, current time-resolved spectral studies of BDs are limited to low spectral resolution (R ∼ 100) with the exception of the study of Luhman 16 AB at a resolution of 100,000 using the VLT+CRIRES. This work yielded the first map of BD surface inhomogeneity, highlighting the importance and unique contribution of high spectral resolution observations. Here, we report on the time-resolved high spectral resolution observations of a nearby BD binary, 2MASSW J0746425+200032AB. We find no coherent spectral variability that is modulated with rotation. Based on simulations, we conclude that the coverage of a single spot on 2MASSW J0746425+200032AB is smaller than 1% or 6.25% if spot contrast is 50% or 80% of its surrounding flux, respectively. Future high spectral resolution observations aided by adaptive optics systems can put tighter constraints on the spectral variability of 2MASSW J0746425+200032AB and other nearby BDs.

  6. High Altitude Measurements of Radiance at High Spectral and Spatial Resolution for SIMBIOS Sensor Calibration, Validation, and Intercomparisons. Chapter 11

    NASA Technical Reports Server (NTRS)

    Green, Robert O.; Pavri, Betina; Chrien, Thomas G.

    2001-01-01

    The successful combination of data from different ocean color sensors depends on the correct interpretation of signal from each of these sensors. Ideally, the sensor measured signals are calibrated to geophysical units of spectral radiance, and sensor artifacts are removed and corrected. The calibration process resamples the signal into a common radiometric data space so that subsequent ocean color algorithms that are applied to the data are based on physical processes and are inherently sensor independent. The objective of this project is to calibrate and validate the on-orbit radiometric characteristics of Sea-Viewing Wide Field-of-view Sensor (SeaWiFS) with underflights of NASA's calibrated Airborne Visible/Infrared Imaging Spectrometer (AVIRIS). This objective is feasible because AVIRIS measures the same spectral range as SeaWIFS at higher spectral resolution. In addition to satellite sensor underflights, the AVIRIS project has supported comparison and analysis of the radiometric calibration standards used for AVIRIS and SeaWIFS. To date, both the OCTS and SeaWIFS satellite sensors have been underflown by AVIRIS with matching spectral, spatial, geometric, radiometric, and temporal domains. The calibration and validation objective of this project is pursued for the following reasons: (1) Calibration is essential for the quantitative use of SeaWIFS and other SIMBIOS (Sensor Intercomparison and Merger for Biological and Interdisciplinary Oceanic Studies) sensor data; (2) Calibration in the laboratory of spaceborne sensors is challenging; (3) Satellite sensors are subjected aging on the ground and to trauma during launch; (4) The Earth orbit environment is significantly different than the laboratory calibration environment; (5) Through years of effort AVIRIS has been demonstrated to be well calibrated; and (6) AVIRIS can match the spectral and spatial observation characteristics near the top of the atmosphere at the time of SeaWIFS measurements.

  7. High-spectral-resolution coherent anti-Stokes Raman scattering with interferometrically detected broadband chirped pulses.

    PubMed

    Jones, Gareth W; Marks, Daniel L; Vinegoni, Claudio; Boppart, Stephen A

    2006-05-15

    To achieve high-spectral-resolution multiplex coherent anti-Stokes Raman scattering (CARS), one typically uses a narrowband pump pulse and a broadband Stokes pulse. This is to ensure a correspondence between anti-Stokes and vibrational frequencies. We obtain high-resolution CARS spectra of isopropanol, using a broadband chirped pump pulse and a broadband Stokes pulse, by detecting the anti-Stokes pulse with spectral interferometry. With the temporally resolved anti-Stokes signal, we can remove the chirp of the anti-Stokes pulse and restore high spectral resolution while also rejecting nonresonant scattering.

  8. Technical Training on High-Order Spectral Analysis and Thermal Anemometry Applications

    NASA Technical Reports Server (NTRS)

    Maslov, A. A.; Shiplyuk, A. N.; Sidirenko, A. A.; Bountin, D. A.

    2003-01-01

    The topics of thermal anemometry and high-order spectral analyses were the subject of the technical training. Specifically, the objective of the technical training was to study: (i) the recently introduced constant voltage anemometer (CVA) for high-speed boundary layer; and (ii) newly developed high-order spectral analysis techniques (HOSA). Both CVA and HOSA are relevant tools for studies of boundary layer transition and stability.

  9. Spectral Apparatus with a Cryogenic, High-Throughput, Multipass Gas Cell for Studies of Absorption of Radiation by Gaseous Media

    NASA Astrophysics Data System (ADS)

    Moskalenko, N. I.; Mirumyants, S. O.; Parzhin, S. N.; Dodov, I. R.

    2016-11-01

    Spectral systems with an MKhK-6 cryogenic, high-throughput, multipass gas cell for studying the absorption spectra of gaseous media with high spectral resolution in the 0.1-6 μm range at pressures of 100 to 5·106 Pa and temperatures of 180-300 K are discussed. Their use in measurements of spectral absorption coefficients, temperature dependences of the spectral transmission function, and parameters of spectral absorption lines is examined.

  10. MULTIPLY: Development of a European HSRL Airborne Facility

    NASA Astrophysics Data System (ADS)

    Binietoglou, Ioannis; Serikov, Ilya; Nicolae, Doina; Amiridis, Vassillis; Belegante, Livio; Boscornea, Andrea; Brugmann, Bjorn; Costa Suros, Montserrat; Hellmann, David; Kokkalis, Panagiotis; Linne, Holger; Stachlewska, Iwona; Vajaiac, Sorin-Nicolae

    2016-08-01

    MULTIPLY is a novel airborne high spectral resolution lidar (HSRL) currently under development by a consortium of European institutions from Romania, Germany, Greece, and Poland. Its aim is to contribute to calibration and validations activities of the upcoming ESA aerosol sensing missions like ADM-Aeolus, EarthCARE and the Sentinel-3/-4/-5/-5p which include products related to atmospheric aerosols. The effectiveness of these missions depends on independent airborne measurements to develop and test the retrieval methods, and validate mission products following launch. The aim of ESA's MULTIPLY project is to design, develop, and test a multi-wavelength depolarization HSRL for airborne applications. The MULTIPLY lidar will deliver the aerosol extinction and backscatter coefficient profiles at three wavelengths (355nm, 532nm, 1064nm), as well as profiles of aerosol intensive parameters (Ångström exponents, extinction- to-backscatter ratios, and linear particle depolarization ratios).

  11. High spectral purity Kerr frequency comb radio frequency photonic oscillator.

    PubMed

    Liang, W; Eliyahu, D; Ilchenko, V S; Savchenkov, A A; Matsko, A B; Seidel, D; Maleki, L

    2015-08-11

    Femtosecond laser-based generation of radio frequency signals has produced astonishing improvements in achievable spectral purity, one of the basic features characterizing the performance of an radio frequency oscillator. Kerr frequency combs hold promise for transforming these lab-scale oscillators to chip-scale level. In this work we demonstrate a miniature 10 GHz radio frequency photonic oscillator characterized with phase noise better than -60 dBc Hz(-1) at 10 Hz, -90 dBc Hz(-1) at 100 Hz and -170 dBc Hz(-1) at 10 MHz. The frequency stability of this device, as represented by Allan deviation measurements, is at the level of 10(-10) at 1-100 s integration time-orders of magnitude better than existing radio frequency photonic devices of similar size, weight and power consumption.

  12. High spectral purity Kerr frequency comb radio frequency photonic oscillator

    PubMed Central

    Liang, W.; Eliyahu, D.; Ilchenko, V. S.; Savchenkov, A. A.; Matsko, A. B.; Seidel, D.; Maleki, L.

    2015-01-01

    Femtosecond laser-based generation of radio frequency signals has produced astonishing improvements in achievable spectral purity, one of the basic features characterizing the performance of an radio frequency oscillator. Kerr frequency combs hold promise for transforming these lab-scale oscillators to chip-scale level. In this work we demonstrate a miniature 10 GHz radio frequency photonic oscillator characterized with phase noise better than −60 dBc Hz−1 at 10 Hz, −90 dBc Hz−1 at 100 Hz and −170 dBc Hz−1 at 10 MHz. The frequency stability of this device, as represented by Allan deviation measurements, is at the level of 10−10 at 1–100 s integration time—orders of magnitude better than existing radio frequency photonic devices of similar size, weight and power consumption. PMID:26260955

  13. High-efficiency spectral purity filter for EUV lithography

    DOEpatents

    Chapman, Henry N.

    2006-05-23

    An asymmetric-cut multilayer diffracts EUV light. A multilayer cut at an angle has the same properties as a blazed grating, and has been demonstrated to have near-perfect performance. Instead of having to nano-fabricate a grating structure with imperfections no greater than several tens of nanometers, a thick multilayer is grown on a substrate and then cut at an inclined angle using coarse and inexpensive methods. Effective grating periods can be produced this way that are 10 to 100 times smaller than those produced today, and the diffraction efficiency of these asymmetric multilayers is higher than conventional gratings. Besides their ease of manufacture, the use of an asymmetric multilayer as a spectral purity filter does not require that the design of an EUV optical system be modified in any way, unlike the proposed use of blazed gratings for such systems.

  14. Optical signal processing for enabling high-speed, highly spectrally efficient and high capacity optical systems

    NASA Astrophysics Data System (ADS)

    Fazal, Muhammad Irfan

    The unabated demand for more capacity due to the ever-increasing internet traffic dictates that the boundaries of the state of the art maybe pushed to send more data through the network. Traditionally, this need has been satisfied by multiple wavelengths (wavelength division multiplexing), higher order modulation formats and coherent communication (either individually or combined together). WDM has the ability to reduce cost by using multiple channels within the same physical fiber, and with EDFA amplifiers, the need for O-E-O regenerators is eliminated. Moreover the availability of multiple colors allows for wavelength-based routing and network planning. Higher order modulation formats increases the capacity of the link by their ability to encode data in both the phase and amplitude of light, thereby increasing the bits/sec/Hz as compared to simple on-off keyed format. Coherent communications has also emerged as a primary means of transmitting and receiving optical data due to its support of formats that utilize both phase and amplitude to further increase the spectral efficiency of the optical channel, including quadrature amplitude modulation (QAM) and quadrature phase shift keying (QPSK). Polarization multiplexing of channels can double capacity by allowing two channels to share the same wavelength by propagating on orthogonal polarization axis and is easily supported in coherent systems where the polarization tracking can be performed in the digital domain. Furthermore, the forthcoming IEEE 100 Gbit/s Ethernet Standard, 802.3ba, provides greater bandwidth, higher data rates, and supports a mixture of modulation formats. In particular, Pol-MUX QPSK is increasingly becoming the industry's format of choice as the high spectral efficiency allows for 100 Gbit/s transmission while still occupying the current 50 GHz/channel allocation of current 10 Gbit/s OOK fiber systems. In this manner, 100 Gbit/s transfer speeds using current fiber links, amplifiers, and filters

  15. Head-high, airborne pollen grains from different areas of metropolitan Delhi.

    PubMed

    Malik, P; Singh, A B; Babu, C R; Gangal, S V

    1990-05-01

    A survey of airborne pollen grains from four zones of metropolitan Delhi was conducted for 1 year (February 1988-January 1989) at human height level (5'-6'). Sampling was carried out in different inhabited areas in the four zones using Burkard Volumetric Personal Samplers. Sampling was carried out at weekly intervals, three times a day (7, 14, & 20 h) for 15 min. Poaceae, Ricinus, Cheno-Amaranth, Morus, Artemisia, Myrtaceae, Parthenium, Prosopis and Cannabis are important pollen contributors to the atmosphere, especially at lower heights. In general, pollen concentration was low at human height. Quantitative zonal variations have been recorded within an urban city.

  16. CNR LARA project, Italy: Airborne laboratory for environmental research

    NASA Technical Reports Server (NTRS)

    Bianchi, R.; Cavalli, R. M.; Fiumi, L.; Marino, C. M.; Pignatti, S.

    1995-01-01

    The increasing interest for the environmental problems and the study of the impact on the environment due to antropic activity produced an enhancement of remote sensing applications. The Italian National Research Council (CNR) established a new laboratory for airborne hyperspectral imaging, the LARA Project (Laboratorio Aero per Ricerche Ambientali - Airborne Laboratory for Environmental Research), equipping its airborne laboratory, a CASA-212, mainly with the Daedalus AA5000 MIVIS (Multispectral Infrared and Visible Imaging Spectrometer) instrument. MIVIS's channels, spectral bandwidths, and locations are chosen to meet the needs of scientific research for advanced applications of remote sensing data. MIVIS can make significant contributions to solving problems in many diverse areas such as geologic exploration, land use studies, mineralogy, agricultural crop studies, energy loss analysis, pollution assessment, volcanology, forest fire management and others. The broad spectral range and the many discrete narrow channels of MIVIS provide a fine quantization of spectral information that permits accurate definition of absorption features from a variety of materials, allowing the extraction of chemical and physical information of our environment. The availability of such a hyperspectral imager, that will operate mainly in the Mediterranean area, at the present represents a unique opportunity for those who are involved in environmental studies and land-management to collect systematically large-scale and high spectral-spatial resolution data of this part of the world. Nevertheless, MIVIS deployments will touch other parts of the world, where a major interest from the international scientific community is present.

  17. Performance characterization of a pressure-tuned wide-angle Michelson interferometric spectral filter for high spectral resolution lidar

    NASA Astrophysics Data System (ADS)

    Seaman, Shane T.; Cook, Anthony L.; Scola, Salvatore J.; Hostetler, Chris A.; Miller, Ian; Welch, Wayne

    2015-09-01

    High Spectral Resolution Lidar (HSRL) is typically realized using an absorption filter to separate molecular returns from particulate returns. NASA Langley Research Center (LaRC) has designed and built a Pressure-Tuned Wide-Angle Michelson Interferometer (PTWAMI) as an alternate means to separate the two types of atmospheric returns. While absorption filters only work at certain wavelengths and suffer from low photon efficiency due to light absorption, an interferometric spectral filter can be designed for any wavelength and transmits nearly all incident photons. The interferometers developed at LaRC employ an air spacer in one arm, and a solid glass spacer in the other. Field widening is achieved by specific design and selection of the lengths and refractive indices of these two arms. The principal challenge in using such an interferometer as a spectral filter for HSRL aboard aircraft is that variations in glass temperature and air pressure cause changes in the interferometer's optical path difference. Therefore, a tuning mechanism is needed to actively accommodate for these changes. The pressure-tuning mechanism employed here relies on changing the pressure in an enclosed, air-filled arm of the interferometer to change the arm's optical path length. However, tuning using pressure will not adjust for tilt, mirror warpage, or thermally induced wavefront error, so the structural, thermal, and optical behavior of the device must be well understood and optimized in the design and manufacturing process. The PTWAMI has been characterized for particulate transmission ratio, wavefront error, and tilt, and shows acceptable performance for use in an HSRL instrument.

  18. Complexity in the high latitude HF radar spectral width boundary region

    NASA Astrophysics Data System (ADS)

    Parkinson, M. L.; Hannah, K. M.; Dyson, P. L.

    2008-05-01

    SuperDARN radars are sensitive to the collective Doppler characteristics of decametre-scale irregularities in the high latitude ionosphere. The radars routinely observe a distinct transition from large spectral width (>100 m s-1) located at higher latitudes to low spectral width (<50 m s-1) located at lower latitudes. Because of its equatorward location, the TIGER Tasmanian radar is very sensitive to the detection of the spectral width boundary (SWB) in the nightside auroral ionosphere. An analysis of the line-of-sight velocities and 2-D beam-swinging vectors suggests the meso-scale (~100 km) convection is more erratic in the high spectral width region, but slower and more homogeneous in the low spectral width region. The radar autocorrelation functions are better modelled using Lorentzian Doppler spectra in the high spectral width region, and Gaussian Doppler spectra in the low spectral width region. However, paradoxically, Gaussian Doppler spectra are associated with the largest spectral widths. Application of the Burg maximum entropy method suggests the occurrence of double-peaked Doppler spectra is greater in the high spectral width region, implying the small-scale (~10 km) velocity fluctuations are more intense above the SWB. These observations combined with collective wave scattering theory imply there is a transition from a fast flowing, turbulent plasma with a correlation length of velocity fluctuations less than the scattering wavelength, to a slower moving plasma with a correlation length greater than the scattering wavelength. Peak scaling and structure function analysis of fluctuations in the SWB itself reveals approximately scale-free behaviour across temporal scales of ~10 s to ~34 min. Preliminary scaling exponents for these fluctuations, αGSF=0.18±0.02 and αGSF=0.09±0.01, are even smaller than that expected for MHD turbulence.

  19. High Broadband Spectral Resolving Transition-Edge Sensors for High Count-Rate Astrophysical Applications

    NASA Technical Reports Server (NTRS)

    Smith, Stephen

    2011-01-01

    We are developing arrays of transition-edge sensor (TES) X-ray detectors optimized for high count-rate solar astronomy applications where characterizing the high velocity motions of X-ray jets in solar flares is of particular interest. These devices are fabricated on thick Si substrates and consist of 35x35micron^2 TESs with 4.5micron thick, 60micron pitch, electroplated absorbers. We have tested devices fabricated with different geometric stem contact areas with the TES and surrounding substrate area, which allows us to investigate the loss of athermal phonons to the substrate. Results show a correlation between the stem contact area and a non-Gaussian broadening in the spectral line shape consistent with athermal phonon loss. When the contact area is minimized we have obtained remarkable board-band spectral resolving capabilities of 1.3 plus or minus 0.leV at an energy of 1.5 keV, 1.6 plus or minus 0.1 eV at 5.9 keV and 2.0 plus or minus 0.1 eV at 8 keV. This, coupled with a capability of accommodating 100's of counts per second per pixel makes these devices an exciting prospect of future x-ray astronomy applications.

  20. Estimating the abundance of airborne pollen and fungal spores at variable elevations using an aircraft: how high can they fly?

    NASA Astrophysics Data System (ADS)

    Damialis, Athanasios; Kaimakamis, Evangelos; Konoglou, Maria; Akritidis, Ioannis; Traidl-Hoffmann, Claudia; Gioulekas, Dimitrios

    2017-03-01

    Airborne pollen and fungal spores are monitored mainly in highly populated, urban environments, for allergy prevention purposes. However, their sources can frequently be located outside cities’ fringes with more vegetation. So as to shed light to this paradox, we investigated the diversity and abundance of airborne pollen and fungal spores at various environmental regimes. We monitored pollen and spores using an aircraft and a car, at elevations from sea level to 2,000 m above ground, in the region of Thesssaloniki, Greece. We found a total of 24 pollen types and more than 15 spore types. Pollen and spores were detected throughout the elevational transect. Lower elevations exhibited higher pollen concentrations in only half of plant taxa and higher fungal spore concentrations in only Ustilago. Pinaceae and Quercus pollen were the most abundant recorded by airplane (>54% of the total). Poaceae pollen were the most abundant via car measurements (>77% of the total). Cladosporium and Alternaria spores were the most abundant in all cases (aircraft: >69% and >17%, car: >45% and >27%, respectively). We conclude that pollen and fungal spores can be diverse and abundant even outside the main source area, evidently because of long-distance transport incidents.

  1. Estimating the abundance of airborne pollen and fungal spores at variable elevations using an aircraft: how high can they fly?

    PubMed Central

    Damialis, Athanasios; Kaimakamis, Evangelos; Konoglou, Maria; Akritidis, Ioannis; Traidl-Hoffmann, Claudia; Gioulekas, Dimitrios

    2017-01-01

    Airborne pollen and fungal spores are monitored mainly in highly populated, urban environments, for allergy prevention purposes. However, their sources can frequently be located outside cities’ fringes with more vegetation. So as to shed light to this paradox, we investigated the diversity and abundance of airborne pollen and fungal spores at various environmental regimes. We monitored pollen and spores using an aircraft and a car, at elevations from sea level to 2,000 m above ground, in the region of Thesssaloniki, Greece. We found a total of 24 pollen types and more than 15 spore types. Pollen and spores were detected throughout the elevational transect. Lower elevations exhibited higher pollen concentrations in only half of plant taxa and higher fungal spore concentrations in only Ustilago. Pinaceae and Quercus pollen were the most abundant recorded by airplane (>54% of the total). Poaceae pollen were the most abundant via car measurements (>77% of the total). Cladosporium and Alternaria spores were the most abundant in all cases (aircraft: >69% and >17%, car: >45% and >27%, respectively). We conclude that pollen and fungal spores can be diverse and abundant even outside the main source area, evidently because of long-distance transport incidents. PMID:28300143

  2. Facility for assessing spectral normal emittance of solid materials at high temperature.

    PubMed

    Mercatelli, Luca; Meucci, Marco; Sani, Elisa

    2015-10-10

    Spectral emittance is a key topic in the study of new compositions, depositions, and mechanical machining of materials for solar absorption and for renewable energies in general. The present work reports on the realization and testing of a new experimental facility for the measurement of directional spectral emittance in the range of 2.5-20 μm. Our setup provides emittance spectral information in a completely controlled environment at medium-high temperatures up to 1200 K. We describe the layout and first tests on the device, comparing the results obtained for hafnium carbide and tantalum diboride ultrarefractory ceramic samples to previous quasi-monochromatic measurements carried out in the PROMES-CNRS (PROcedes, Materiaux et Energie Solaire- Centre National de la Recherche Scientifique, France) solar furnace, obtaining a good agreement. Finally, to assess the reliability of the widely used approach of estimating the spectral emittance from room-temperature reflectance spectrum, we compared the calculation in the 2.5-17 μm spectral range to the experimental high-temperature spectral emittance, obtaining that the spectral trend of calculated and measured curves is similar but the calculated emittance underestimates the measured value.

  3. Designing and optimizing highly efficient grating for high-brightness laser based on spectral beam combining

    SciTech Connect

    Yang, Ying-Ying E-mail: yangyy@semi.ac.cn; Zhao, Ya-Ping; Wang, Li-Rong; Zhang, Ling; Lin, Xue-Chun E-mail: yangyy@semi.ac.cn

    2015-03-14

    A highly efficient nano-periodical grating is theoretically investigated for spectral beam combining (SBC) and is experimentally implemented for attaining high-brightness laser from a diode laser array. The rigorous coupled-wave analysis with the S matrix method is employed to optimize the parameters of the grating. According the optimized parameters, the grating is fabricated and plays a key role in SBC cavity. The diffraction efficiency of this grating is optimized to 95% for the output laser which is emitted from the diode laser array. The beam parameter product of 3.8 mm mrad of the diode laser array after SBC is achieved at the output power of 46.3 W. The optical-to-optical efficiency of SBC cavity is measured to be 93.5% at the maximum operating current in the experiment.

  4. Designing and optimizing highly efficient grating for high-brightness laser based on spectral beam combining

    NASA Astrophysics Data System (ADS)

    Yang, Ying-Ying; Zhao, Ya-Ping; Wang, Li-Rong; Zhang, Ling; Lin, Xue-Chun

    2015-03-01

    A highly efficient nano-periodical grating is theoretically investigated for spectral beam combining (SBC) and is experimentally implemented for attaining high-brightness laser from a diode laser array. The rigorous coupled-wave analysis with the S matrix method is employed to optimize the parameters of the grating. According the optimized parameters, the grating is fabricated and plays a key role in SBC cavity. The diffraction efficiency of this grating is optimized to 95% for the output laser which is emitted from the diode laser array. The beam parameter product of 3.8 mm mrad of the diode laser array after SBC is achieved at the output power of 46.3 W. The optical-to-optical efficiency of SBC cavity is measured to be 93.5% at the maximum operating current in the experiment.

  5. Airborne Infrared Spectrograph for Eclipse Observations

    NASA Astrophysics Data System (ADS)

    Golub, L.; Cheimets, P.; DeLuca, E. E.; Samra, J.; Judge, P. G.

    2015-12-01

    Direct measurements of the coronal magnetic field have significant potential to enhance our understanding of coronal dynamics, and improve forecasting models. Of particular interest are observations of coronal field lines in the Transition Corona, the transitional region between closed and open flux systems, providing important information on eruptive instabilities and on the origin of the slow solar wind. While current instruments routinely observe the photospheric and chromospheric magnetic fields, the proposed airborne spectrometer will take a step toward the direct observation of coronal fields by measuring plasma emission in the infrared at high spatial and spectral resolution. The targeted lines are five forbidden magnetic dipole transitions between 1.4 and 4 um. The airborne system will consist of a telescope, grating spectrometer and pointing/stabilization system to be flown on the NSF/NCAR High-performance Instrumented Airborne Platform for Environmental Research (HIAPER) during the 21 August 2017 total solar eclipse. We will discuss the scientific objectives of the 2017 flight, describe details of the instrument design, and present the observing program for the eclipse.

  6. Fourth Airborne Geoscience Workshop

    NASA Technical Reports Server (NTRS)

    1991-01-01

    The focus of the workshop was on how the airborne community can assist in achieving the goals of the Global Change Research Program. The many activities that employ airborne platforms and sensors were discussed: platforms and instrument development; airborne oceanography; lidar research; SAR measurements; Doppler radar; laser measurements; cloud physics; airborne experiments; airborne microwave measurements; and airborne data collection.

  7. Ground- and aircraft-based cirrus cloud measurements using lidar and high-spectral-resolution FTS during the AFWEX 2000 field campaign

    NASA Astrophysics Data System (ADS)

    DeSlover, Daniel H.; Turner, David; Whiteman, David N.; Smith, William L.

    2002-09-01

    The ARM-FIRE Water Vapor Experiment (AFWEX) was conducted during November-December 2000 at the Southern Great Plains (SGP) Cloud and Radiation Testbed (CART). A cirrus event which occurred on 7-8 December was analyzed using ground- and aircraft-based measurements. The ground-based Atmospheric Emitted Radiance Interferometer (AERI) and NPOESS Airborne Sounder Testbed-Interferometer (NAST-I) are high spectral resolution interferometers which measure downwelling and upwelling infrared radiation, respectively. Analysis between water vapor absorption lines within the 8 to 12 micrometers atmospheric window allow inversion of the radiative transfer equation to derive the cirrus cloud optical depth. These data will be compared to ground-based Raman lidar (GSFC and ARM) measurements of cirrus optical depth. The NAST-I measurements were conducted from the Proteus aircraft.

  8. Use of high-performance liquid chromatography to assess airborne mycotoxins. Aflatoxins and ochratoxin A.

    PubMed

    Tarín, A; Rosell, M G; Guardino, X

    2004-08-27

    An HPLC analytical method combining methanol-deionised water (80:20, v/v) extraction, methanol-acetonitrile (50:50, v/v) extraction and fluorescence detection was implanted to analyse ochratoxin A and aflatoxins B1, B2, G1 and G2 of air samples collected during the usual production process in a number of workplaces of a coffee factory to assess the occupational exposure of the engaged workers. The average levels of airborne ochratoxin A and aflatoxins were less than 1.2 and 0.4 ng/m3, respectively, using 50 L air samples. When 150 L air samples were used, levels lower than 0.04 ng/m3 ochratoxin A and 0.013 ng/m3 for aflatoxins B1, B2, G1 and G2, could be detected.

  9. High-resolution satellite and airborne thermal infrared imaging of precursory unrest and 2009 eruption of Redoubt Volcano, Alaska

    USGS Publications Warehouse

    Wessels, Rick L.; Vaughan, R. Greg; Patrick, Matthew R.; Coombs, Michelle L.

    2013-01-01

    A combination of satellite and airborne high-resolution visible and thermal infrared (TIR) image data detected and measured changes at Redoubt Volcano during the 2008–2009 unrest and eruption. The TIR sensors detected persistent elevated temperatures at summit ice-melt holes as seismicity and gas emissions increased in late 2008 to March 2009. A phreatic explosion on 15 March was followed by more than 19 magmatic explosive events from 23 March to 4 April that produced high-altitude ash clouds and large lahars. Two (or three) lava domes extruded and were destroyed between 23 March and 4 April. After 4 April, the eruption extruded a large lava dome that continued to grow until at least early July 2009.

  10. Compensation of spectral and RF errors in swept-source OCT for high extinction complex demodulation

    PubMed Central

    Siddiqui, Meena; Tozburun, Serhat; Zhang, Ellen Ziyi; Vakoc, Benjamin J.

    2015-01-01

    We provide a framework for compensating errors within passive optical quadrature demodulation circuits used in swept-source optical coherence tomography (OCT). Quadrature demodulation allows for detection of both the real and imaginary components of an interference fringe, and this information separates signals from positive and negative depth spaces. To achieve a high extinction (∼60 dB) between these positive and negative signals, the demodulation error must be less than 0.1% in amplitude and phase. It is difficult to construct a system that achieves this low error across the wide spectral and RF bandwidths of high-speed swept-source systems. In a prior work, post-processing methods for removing residual spectral errors were described. Here, we identify the importance of a second class of errors originating in the RF domain, and present a comprehensive framework for compensating both spectral and RF errors. Using this framework, extinctions >60 dB are demonstrated. A stability analysis shows that calibration parameters associated with RF errors are accurate for many days, while those associated with spectral errors must be updated prior to each imaging session. Empirical procedures to derive both RF and spectral calibration parameters simultaneously and to update spectral calibration parameters are presented. These algorithms provide the basis for using passive optical quadrature demodulation circuits with high speed and wide-bandwidth swept-source OCT systems. PMID:25836784

  11. Spectral shape variation of interstellar electrons at high energies

    NASA Technical Reports Server (NTRS)

    Tan, L. C.

    1985-01-01

    The high energy electron spectrum analysis has shown that the electron intensity inside the H2 cloud region, or in a spiral arm, should be much lower than that outside it and the observed electron energy spectrum should flatten again at about 1 TeV. In the framework of the leady box model the recently established rigidity dependence of the escape pathlength of cosmic rays would predict a high energy electron spectrum which is flatter than the observed one. This divergence is explained by assuming that the leaky box model can only apply to cosmic ray heavy nuclei, and light nuclei and electrons in cosmic rays may have different behaviors in the interstellar propagation. Therefore, the measured data on high energy electrons should be analyzed based on the proposed nonuniform galactic disk (NUGD) mode.

  12. Airborne Oceanographic Lidar System

    NASA Technical Reports Server (NTRS)

    Bressel, C.; Itzkan, I.; Nunes, J. E.; Hoge, F.

    1977-01-01

    The Airborne Oceanographic Lidar (AOL), a spatially scanning range-gated device installed on board a NASA C-54 aircraft, is described. The AOL system is capable of measuring topographical relief or water depth (bathymetry) with a range resolution of plus or minus 0.3 m in the vertical dimension. The system may also be used to measure fluorescent spectral signatures from 3500 to 8000 A with a resolution of 100 A. Potential applications of the AOL, including sea state measurements, water transparency assessments, oil spill identification, effluent identification and crop cover assessment are also mentioned.

  13. The spectral lines of highly charged gold ions

    NASA Astrophysics Data System (ADS)

    Hu, Feng; Yang, Jiamin; Zhang, Jiyan; Jiang, Gang

    2015-02-01

    Extreme ultraviolet spectra of highly charged gold were produced with an electron beam ion trap at the University of Electro-Communications, Tokyo. The X-ray spectra (3240-3360 eV) of Au with well-defined maximum charge states ranging from Cu- to Se-like ions were recorded. Guided by configuration interaction calculations, the strongest 3d-5f transitions have been well defined.

  14. Nonadiabatic spectral redshift of high-order harmonics with the help of a VUV pulse

    NASA Astrophysics Data System (ADS)

    Du, Hongchuan; Xue, Shan; Wang, Huiqiao; Zhang, Zhilei; Hu, Bitao

    2015-06-01

    We theoretically investigate the nonadiabatic spectral redshift of high-order harmonics with the help of a VUV pulse. It is found that the nonadiabatic spectral redshift of high-order harmonics can be observed when a weak VUV pulse is properly added in the falling part of the fundamental laser due to the nonadiabatic response of the dipole to rapid change of laser intensity. Further time-frequency analysis shows that the high-order harmonics are mainly generated in the falling part of the fundamental pulse. This is because the VUV pulse enhances the ionization in the falling part of the fundamental pulse by the 1s-2p transition of He+ . In addition, this scheme is also used to observe the nonadiabatic spectral blueshift of high-order harmonics by changing the time delay between the fundamental laser and the VUV pulse.

  15. Airborne multispectral detection of regrowth cotton fields

    NASA Astrophysics Data System (ADS)

    Westbrook, John K.; Suh, Charles P.-C.; Yang, Chenghai; Lan, Yubin; Eyster, Ritchie S.

    2015-01-01

    Effective methods are needed for timely areawide detection of regrowth cotton plants because boll weevils (a quarantine pest) can feed and reproduce on these plants beyond the cotton production season. Airborne multispectral images of regrowth cotton plots were acquired on several dates after three shredding (i.e., stalk destruction) dates. Linear spectral unmixing (LSU) classification was applied to high-resolution airborne multispectral images of regrowth cotton plots to estimate the minimum detectable size and subsequent growth of plants. We found that regrowth cotton fields can be identified when the mean plant width is ˜0.2 m for an image resolution of 0.1 m. LSU estimates of canopy cover of regrowth cotton plots correlated well (r2=0.81) with the ratio of mean plant width to row spacing, a surrogate measure of plant canopy cover. The height and width of regrowth plants were both well correlated (r2=0.94) with accumulated degree-days after shredding. The results will help boll weevil eradication program managers use airborne multispectral images to detect and monitor the regrowth of cotton plants after stalk destruction, and identify fields that may require further inspection and mitigation of boll weevil infestations.

  16. Seasonal variability in airborne bacterial communities at a high elevation site and their relationship to other air studies and to potential sources

    NASA Astrophysics Data System (ADS)

    Bowers, R. M.; Mccubbin, I. B.; Hallar, A. G.; Fierer, N.

    2012-12-01

    Airborne bacteria are a large component of the near-surface atmospheric aerosol; however we know surprisingly little about their spatiotemporal dynamics and even less about their distributions at high-elevation. With this work, we describe seasonal shifts in bacterial abundances, total particle abundances, and bacterial community structure at a high-elevation research station located in Colorado, USA. In addition, we describe the unique composition of these high-elevation airborne bacterial communities as compared to the bacteria commonly observed throughout the lower elevation atmosphere as well as bacteria common to major sources such as leaf surfaces, soils, water bodies and various other surfaces. To address these knowledge gaps, we collected aerosol samples on the rooftop of Storm Peak Laboratory (3200 m ASL) over the course of 2-3 week periods during each of the four calendar seasons. Total bacterial abundances were assessed via flow cytometry, total particle abundances were calculated with an aerodynamic particle sizer, and bacterial communities were characterized using a high-throughput barcoded DNA sequencing approach. The airborne bacterial communities at Storm Peak Lab were then used in a meta-analysis comparing Storm Peak bacteria to other near-surface (lower elevation) bacterial communities and to the communities of likely source environments. Bacterial abundances varied by season, which was similar but not identical to the changes in total particle abundances across the same sampling period. Airborne bacterial community structure varied significantly by season, with the summer communities being the most distinct. Season specific bacterial groups were identified, suggesting that a large proportion of the airborne community may be derived from nearby sources. However following a multi-environment meta-analysis using several air and source derived bacterial community datasets, the high-elevation air communities were the most distinct as compared to the

  17. Airborne Particles.

    ERIC Educational Resources Information Center

    Ojala, Carl F.; Ojala, Eric J.

    1987-01-01

    Describes an activity in which students collect airborne particles using a common vacuum cleaner. Suggests ways for the students to convert their data into information related to air pollution and human health. Urges consideration of weather patterns when analyzing the results of the investigation. (TW)

  18. Airborne Imagery

    NASA Technical Reports Server (NTRS)

    1983-01-01

    ATM (Airborne Thematic Mapper) was developed for NSTL (National Space Technology Companies) by Daedalus Company. It offers expanded capabilities for timely, accurate and cost effective identification of areas with prospecting potential. A related system is TIMS, Thermal Infrared Multispectral Scanner. Originating from Landsat 4, it is also used for agricultural studies, etc.

  19. High sensitivity dynamic spectral search for flare star radio

    NASA Technical Reports Server (NTRS)

    Abada-Simon, M.; Lecacheux, A.; Louarn, P.; Dulk, G. A.; Belkora, L.; Bookbinder, J. A.; Rosolen, C.

    1994-01-01

    We observed ten well-known flare stars with the Arcibo radio telescope at 1.4 GHz and 5 GHz, using a special observing technique to discriminate between real flares and radio freqeuncy interference. With a high sensitivity of 5.5 K/Jy at 1.4 GHz when averaged over a 50 MHz band, we are able to recognize flux enhancements as weak as approximately 6 mJy above the sky background variations. In about 85 hours of observation, about a dozen bursts were detected, only from AD Leo. All had flux densities lower than 70 mJy, which probably explains their lack of fine structures (except for the strongest one), such as were reported in the literature for stronger flares. Half of the bursts that we recorded are 100% circularly polarized, and half are not circularly polarized. Our results are a first attempt of reliable statistics on dMe flare rates at 1.4 GHz. The high brightness temperatures we infer for the observed bursts are interpreted in terms of coherent emission processes, either the cyclotron maser instability or plasma radiation. Efficiencies are comparable to those of solar or planetary radio emissions in the case of the cyclotron maser, and higher than the solar efficiency in the case of plasma radiation, with the caveat that there are great uncertainties in the coronal model and the source size.

  20. Spectral variability of the Martian high latitude surfaces

    NASA Astrophysics Data System (ADS)

    Poulet, F.; Langevin, Y.; Boubin, G.; Jouglet, D.; Bibring, J.-P.; Gondet, B.

    2008-10-01

    We report the surface distributions of some minerals in the high latitude (>50°) regions of Mars using the OMEGA/MEx observations in the near-infrared wavelength domains (1-2.5 μm). Mafic minerals (pyroxene and olivine) are observed in the low albedo terrains. The identification of these minerals is consistent with the presence of volcanic features identified by geologic mappings. Water-bearing minerals identified on the basis of the 1.9 μm band cover the surfaces of latitudes larger than 60°. The presence of this hydration is likely the result of diffusive exchange of water between the sub-surface ice, the pore space of the regolith and the atmosphere, rather than chemically bound water resulting from hydrous alteration during the formation of the minerals. These observations will allow for comprehensive, coordinated analyses of data from the orbital and Phoenix platforms.

  1. Broadband high resolution X-ray spectral analyzer

    DOEpatents

    Silver, Eric H.; Legros, Mark; Madden, Norm W.; Goulding, Fred; Landis, Don

    1998-01-01

    A broad bandwidth high resolution x-ray fluorescence spectrometer has a performance that is superior in many ways to those currently available. It consists of an array of 4 large area microcalorimeters with 95% quantum efficiency at 6 keV and it produces x-ray spectra between 0.2 keV and 7 keV with an energy resolution of 7 to 10 eV. The resolution is obtained at input count rates per array element of 10 to 50 Hz in real-time, with analog pulse processing and thermal pile-up rejection. This performance cannot be matched by currently available x-ray spectrometers. The detectors are incorporated into a compact and portable cryogenic refrigerator system that is ready for use in many analytical spectroscopy applications as a tool for x-ray microanalysis or in research applications such as laboratory and astrophysical x-ray and particle spectroscopy.

  2. Broadband high resolution X-ray spectral analyzer

    DOEpatents

    Silver, E.H.; Legros, M.; Madden, N.W.; Goulding, F.; Landis, D.

    1998-07-07

    A broad bandwidth high resolution X-ray fluorescence spectrometer has a performance that is superior in many ways to those currently available. It consists of an array of 4 large area microcalorimeters with 95% quantum efficiency at 6 keV and it produces X-ray spectra between 0.2 keV and 7 keV with an energy resolution of 7 to 10 eV. The resolution is obtained at input count rates per array element of 10 to 50 Hz in real-time, with analog pulse processing and thermal pile-up rejection. This performance cannot be matched by currently available X-ray spectrometers. The detectors are incorporated into a compact and portable cryogenic refrigerator system that is ready for use in many analytical spectroscopy applications as a tool for X-ray microanalysis or in research applications such as laboratory and astrophysical X-ray and particle spectroscopy. 6 figs.

  3. An investigation of airborne GPS/INS for high accuracy position and velocity determination

    SciTech Connect

    Sun, H.; Cannon, M.E.; Owen, T.E.; Meindl, M.A.

    1993-12-31

    An airborne test using a differential GPS-INS system in a Twin Otter was conducted by Sandia National Laboratories to assess the feasibility of using the integrated system for cm-level position and cm/s velocity. The INS is a miniaturized ring-laser gyro IMU jointly developed by Sandia and Honeywell while the GPS system consists of the NovAtel GPSCard{trademark}. INS position, velocity and attitude data were computed using Sandia`s SANDAC flight computer system and logged at 4 Hz and GPS data was acquired at a 1 Hz rate. The mission was approximately 2.5 hours in duration and the aircraft reached separations of up to 19 km from the base station. The data was post-processed using a centralized Kalman filter approach in which the double differenced carrier phase measurements are used to update the INS data. The INS position is in turn used to detect and correct GPS carrier phase cycle slips and also to bridge GPS outages. Results are presented for the GPS-only case and also for integrated GPS/INS.

  4. Selective suppression of high-order harmonics within phase-matched spectral regions.

    PubMed

    Lerner, Gavriel; Diskin, Tzvi; Neufeld, Ofer; Kfir, Ofer; Cohen, Oren

    2017-04-01

    Phase matching in high-harmonic generation leads to enhancement of multiple harmonics. It is sometimes desired to control the spectral structure within the phase-matched spectral region. We propose a scheme for selective suppression of high-order harmonics within the phase-matched spectral region while weakly influencing the other harmonics. The method is based on addition of phase-mismatched segments within a phase-matched medium. We demonstrate the method numerically in two examples. First, we show that one phase-mismatched segment can significantly suppress harmonic orders 9, 15, and 21. Second, we show that two phase-mismatched segments can efficiently suppress circularly polarized harmonics with one helicity over the other when driven by a bi-circular field. The new method may be useful for various applications, including the generation of highly helical bright attosecond pulses.

  5. Retrieval of high-spectral-resolution lidar for atmospheric aerosol optical properties profiling

    NASA Astrophysics Data System (ADS)

    Liu, Dong; Luo, Jing; Yang, Yongying; Cheng, Zhongtao; Zhang, Yupeng; Zhou, Yudi; Duan, Lulin; Su, Lin

    2015-10-01

    High-spectral-resolution lidars (HSRLs) are increasingly being developed for atmospheric aerosol remote sensing applications due to the straightforward and independent retrieval of aerosol optical properties without reliance on assumptions about lidar ratio. In HSRL technique, spectral discrimination between scattering from molecules and aerosol particles is one of the most critical processes, which needs to be accomplished by means of a narrowband spectroscopic filter. To ensure a high retrieval accuracy of an HSRL system, the high-quality design of its spectral discrimination filter should be made. This paper reviews the available algorithms that were proposed for HSRLs and makes a general accuracy analysis of the HSRL technique focused on the spectral discrimination, in order to provide heuristic guidelines for the reasonable design of the spectral discrimination filter. We introduce a theoretical model for retrieval error evaluation of an HSRL instrument with general three-channel configuration. Monte Carlo (MC) simulations are performed to validate the correctness of the theoretical model. Results from both the model and MC simulations agree very well, and they illustrate one important, although not well realized fact: a large molecular transmittance and a large spectral discrimination ratio (SDR, i.e., ratio of the molecular transmittance to the aerosol transmittance) are beneficial t o promote the retrieval accuracy. The application of the conclusions obtained in this paper in the designing of a new type of spectroscopic filter, that is, the field-widened Michelson interferometer, is illustrated in detail. These works are with certain universality and expected to be useful guidelines for HSRL community, especially when choosing or designing the spectral discrimination filter.

  6. A Spectral Finite Element Approach to Modeling Soft Solids Excited with High-Frequency Harmonic Loads.

    PubMed

    Brigham, John C; Aquino, Wilkins; Aguilo, Miguel A; Diamessis, Peter J

    2011-01-15

    An approach for efficient and accurate finite element analysis of harmonically excited soft solids using high-order spectral finite elements is presented and evaluated. The Helmholtz-type equations used to model such systems suffer from additional numerical error known as pollution when excitation frequency becomes high relative to stiffness (i.e. high wave number), which is the case, for example, for soft tissues subject to ultrasound excitations. The use of high-order polynomial elements allows for a reduction in this pollution error, but requires additional consideration to counteract Runge's phenomenon and/or poor linear system conditioning, which has led to the use of spectral element approaches. This work examines in detail the computational benefits and practical applicability of high-order spectral elements for such problems. The spectral elements examined are tensor product elements (i.e. quad or brick elements) of high-order Lagrangian polynomials with non-uniformly distributed Gauss-Lobatto-Legendre nodal points. A shear plane wave example is presented to show the dependence of the accuracy and computational expense of high-order elements on wave number. Then, a convergence study for a viscoelastic acoustic-structure interaction finite element model of an actual ultrasound driven vibroacoustic experiment is shown. The number of degrees of freedom required for a given accuracy level was found to consistently decrease with increasing element order. However, the computationally optimal element order was found to strongly depend on the wave number.

  7. A Spectral Finite Element Approach to Modeling Soft Solids Excited with High-Frequency Harmonic Loads

    PubMed Central

    Brigham, John C.; Aquino, Wilkins; Aguilo, Miguel A.; Diamessis, Peter J.

    2010-01-01

    An approach for efficient and accurate finite element analysis of harmonically excited soft solids using high-order spectral finite elements is presented and evaluated. The Helmholtz-type equations used to model such systems suffer from additional numerical error known as pollution when excitation frequency becomes high relative to stiffness (i.e. high wave number), which is the case, for example, for soft tissues subject to ultrasound excitations. The use of high-order polynomial elements allows for a reduction in this pollution error, but requires additional consideration to counteract Runge's phenomenon and/or poor linear system conditioning, which has led to the use of spectral element approaches. This work examines in detail the computational benefits and practical applicability of high-order spectral elements for such problems. The spectral elements examined are tensor product elements (i.e. quad or brick elements) of high-order Lagrangian polynomials with non-uniformly distributed Gauss-Lobatto-Legendre nodal points. A shear plane wave example is presented to show the dependence of the accuracy and computational expense of high-order elements on wave number. Then, a convergence study for a viscoelastic acoustic-structure interaction finite element model of an actual ultrasound driven vibroacoustic experiment is shown. The number of degrees of freedom required for a given accuracy level was found to consistently decrease with increasing element order. However, the computationally optimal element order was found to strongly depend on the wave number. PMID:21461402

  8. Spectral characteristics of high-power 1. 5. mu. m broad-band superluminescent fiber sources

    SciTech Connect

    Wysocki, P.F.; Digonnet, M.J.F.; Kim, B.Y. . Edward L. Ginzton Lab.)

    1990-03-01

    The authors study the spectral variation of spontaneous emission from erbium-doped single-mode fibers with the aim of producing high-power (more than 5 mW), broad-band (in excess of 10 nm) amplified spontaneous emission sources for fiber gyroscope applications. In particular, they demonstrate the evolution of spectral shape and center wavelength with fiber length and output power in the previously unstudied high-power regime where saturation effects dominate. Also presented is a visibility curve for a potential twin-peaked nonresonant erbium-doped fiber gyroscope source with a short (210 {mu}m) coherence length.

  9. High-Sensitivity Optical Pulse Characterization Using Sagnac Electro-Optic Spectral Shearing Interferometry

    SciTech Connect

    Dorrer, C.; Bromage, J.

    2010-05-04

    An electro-optic spectral shearing interferometer for high-sensitivity optical pulse characterization is described. Two replicas of the test pulse counterpropagate in a Sagnac interferometer with orthogonal polarization states, resulting in two relatively sheared copolarized replicas after temporal phase modulation. The polarization interferometer is intrinsically stable, and its birefringence sets the delay between interfering replicas to reduce the spectrometer resolution requirement. Experimental implementations demonstrate real-time pulse characterization at average powers as low as 1 nWwith spectral shears as high as 280 GHz.

  10. High spectral power femtosecond supercontinuum source by use of microlens array.

    PubMed

    Camino, Acner; Hao, Zuoqiang; Liu, Xu; Lin, Jingquan

    2014-02-15

    Generation of a high spectral power supercontinuum (SC) is reported from controlled multifilamentation of femtosecond pulses in fused silica. The use of a microlens array allows the manipulation of the filamentation pattern under very high-incident laser pulse energy without sample damage and, consequently, compared with using a single focusing lens, higher power of SC generation with a similar spectral broadening can be obtained. Moreover, the role of the interplay between diffraction pattern and proximity to the focus of the microlens array in SC generation is discussed.

  11. Identification of high explosive RDX using terahertz imaging and spectral fingerprints

    NASA Astrophysics Data System (ADS)

    Liu, Jia; Fan, Wen-Hui; Chen, Xu; Xie, Jun

    2016-01-01

    We experimentally investigated the spectral fingerprints of high explosive cyclo-1,3,5- trimethylene-2,4,6-trinitramine (RDX) in terahertz frequency region. A home-made terahertz time-domain spectroscopy ranging from 0.2 THz∼ 3.4 THz was deployed. Furthermore, two sample pellets (RDX pellet and polyethylene pellet), which were concealed in an opaque envelop, could be identified by using terahertz pulse imaging system. For the purpose of distinguishing the RDX between two pellets, we further calculated the THz frequency -domain map using its spectral fingerprints. It is demonstrated that the high explosive RDX could similarly be identified using terahertz frequency-domain imaging.

  12. High Spectral Resolution, High Cadence, Imaging X-Ray Microcalorimeters for Solar Physics

    NASA Technical Reports Server (NTRS)

    Bandler, Simon R.; Bailey, Catherine N.; Bookbinder, Jay A.; DeLuca, Edward E.; Chervenak, Jay A.; Eckart, Megan E.; Finkbeiner, Fred M.; Kelley, Daniel P.; Kelley, Richard L.; Kilbourne, Caroline A.; Porter, Frederick S.; Sadleir, Jack E.; Smith, Stephen J.; Smith, Randall K.

    2010-01-01

    High spectral resolution, high cadence, imaging x-ray spectroscopy has the potential to revolutionize the study of the solar corona. To that end we have been developing transition-edge-sensor (TES) based x-ray micro calorimeter arrays for future solar physics missions where imaging and high energy resolution spectroscopy will enable previously impossible studies of the dynamics and energetics of the solar corona. The characteristics of these x-ray microcalorimeters are significantly different from conventional micro calorimeters developed for astrophysics because they need to accommodate much higher count rates (300-1000 cps) while maintaining high energy resolution of less than 4 eV FWHM in the X-ray energy band of 0.2-10 keV. The other main difference is a smaller pixel size (less than 75 x 75 square microns) than is typical for x-ray micro calorimeters in order to provide angular resolution less than 1 arcsecond. We have achieved at energy resolution of 2.15 eV at 6 keV in a pixel with a 12 x 12 square micron TES sensor and 34 x 34 x 9.1 micron gold absorber, and a resolution of 2.30 eV at 6 keV in a pixel with a 35 x 35 micron TES and a 57 x 57 x 9.1 micron gold absorber. This performance has been achieved in pixels that are fabricated directly onto solid substrates, ie. they are not supported by silicon nitride membranes. We present the results from these detectors, the expected performance at high count-rates, and prospects for the use of this technology for future Solar missions.

  13. Spectral Unmixing Plate Reader: High-Throughput, High-Precision FRET Assays in Living Cells.

    PubMed

    Schaaf, Tory M; Peterson, Kurt C; Grant, Benjamin D; Thomas, David D; Gillispie, Gregory D

    2017-03-01

    We have developed a microplate reader that records a complete high-quality fluorescence emission spectrum on a well-by-well basis under true high-throughput screening (HTS) conditions. The read time for an entire 384-well plate is less than 3 min. This instrument is particularly well suited for assays based on fluorescence resonance energy transfer (FRET). Intramolecular protein biosensors with genetically encoded green fluorescent protein (GFP) donor and red fluorescent protein (RFP) acceptor tags at positions sensitive to structural changes were stably expressed and studied in living HEK cells. Accurate quantitation of FRET was achieved by decomposing each observed spectrum into a linear combination of four component (basis) spectra (GFP emission, RFP emission, water Raman, and cell autofluorescence). Excitation and detection are both conducted from the top, allowing for thermoelectric control of the sample temperature from below. This spectral unmixing plate reader (SUPR) delivers an unprecedented combination of speed, precision, and accuracy for studying ensemble-averaged FRET in living cells. It complements our previously reported fluorescence lifetime plate reader, which offers the feature of resolving multiple FRET populations within the ensemble. The combination of these two direct waveform-recording technologies greatly enhances the precision and information content for HTS in drug discovery.

  14. High Resolution Airborne Gravity Gradiometer Based on an Othogonal Mass Quadruploe

    NASA Astrophysics Data System (ADS)

    Tryggvason, B. V.

    2003-04-01

    The Gedex Airborne Gravity Gradiometer (AGG) uses an orthogonal quadrupole responder (OQR) developed at the University of Western Australia with support from Rio Tinto. The OQR design is based on pairs of balance beams orientated at 90 degrees to one another, with each beam supported on a micro-flexure. A gradient along the length of a beam in the gravitational acceleration component that is perpendicular to the beam axis and the web axis will generate a small torque about the flexure. With two orthogonal beams, rotations of the base will result in both beams rotating in a common direction compared to the base, whereas the beams will rotate in opposite, or differential, directions due to gravity gradients. The differential rotation arises because of the properties of the gravity gradient tensor. The sensor can thus in principle distinguish between base rotations and gravity gradients. Additionally the beams are designed such that the center of rotation about the supporting flexures coincides with the location of the center of mass of the beams. This eliminates rotational response of the beams when subjected to linear accelerations. Thus the OQR configuration provides a sensor that is inherently insensitive to both rotational and linear accelerations of the support. However, the practical world has a habit of complicating seemingly simple situations. The first design challenge is that fabrication of the beams and the supporting flexures has to be done to very stringent tolerances, which has only recently become possible with the development of technologies such as Electric Discharge Machining (EDM). The second major obstacle is that there are higher order terms in the response of the sensing elements that can be driven by base vibrations and aircraft motions. These require mounting the sensor on an isolation system designed to provide a very low level of disturbance to the gradiometer. In the Gedex development this isolation system is based on technology developed

  15. Highly accurate spectral retardance characterization of a liquid crystal retarder including Fabry-Perot interference effects

    SciTech Connect

    Vargas, Asticio; Mar Sánchez-López, María del; García-Martínez, Pascuala; Arias, Julia; Moreno, Ignacio

    2014-01-21

    Multiple-beam Fabry-Perot (FP) interferences occur in liquid crystal retarders (LCR) devoid of an antireflective coating. In this work, a highly accurate method to obtain the spectral retardance of such devices is presented. On the basis of a simple model of the LCR that includes FP effects and by using a voltage transfer function, we show how the FP features in the transmission spectrum can be used to accurately retrieve the ordinary and extraordinary spectral phase delays, and the voltage dependence of the latter. As a consequence, the modulation characteristics of the device are fully determined with high accuracy by means of a few off-state physical parameters which are wavelength-dependent, and a single voltage transfer function that is valid within the spectral range of characterization.

  16. Compact high-resolution micro-spectrometer on chip: spectral calibration and first spectrum

    NASA Astrophysics Data System (ADS)

    Diard, Thomas; de la Barrière, Florence; Ferrec, Yann; Guérineau, Nicolas; Rommeluère, Sylvain; Le Coarer, Etienne; Martin, Guillermo

    2016-05-01

    Compact and hand-held spectrometers may be very interesting for the measurement of spectral signatures of chemicals or objects. To achieve this goal, ONERA and IPAG have developed a new on chip Fourier Transform Spectrometer operating in the visible spectral range with a high spectral resolution (near 2 cm-1), named visible HR SPOC (visible High Resolution Spectrometer On Chip). It is directly inspired from the MICROSPOC infrared spectrometer, studied at ONERA in the past years. This spectrometer is made of a stair-step two-wave interferometer directly glued on a CMOS detector making it a very compact prototype. After calibrating the optical path difference, measurements of experimental spectra are presented.

  17. Advanced Airborne Hyperspectral Imaging System (AAHIS)

    NASA Astrophysics Data System (ADS)

    Topping, Miles Q.; Pfeiffer, Joel E.; Sparks, Andrew W.; Jim, Kevin T. C.; Yoon, Dugan

    2002-11-01

    The design, operation, and performance of the fourth generation of Science and Technology International's Advanced Airborne Hyperspectral Imaging Sensors (AAHIS) are described. These imaging spectrometers have a variable bandwidth ranging from 390-840 nm. A three-axis image stabilization provides spatially and spectrally coherent imagery by damping most of the airborne platform's random motion. A wide 40-degree field of view coupled with sub-pixel detection allows for a large area coverage rate. A software controlled variable aperture, spectral shaping filters, and high quantum efficiency, back-illuminated CCD's contribute to the excellent sensitivity of the sensors. AAHIS sensors have been operated on a variety of fixed and rotary wing platforms, achieving ground-sampling distances ranging from 6.5 cm to 2 m. While these sensors have been primarily designed for use over littoral zones, they are able to operate over both land and water. AAHIS has been used for detecting and locating submarines, mines, tanks, divers, camouflage and disturbed earth. Civilian applications include search and rescue on land and at sea, agricultural analysis, environmental time-series, coral reef assessment, effluent plume detection, coastal mapping, damage assessment, and seasonal whale population monitoring

  18. APEX - the Hyperspectral ESA Airborne Prism Experiment

    PubMed Central

    Itten, Klaus I.; Dell'Endice, Francesco; Hueni, Andreas; Kneubühler, Mathias; Schläpfer, Daniel; Odermatt, Daniel; Seidel, Felix; Huber, Silvia; Schopfer, Jürg; Kellenberger, Tobias; Bühler, Yves; D'Odorico, Petra; Nieke, Jens; Alberti, Edoardo; Meuleman, Koen

    2008-01-01

    The airborne ESA-APEX (Airborne Prism Experiment) hyperspectral mission simulator is described with its distinct specifications to provide high quality remote sensing data. The concept of an automatic calibration, performed in the Calibration Home Base (CHB) by using the Control Test Master (CTM), the In-Flight Calibration facility (IFC), quality flagging (QF) and specific processing in a dedicated Processing and Archiving Facility (PAF), and vicarious calibration experiments are presented. A preview on major applications and the corresponding development efforts to provide scientific data products up to level 2/3 to the user is presented for limnology, vegetation, aerosols, general classification routines and rapid mapping tasks. BRDF (Bidirectional Reflectance Distribution Function) issues are discussed and the spectral database SPECCHIO (Spectral Input/Output) introduced. The optical performance as well as the dedicated software utilities make APEX a state-of-the-art hyperspectral sensor, capable of (a) satisfying the needs of several research communities and (b) helping the understanding of the Earth's complex mechanisms. PMID:27873868

  19. High-resolution spectral mapping of a lensed high power laser bar

    NASA Astrophysics Data System (ADS)

    Gannon, Caleb D.; Koenning, Tobias; Patterson, Steve G.; Leisher, Paul O.

    2014-03-01

    Alkali gas lasers based on rubidium vapor have an extremely narrow absorption band (<0.01 nm at STP) at 780 nm. Diode-pumped alkali lasers (DPALs) require high-power diode arrays having emission spectra which are closely matched to this absorption peak. There are several methods which can be used for narrowing and stabilizing the output spectrum of a diode laser bar including external locking via a volumetric holographic grating (VHG). While this approach offers several advantages over internal stabilization techniques, the effect of pointing error arising from bar smile can be detrimental to the locked performance of the lensed array. In order to investigate the effect of smile on wavelength locking, a system capable of mapping the emission spectrum of the lensed diode laser bar was developed. The approach utilizes an imaging system and spatial filter to couple light from individual emitters of the lensed array into a commercial optical spectrum analyzer. This approach offers a larger dynamic range than traditional spectral mapping techniques, with a resolved signal to noise ratio in excess of 60 dB. Results from the characterization of a VHG-locked 780 nm laser bar array will be presented.

  20. Spectrally beam combined fiber lasers for high power, efficiency, and brightness

    NASA Astrophysics Data System (ADS)

    Honea, Eric; Afzal, Robert S.; Savage-Leuchs, Matthias; Gitkind, Neil; Humphreys, Richard; Henrie, Jason; Brar, Khush; Jander, Don

    2013-03-01

    Spectral Beam Combining (SBC) of fiber lasers provides a simple, robust architecture for power scaling lasers to high power. With appropriate designs, power scaling beyond the single fiber limit can be achieved while maintaining near diffraction limited beam quality and high efficiency. We present experimental results where we achieved > 3 kW at an M2 = 1.35 and > 39% E-O efficiency by combining 12 individual fiber lasers into a single high brightness beam.

  1. Self-Organized Quantum Dots for High-Performance Multi-Spectral Infrared Photodetectors

    DTIC Science & Technology

    2010-06-29

    31, 2009 Program Managers: Donald Silversmith (AFOSR) PI: Anupam Madhukar University of Southern California Los Angeles, CA 90089-0241 Tel...Quantum Dots for High- Performance Multi-Spectral Infrared Photodetectors” (Jul. 1, 2006- Dec. 31, 2009) Program Managers: Donald Silversmith (AFOSR

  2. Variational multiscale turbulence modelling in a high order spectral element method

    SciTech Connect

    Wasberg, Carl Erik Gjesdal, Thor Reif, Bjorn Anders Pettersson Andreassen, Oyvind

    2009-10-20

    In the variational multiscale (VMS) approach to large eddy simulation (LES), the governing equations are projected onto an a priori scale partitioning of the solution space. This gives an alternative framework for designing and analyzing turbulence models. We describe the implementation of the VMS LES methodology in a high order spectral element method with a nodal basis, and discuss the properties of the proposed scale partitioning. The spectral element code is first validated by doing a direct numerical simulation of fully developed plane channel flow. The performance of the turbulence model is then assessed by several coarse grid simulations of channel flow at different Reynolds numbers.

  3. Airborne FTIR remote sensing of methane from the FAAM aircraft

    NASA Astrophysics Data System (ADS)

    Allen, Grant; Illingworth, Samuel; Mead, Iq; Harlow, Chawn; Newman, Stuart; Vance, Alan

    2015-04-01

    This paper presents the first campaign results for retrievals of methane (and other gases and thermodynamic parameters) from the Airborne Research Interferometer Evaluation System (ARIES) FTIR instrument on the UK Facility for Airborne Atmospheric Measurement (FAAM) BAE-146 aircraft. The ARIES is a thermal infrared BOMEM FTS tailored for airborne use and has an unapodised spectral resolution of 1 cm-1. It was developed as an IASI analogue for radiometric calibration of its satellite countepart. We will discuss the technical and theoretical assessment of the ARIES retrieval processor and present retrievals and interpretation of remote sampling over several years of campaign data in the tropics, around the UK, and in the high Arctic, during the Jaivex, GAUGE and MAMM campaigns respectively. Validation studies against airborne in situ data have shown that ARIES can achieve accuracties of ~2% in partial column retrievals of methane, while providing simultaneous information on a wide range of other trace gases typical of FTIR measurement. The ARIES has now beein in operation on the FAAM aircraft for a range of campaigns around the world and represents a useful validation bridge between high precision in situ point measurements (on the ground and by aircraft) and satellite remote sensing.

  4. Real-time high-resolution heterodyne-based measurements of spectral dynamics in fibre lasers

    NASA Astrophysics Data System (ADS)

    Sugavanam, Srikanth; Fabbri, Simon; Le, Son Thai; Lobach, Ivan; Kablukov, Sergey; Khorev, Serge; Churkin, Dmitry

    2016-03-01

    Conventional tools for measurement of laser spectra (e.g. optical spectrum analysers) capture data averaged over a considerable time period. However, the generation spectrum of many laser types may involve spectral dynamics whose relatively fast time scale is determined by their cavity round trip period, calling for instrumentation featuring both high temporal and spectral resolution. Such real-time spectral characterisation becomes particularly challenging if the laser pulses are long, or they have continuous or quasi-continuous wave radiation components. Here we combine optical heterodyning with a technique of spatio-temporal intensity measurements that allows the characterisation of such complex sources. Fast, round-trip-resolved spectral dynamics of cavity-based systems in real-time are obtained, with temporal resolution of one cavity round trip and frequency resolution defined by its inverse (85 ns and 24 MHz respectively are demonstrated). We also show how under certain conditions for quasi-continuous wave sources, the spectral resolution could be further increased by a factor of 100 by direct extraction of phase information from the heterodyned dynamics or by using double time scales within the spectrogram approach.

  5. Compact hybrid real-time hyperspectral imaging system with high effective spatial, spectral, and temporal resolution

    NASA Astrophysics Data System (ADS)

    Roth, Filip; Abbadi, Ahmad; Herman, Ondrej; Pavelek, Martin; Prenosil, Vaclav

    2016-10-01

    Medical endoscopes for image-guided surgery commonly use standard color image sensors, discarding any more detailed spectral information. Medical spectroscopy devices with various spectral working ranges are specialized to specific medical procedures and in general are not usable for image-guided surgery due to limitations in spatial or temporal resolution. In this paper, we present an initial demonstrator of hyperspectral endoscope, composed of two image sensors with complementing parameters. Using this hybrid approach, combining sensors with different spatial and spectral resolutions and spectral ranges, we obtain improved coverage of all the respective parameters. After digitally processing and merging the video streams, while maintaining the better features of both, we obtain an imaging system providing high effective spatial, spectral, and temporal resolution. The system is based on field programmable gate arrays. It provides real-time video output (60 Hz), which is usable for navigation during image-guided surgery. The flexible system architecture allows for an easy extension of the processing algorithms and enables minimal video signal latency. Physical dimensions and portability of the system are comparable to standard off-the-shelf medical endoscope cameras. The device can output both processed video and standard visible light video signals on one or more video outputs of the system. The resulting processed video signal obtained from the combined image sensor data greatly increases the amount of useful information available to the end user.

  6. Real-time high-resolution heterodyne-based measurements of spectral dynamics in fibre lasers.

    PubMed

    Sugavanam, Srikanth; Fabbri, Simon; Le, Son Thai; Lobach, Ivan; Kablukov, Sergey; Khorev, Serge; Churkin, Dmitry

    2016-03-17

    Conventional tools for measurement of laser spectra (e.g. optical spectrum analysers) capture data averaged over a considerable time period. However, the generation spectrum of many laser types may involve spectral dynamics whose relatively fast time scale is determined by their cavity round trip period, calling for instrumentation featuring both high temporal and spectral resolution. Such real-time spectral characterisation becomes particularly challenging if the laser pulses are long, or they have continuous or quasi-continuous wave radiation components. Here we combine optical heterodyning with a technique of spatio-temporal intensity measurements that allows the characterisation of such complex sources. Fast, round-trip-resolved spectral dynamics of cavity-based systems in real-time are obtained, with temporal resolution of one cavity round trip and frequency resolution defined by its inverse (85 ns and 24 MHz respectively are demonstrated). We also show how under certain conditions for quasi-continuous wave sources, the spectral resolution could be further increased by a factor of 100 by direct extraction of phase information from the heterodyned dynamics or by using double time scales within the spectrogram approach.

  7. Real-time high-resolution heterodyne-based measurements of spectral dynamics in fibre lasers

    PubMed Central

    Sugavanam, Srikanth; Fabbri, Simon; Le, Son Thai; Lobach, Ivan; Kablukov, Sergey; Khorev, Serge; Churkin, Dmitry

    2016-01-01

    Conventional tools for measurement of laser spectra (e.g. optical spectrum analysers) capture data averaged over a considerable time period. However, the generation spectrum of many laser types may involve spectral dynamics whose relatively fast time scale is determined by their cavity round trip period, calling for instrumentation featuring both high temporal and spectral resolution. Such real-time spectral characterisation becomes particularly challenging if the laser pulses are long, or they have continuous or quasi-continuous wave radiation components. Here we combine optical heterodyning with a technique of spatio-temporal intensity measurements that allows the characterisation of such complex sources. Fast, round-trip-resolved spectral dynamics of cavity-based systems in real-time are obtained, with temporal resolution of one cavity round trip and frequency resolution defined by its inverse (85 ns and 24 MHz respectively are demonstrated). We also show how under certain conditions for quasi-continuous wave sources, the spectral resolution could be further increased by a factor of 100 by direct extraction of phase information from the heterodyned dynamics or by using double time scales within the spectrogram approach. PMID:26984634

  8. Approximate Solution Methods for Spectral Radiative Transfer in High Refractive Index Layers

    NASA Technical Reports Server (NTRS)

    Siegel, R.; Spuckler, C. M.

    1994-01-01

    Some ceramic materials for high temperature applications are partially transparent for radiative transfer. The refractive indices of these materials can be substantially greater than one which influences internal radiative emission and reflections. Heat transfer behavior of single and laminated layers has been obtained in the literature by numerical solutions of the radiative transfer equations coupled with heat conduction and heating at the boundaries by convection and radiation. Two-flux and diffusion methods are investigated here to obtain approximate solutions using a simpler formulation than required for exact numerical solutions. Isotropic scattering is included. The two-flux method for a single layer yields excellent results for gray and two band spectral calculations. The diffusion method yields a good approximation for spectral behavior in laminated multiple layers if the overall optical thickness is larger than about ten. A hybrid spectral model is developed using the two-flux method in the optically thin bands, and radiative diffusion in bands that are optically thick.

  9. Stable high-spectral-flatness mid-infrared supercontinuum generation in Tm-doped fiber amplifier

    NASA Astrophysics Data System (ADS)

    Xue, Guanghui; Zhang, Bin; Yang, Weiqiang; Yin, Ke; Hou, Jing

    2015-08-01

    We demonstrate a stable high-spectral-flatness mid-infrared (mid-IR) supercontinuum (SC) generation in a thulium-doped fiber amplifier (TDFA) with an average output power of 2.32 W in a spectral band of ∼(1875-2700 nm). A 1550 nm distributed feedback (DFB) pulsed laser diode (LD) with repetition rate of 600 kHz and pulse width of 900 ps was used as the seed source. The measured long term stability of SC output power is less than 1.1% rms (root mean square) at the average output power of 2.32 W. The measured slope efficiency from the 793 nm pump power of the TDFA to the total SC output power is ∼14%. The output SC has a 6 dB spectral flatness in the wavelength ranging from 1955 to 2505 nm (550 nm span) at the average output power of 2.32 W.

  10. Integration of spectral coronagraphy within VIPA-based spectrometers for high extinction Brillouin imaging

    NASA Astrophysics Data System (ADS)

    Edrei, Eitan; Gather, Malte C.; Scarcelli, Giuliano

    2017-03-01

    VIPA-based spectrometers have enabled rapid Brillouin spectrum measurements and current designs of multi-stage VIPA spectrometers offer enough spectral extinction to probe transparent tissue, cells and biomaterials. However, in highly scattering media or in the presence of strong back-reflections, such as at interfaces between materials of different refractive indices, VIPA-based Brillouin spectral measurements are limited. While several approaches to address this issue have recently been pursued, important challenges remain. Here we have adapted the design of coronagraphs used for exosolar planet imaging to the spectral domain and integrated it in a double-stage VIPA spectrometer. We demonstrate that this yields an increase in extinction up to 20dB, with nearly no added insertion loss. The power of this improvement is vividly demonstrated by Brillouin imaging close to reflecting interfaces without need of index matching or sample tilting

  11. Highly Integrated Polysulfone/polyacrylonitrile/polyamide-6 Air Filter for Multi-level Physical Sieving Airborne Particles.

    PubMed

    Zhang, Shichao; Tang, Ning; Cao, Leitao; Yin, Xia; Yu, Jianyong; Ding, Bin

    2016-10-04

    Rational structural design involving controlled pore size, high porosity, and particle-targeted function is critical to the realization of highly efficient air filters, and the filter with absolute particle-screen ability has significant technological implications for applications including individual protection, industrial security, and environmental governance; however, it remains an ongoing challenge. In this study, we first report a facile and scalable strategy to fabricate the highly integrated polysulfone/polyacrylonitrile/polyamide-6 (PSU/PAN/PA-6) air filter for multi-level physical sieving airborne particles via sequential electrospinning. Our strategy causes the PSU microfiber (diameter of ~1 μm) layer, PAN nanofiber (diameter of ~200 nm) layer, and PA-6 nanonets (diameter of ~20 nm) layer to orderly assemble into the integrated filter with gradually varied pore structures and high porosity; thus enables the filter to work efficiently by employing different layers to cut off penetration of particles with certain size that exceeds the designed threshold level. By virtue of its elaborate gradient structure, robust hydrophobicity (WCA of ~130o), and superior mechanical property (5.6 MPa), our PSU/PAN/PA-6 filter even can filtrate the 300 nm particles with a high removal efficiency of 99.992% and a low pressure drop of 118 Pa in the way of physical sieving manner, which completely gets rid of the negative impact from high airflow speed, electret failure, and high humidity. It is expected that our highly integrated filter has wider applications for filtration and separation, and design of 3D functional structure in the future.

  12. Ecosystem services - from assessements of estimations to quantitative, validated, high-resolution, continental-scale mapping via airborne LIDAR

    NASA Astrophysics Data System (ADS)

    Zlinszky, András; Pfeifer, Norbert

    2016-04-01

    service potential" which is the ability of the local ecosystem to deliver various functions (water retention, carbon storage etc.), but can't quantify how much of these are actually used by humans or what the estimated monetary value is. Due to its ability to measure both terrain relief and vegetation structure in high resolution, airborne LIDAR supports direct quantification of the properties of an ecosystem that lead to it delivering a given service (such as biomass, water retention, micro-climate regulation or habitat diversity). In addition, its high resolution allows direct calibration with field measurements: routine harvesting-based ecological measurements, local biodiversity indicator surveys or microclimate recordings all take place at the human scale and can be directly linked to the local value of LIDAR-based indicators at meter resolution. Therefore, if some field measurements with standard ecological methods are performed on site, the accuracy of LIDAR-based ecosystem service indicators can be rigorously validated. With this conceptual and technical approach high resolution ecosystem service assessments can be made with well established credibility. These would consolidate the concept of ecosystem services and support both scientific research and evidence-based environmental policy at local and - as data coverage is continually increasing - continental scale.

  13. Routing architecture and security for airborne networks

    NASA Astrophysics Data System (ADS)

    Deng, Hongmei; Xie, Peng; Li, Jason; Xu, Roger; Levy, Renato

    2009-05-01

    Airborne networks are envisioned to provide interconnectivity for terrestial and space networks by interconnecting highly mobile airborne platforms. A number of military applications are expected to be used by the operator, and all these applications require proper routing security support to establish correct route between communicating platforms in a timely manner. As airborne networks somewhat different from traditional wired and wireless networks (e.g., Internet, LAN, WLAN, MANET, etc), security aspects valid in these networks are not fully applicable to airborne networks. Designing an efficient security scheme to protect airborne networks is confronted with new requirements. In this paper, we first identify a candidate routing architecture, which works as an underlying structure for our proposed security scheme. And then we investigate the vulnerabilities and attack models against routing protocols in airborne networks. Based on these studies, we propose an integrated security solution to address routing security issues in airborne networks.

  14. Airborne measurements in the longwave infrared using an imaging hyperspectral sensor

    NASA Astrophysics Data System (ADS)

    Allard, Jean-Pierre; Chamberland, Martin; Farley, Vincent; Marcotte, Frédérick; Rolland, Matthias; Vallières, Alexandre; Villemaire, André

    2008-07-01

    Emerging applications in Defense and Security require sensors with state-of-the-art sensitivity and capabilities. Among these sensors, the imaging spectrometer is an instrument yielding a large amount of rich information about the measured scene. Standoff detection, identification and quantification of chemicals in the gaseous state is one important application. Analysis of the surface emissivity as a means to classify ground properties and usage is another one. Imaging spectrometers have unmatched capabilities to meet the requirements of these applications. Telops has developed the FIRST, a LWIR hyperspectral imager. The FIRST is based on the Fourier Transform technology yielding high spectral resolution and enabling high accuracy radiometric calibration. The FIRST, a man portable sensor, provides datacubes of up to 320×256 pixels at 0.35mrad spatial resolution over the 8-12 μm spectral range at spectral resolutions of up to 0.25cm-1. The FIRST has been used in several field campaigns, including the demonstration of standoff chemical agent detection [http://dx.doi.org/10.1117/12.788027.1]. More recently, an airborne system integrating the FIRST has been developed to provide airborne hyperspectral measurement capabilities. The airborne system and its capabilities are presented in this paper. The FIRST sensor modularity enables operation in various configurations such as tripod-mounted and airborne. In the airborne configuration, the FIRST can be operated in push-broom mode, or in staring mode with image motion compensation. This paper focuses on the airborne operation of the FIRST sensor.

  15. Quantifying erosion and deposition patterns using airborne LiDAR following the 2012 High Park Fire and 2013 Colorado Flood

    NASA Astrophysics Data System (ADS)

    Brogan, D. J.; Nelson, P. A.; MacDonald, L. H.

    2015-12-01

    Quantifying and predicting geomorphic change over large spatial scales is increasingly feasible and of growing interest as repeat high resolution topography becomes available. We began detailed field studies of channel geomorphic change using RTK-GPS in two 15 km2 watersheds following the 2012 High Park Fire; the watersheds were then subjected to a several-hundred year flood in September 2013. During this time a series of airborne LiDAR datasets were collected, and the objectives of this study were to: 1) determine and compare the spatial variability in channel and valley erosion and deposition over time from the LiDAR; and 2) determine if the observed changes can be predicted from channel and valley bottom characteristics. Data quality issues in the initial LiDAR required us to rotate and translate flight lines in order to co-register ground-classified point clouds between successive datasets; uncertainty was then estimated using our RTK-GPS field measurements. Topographic changes were calculated using the Multiscale Model to Model Cloud Comparison (M3C2) algorithm. Results indicate that the 2013 flood mobilized much more sediment than was mobilized due to the fire alone; unfortunately the uncertainty in differencing is still frequently greater than the observed changes, especially within transfer reaches. Valley expansion and constriction are major controls on spatial patterns of erosion and deposition, suggesting that topographic metrics such as longitudinal distributions of channel slope and valley confinement may provide quasi-physically based estimates of sediment deposition and delivery potential.

  16. Semantic segmentation of forest stands of pure species combining airborne lidar data and very high resolution multispectral imagery

    NASA Astrophysics Data System (ADS)

    Dechesne, Clément; Mallet, Clément; Le Bris, Arnaud; Gouet-Brunet, Valérie

    2017-04-01

    Forest stands are the basic units for forest inventory and mapping. Stands are defined as large forested areas (e.g., ⩾ 2 ha) of homogeneous tree species composition and age. Their accurate delineation is usually performed by human operators through visual analysis of very high resolution (VHR) infra-red images. This task is tedious, highly time consuming, and should be automated for scalability and efficient updating purposes. In this paper, a method based on the fusion of airborne lidar data and VHR multispectral images is proposed for the automatic delineation of forest stands containing one dominant species (purity superior to 75%). This is the key preliminary task for forest land-cover database update. The multispectral images give information about the tree species whereas 3D lidar point clouds provide geometric information on the trees and allow their individual extraction. Multi-modal features are computed, both at pixel and object levels: the objects are individual trees extracted from lidar data. A supervised classification is then performed at the object level in order to coarsely discriminate the existing tree species in each area of interest. The classification results are further processed to obtain homogeneous areas with smooth borders by employing an energy minimum framework, where additional constraints are joined to form the energy function. The experimental results show that the proposed method provides very satisfactory results both in terms of stand labeling and delineation (overall accuracy ranges between 84 % and 99 %).

  17. Levee crest elevation profiles derived from airborne lidar-based high resolution digital elevation models in south Louisiana

    USGS Publications Warehouse

    Palaseanu-Lovejoy, Monica; Thatcher, Cindy A.; Barras, John A.

    2014-01-01

    This study explores the feasibility of using airborne lidar surveys to construct high-resolution digital elevation models (DEMs) and develop an automated procedure to extract levee longitudinal elevation profiles for both federal levees in Atchafalaya Basin and local levees in Lafourche Parish, south Lousiana. This approach can successfully accommodate a high degree of levee sinuosity and abrupt changes in levee orientation (direction) in planar coordinates, variations in levee geometries, and differing DEM resolutions. The federal levees investigated in Atchafalaya Basin have crest elevations between 5.3 and 12 m while the local counterparts in Lafourche Parish are between 0.76 and 2.3 m. The vertical uncertainty in the elevation data is considered when assessing federal crest elevation against the U.S. Army Corps of Engineers minimum height requirements to withstand the 100-year flood. Only approximately 5% of the crest points of the two federal levees investigated in the Atchafalaya Basin region met this requirement.

  18. The enhanced MODIS airborne simulator hyperspectral imager

    NASA Astrophysics Data System (ADS)

    Guerin, Daniel C.; Fisher, John; Graham, Edward R.

    2011-06-01

    The EMAS-HS or Enhanced MODIS Airborne Simulator is an upgrade to the solar reflected and thermal infrared channels of NASA's MODIS Airborne Simulator (MAS). In the solar reflected bands, the MAS scanner functionality will be augmented with the addition of this separate pushbroom hyperspectral instrument. As well as increasing the spectral resolution of MAS beyond 10 nm, this spectrometer is designed to maintain a stable calibration that can be transferred to the existing MAS sensor. The design emphasizes environmental control and on-board radiometric stability monitoring. The system is designed for high-altitude missions on the ER-2 and the Global Hawk platforms. System trades optimize performance in MODIS spectral bands that support land, cloud, aerosol, and atmospheric water studies. The primary science mission driving the development is high altitude cloud imaging, with secondary missions possible for ocean color. The sensor uses two Offner spectrometers to cover the 380-2400 nm spectral range. It features an all-reflective telescope with a 50° full field-of-view. A dichroic cold mirror will split the image from the telescope, with longer radiation transmitted to the SWIR spectrometer. The VNIR spectrometer uses a TE-cooled Si CCD detector that samples the spectrum at 2.5 nm intervals, while the SWIR spectrometer uses a Stirling-cooled hybrid HgCdTe detector to sample the spectrum at 10 nm per band. Both spectrometers will feature 1.05 mRad instantaneous fields-of-view registered to the MAS scanner IFOV's.

  19. The NASA enhanced MODIS airborne simulator

    NASA Astrophysics Data System (ADS)

    Ellis, Thomas A.; Myers, Jeffrey; Grant, Patrick; Platnick, Steven; Guerin, Daniel C.; Fisher, John; Song, Kai; Kimchi, Joseph; Kilmer, Louis; LaPorte, Daniel D.; Moeller, Christopher C.

    2011-10-01

    The new NASA Enhanced MODIS Airborne Simulator (eMAS) is based on the legacy MAS system, which has been used extensively in support of the NASA Earth Observing System program since 1995. eMAS consists of two separate instruments designed to fly together on the NASA ER-2 and Global Hawk high altitude aircraft. The eMAS-IR instrument is an upgraded version of the legacy MAS line-scanning spectrometer, with 38 spectral bands in the wavelength range from 0.47 to 14.1 μm. The original LN2-cooled MAS MWIR and LWIR spectrometers are replaced with a single vacuum-sealed, Stirling-cooled assembly, having a single MWIR and twelve LWIR bands. This spectrometer module contains a cold optical bench where both dispersive optics and detector arrays are maintained at cryogenic temperatures to reduce infrared background noise, and ensure spectral stability during high altitude airborne operations. The EMAS-HS instrument is a stand-alone push-broom imaging spectrometer, with 202 contiguous spectral bands in the wavelength range from 0.38 to 2.40 μm. It consists of two Offner spectrometers, mated to a 4-mirror anastigmatic telescope. The system has a single slit, and uses a dichroic beam-splitter to divide the incoming energy between VNIR and SWIR focal plane arrays. It will be synchronized and bore-sighted with the IR line-scanner, and includes an active source for monitoring calibration stability. eMAS is intended to support future satellite missions including the Hyperspectral Infrared Imager ( HyspIRI,) the National Polar-orbiting Operational Environmental Satellite System (NPOESS) Preparatory Project (NPP,) and the follow-on Joint Polar Satellite System (JPSS.)

  20. Digital logarithmic airborne gamma ray spectrometer

    NASA Astrophysics Data System (ADS)

    Zeng, Guo-Qiang; Zhang, Qing-Xian; Li, Chen; Tan, Cheng-Jun; Ge, Liang-Quan; Gu, Yi; Cheng, Feng

    2014-07-01

    A new digital logarithmic airborne gamma ray spectrometer is designed in this study. The spectrometer adopts a high-speed and high-accuracy logarithmic amplifier (LOG114) to amplify the pulse signal logarithmically and to improve the utilization of the ADC dynamic range because the low-energy pulse signal has a larger gain than the high-energy pulse signal. After energy calibration, the spectrometer can clearly distinguish photopeaks at 239, 352, 583 and 609 keV in the low-energy spectral sections. The photopeak energy resolution of 137Cs improves to 6.75% from the original 7.8%. Furthermore, the energy resolution of three photopeaks, namely, K, U, and Th, is maintained, and the overall stability of the energy spectrum is increased through potassium peak spectrum stabilization. Thus, it is possible to effectively measure energy from 20 keV to 10 MeV.

  1. Higher-order modulation formats for spectral-efficient high-speed metro systems

    NASA Astrophysics Data System (ADS)

    Freund, R.; Nölle, M.; Seimetz, M.; Hilt, J.; Fischer, J.; Ludwig, R.; Schubert, C.; Bach, H.-G.; Velthaus, K.-O.; Schell, M.

    2011-01-01

    Worldwide, higher-order modulation formats are intensively investigated to further increase the spectral efficiency for building the next generation of high-speed metro systems. IQ-modulators, coherent receivers and electronic equalizers are hereby discussed as key devices. We report on system design issues as well as on HHI's latest achievements in developing InP based high-speed modulators and coherent receiver frontends.

  2. High-Order Harmonic Spectral Filter with the Double Fourier Series on a Sphere

    NASA Astrophysics Data System (ADS)

    Cheong, Hyeong-Bin; Kwon, In-Hyuk; Goo, Tae-Young; Lee, Myeong-Joo

    2002-04-01

    A high-order harmonic spectral filter (HSF) is implemented to smooth out a field variable defined on a spherical surface using the double Fourier series (DFS) as orthogonal basis functions. The filter consists of the solution of the high-order harmonic diffusion equation with the implicit method, where the high-order harmonic operator is split into second- or lower-order harmonic operators. The second-order harmonic operator is replaced by a pentadiagonal matrix whose elements are the spectral coefficients. First, a biharmonic spectral filter (BiHSF), the prototype of the high-order HSF, is developed where only the second-order harmonic operator is included. It is found that the computational error for the inversion of a pentadiagonal matrix remains in the order of machine rounding. Compared to the mixed-order HSF with DFS used in the previous study, which contains the second- and third-order harmonic operators, the BiHSF can provide a sharper cutoff of high wavenumbers as well as improved computational efficiency. These advantages come from the fact that for each set of spectral coefficients the BiHSF needs only a single inversion of the pentadiagonal matrix whereas the mixed-order HSF requires triple inversions and an auxiliary operation of the tridiagonal matrix. Based on the BiHSF, the high-order HSF up to the sixth order, which is composed of a multiple inversion of tri- or pentadiagonal matrices, is designed. Tests with the rotated Gaussian fields revealed that the HSF with DFS is isotropic. Application to various problems, including a time-dependent strongly nonlinear case and the observed flow, indicates that the high-order HSF is well capable of smoothing out selectively high-wavenumber components without significantly affecting the conserved quantity, such as total (kinetic) energy.

  3. Investigation and development of a high spectral resolution coherent optical spectrum analysis system.

    PubMed

    Feng, Kunpeng; Cui, Jiwen; Dang, Hong; Zhao, Shiyuan; Wu, Weidong; Tan, Jiubin

    2016-10-31

    Focusing on high resolution optical spectroscopy, a coherent optical spectrum analysis (COSA) system is investigated in this paper. Principle is built to demonstrate the operation of COSA and its signal processing in both time and frequency domain. According to COSA principle, resolution bandwidth (RBW) filters are found to have significant influence on power accuracy and spectral resolution of the optical spectrum analysis (OSA). Much effort is paid to design RBW filters, including center frequency, bandwidth and type of filters. Two RBW filters are optimized to reduce the power uncertainty of different spectral resolution and satisfy different signal under test. Then, simulations and experiments are conducted to verify COSA principle and results show that the power uncertainty is less than 0.5% and 1.2% for high and medium spectral resolution application, respectively. Finally, experiments on the OSA of actual spectra indicate that COSA system can achieve a 6 MHz spectral resolution and has an excellent capacity in analysis of fine spectrum structures.

  4. A fully-automated approach to land cover mapping with airborne LiDAR and high resolution multispectral imagery in a forested suburban landscape

    NASA Astrophysics Data System (ADS)

    Parent, Jason R.; Volin, John C.; Civco, Daniel L.

    2015-06-01

    Information on land cover is essential for guiding land management decisions and supporting landscape-level ecological research. In recent years, airborne light detection and ranging (LiDAR) and high resolution aerial imagery have become more readily available in many areas. These data have great potential to enable the generation of land cover at a fine scale and across large areas by leveraging 3-dimensional structure and multispectral information. LiDAR and other high resolution datasets must be processed in relatively small subsets due to their large volumes; however, conventional classification techniques cannot be fully automated and thus are unlikely to be feasible options when processing large high-resolution datasets. In this paper, we propose a fully automated rule-based algorithm to develop a 1 m resolution land cover classification from LiDAR data and multispectral imagery. The algorithm we propose uses a series of pixel- and object-based rules to identify eight vegetated and non-vegetated land cover features (deciduous and coniferous tall vegetation, medium vegetation, low vegetation, water, riparian wetlands, buildings, low impervious cover). The rules leverage both structural and spectral properties including height, LiDAR return characteristics, brightness in visible and near-infrared wavelengths, and normalized difference vegetation index (NDVI). Pixel-based properties were used initially to classify each land cover class while minimizing omission error; a series of object-based tests were then used to remove errors of commission. These tests used conservative thresholds, based on diverse test areas, to help avoid over-fitting the algorithm to the test areas. The accuracy assessment of the classification results included a stratified random sample of 3198 validation points distributed across 30 1 × 1 km tiles in eastern Connecticut, USA. The sample tiles were selected in a stratified random manner from locations representing the full range of

  5. Atmospheric correction for ocean spectra retrievals from high-altitude multi-angle, multi-spectral photo-polarimetric remote sensing observations: Results for coastal ocean waters.

    NASA Astrophysics Data System (ADS)

    Chowdhary, J.; van Diedenhoven, B.; Knobelspiesse, K. D.; Cairns, B.; Wasilewski, A. P.; McCubbin, I.

    2015-12-01

    A major challenge for spaceborne observations of ocean color is to correct for atmospheric scattering, which typically contributes ≥85% to the top-of-atmosphere (TOA) radiance and varies substantially with aerosols. Ocean color missions traditionally analyze TOA radiance in the near-infrared (NIR), where the ocean is black, to constrain the TOA atmospheric scattering in the visible (VIS). However, this procedure is limited by insufficient sensitivity of NIR radiance to absorption and vertical distribution of aerosols, and by uncertainties in the extrapolation of aerosol properties from the NIR to the VIS.To improve atmospheric correction for ocean color observations, one needs to change the traditional procedure for this correction and/or increase the aerosol information. The instruments proposed to increase the aerosol information content for the Pre-Aerosol, Clouds, and ocean Ecosystem (PACE) mission include ultraviolet and Oxygen A-band observations, as well as multispectral and multiangle polarimetry. However few systematic studies have been performed to quantify the improvement such measurements bring to atmospheric correction. To study the polarimetric atmospheric correction capabilities of PACE-like instruments, we conducted field experiments off the Coast of California to obtain high-altitude (65,000 ft) and ship-based observations of water-leaving radiance. The airborne data sets consist of hyperspectral radiance between 380-2500 nm by the Airborne Visible/Infrared Imaging Spectrometer, and multi-spectral multi-angle polarimetric data between 410-2250 nm by the Research Scanning Polarimeter. We discuss examples of retrieved atmosphere and ocean state vectors, and of corresponding ocean color spectra obtained by subtracting the computed atmospheric scattering contribution from the high-altitude radiance measurements. The ocean color spectra thus obtained are compared with those measured from the ship.

  6. Airborne measurements of Black Carbon using miniature high-performance Aethalometers during global circumnavigation campaign GLWF 2012

    NASA Astrophysics Data System (ADS)

    Močnik, Griša; Drinovec, Luka; Vidmar, Primož; Lenarčič, Matevž

    2013-04-01

    While ground-level measurements of atmospheric aerosols are routinely performed around the world, there exists very little data on their vertical and geographical distribution in the global atmosphere. This data is a crucial requirement for our understanding of the dispersion of pollutant species of anthropogenic origin, and their possible effects on radiative forcing, cloud condensation, and other phenomena which can contribute to adverse outcomes. Black Carbon (BC) is a unique tracer for combustion emissions, and can be detected rapidly and with great sensitivity by filter-based optical methods. It has no non-combustion sources and is not transformed by atmospheric processes. Its presence at altitude is unequivocal. Recent technical advances have led to the development of miniaturized instruments which can be operated on ultra-light aircraft, balloons or UAV's. From January to April 2012, a 'Pipistrel Virus' single-seat ultra-light aircraft flew around the world on a photographic and environmental-awareness mission. The flight track covered all seven continents; crossed all major oceans; and operated at altitudes around 3000 m ASL and up to 8900 m ASL. The aircraft carried a specially-developed high-sensitivity miniaturized dual-wavelength Aethalometer, which recorded BC concentrations with very high temporal resolution and sensitivity (see Reference below). We present examples of data from flight tracks over remote oceans, uninhabited land masses, and densely populated areas. Back-trajectories are used to show transport of polluted air masses. Measuring the dependence of the aerosol absorption on the wavelength, we show that aerosols produced during biomass combustion can be transported to high altitude in high concentrations. 1. __, Carbon Sampling Takes Flight, Science 2012, 335, 1286. 2. G. Močnik, L. Drinovec, M. Lenarčič, Airborne measurements of Black Carbon during the GLW Flight using miniature high-performance Aethalometers, accessed 8 January 2013

  7. Further study on the high-order double-Fourier-series spectral filtering on a sphere

    NASA Astrophysics Data System (ADS)

    Cheong, Hyeong-Bin; Kwon, In-Hyuk; Goo, Tae-Young

    2004-01-01

    A high-order harmonic spectral filter (HSF) is further studied using double Fourier series (DFS), which performs filtering in terms of successive inversion of tridiagonal matrices with complex-valued elements. The high-order harmonics filter equation is split into multiple Helmholtz equations. It is found that the filter provides the same order of accuracy as the spectral filter in [J. Comput. Phys. 177 (2002) 313] that consists of the pentadiagonal matrices with real-valued elements. The advantage of the filter over the previous one lies on the simplicity and easiness of numerical implementation or computer coding, just requiring the same complexity as Poisson's equation solver. However, the operation count associated with the filter increases by a factor of about 2. To circumvent the inefficiency while preserving the simplicity, an easy way to construct pentadiagonal matrices associated with the biharmonic equation is presented in which the tridiagonal matrices related with Poisson's equation are manipulated. Computational efficiency of the spectral filter is discussed in terms of the relative computing time to the spectral transform. It is revealed that the computing cost (requiring O( N2) operations with N being the truncation) for the spectral filtering, even with the complex-valued matrices, is not significant in the DFS spectral model that is characterized by O( N2log 2N) operations. Filtering with different DFS expansions is discussed with a focus on the accuracy and pole condition. It is shown that the DFS violating the pole conditions produces a discontinuity at poles in case of wave truncation, and its influence spreads over the globe. The spectral filter is applied to two kinds of uniform-grid data, the regular and the shifted grids, and the results are compared with each other. The operator splitting (or spherical harmonics factorization) makes it feasible to apply the finite difference method to the high-order harmonics filter with ease because only

  8. The dynamic monitoring of warm-water discharge based on the airborne high-resolution thermal infrared remote sensing data

    NASA Astrophysics Data System (ADS)

    Shao, Honglan; Xie, Feng; Liu, Chengyu; Liu, Zhihui; Zhang, Changxing; Yang, Gui; Wang, Jianyu

    2016-04-01

    The cooling water discharged from the coastal plants flow into the sea continuously, whose temperature is higher than original sea surface temperature (SST). The fact will have non-negligible influence on the marine environment in and around where the plants site. Hence, it's significant to monitor the temporal and spatial variation of the warm-water discharge for the assessment of the effect of the plant on its surrounding marine environment. The paper describes an approach for the dynamic monitoring of the warm-water discharge of coastal plants based on the airborne high-resolution thermal infrared remote sensing technology. Firstly, the geometric correction was carried out for the thermal infrared remote sensing images acquired on the aircraft. Secondly, the atmospheric correction method was used to retrieve the sea surface temperature of the images. Thirdly, the temperature-rising districts caused by the warm-water discharge were extracted. Lastly, the temporal and spatial variations of the warm-water discharge were analyzed through the geographic information system (GIS) technology. The approach was applied to Qinshan nuclear power plant (NPP), in Zhejiang Province, China. In considering with the tide states, the diffusion, distribution and temperature-rising values of the warm-water discharged from the plant were calculated and analyzed, which are useful to the marine environment assessment.

  9. Ultra-high degree spectral modelling of Earth and planetary topography

    NASA Astrophysics Data System (ADS)

    Rexer, Moritz; Hirt, Christian

    2016-04-01

    New methods for ultra-high degree spherical harmonic analyses and syntheses have been developed and studied over the past years. The focus group "High-resolution Gravity Modelling", established in 2013 at TU Munich, has implemented ultra-high degree spectral modelling techniques and used successfully to transform high-resolution topography grids of Earth, Moon and Mars into spherical harmonics. For Earth, a new set of 1 arc-min topography models, developed by our group and released under the name Earth2014, was expanded into a spherical harmonic series to degree 10,800. For the 15 arc-sec resolution SRTM15_plus topography and bathymetry, a spectral resolution of degree 43,200 was achieved. For Moon and Mars, topography grids from laser altimetry were harmonically analysed up to degree ~46,000. The spectral representations of the topography grids presented in this contribution are required in the context of spectral gravity forward modelling with ultra-high degree, where the topographic potential is computed as a function of the spherical harmonic series of the topography and its integer powers. References: Hirt, C., and M. Rexer (2015) Earth2014: 1 arc-min shape, topography, bedrock and ice-sheet models - available as gridded data and degree-10,800 spherical harmonics, International Journal of Applied Earth Observation and Geoinformation 39, 103-112, doi:10.1016/j.jag.2015.03.001. Rexer, M. and C. Hirt (2015), Ultra-high degree surface spherical harmonic analysis using the Gauss-Legendre and the Driscoll/Healy quadrature theorem and application to planetary topography models of Earth, Moon and Mars. Surveys in Geophysics 36(6), 803-830, doi: 10.1007/s10712-015-9345-z.

  10. Geodetic Imaging Lidar: Applications for high-accuracy, large area mapping with NASA's upcoming high-altitude waveform-based airborne laser altimetry Facility

    NASA Astrophysics Data System (ADS)

    Blair, J. B.; Rabine, D.; Hofton, M. A.; Citrin, E.; Luthcke, S. B.; Misakonis, A.; Wake, S.

    2015-12-01

    Full waveform laser altimetry has demonstrated its ability to capture highly-accurate surface topography and vertical structure (e.g. vegetation height and structure) even in the most challenging conditions. NASA's high-altitude airborne laser altimeter, LVIS (the Land Vegetation, and Ice Sensor) has produced high-accuracy surface maps over a wide variety of science targets for the last 2 decades. Recently NASA has funded the transition of LVIS into a full-time NASA airborne Facility instrument to increase the amount and quality of the data and to decrease the end-user costs, to expand the utilization and application of this unique sensor capability. Based heavily on the existing LVIS sensor design, the Facility LVIS instrument includes numerous improvements for reliability, resolution, real-time performance monitoring and science products, decreased operational costs, and improved data turnaround time and consistency. The development of this Facility instrument is proceeding well and it is scheduled to begin operations testing in mid-2016. A comprehensive description of the LVIS Facility capability will be presented along with several mission scenarios and science applications examples. The sensor improvements included increased spatial resolution (footprints as small as 5 m), increased range precision (sub-cm single shot range precision), expanded dynamic range, improved detector sensitivity, operational autonomy, real-time flight line tracking, and overall increased reliability and sensor calibration stability. The science customer mission planning and data product interface will be discussed. Science applications of the LVIS Facility include: cryosphere, territorial ecology carbon cycle, hydrology, solid earth and natural hazards, and biodiversity.

  11. Ultra-high spectral extinction Brillouin spectroscopy for turbid tissue measurements (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Zhang, Jitao; Fiore, Antonio; Shao, Peng; Yun, Seok-Hyun; Scarcelli, Giuliano

    2016-03-01

    Brillouin spectroscopy allows non-invasive measurement of the mechanical properties of a sample by measuring the spectra of acoustically induced light scattering therein, and thus has been widely investigated for biomedical application. Recently, the development of fast Brillouin spectrometry based on virtually-imaged phased array (VIPA) has made in-situ measurement of biomedical sample possible. However, one limitation of current Brillouin technique is the low spectral extinction, which limits the measurement to nearly transparent sample. In order to measure turbid sample, multistage VIPA can be cascaded to gain spectral extinction. For example, spectral extinction of ~80 dB was achieved using three-stage VIPA; however, this approach significantly sacrificed measurement throughput. In this work, we develop a novel spectrometer that achieves high extinction without significant signal loss. To achieve this goal, we combine a two-stage VIPA spectrometer with a triple-pass Fabry-Perot interferometer. The triple-pass Fabry-Perot interferometer acts as a band-pass filter with ~3 GHz bandwidth and ~35-dB spectral extinction. Therefore, the overall extinction of this spectrometer greatly surpasses 80 dB with only ~20% excess loss. We demonstrated the performance of this spectrometer measuring background-free Brillouin spectra from Intralipid solutions and within chicken tissue.

  12. Mineral identification and mapping of hydrothermal alteration zones using high-spectral resolution images (AVIRIS)

    NASA Technical Reports Server (NTRS)

    Van Der Meer, Freek D.

    1994-01-01

    High-spectral resolution images (AVIRIS) of the cuprite mining area were used to evaluate atmospheric calibration algorithms and test several mineral mapping techniques. Four scene normalization techniques were used: (1) the flat-field method, (2) the internal average reflectance method, (3) the empirical line method, and (4) the atmospheric absorption removal method (ATREM). The algorithms were evaluated in terms of their spectral interpret- ability and their ability to remove both solar irradiance and atmospheric absorption features, noise, and artifacts. Noise was quantified by calculating the coefficient of variation of the spectra, and spectral interpretability was quantified by calcu- lating a difference spectrum (eg, laboratory spectrum minus pixel spectrum) for areas with known occurrences of clay minerals. These difference spectra were useful in evaluating the degree of removal of atmospheric features. The empirical line method produced the best calibration results. Mineral mapping as done using (1) color-composites of bands on the shoulders and centers of expected absorption features, (2) color-coded spectra, and (3) spectral angle mapping.

  13. Application of spectral line shapes to the study of high density ICF plasmas

    SciTech Connect

    Keane, C.J.; Hammel, B.A.; Langer, S.H.; Lee, R.W.; Calisti, A.; Godbert, L.; Stamm, R.; Talin, B.

    1994-09-01

    Spectral line broadening manifests itself in the study of high density inertial confinement fusion (ICF) plasmas in two important ways. First, comparison between measured and calculated lineshapes of individual spectral lines or groups of lines is used to diagnose plasma conditions in dense ICF plasmas, particularly in implosions. Secondly, through the emission and absorption coefficients spectral lineshapes serve as important inputs to plasma spectroscopy simulation codes which calculate simulated spectra from ICF targets. We discuss recent results from each of these areas. With regard to lineshape diagnostics, the advent of generalized line broadening codes has allowed the line profiles of complex multielectron emitters to be considered for diagnostic purposes. Particular example of this is the use of Ar He-{beta} and its associated dielectronic satellites as a diagnostic of T{sub e} and N{sub e}, as well as the development of Ne-like Xe line broadening as a density diagnostic. With respect to simulation codes, the implementation of detailed lineshapes in calculations of this type is in many ways in its infancy. We present here examples of cases where effects related to spectral lineshapes such as continuum lowering and line transfer of Stark broadened lines are important so as to provide a stimulus for future work in this field. 34 refs., 9 figs., 1 tab.

  14. Spectral characteristics of chlorites and Mg-serpentines using high- resolution reflectance spectroscopy

    USGS Publications Warehouse

    King, T.V.V.; Clark, R.N.

    1989-01-01

    The present laboratory study using high-resolution reflectance spectroscopy (0.25-2.7 ??m) focuses on two primary phyllosilicate groups, serpentines and chlorites. The results show that it is possible to spectrally distinguish between isochemical end-members of the Mg-rich serpentine group (chrysotile, antigorite, and lizardite) and to recognize spectral variations in chlorites as a function of Fe/Mg ratio (~8-38 wt% Fe). The position and relative strength of the 1.4-??m absorption feature in the trioctahedral chlorites appear to be correlated to the total iron content and/or the Mg/Si ratio and the loss on ignition values of the sample. Spectral differences in the 2.3-??m wavelength region can be attributed to differences in lattice environments and are characteristic for specific trioctahedral chlorites. The 1.4-??m feature in the isochemical Mg-rich serpentines (total iron content ~1.5-7.0 wt%) show marked spectral differences, apparently due to structural differences. -Authors

  15. 3D high spectral and spatial resolution imaging of ex vivo mouse brain

    SciTech Connect

    Foxley, Sean Karczmar, Gregory S.; Domowicz, Miriam; Schwartz, Nancy

    2015-03-15

    Purpose: Widely used MRI methods show brain morphology both in vivo and ex vivo at very high resolution. Many of these methods (e.g., T{sub 2}{sup *}-weighted imaging, phase-sensitive imaging, or susceptibility-weighted imaging) are sensitive to local magnetic susceptibility gradients produced by subtle variations in tissue composition. However, the spectral resolution of commonly used methods is limited to maintain reasonable run-time combined with very high spatial resolution. Here, the authors report on data acquisition at increased spectral resolution, with 3-dimensional high spectral and spatial resolution MRI, in order to analyze subtle variations in water proton resonance frequency and lineshape that reflect local anatomy. The resulting information compliments previous studies based on T{sub 2}{sup *} and resonance frequency. Methods: The proton free induction decay was sampled at high resolution and Fourier transformed to produce a high-resolution water spectrum for each image voxel in a 3D volume. Data were acquired using a multigradient echo pulse sequence (i.e., echo-planar spectroscopic imaging) with a spatial resolution of 50 × 50 × 70 μm{sup 3} and spectral resolution of 3.5 Hz. Data were analyzed in the spectral domain, and images were produced from the various Fourier components of the water resonance. This allowed precise measurement of local variations in water resonance frequency and lineshape, at the expense of significantly increased run time (16–24 h). Results: High contrast T{sub 2}{sup *}-weighted images were produced from the peak of the water resonance (peak height image), revealing a high degree of anatomical detail, specifically in the hippocampus and cerebellum. In images produced from Fourier components of the water resonance at −7.0 Hz from the peak, the contrast between deep white matter tracts and the surrounding tissue is the reverse of the contrast in water peak height images. This indicates the presence of a shoulder in

  16. Spectral combining of high-power fiber laser beams using Bragg grating in PTR glass

    NASA Astrophysics Data System (ADS)

    Ciapurin, Igor V.; Glebov, Leonid B.; Smirnov, Vadim I.

    2004-06-01

    High-efficient volume Bragg gratings (VBG) in inorganic photo-thermo-refractive (PTR) glass were recently reported for the use in high-power laser systems. Both transmission and reflection gratings have shown diffraction efficiency greater than 95% from visible to near IR spectra in a wide range of spatial frequencies. Those gratings have exhibited perfect thermal, optical and mechanical stability. Spectral beam combining (SBC) using PTR Bragg grating with efficiency more than 92% for two 100 W Yb-fiber-laser beams with the 11 nm wavelength separation between them is reported. The paper presents results of modeling and experimental study of a beam combiner for high-power lasers with the only passive PTR grating component in it. Two laser beams illuminate a thick Bragg grating which has only two symmetric resonant angles providing total diffraction of a beam with a certain wavelength. Incidence angle for all transmitting beams should correspond to the Bragg angle for the diffracted beam. Transmitting beams are not diffracted by grating if spectral sift corresponds to zeros in a spectral selectivity curve, and propagate in the same direction as a diffracted beam. It is shown the efficient trade-off between grating period and refractive index modulation allows modeling of high-efficient combining setup for each of arbitrary chosen grating thickness. Comparison between calculation results and experimental data is given.

  17. High-Spatial- and High-Spectral-Resolution Observations of the Inhomogeneous Outer Atmosphere of the M Giant BK Vir

    NASA Astrophysics Data System (ADS)

    Ohnaka, K.

    2011-09-01

    We present high-spatial- and high-spectral-resolution observations of the normal M-type AGB star BK Vir using the AMBER instrument at the Very Large Telescope Interferometer. AMBER's high spatial resolution (9.5 mas) and high spectral resolution (λ/Δλ = 12000) enable us to probe the inhomogeneous structure of the atmosphere using the CO first-overtone lines near 2.3μm. The AMBER data in the CO lines reveal the presence of inhomogeneous CO layers, which are much more extended than predicted by hydrostatic photospheric models. These AMBER observations are the first to spatially resolve the “warm molecular envelope” toward AGB stars in individual CO lines.

  18. USGS Spectral Library Version 7

    USGS Publications Warehouse

    Kokaly, Raymond F.; Clark, Roger N.; Swayze, Gregg A.; Livo, K. Eric; Hoefen, Todd M.; Pearson, Neil C.; Wise, Richard A.; Benzel, William M.; Lowers, Heather A.; Driscoll, Rhonda L.; Klein, Anna J.

    2017-04-10

    We have assembled a library of spectra measured with laboratory, field, and airborne spectrometers. The instruments used cover wavelengths from the ultraviolet to the far infrared (0.2 to 200 microns [μm]). Laboratory samples of specific minerals, plants, chemical compounds, and manmade materials were measured. In many cases, samples were purified, so that unique spectral features of a material can be related to its chemical structure. These spectro-chemical links are important for interpreting remotely sensed data collected in the field or from an aircraft or spacecraft. This library also contains physically constructed as well as mathematically computed mixtures. Four different spectrometer types were used to measure spectra in the library: (1) Beckman™ 5270 covering the spectral range 0.2 to 3 µm, (2) standard, high resolution (hi-res), and high-resolution Next Generation (hi-resNG) models of Analytical Spectral Devices (ASD) field portable spectrometers covering the range from 0.35 to 2.5 µm, (3) Nicolet™ Fourier Transform Infra-Red (FTIR) interferometer spectrometers covering the range from about 1.12 to 216 µm, and (4) the NASA Airborne Visible/Infra-Red Imaging Spectrometer AVIRIS, covering the range 0.37 to 2.5 µm. Measurements of rocks, soils, and natural mixtures of minerals were made in laboratory and field settings. Spectra of plant components and vegetation plots, comprising many plant types and species with varying backgrounds, are also in this library. Measurements by airborne spectrometers are included for forested vegetation plots, in which the trees are too tall for measurement by a field spectrometer. This report describes the instruments used, the organization of materials into chapters, metadata descriptions of spectra and samples, and possible artifacts in the spectral measurements. To facilitate greater application of the spectra, the library has also been convolved to selected spectrometer and imaging spectrometers sampling and

  19. Airborne DIAL Ozone and Aerosol Trends Observed at High Latitudes Over North America from February to May 2000

    NASA Technical Reports Server (NTRS)

    Hair, Jonathan W.; Browell, Edward V.; Butler, Carolyn F.; Grant, William B.; DeYoung, Russell J.; Fenn, Marta A.; Brackett, Vince G.; Clayton, Marian B.; Brasseur, Lorraine

    2002-01-01

    Ozone (O3) and aerosol scattering ratio profiles were obtained from airborne lidar measurements on thirty-eight aircraft flights over seven aircraft deployments covering the latitudes of 40 deg.-85 deg.N between 4 February and 23 May 2000 as part of the TOPSE (Tropospheric Ozone Production about the Spring Equinox) field experiment. The remote and in situ O3 measurements were used together to produce a vertically-continuous O3 profile from near the surface to above the tropopause. Ozone, aerosol, and potential vorticity (PV) distributions were used together to identify the presence of pollution plumes and stratospheric intrusions. The number of observed pollution plumes was found to increase into the spring along with a significant increase in aerosol loading. Ozone was found to increase in the middle free troposphere (4-6 km) at high latitudes (60 deg.-85 deg. N) by an average of 4.3 ppbv/mo from about 55 ppbv in early February to over 72 ppbv in mid-May. The average aerosol scattering ratios in the same region increased at an average rate of 0.37/mo from about 0.35 to over 1.7. Ozone and aerosol scattering were highly correlated over entire field experiment. Based on the above results and the observed aircraft in-situ measurements, it was estimated that stratospherically-derived O3 accounted for less than 20% of the observed increase in mid tropospheric O3 at high latitudes. The primary cause of the observed O3 increase was found to be the photochemical production of O3 in pollution plumes.

  20. Solid optical ring interferometer for high-throughput feedback-free spectral analysis and filtering

    SciTech Connect

    Petrak, B.; Peiris, M.; Muller, A.

    2015-02-15

    We describe a simple and inexpensive optical ring interferometer for use in high-resolution spectral analysis and filtering. It consists of a solid cuboid, reflection-coated on two opposite sides, in which constructive interference occurs for waves in a rhombic trajectory. Due to its monolithic design, the interferometer’s resonance frequencies are insensitive to environmental disturbances over time. Additional advantages are its simplicity of alignment, high-throughput, and feedback-free operation. If desired, it can be stabilized with a secondary laser without disturbance of the primary signal. We illustrate the use of the interferometer for the measurement of the spectral Mollow triplet from a quantum dot and characterize its long-term stability for filtering applications.

  1. A spectral multidomain penalty method model for high Reynolds number incompressible flows

    NASA Astrophysics Data System (ADS)

    Escobar-Vargas, Jorge; Diamessis, Peter

    2010-11-01

    We present the latest results of a spectral multidomain penalty method-based incompressible Navier Stokes solver for high Reynolds number stratified turbulent flows in doubly non-periodic domains that is currently under development. Time is discretized with a high-order stiffly stable scheme, whereas space is discretized with a Gauss-Lobatto-Legendre collocation approach in discontinuous quadrilateral subdomains. Numerical stability is guaranteed through a penalty scheme, spectral filtering and dealiasing techniques. The Poisson system of equations that arises from the temporal discretization is analyzed in detail as well as different preconditioning strategies to solve it efficiently, such as Kronecker product, deflation, multigrid, Jacobi, and finite difference based techniques. The efficiency and accuracy of the Navier Stokes solver are assessed through the solution of the driven cavity flow, Taylor vortex, and Couette flow.

  2. Laser Imaging of Airborne Acoustic Emission by Nonlinear Defects

    NASA Astrophysics Data System (ADS)

    Solodov, Igor; Döring, Daniel; Busse, Gerd

    2008-06-01

    Strongly nonlinear vibrations of near-surface fractured defects driven by an elastic wave radiate acoustic energy into adjacent air in a wide frequency range. The variations of pressure in the emitted airborne waves change the refractive index of air thus providing an acoustooptic interaction with a collimated laser beam. Such an air-coupled vibrometry (ACV) is proposed for detecting and imaging of acoustic radiation of nonlinear spectral components by cracked defects. The photoelastic relation in air is used to derive induced phase modulation of laser light in the heterodyne interferometer setup. The sensitivity of the scanning ACV to different spatial components of the acoustic radiation is analyzed. The animated airborne emission patterns are visualized for the higher harmonic and frequency mixing fields radiated by planar defects. The results confirm a high localization of the nonlinear acoustic emission around the defects and complicated directivity patterns appreciably different from those observed for fundamental frequencies.

  3. Interferometric filters for spectral discrimination in high-spectral-resolution lidar: performance comparisons between Fabry-Perot interferometer and field-widened Michelson interferometer.

    PubMed

    Cheng, Zhongtao; Liu, Dong; Yang, Yongying; Yang, Liming; Huang, Hanlu

    2013-11-10

    Thanks to wavelength flexibility, interferometric filters such as Fabry-Perot interferometers (FPIs) and field-widened Michelson interferometers (FWMIs) have shown great convenience for spectrally separating the molecule and aerosol scattering components in the high-spectral-resolution lidar (HSRL) return signal. In this paper, performance comparisons between the FPI and FWMI as a spectroscopic discrimination filter in HSRL are performed. We first present a theoretical method for spectral transmission analysis and quantitative evaluation on the spectral discrimination. Then the process in determining the parameters of the FPI and FWMI for the performance comparisons is described. The influences from the incident field of view (FOV), the cumulative wavefront error induced by practical imperfections, and the frequency locking error on the spectral discrimination performance of the two filters are discussed in detail. Quantitative analyses demonstrate that FPI can produce higher transmittance while the remarkable spectral discrimination is one of the most appealing advantages of FWMI. As a result of the field-widened design, the FWMI still performs well even under the illumination with large FOV while the FPI is only qualified for a small incident angle. The cumulative wavefront error attaches a great effect on the spectral discrimination performance of the interferometric filters. We suggest if a cumulative wavefront error is less than 0.05 waves RMS, it is beneficial to employ the FWMI; otherwise, FPI may be more proper. Although the FWMI shows much more sensitivity to the frequency locking error, it can outperform the FPI given a locking error less than 0.1 GHz is achieved. In summary, the FWMI is very competent in HSRL applications if these practical engineering and control problems can be solved, theoretically. Some other estimations neglected in this paper can also be carried out through the analytical method illustrated herein.

  4. SPECTRAL REFLECTANCE OF THE CARBONATITE COMPLEXES AT MOUNTAIN PASS, CALIFORNIA AND IRON HILL, COLORADO.

    USGS Publications Warehouse

    Rowan, Lawrence C.; Collins, Williams; Kingston, Marguerite J.; Crowley, James K.

    1984-01-01

    This paper describes the distinctive spectral reflectance of these two carbonatites and their related rocks, and also discusses the possible use of spectral reflectance measurements for exploring carbonatites. Laboratory spectra recorded in the 0. 4-2. 5 micrometer wavelength range showed absorption features discussed in the abstract. High spectral-resolution airborne radiance measurements were obtained in the 0. 4-1. 0 micrometer and 2. 0-2. 5 micrometer wavelength ranges. Preliminary analysis of the airborne measurements at Mountain Pass showed neodymium-absorption bands over the mining area and in several undisturbed areas of carbonatite. The results indicate that spectral reflectance measurements may provide a rapid laboratory method for determining the presence of anomalously high rare earth (RE) content, and possibly, for estimating relative amounts of certain RE elements.

  5. High Speed Buffered Injection Readout for Airborne Visible and Infrared Imaging Spectrometer (AVIRIS)

    NASA Technical Reports Server (NTRS)

    Pain, B.; Shaw, T.; Eastwood, M.; Green, R. O.

    1998-01-01

    Design and operation of a high speed, low noise, wide dynamic range linear infrared multiplexer array for readout of infrared detectors with large detector capacitance is presented. Image lag related to abrupt transitions of signal currents is analyzed.

  6. Numerical solution of multiparameter spectral problems by high order finite different schemes

    NASA Astrophysics Data System (ADS)

    Amodio, Pierluigi; Settanni, Giuseppina

    2016-10-01

    We report on the progress achieved in the numerical simulation of self-adjoint multiparameter spectral problems for ordinary differential equations. We describe how to obtain a discrete problem by means of High Order Finite Difference Schemes and discuss its numerical solution. Based on this approach, we also define a recursive algorithm to compute approximations of the parameters by means of the solution of a set of problems converging to the original one.

  7. Infrared calibration for climate: a perspective on present and future high-spectral resolution instruments

    NASA Astrophysics Data System (ADS)

    Revercomb, Henry E.; Anderson, James G.; Best, Fred A.; Tobin, David C.; Knuteson, Robert O.; LaPorte, Daniel D.; Taylor, Joe K.

    2006-12-01

    The new era of high spectral resolution infrared instruments for atmospheric sounding offers great opportunities for climate change applications. A major issue with most of our existing IR observations from space is spectral sampling uncertainty and the lack of standardization in spectral sampling. The new ultra resolution observing capabilities from the AIRS grating spectrometer on the NASA Aqua platform and from new operational FTS instruments (IASI on Metop, CrIS for NPP/NPOESS, and the GIFTS for a GOES demonstration) will go a long way toward improving this situation. These new observations offer the following improvements: 1. Absolute accuracy, moving from issues of order 1 K to <0.2-0.4 K brightness temperature, 2. More complete spectral coverage, with Nyquist sampling for scale standardization, and 3. Capabilities for unifying IR calibration among different instruments and platforms. However, more needs to be done to meet the immediate needs for climate and to effectively leverage these new operational weather systems, including 1. Place special emphasis on making new instruments as accurate as they can be to realize the potential of technological investments already made, 2. Maintain a careful validation program for establishing the best possible direct radiance check of long-term accuracy--specifically, continuing to use aircraft-or balloon-borne instruments that are periodically checked directly with NIST, and 3. Commit to a simple, new IR mission that will provide an ongoing backbone for the climate observing system. The new mission would make use of Fourier Transform Spectrometer measurements to fill in spectral and diurnal sampling gaps of the operational systems and provide a benchmark with better than 0.1K 3-sigma accuracy based on standards that are verifiable in-flight.

  8. [Development of multi-target multi-spectral high-speed pyrometer].

    PubMed

    Xiao, Peng; Dai, Jing-Min; Wang, Qing-Wei

    2008-11-01

    The plume temperature of a solid propellant rocket engine (SPRE) is a fundamental parameter in denoting combustion status. It is necessary to measure the temperature along both the axis and the radius of the engine. In order to measure the plume temperature distribution of a solid propellant rocket engine, the multi-spectral thermometry has been approved. Previously the pyrometer was developed in the Harbin Institute of Technology of China in 1999, which completed the measurement of SPRE plume temperature and its distribution with multi-spectral technique in aerospace model development for the first time. Following this experience, a new type of multi-target multi-spectral high-speed pyrometer used in the ground experiments of SPRE plume temperature measurement was developed. The main features of the instrument include the use of a dispersing prism and a photo-diode array to cover the entire spectral band of 0.4 to 1.1 microm. The optic fibers are used in order to collect and transmit the thermal radiation fluxes. The instrument can measure simultaneously the temperature and emissivity of eight spectra for six uniformly distributed points on the target surface, which are well defined by the hole on the field stop lens. A specially designed S/H (Sample/Hold) circuit, with 48 sample and hold units that were triggered with a signal, measures the multi-spectral and multi-target outputs. It can sample 48 signals with a less than 10ns time difference which is most important for the temperature calculation.

  9. [Development of a High Spectral Resolution UV Flat-Field Spectrograph].

    PubMed

    Du, Liang-liang; Du, Xue-wei; Li, Chao-yang; An, Ning; Wang, Qiu-ping

    2015-06-01

    As an important optical splitting element, grating is used in many different spectrometers and spectrographs. Spherical varied-line-spacing grating (SVLSG) is easily combined with array detectors to get a wide wavelength range of spectrums in one time, because it can focus the spectrums in approximately a plane. Therefore, it's widely used in many spectral instruments. We usually only know the central groove density of a commercial grating and its mounting parameters, while its line spacing parameters are unknown. Moreover, the mounting parameters are optimized within the whole using wavelength range of the grating. However, in most circumstances only part of the wavelength range is used. Therefore, the mounting parameters are not optimized for the needed wavelength range. Under this condition, in this article we developed a method based on the focusing theory of the flat-field grating and the mounting parameters the manufacture provided to deduce the line spacing parameters of the grating. With these parameters, we can optimize the detector position according to the wavelength range we need and ray tracing can be done to test the optical system. In this article we developed a high spectral resolution ultraviolet spectrograph, covering a wavelength range of 230-280 nm. The grating used in this spectrograph has a central groove density of 1 200 lines x mm(-1) and a designed wavelength range of 170-500 nm. We deduced the line spacing parameters of the grating and optimized the detector mounting parameters. Hollow cathode lamps of different elements were used to calibrate the spectrograph and test the spectral resolution of it. Wavelength calibration of the spectrograph has been done with the parameter fitting method, and the calibration accuracy is better than 0.01 nm. Results show the spectral resolution of the spectral graph is about 0.08 nm at 280.20 nm.

  10. A Novel High-Throughput Approach to Measure Hydroxyl Radicals Induced by Airborne Particulate Matter

    PubMed Central

    Son, Yeongkwon; Mishin, Vladimir; Welsh, William; Lu, Shou-En; Laskin, Jeffrey D.; Kipen, Howard; Meng, Qingyu

    2015-01-01

    Oxidative stress is one of the key mechanisms linking ambient particulate matter (PM) exposure with various adverse health effects. The oxidative potential of PM has been used to characterize the ability of PM induced oxidative stress. Hydroxyl radical (•OH) is the most destructive radical produced by PM. However, there is currently no high-throughput approach which can rapidly measure PM-induced •OH for a large number of samples with an automated system. This study evaluated four existing molecular probes (disodium terephthalate, 3′-p-(aminophenyl)fluorescein, coumarin-3-carboxylic acid, and sodium benzoate) for their applicability to measure •OH induced by PM in a high-throughput cell-free system using fluorescence techniques, based on both our experiments and on an assessment of the physicochemical properties of the probes reported in the literature. Disodium terephthalate (TPT) was the most applicable molecular probe to measure •OH induced by PM, due to its high solubility, high stability of the corresponding fluorescent product (i.e., 2-hydroxyterephthalic acid), high yield compared with the other molecular probes, and stable fluorescence intensity in a wide range of pH environments. TPT was applied in a high-throughput format to measure PM (NIST 1648a)-induced •OH, in phosphate buffered saline. The formed fluorescent product was measured at designated time points up to 2 h. The fluorescent product of TPT had a detection limit of 17.59 nM. The soluble fraction of PM contributed approximately 76.9% of the •OH induced by total PM, and the soluble metal ions of PM contributed 57.4% of the overall •OH formation. This study provides a promising cost-effective high-throughput method to measure •OH induced by PM on a routine basis. PMID:26516887

  11. Ultra-high resolution spectral domain optical coherence tomography using supercontinuum light source

    NASA Astrophysics Data System (ADS)

    Lim, Yiheng; Yatagai, Toyohiko; Otani, Yukitoshi

    2016-04-01

    An ultra-high resolution spectral domain optical coherence tomography (SD-OCT) was developed using a cost-effective supercontinuum laser. A spectral filter consists of a dispersive prism, a cylindrical lens and a right-angle prism was built to transmit the wavelengths in range 680-940 nm to the OCT system. The SD-OCT has achieved 1.9 μm axial resolution and the sensitivity was estimated to be 91.5 dB. A zero-crossing fringes matching method which maps the wavelengths to the pixel indices of the spectrometer was proposed for the OCT spectral calibration. A double sided foam tape as a static sample and the tip of a middle finger as a biological sample were measured by the OCT. The adhesive and the internal structure of the foam of the tape were successfully visualized in three dimensions. Sweat ducts was clearly observed in the OCT images at very high resolution. To the best of our knowledge, this is the first demonstration of ultra-high resolution visualization of sweat duct by OCT.

  12. Mercury Sodium Atmosphere Spectral Imager (MSASI) - taking High Resolution Interferometry to the Planets

    NASA Astrophysics Data System (ADS)

    Yoshikawa, Ichiro; Kameda, Shingo; Korablev, Oleg; Rees, David

    The Mercury Sodium Atmosphere Spectral Imager (MSASI) on the Mercury Magnetospheric Orbiter of the JAXA / ESA Bepi-Colombo (BC) Mission will address a range of fundamental scientific questions pertaining to Mercury's exosphere. The measurements will provide new information on regolith-exosphere-magnetosphere coupling as well as new understanding of the dynamics governing the exosphere bounded by the planetary surface, the solar wind and interplanetary space. MSASI is a high-dispersion visible spectrometer working in the spectral region near the sodium D2 emission (589 nm), a major constituent of the Mercury exosphere. A single high-resolution Fabry-Perot etalon is used in combination with a narrow-band interference filter to achieve a compact and efficient instrument design. The etalon and filter are extremely stable with respect to long-term ageing and temperature variations. Full-disk images of the planet are obtained by means of a single-axis scanning mirror in combination with the spin of the MMO spacecraft . This paper presents an overview of the MSASI and the design of the Fabry- Perot interferometer used as its spectral analyser. It is concluded that: (1) The MSASI optical design is practical and can be implemented without new or critical technology developments; (2) The thermally-stable etalon design is based on concepts, designs and materials that have a good space heritage. (3) The MSASI instrument will achieve a high SNR (˜10) in the range of 2K-10M Rayleigh.

  13. Spectral Changes in Metal Halide and High-Pressure Sodium Lamps Equipped with Electronic Dimming

    NASA Technical Reports Server (NTRS)

    Bubenheim, David L.; Sargis, Raman; Wilson, David

    1995-01-01

    Electronic dimming of high-intensity discharge lamps offers control of Photosynthetic Photon Flux (PPF) but is often characterized as causing significant spectral changes. Growth chambers with 400-W Metal Halide (MH) and High-Pressure Sodium (HPS) lamps were equipped with a dimmer system using Silicon-Controlled Rectifiers (SCR) as high-speed switches. Phase control operation turned the line power off for some period of the alternating current cycle. At full power, the electrical input to HPS and MH lamps was 480 W (root mean squared) and could be decreased to 267 W and 428 W, respectively, before the arc was extinguished. Concomitant with this decrease in input power, PPF decreased by 60% in HPS and 50% in MH. The HPS lamp has characteristic spectral peaks at 589 and 595 nm. As power to the HPS lamps was decreased, the 589-nm peak remained constant while the 595-nm peak decreased, equaling the 589-nm peak at 345-W input, and 589-nm peak was almost absent at 270-W input. The MH lamp has a broader spectral output but also has a peak at 589 nm and another smaller peak at 545 nm. As input power approached 428 W, the 589-nm peak shifted to 570 nm. While the spectrum changed as input power was decreased in the MH and HPS lamps, the phytochrome equilibrium ratio (P(sub ft):P(sub tot)) remains unchanged for both lamp types.

  14. A compressible high-order unstructured spectral difference code for stratified convection in rotating spherical shells

    NASA Astrophysics Data System (ADS)

    Wang, Junfeng; Liang, Chunlei; Miesch, Mark S.

    2015-06-01

    We present a novel and powerful Compressible High-ORder Unstructured Spectral-difference (CHORUS) code for simulating thermal convection and related fluid dynamics in the interiors of stars and planets. The computational geometries are treated as rotating spherical shells filled with stratified gas. The hydrodynamic equations are discretized by a robust and efficient high-order Spectral Difference Method (SDM) on unstructured meshes. The computational stencil of the spectral difference method is compact and advantageous for parallel processing. CHORUS demonstrates excellent parallel performance for all test cases reported in this paper, scaling up to 12 000 cores on the Yellowstone High-Performance Computing cluster at NCAR. The code is verified by defining two benchmark cases for global convection in Jupiter and the Sun. CHORUS results are compared with results from the ASH code and good agreement is found. The CHORUS code creates new opportunities for simulating such varied phenomena as multi-scale solar convection, core convection, and convection in rapidly-rotating, oblate stars.

  15. Nonlinear inverse synthesis for high spectral efficiency transmission in optical fibers.

    PubMed

    Le, Son Thai; Prilepsky, Jaroslaw E; Turitsyn, Sergei K

    2014-11-03

    In linear communication channels, spectral components (modes) defined by the Fourier transform of the signal propagate without interactions with each other. In certain nonlinear channels, such as the one modelled by the classical nonlinear Schrödinger equation, there are nonlinear modes (nonlinear signal spectrum) that also propagate without interacting with each other and without corresponding nonlinear cross talk, effectively, in a linear manner. Here, we describe in a constructive way how to introduce such nonlinear modes for a given input signal. We investigate the performance of the nonlinear inverse synthesis (NIS) method, in which the information is encoded directly onto the continuous part of the nonlinear signal spectrum. This transmission technique, combined with the appropriate distributed Raman amplification, can provide an effective eigenvalue division multiplexing with high spectral efficiency, thanks to highly suppressed channel cross talk. The proposed NIS approach can be integrated with any modulation formats. Here, we demonstrate numerically the feasibility of merging the NIS technique in a burst mode with high spectral efficiency methods, such as orthogonal frequency division multiplexing and Nyquist pulse shaping with advanced modulation formats (e.g., QPSK, 16QAM, and 64QAM), showing a performance improvement up to 4.5 dB, which is comparable to results achievable with multi-step per span digital back propagation.

  16. All-fiber upconversion high spectral resolution wind lidar using a Fabry-Perot interferometer.

    PubMed

    Shangguan, Mingjia; Xia, Haiyun; Wang, Chong; Qiu, Jiawei; Shentu, Guoliang; Zhang, Qiang; Dou, Xiankang; Pan, Jian-Wei

    2016-08-22

    An all-fiber, micro-pulse and eye-safe high spectral resolution wind lidar (HSRWL) at 1.5 μm is proposed and demonstrated by using a pair of upconversion single-photon detectors and a fiber Fabry-Perot scanning interferometer (FFP-SI). In order to improve the optical detection efficiency, both the transmission spectrum and the reflection spectrum of the FFP-SI are used for spectral analyses of the aerosol backscatter and the reference laser pulse. Taking advantages of high signal-to-noise ratio of the detectors and high spectral resolution of the FFP-SI, the center frequencies and the bandwidths of spectra of the aerosol backscatter are obtained simultaneously. Continuous LOS wind observations are carried out on two days at Hefei (31.843 °N, 117.265 °E), China. The horizontal detection range of 4 km is realized with temporal resolution of 1 minute. The spatial resolution is switched from 30 m to 60 m at distance of 1.8 km. In a comparison experiment, LOS wind measurements from the HSRWL show good agreement with the results from an ultrasonic wind sensor (Vaisala windcap WMT52). An empirical method is adopted to evaluate the precision of the measurements. The standard deviation of the wind speed is 0.76 m/s at 1.8 km. The standard deviation of bandwidth variation is 2.07 MHz at 1.8 km.

  17. High-power spectral beam combining of linearly polarized Tm:fiber lasers.

    PubMed

    Shah, Lawrence; Sims, R Andrew; Kadwani, Pankaj; Willis, Christina C C; Bradford, Joshua B; Sincore, Alex; Richardson, Martin

    2015-02-01

    To date, high-power scaling of Tm:fiber lasers has been accomplished by maximizing the power from a single fiber aperture. In this work, we investigate power scaling by spectral beam combination of three linearly polarized Tm:fiber MOPA lasers using dielectric mirrors with a steep transition from highly reflective to highly transmissive that enable a minimum wavelength separation of 6 nm between individual laser channels within the wavelength range from 2030 to 2050 nm. Maximum output power is 253 W with M(2)<2, ultimately limited by thermal lensing in the beam combining elements.

  18. Frequency spectrum analysis for spectrum stabilization in airborne gamma-ray spectrometer.

    PubMed

    Zeng, Guoqiang; Tan, Chengjun; Ge, Liangquan; Zhang, Qingxian; Gu, Yi

    2014-02-01

    Abnormal multi-crystal spectral drifts often can be observed when power on the airborne gamma-ray spectrometer. Currently, these spectral drifts of each crystal are generally eliminated through manual adjustment, which is time-consuming and labor-ineffective. To realize this quick automatic spectrum stabilization of multi-crystal, a frequency spectrum analysis method for natural gamma-ray background spectrum is put forward in this paper to replace traditional spectrum stabilization method used characteristic peak. Based on the polynomial fitting of high harmonics in frequency spectrum and gamma-ray spectral drift, it calculates overall spectral drift of natural gamma-ray spectrum and adjusts the gain of spectrometer by this spectral drift value, thus completing quick spectrum stabilization in the power on stage of spectrometer. This method requires no manual intervention and can obtain the overall spectral drift value automatically under no time-domain pre-processing to the natural gamma-ray spectra. The spectral drift value calculated by this method has an absolute error less than five channels (1024 resolution) and a relative error smaller than 0.80%, which can satisfy the quick automatic spectrum stabilization requirement when power on the airborne gamma-ray spectrometer instead of manual operation.

  19. Comparison of Methods to Map and Measure River Terraces using High-Resolution Airborne LiDAR Data

    NASA Astrophysics Data System (ADS)

    Hopkins, A. J.; Snyder, N. P.

    2013-12-01

    Fluvial terraces are important recorders of land-use, climate, and tectonic history that form in both erosional and depositional landscapes and consist of a flat surface bounded by valley walls and a steep-sloping scarp adjacent to the river channel. Combining these defining characteristics with high-resolution digital elevation models (DEMs) derived from airborne light detection and ranging (lidar) surveys, several methods have been developed to identify and map terraces. The goals of this research are to compare some of these existing techniques and develop an objective approach to map terraces over entire watersheds using lidar DEMs. Additionally, we aim to quantify the thickness and volume of fill terrace deposits. Our preliminary application is to the Sheepscot River watershed, Maine, where strath and fill terraces are present and record Pleistocene deglaciation, Holocene eustatic forcing, and Anthropocene land-use change. We identify terraces along the longitudinal profile using an algorithm developed by Finnegan and Balco (2013), that computes the elevation frequency distribution at regularly spaced cross-sections normal to the channel. Next, we delineate terrace spatial extent using three separate methodologies: (1) image processing using Matlab, (2) feature classification algorithms developed by Wood (1996), and (3) image interpretation using manually placed points on known terraces to construct interpolated surfaces (Walter and Merritts, 2008). Lastly, we determine the thickness and volume of fill terrace sediments by subtracting an interpolated, adjacent water surface elevation from the defined terrace points. We compare our LiDAR-based results with field mapping, stratigraphic columns of terrace landforms, and ground penetrating radar over terrace surfaces. These findings suggest powerful new ways to rapidly analyze landscape history over large regions using high-resolution lidar DEMs, with less reliance on detailed and costly field data collection.

  20. Characteristics of Deep Tropical and Subtropical Convection from Nadir-Viewing High-Altitude Airborne Doppler Radar

    NASA Technical Reports Server (NTRS)

    Heymsfield, Gerald M.; Tian, Lin; Heymsfield, Andrew J.; Li, Lihua; Guimond, Stephen

    2010-01-01

    This paper presents observations of deep convection characteristics in the tropics and subtropics that have been classified into four categories: tropical cyclone, oceanic, land, and sea breeze. Vertical velocities in the convection were derived from Doppler radar measurements collected during several NASA field experiments from the nadir-viewing high-altitude ER-2 Doppler radar (EDOP). Emphasis is placed on the vertical structure of the convection from the surface to cloud top (sometimes reaching 18-km altitude). This unique look at convection is not possible from other approaches such as ground-based or lower-altitude airborne scanning radars. The vertical motions from the radar measurements are derived using new relationships between radar reflectivity and hydrometeor fall speed. Various convective properties, such as the peak updraft and downdraft velocities and their corresponding altitude, heights of reflectivity levels, and widths of reflectivity cores, are estimated. The most significant findings are the following: 1) strong updrafts that mostly exceed 15 m/s, with a few exceeding 30 m/s, are found in all the deep convection cases, whether over land or ocean; 2) peak updrafts were almost always above the 10-km level and, in the case of tropical cyclones, were closer to the 12-km level; and 3) land-based and sea-breeze convection had higher reflectivities and wider convective cores than oceanic and tropical cyclone convection. In addition, the high-resolution EDOP data were used to examine the connection between reflectivity and vertical velocity, for which only weak linear relationships were found. The results are discussed in terms of dynamical and microphysical implications for numerical models and future remote sensors.

  1. Analysis of Vegetation Within A Semi-Arid Urban Environment Using High Spatial Resolution Airborne Thermal Infrared Remote Sensing Data

    NASA Technical Reports Server (NTRS)

    Quattrochi, Dale A.; Ridd, Merrill K.

    1998-01-01

    High spatial resolution (5 m) remote sensing data obtained using the airborne Thermal Infrared Multispectral Scanner (TIMS) sensor for daytime and nighttime have been used to measure thermal energy responses for 2 broad classes and 10 subclasses of vegetation typical of the Salt Lake City, Utah urban landscape. Polygons representing discrete areas corresponding to the 10 subclasses of vegetation types have been delineated from the remote sensing data and are used for analysis of upwelling thermal energy for day, night, and the change in response between day and night or flux, as measured by the TIMS. These data have been used to produce three-dimensional graphs of energy responses in W/ sq m for day, night, and flux, for each urban vegetation land cover as measured by each of the six channels of the TIMS sensor. Analysis of these graphs provides a unique perspective for both viewing and understanding thermal responses, as recorded by the TIMS, for selected vegetation types common to Salt Lake City. A descriptive interpretation is given for each of the day, night, and flux graphs along with an analysis of what the patterns mean in reference to the thermal properties of the vegetation types surveyed in this study. From analyses of these graphs, it is apparent that thermal responses for vegetation can be highly varied as a function of the biophysical properties of the vegetation itself, as well as other factors. Moreover, it is also seen where vegetation, particularly trees, has a significant influence on damping or mitigating the amount of thermal radiation upwelling into the atmosphere across the Salt Lake City urban landscape. Published by Elsevier Science Ltd.

  2. Airborne fission products in the High Arctic after the Fukushima nuclear accident.

    PubMed

    Paatero, Jussi; Vira, Julius; Siitari-Kauppi, Marja; Hatakka, Juha; Holmén, Kim; Viisanen, Yrjö

    2012-12-01

    High-volume aerosol samples were collected at the Mt. Zeppelin Global Atmosphere Watch station, Ny-Ålesund, Svalbard (78°58'N, 11°53'E). The samples were analysed to find out if the radionuclide emissions from the Fukushima nuclear power plant accident in March 2011 could be detected also in the atmosphere of the High Arctic. Iodine-131 and (134)Cs and (137)Cs were observed from 25 March 2011 onwards. The maximum (131)I, (134)Cs and (137)Cs activity concentrations were 810 ± 20, 659 ± 13, and 675 ± 7 μBq/m(3), respectively. The comparison between the measured (131)I activity concentrations at Mt. Zeppelin and those calculated with the SILAM dispersion model revealed that the timing of plume movements could be rather well predicted with the model. The activity concentration levels between the measurements and the model calculations deviated. This can be due to the inaccuracies in the source term. The (134)Cs:(137)Cs activity ratio recorded in Svalbard was high compared to earlier incidents. The ratio was close to 1 which is in agreement with other studies of the Fukushima releases. This distinctive activity ratio in the Fukushima debris could be used as a tracer in Arctic radioecology studies if the activity concentrations are high enough to be detected.

  3. Airborne transmission of H5N1 high pathogenicity avian influenza viruses during simulated home slaughter

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Most H5N1 human infections have occurred following exposure to H5N1 high pathogenicity avian influenza (HPAI) virus-infected poultry, especially when poultry are home slaughtered or slaughtered in live poultry markets. Previous studies have demonstrated that slaughter of clade 1 isolate A/Vietnam/1...

  4. Aerosol plume transport and transformation in high spectral resolution lidar measurements and WRF-Flexpart simulations during the MILAGRO Field Campaign

    NASA Astrophysics Data System (ADS)

    de Foy, B.; Burton, S. P.; Ferrare, R. A.; Hostetler, C. A.; Hair, J. W.; Wiedinmyer, C.; Molina, L. T.

    2010-11-01

    The Mexico City Metropolitan Area (MCMA) experiences high loadings of atmospheric aerosols from anthropogenic sources, biomass burning and wind-blown dust. This paper uses a combination of measurements and numerical simulations to identify different plumes affecting the basin and to characterize transformation inside the plumes. The airborne High Spectral Resolution Lidar measures extinction coefficients and extinction to backscatter ratio at 532 nm, and backscatter coefficients and depolarization ratios at 532 and 1064 nm. These can be used to identify aerosol types. The measurement curtains are compared with particle trajectory simulations using WRF-Flexpart for different source groups. The good correspondence between measurements and simulations suggests that the aerosol transport is sufficiently well characterized by the models to estimate aerosol types and ages. Plumes in the basin undergo complex transport, and are frequently mixed together. Urban aerosols are readily identifiable by their low depolarization ratios and high lidar ratios, and dust by the opposite properties. Fresh biomass burning plumes have very low depolarization ratios which increase rapidly with age. This rapid transformation is consistent with the presence of atmospheric tar balls in the fresh plumes.

  5. High spectral resolution observation of extended sources in future interplanetary missions

    NASA Astrophysics Data System (ADS)

    Hosseini, Sona

    2016-10-01

    The most commonly used technique for high spectral resolution (R) studies are grating spectrometers. They can achieve broad bandpasses but they have small FOV and relatively low étendue so they have to be paired with large aperture telescopes such Keck (10m), Hubble (2.4m) or JWST (6.5m). Fabry-Pérot Interferometers (FPI) and FTS are the other best known types of high étendue, high R spectrometers used in astronomy. But their opto-mechnical tolerances becomes challenging and they use transmitting optics, where transmission drops especially below 130 nm. Spatial Heterodyne Spectrometer (SHS) is a candidate for high étendue, high spectral R spectroscopy in compact low cost, low-mass, low-power architecture using no or small aperture telescope for UV to IR wavelengths. High R spectrometers are usually limited by the telescope aperture size and complicated opto-mechanical tolerances but that's not the case for SHS. SHS provides integrated spectra at high spectral R, over a wide FOV in compact designs in which it offers the ability to make key science measurements for a variety of planetary targets. SHS could be implemented on a dedicated SmallSat or ISS that can sit and stare at its target for long duration of time that cannot be done from the ground or on big missions. SmallSats are lower cost, faster to build, relatively easy to correct and upgrade. For UV observation, currently HST is the only telescope capable of collecting the necessary observations and the next major UV space telescope might be able to fly in 10 years or more. SHS instrument can quickly fill the technology gap for UV space spectrometers.

  6. Tropospheric ozone and aerosol variability observed at high latitudes with an airborne lidar

    NASA Technical Reports Server (NTRS)

    Browell, Edward V.; Butler, Carolyn F.; Fenn, Marta A.; Kooi, Susan A.; Grant, William B.

    1994-01-01

    Large-scale summertime (July-August) distributions of O3 and aerosols were observed in a broad range of atmosphere conditions over the tundra, ice, and ocean regions near Alaska in 1988 and over the lowlands and boreal forests of Canada in 1990. The tropospheric O3 budget in the high-latitude regions was found to be strongly influenced by stratospheric intrusions, and deposition at the surface was found to be the main sink for O3 in the troposphere. Enhanced levels of O3 were observed in plumes from fires in Alaska and Canada. This paper discusses the large-scale variability of O3 and aerosols observed in the high-latitude regions during these field experiments.

  7. Resolving range ambiguities in high-repetition rate airborne lidar applications

    NASA Astrophysics Data System (ADS)

    Rieger, Peter; Ullrich, Andreas

    2011-11-01

    Correctly determining a measurement range in LIDAR instruments, based on time-of-flight measurements on laser pulses, requires the allocation of each received echo pulse to its causative emitted laser pulse. Without further precautions this definite allocation is only possible under specific conditions constraining the usability of range finders and laser scanners with very high measurement rates. Losing the unambiguity of ranges in high repetition systems is well known in RADAR and the term "multiple time around" (MTA) has been coined. However because of fundamental differences between scanning LIDAR and RADAR, with respect to MTA processing, new approaches for resolving range ambiguities in LIDAR are possible. In this paper we compare known and novel techniques for avoiding or even resolving range ambiguities without any further user interaction required. Such techniques may be based upon measures affecting hardware (e.g. spatial multiplexing or modulation of consecutive laser pulses), software (e.g. assumptions about the true measurement range based on a rough DTM) or both hard- and soft-ware in order to achieve a high probability of correctly resolved range ambiguities. Furthermore a comparison of different approaches is given, discussing their specific (dis-) advantages and their current status of implementation.

  8. Design and algorithm research of high precision airborne infrared touch screen

    NASA Astrophysics Data System (ADS)

    Zhang, Xiao-Bing; Wang, Shuang-Jie; Fu, Yan; Chen, Zhao-Quan

    2016-10-01

    There are shortcomings of low precision, touch shaking, and sharp decrease of touch precision when emitting and receiving tubes are failure in the infrared touch screen. A high precision positioning algorithm based on extended axis is proposed to solve these problems. First, the unimpeded state of the beam between emitting and receiving tubes is recorded as 0, while the impeded state is recorded as 1. Then, the method of oblique scan is used, in which the light of one emitting tube is used for five receiving tubes. The impeded information of all emitting and receiving tubes is collected as matrix. Finally, according to the method of arithmetic average, the position of the touch object is calculated. The extended axis positioning algorithm is characteristic of high precision in case of failure of individual infrared tube and affects slightly the precision. The experimental result shows that the 90% display area of the touch error is less than 0.25D, where D is the distance between adjacent emitting tubes. The conclusion is gained that the algorithm based on extended axis has advantages of high precision, little impact when individual infrared tube is failure, and using easily.

  9. In Situ Measurements of Spectral Emissivity of Materials for Very High Temperature Reactors

    SciTech Connect

    G. Cao; S. J. Weber; S. O. Martin; T. L. Malaney; S. R. Slattery; M. H. Anderson; K. Sridharan; T. R. Allen

    2011-08-01

    An experimental facility for in situ measurements of high-temperature spectral emissivity of materials in environments of interest to the gas-cooled very high temperature reactor (VHTR) has been developed. The facility is capable of measuring emissivities of seven materials in a single experiment, thereby enhancing the accuracy in measurements due to even minor systemic variations in temperatures and environments. The system consists of a cylindrical silicon carbide (SiC) block with seven sample cavities and a deep blackbody cavity, a detailed optical system, and a Fourier transform infrared spectrometer. The reliability of the facility has been confirmed by comparing measured spectral emissivities of SiC, boron nitride, and alumina (Al2O3) at 600 C against those reported in literature. The spectral emissivities of two candidate alloys for VHTR, INCONEL{reg_sign} alloy 617 (INCONEL is a registered trademark of the Special Metals Corporation group of companies) and SA508 steel, in air environment at 700 C were measured.

  10. a High-Efficiency Fusion Method of Multi-Spectral Image and Panchromatic Image

    NASA Astrophysics Data System (ADS)

    Xue, X.; Wang, J. P.; Wang, H.; Xiang, F.

    2013-07-01

    With the development of modern remote sensing technology, a variety of earth observation satellites could continue to tremendously provide image data of different spatial resolution, time resolution, spectral resolution remote sensing, and the remote sensing data obtained is increasing with great capacity, which forms multi-source image pyramid in the same area. To play the advantages of a variety of remote sensing data, the application of remote sensing image fusion is a very important choice. When remote sensing data is large, fusion is large in computing capacity and time-consuming, so it is difficult to carry out rapid, real-time fusion. However, in some remote sensing applications, such as disaster prevention and relief quick, etc., timely fusion is required. Based on image fusion method of principal component analysis (PCA) and the advantage of parallel computing, a high-efficiency fusion method of multi-spectral image and panchromatic image is proposed. Beijing-1 Micro-satellite is a high-performance small satellite for earth observation,With Beijing-1 Micro-satellite remote sensing images as the experimental data, it is proved that good fusion results of multi-spectral image and panchromatic image can be obtained with the proposed method, and the fusion speed is also fast. At the same time, some measures of improving the efficiency of parallel image fusion are also discussed.

  11. Generation of high-intensity spectral supercontinuum of more than two octaves in a water jet.

    PubMed

    Tcypkin, A N; Putilin, S E; Melnik, M V; Makarov, E A; Bespalov, V G; Kozlov, S A

    2016-10-10

    In this paper, we demonstrate experimentally for the first time (to our knowledge) the generation of spectral supercontinuum (SC) of more than two octaves with high intensity in a water jet. The spectrum of the generated SC extends from 350 to 1400 nm, with intensities up to 1011  W/cm2, and its generation efficiency is more than 50%. For the pump intensity 3.0×1012  W/cm2 in the spectral range from 400 to 800 nm, the spectrum is nearly flat (less than 40% deviation), which is useful for many applications.

  12. Improved mid infrared detector for high spectral or spatial resolution and synchrotron radiation use

    NASA Astrophysics Data System (ADS)

    Faye, Mbaye; Bordessoule, Michel; Kanouté, Brahim; Brubach, Jean-Blaise; Roy, Pascale; Manceron, Laurent

    2016-06-01

    When using bright, small effective size sources, such as synchrotron radiation light beam, for broadband spectroscopy at spectral or spatial high resolution for mid-IR FTIR measurements, a marked detectivity improvement can be achieved by setting up a device matching the detector optical étendue to that of the source. Further improvement can be achieved by reducing the background unmodulated flux and other intrinsic noise sources using a lower temperature cryogen, such as liquid helium. By the combined use of cooled apertures, cold reimaging optics, filters and adapted detector polarization, and preamplification electronics, the sensitivity of a HgCdTe photoconductive IR detector can be improved by a significant factor with respect to standard commercial devices (more than one order of magnitude on average over 6-20 μm region) and the usable spectral range extended to longer wavelengths. The performances of such an optimized detector developed on the AILES Beamline at SOLEIL are presented here.

  13. Super-Nyquist shaping and processing technologies for high-spectral-efficiency optical systems

    NASA Astrophysics Data System (ADS)

    Jia, Zhensheng; Chien, Hung-Chang; Zhang, Junwen; Dong, Ze; Cai, Yi; Yu, Jianjun

    2013-12-01

    The implementations of super-Nyquist pulse generation, both in a digital field using a digital-to-analog converter (DAC) or an optical filter at transmitter side, are introduced. Three corresponding signal processing algorithms at receiver are presented and compared for high spectral-efficiency (SE) optical systems employing the spectral prefiltering. Those algorithms are designed for the mitigation towards inter-symbol-interference (ISI) and inter-channel-interference (ICI) impairments by the bandwidth constraint, including 1-tap constant modulus algorithm (CMA) and 3-tap maximum likelihood sequence estimation (MLSE), regular CMA and digital filter with 2-tap MLSE, and constant multi-modulus algorithm (CMMA) with 2-tap MLSE. The principles and prefiltering tolerance are given through numerical and experimental results.

  14. A Quadrilateral Spectral Multidomain Penalty Method Model For High Reynolds Number Incompressible Stratified Flows

    NASA Astrophysics Data System (ADS)

    Escobar-Vargas, Jorge; Diamessis, Peter

    2011-11-01

    We present a spectral multidomain penalty method-based incompressible Navier Stokes solver for high Reynolds number stratified turbulent flows in doubly non-periodic domains. Within the solver, time is discretized with a fractional-step method, and, in space, a Gauss-Lobatto-Legendre collocation approach is used in discontinuous quadrilateral subdomains. Stability of the numerical scheme is guaranteed through a penalty scheme and spectral filtering, further buttressed by a overintegration-based dealiasing technique. The efficient iterative solution of the associated discrete pressure Poisson equation is ensured through a Kronecker product based computation of the null vector associated with the global matrix, plus a two-level preconditioner within a GMRES solver. Efficiency and accuracy of the Navier Stokes solver are assessed through the solution of the lid-driven cavity flow, Taylor vortex and double shear layer. The canonical lock exchange problem is also presented to assess the potential of the solver for the study of environmental stratified flows.

  15. Improved mid infrared detector for high spectral or spatial resolution and synchrotron radiation use.

    PubMed

    Faye, Mbaye; Bordessoule, Michel; Kanouté, Brahim; Brubach, Jean-Blaise; Roy, Pascale; Manceron, Laurent

    2016-06-01

    When using bright, small effective size sources, such as synchrotron radiation light beam, for broadband spectroscopy at spectral or spatial high resolution for mid-IR FTIR measurements, a marked detectivity improvement can be achieved by setting up a device matching the detector optical étendue to that of the source. Further improvement can be achieved by reducing the background unmodulated flux and other intrinsic noise sources using a lower temperature cryogen, such as liquid helium. By the combined use of cooled apertures, cold reimaging optics, filters and adapted detector polarization, and preamplification electronics, the sensitivity of a HgCdTe photoconductive IR detector can be improved by a significant factor with respect to standard commercial devices (more than one order of magnitude on average over 6-20 μm region) and the usable spectral range extended to longer wavelengths. The performances of such an optimized detector developed on the AILES Beamline at SOLEIL are presented here.

  16. A simple method for vignette correction of airborne digital camera data

    SciTech Connect

    Nguyen, A.T.; Stow, D.A.; Hope, A.S.

    1996-11-01

    Airborne digital camera systems have gained popularity in recent years due to their flexibility, high geometric fidelity and spatial resolution, and fast data turn-around time. However, a common problem that plagues these types of framing systems is vignetting which causes falloff in image brightness away from principle nadir point. This paper presents a simple method for vignetting correction by utilizing laboratory images of a uniform illumination source. Multiple lab images are averaged and inverted to create digital correction templates which then are applied to actual airborne data. The vignette correction was effective in removing the systematic falloff in spectral values. We have shown that the vignette correction is a necessary part of the preprocessing of raw digital airborne remote sensing data. The consequences of not correcting for these effects are demonstrated in the context of monitoring of salt marsh habitat. 4 refs.

  17. The NASA airborne astronomy program - A perspective on its contributions to science, technology, and education

    NASA Technical Reports Server (NTRS)

    Larson, Harold P.

    1992-01-01

    The publication records from NASA's airborne observatories are examined to evaluate the contribution of the airborne astronomy program to technological development and scientific/educational progress. The breadth and continuity of program is detailed with reference to its publication history, discipline representation, literature citations, and to the ability of such a program to address nonrecurring and unexpected astronomical phenomena. Community involvement in the airborne-observation program is described in terms of the number of participants, institutional affiliation, and geographic distribution. The program utilizes instruments including heterodyne and grating spectrometers, high-speed photometers, and Fabry-Perot spectrometers with wide total spectral ranges, resolutions, and numbers of channels. The potential of the program for both astronomical training and further scientific, theoretical, and applied development is underscored.

  18. High-throughput quantum cascade laser (QCL) spectral histopathology: a practical approach towards clinical translation.

    PubMed

    Pilling, Michael J; Henderson, Alex; Bird, Benjamin; Brown, Mick D; Clarke, Noel W; Gardner, Peter

    2016-06-23

    Infrared microscopy has become one of the key techniques in the biomedical research field for interrogating tissue. In partnership with multivariate analysis and machine learning techniques, it has become widely accepted as a method that can distinguish between normal and cancerous tissue with both high sensitivity and high specificity. While spectral histopathology (SHP) is highly promising for improved clinical diagnosis, several practical barriers currently exist, which need to be addressed before successful implementation in the clinic. Sample throughput and speed of acquisition are key barriers and have been driven by the high volume of samples awaiting histopathological examination. FTIR chemical imaging utilising FPA technology is currently state-of-the-art for infrared chemical imaging, and recent advances in its technology have dramatically reduced acquisition times. Despite this, infrared microscopy measurements on a tissue microarray (TMA), often encompassing several million spectra, takes several hours to acquire. The problem lies with the vast quantities of data that FTIR collects; each pixel in a chemical image is derived from a full infrared spectrum, itself composed of thousands of individual data points. Furthermore, data management is quickly becoming a barrier to clinical translation and poses the question of how to store these incessantly growing data sets. Recently, doubts have been raised as to whether the full spectral range is actually required for accurate disease diagnosis using SHP. These studies suggest that once spectral biomarkers have been predetermined it may be possible to diagnose disease based on a limited number of discrete spectral features. In this current study, we explore the possibility of utilising discrete frequency chemical imaging for acquiring high-throughput, high-resolution chemical images. Utilising a quantum cascade laser imaging microscope with discrete frequency collection at key diagnostic wavelengths, we

  19. Airborne spacecraft - A remotely powered, high-altitude RPV for environmental applications

    NASA Technical Reports Server (NTRS)

    Youngblood, J. W.; Darnell, W. L.; Johnson, R. W.; Harriss, R. C.

    1979-01-01

    A high-altitude, unmanned, propeller-driven electric airplane is proposed for remote sensing of environmental phenomena. With motive power from surface-mounted solar arrays or microwave receivers, flight endurance of weeks to months could be anticipated. The proposed system offers unique capability for monitoring oceanic and atmospheric characteristics on local or regional scales. Coastal marine and tropospheric research activities, which require temporal resolutions of 2-72 hours, would be prime application areas. Potential missions might include the monitoring of ocean disposals, episodic marine biological events, and river/ocean interactions. Preliminary sizing and performance calculations are presented along with possible mission scenarios and payload complements.

  20. Measurement of high-temperature spectral emissivity using integral blackbody approach

    NASA Astrophysics Data System (ADS)

    Pan, Yijie; Dong, Wei; Lin, Hong; Yuan, Zundong; Bloembergen, Pieter

    2016-11-01

    Spectral emissivity is one of the most critical thermophysical properties of a material for heat design and analysis. Especially in the traditional radiation thermometry, normal spectral emissivity is very important. We developed a prototype instrument based upon an integral blackbody method to measure material's spectral emissivity at elevated temperatures. An optimized commercial variable-high-temperature blackbody, a high speed linear actuator, a linear pyrometer, and an in-house designed synchronization circuit was used to implemented the system. A sample was placed in a crucible at the bottom of the blackbody furnace, by which the sample and the tube formed a simulated reference blackbody which had an effective total emissivity greater than 0.985. During the measurement, a pneumatic cylinder pushed a graphite rode and then the sample crucible to the cold opening within hundreds of microseconds. The linear pyrometer was used to monitor the brightness temperature of the sample surface, and the corresponding opto-converted voltage was fed and recorded by a digital multimeter. To evaluate the temperature drop of the sample along the pushing process, a physical model was proposed. The tube was discretized into several isothermal cylindrical rings, and the temperature of each ring was measurement. View factors between sample and rings were utilized. Then, the actual surface temperature of the sample at the end opening was obtained. Taking advantages of the above measured voltage signal and the calculated actual temperature, normal spectral emissivity under the that temperature point was obtained. Graphite sample at 1300°C was measured to prove the validity of the method.

  1. New optical sensor systems for high-resolution satellite, airborne and terrestrial imaging systems

    NASA Astrophysics Data System (ADS)

    Eckardt, Andreas; Börner, Anko; Lehmann, Frank

    2007-10-01

    The department of Optical Information Systems (OS) at the Institute of Robotics and Mechatronics of the German Aerospace Center (DLR) has more than 25 years experience with high-resolution imaging technology. The technology changes in the development of detectors, as well as the significant change of the manufacturing accuracy in combination with the engineering research define the next generation of spaceborne sensor systems focusing on Earth observation and remote sensing. The combination of large TDI lines, intelligent synchronization control, fast-readable sensors and new focal-plane concepts open the door to new remote-sensing instruments. This class of instruments is feasible for high-resolution sensor systems regarding geometry and radiometry and their data products like 3D virtual reality. Systemic approaches are essential for such designs of complex sensor systems for dedicated tasks. The system theory of the instrument inside a simulated environment is the beginning of the optimization process for the optical, mechanical and electrical designs. Single modules and the entire system have to be calibrated and verified. Suitable procedures must be defined on component, module and system level for the assembly test and verification process. This kind of development strategy allows the hardware-in-the-loop design. The paper gives an overview about the current activities at DLR in the field of innovative sensor systems for photogrammetric and remote sensing purposes.

  2. Advances in airborne remote sensing of ecosystem processes and properties: toward high-quality measurement on a global scale

    NASA Astrophysics Data System (ADS)

    Kampe, Thomas U.; Asner, Gregory P.; Green, Robert O.; Eastwood, Michael; Johnson, Brian R.; Kuester, Michele

    2010-08-01

    Airborne remote sensing provides the opportunity to quantitatively measure biochemical and biophysical properties of vegetation at regional scales, therefore complementing surface and satellite measurements. Next-generation programs are poised to advance ecological research and monitoring in the United States, the tropical regions of the globe, and to support future satellite missions. The Carnegie Institution will integrate a next generation imaging spectrometer with a waveform LiDAR into the Airborne Taxonomic Mapping System (AToMS) to identify the chemical, structural and taxonomic makeup of tropical forests at an unprecedented scale and detail. The NEON Airborne Observation Platform (AOP) is under development with similar technologies with a goal to provide long-term measurements of ecosystems across North America. The NASA Next Generation Airborne Visible/Infrared Imaging Spectrometer (AVIRISng) is also under development to address the science measurement requirements for both the NASA Earth Science Research and Analysis Program and the spaceborne NASA HyspIRI Mission. Carnegie AToMS, NEON AOP, and AVIRISng are being built by the Jet Propulsion Laboratory as a suite of instruments. We discuss the synergy between these programs and anticipated benefits to ecologists and decision-makers.

  3. Spectral broadening of parametric instability in lower hybrid current drive at a high density

    NASA Astrophysics Data System (ADS)

    Cesario, R.; Amicucci, L.; Cardinali, A.; Castaldo, C.; Marinucci, M.; Napoli, F.; Paoletti, F.; De Arcangelis, D.; Ferrari, M.; Galli, A.; Gallo, G.; Pullara, E.; Schettini, G.; Tuccillo, A. A.

    2014-04-01

    The important goal of adding to the bootstrap current a more flexible tool, capable of producing and controlling steady-state profiles with a high fraction of non-inductive plasma current, could be reached using the lower hybrid current drive (LHCD) effect. Experiments performed on FTU (Frascati Tokamak Upgrade) demonstrated that LHCD can occur at reactor-graded high plasma density, provided that the parametric instability (PI)-produced broadening of the spectrum launched by the antenna is reduced under proper operating conditions, capable of producing relatively high temperature in the outer region of plasma column. This condition was produced by operations that reduce particle recycling from the vessel walls, and enhance the gas fuelling in the core by means of fast pellet. New results of FTU experiments are presented documenting that the useful effect of temperature at the periphery, which reduces the LH spectral broadening and enhances the LH-induced hard-x ray emission level, occurs in a broader range of plasma parameters than in previous work. Modelling results show that a further tool for helping LHCD at a high density would be provided by electron cyclotron resonant heating of plasma periphery. New information is provided on the modelling, able determining frequencies, growth rates and LH spectral broadening produced by PI, which allowed assessing the new method for enabling LHCD at high densities. Further robustness is provided to theoretical and experimental fundaments of the method for LHCD at a high density.

  4. Probing Atlas model atmospheres at high spectral resolution. Stellar synthesis and reference template validation

    NASA Astrophysics Data System (ADS)

    Bertone, E.; Buzzoni, A.; Chávez, M.; Rodríguez-Merino, L. H.

    2008-07-01

    Aims: The fast improvement of spectroscopic observations makes mandatory a strong effort on the theoretical side to better reproduce the spectral energy distribution (SED) of stars at high spectral resolution. In this regard, relying on the Kurucz Atlas/Synthe original codes we computed the Bluered library, consisting of 832 synthetic SED of stars, that cover a large parameter space at very high spectral resolution (R = 500 000) along the 3500-7000 Å wavelength range. Methods: Bluered synthetic spectra have been used to assess in finer detail the intrinsic reliability and the performance limits of the Atlas theoretical framework. The continuum-normalized spectra of the Sun, Arcturus, and Vega, plus a selected list of 45 bright stars with high-quality SEDs from the Prugniel & Soubiran Elodie catalog, form our sample designed to probe the global properties of synthetic spectra across the entire range of H-R parameters. Results: Atlas models display a better fitting performance with increasing stellar temperature. High-resolution spectra of Vega, the Sun, and Arcturus have been reproduced at R=100 000, respectively, within a 0.7%, 4.5%, and 8.8% relative scatter in residual flux. In all the three cases, the residual flux distribution shows a significant asymmetry (skewness parameter γ = -2.21, -0.98, -0.67, respectively), which neatly confirms an overall “excess” of theoretical line blanketing. For the Sun, this apparent discrepancy is alleviated, but not recovered, by a systematic decrease (-40%) of the line oscillator strengths, log (gf), especially referring to iron transitions. Definitely, a straight “astrophysical” determination of log (gf) for each individual atomic transition has to be devised to overcome the problem. By neglecting overblanketing effects in theoretical models when fitting high-resolution continuum-normalized spectra of real stars, we lead to a systematically warmer effective temperature (between +80 and +300 K for the solar fit) and a

  5. Highly Sensitive Protein Translation Assay for Trichothecene Toxicity in Airborne Particulates: Comparison with Cytotoxicity Assays

    PubMed Central

    Yike, Iwona; Allan, Terry; Sorenson, William G.; Dearborn, Dorr G.

    1999-01-01

    Screening assays for environmental mycotoxins in bulk samples currently use cytotoxicity in cell cultures, but their application to air particulate samples often lacks sensitivity and specificity for fungal spores. An assay based on inhibition of protein synthesis using translation of firefly luciferase in a rabbit reticulocyte system has been developed for the detection of trichothecene mycotoxins found in the spores of toxigenic fungi. Ethanol extracts of air particulates trapped on polycarbonate filters are ultrafiltered and applied at several dilutions to a translation reaction mixture. The activity of translated luciferase is measured directly in a luminometer, eliminating the need for radioisotopes and time-consuming sample processing. Parallel standard curves using a commercially available trichothecene provide for expression of the results in T-2 toxin equivalents per cubic meter of air. The assay can be completed in 2 h and is readily applicable to multiple samples. Comparison to the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide cytotoxicity assay indicates a 400-fold increase in sensitivity of trichothecene detection in addition to a much higher specificity for these toxins. Initial field testing indicates a strong correlation between the measured level of toxicity and the presence of toxigenic fungi detected with microbiological methods. In conclusion, this luciferase translation assay offers a rapid and highly sensitive and specific method for quantitative detection of trichothecene mycotoxin activity in air particulate samples. PMID:9872764

  6. Analysis of high allergenicity airborne pollen dispersion: common ragweed study case in Lithuania.

    PubMed

    Šaulienė, Ingrida; Veriankaitė, Laura

    2012-01-01

    The appearance of ragweed pollen in the air became more frequent in northerly countries. Attention of allergologists and aerobiologists in these countries is focused on the phenomenon that Ambrosia plants found relatively sporadic but the amount of pollen is high in particular days. Over the latter decade, a matter of particular concern has been Ambrosia pollen, whose appearance in the air is determined by the plants dispersing it and meteorological processes that alter pollen release, dissemination, transport or deposition on surfaces. Pollen data used in this study were collected in three pollen-trapping sites in Lithuania. The data corresponding to 2006-2011 years of pollen monitoring were documented graphically and evaluated statistically. Analysis of the pollen data suggests that although the number of ragweed plants identified has not increased over the latter decade, the total pollen count has been on the increase during the recent period. The highest atmospheric pollen load is established on the last days of August and first days of September. The estimated effect of meteorological parameters on pollen dispersal in the air showed that in Lithuania ragweed pollen is recorded when the relative air humidity is about 70%, and the minimal air temperature is not less than 12°C. Analysis of wind change effect on pollen count indicates that pollen is most often recorded in the air when the changes in wind speed are low (1-2 m/s). We have established a regularity exhibiting an increase in ragweed pollen count conditioned by south-eastern winds in Lithuania.

  7. Screening procedure for airborne pollutants emitted from a high-tech industrial complex in Taiwan.

    PubMed

    Wang, John H C; Tsai, Ching-Tsan; Chiang, Chow-Feng

    2015-11-01

    Despite the modernization of computational techniques, atmospheric dispersion modeling remains a complicated task as it involves the use of large amounts of interrelated data with wide variability. The continuously growing list of regulated air pollutants also increases the difficulty of this task. To address these challenges, this study aimed to develop a screening procedure for a long-term exposure scenario by generating a site-specific lookup table of hourly averaged dispersion factors (χ/Q), which could be evaluated by downwind distance, direction, and effective plume height only. To allow for such simplification, the average plume rise was weighted with the frequency distribution of meteorological data so that the prediction of χ/Q could be decoupled from the meteorological data. To illustrate this procedure, 20 receptors around a high-tech complex in Taiwan were selected. Five consecutive years of hourly meteorological data were acquired to generate a lookup table of χ/Q, as well as two regression formulas of plume rise as functions of downwind distance, buoyancy flux, and stack height. To calculate the concentrations for the selected receptors, a six-step Excel algorithm was programmed with four years of emission records and 10 most critical toxics were screened out. A validation check using Industrial Source Complex (ISC3) model with the same meteorological and emission data showed an acceptable overestimate of 6.7% in the average concentration of 10 nearby receptors. The procedure proposed in this study allows practical and focused emission management for a large industrial complex and can therefore be integrated into an air quality decision-making system.

  8. Airborne LIDAR and high resolution satellite data for rapid 3D feature extraction

    NASA Astrophysics Data System (ADS)

    Jawak, S. D.; Panditrao, S. N.; Luis, A. J.

    2014-11-01

    This work uses the canopy height model (CHM) based workflow for individual tree crown delineation and 3D feature extraction approach (Overwatch Geospatial's proprietary algorithm) for building feature delineation from high-density light detection and ranging (LiDAR) point cloud data in an urban environment and evaluates its accuracy by using very high-resolution panchromatic (PAN) (spatial) and 8-band (multispectral) WorldView-2 (WV-2) imagery. LiDAR point cloud data over San Francisco, California, USA, recorded in June 2010, was used to detect tree and building features by classifying point elevation values. The workflow employed includes resampling of LiDAR point cloud to generate a raster surface or digital terrain model (DTM), generation of a hill-shade image and an intensity image, extraction of digital surface model, generation of bare earth digital elevation model (DEM) and extraction of tree and building features. First, the optical WV-2 data and the LiDAR intensity image were co-registered using ground control points (GCPs). The WV-2 rational polynomial coefficients model (RPC) was executed in ERDAS Leica Photogrammetry Suite (LPS) using supplementary *.RPB file. In the second stage, ortho-rectification was carried out using ERDAS LPS by incorporating well-distributed GCPs. The root mean square error (RMSE) for the WV-2 was estimated to be 0.25 m by using more than 10 well-distributed GCPs. In the second stage, we generated the bare earth DEM from LiDAR point cloud data. In most of the cases, bare earth DEM does not represent true ground elevation. Hence, the model was edited to get the most accurate DEM/ DTM possible and normalized the LiDAR point cloud data based on DTM in order to reduce the effect of undulating terrain. We normalized the vegetation point cloud values by subtracting the ground points (DEM) from the LiDAR point cloud. A normalized digital surface model (nDSM) or CHM was calculated from the LiDAR data by subtracting the DEM from the DSM

  9. Human high intelligence is involved in spectral redshift of biophotonic activities in the brain

    PubMed Central

    Wang, Niting; Li, Zehua; Xiao, Fangyan; Dai, Jiapei

    2016-01-01

    Human beings hold higher intelligence than other animals on Earth; however, it is still unclear which brain properties might explain the underlying mechanisms. The brain is a major energy-consuming organ compared with other organs. Neural signal communications and information processing in neural circuits play an important role in the realization of various neural functions, whereas improvement in cognitive function is driven by the need for more effective communication that requires less energy. Combining the ultraweak biophoton imaging system (UBIS) with the biophoton spectral analysis device (BSAD), we found that glutamate-induced biophotonic activities and transmission in the brain, which has recently been demonstrated as a novel neural signal communication mechanism, present a spectral redshift from animals (in order of bullfrog, mouse, chicken, pig, and monkey) to humans, even up to a near-infrared wavelength (∼865 nm) in the human brain. This brain property may be a key biophysical basis for explaining high intelligence in humans because biophoton spectral redshift could be a more economical and effective measure of biophotonic signal communications and information processing in the human brain. PMID:27432962

  10. Spectral behavior of AM Her and QQ Vul in high and intermediate states in the UV

    NASA Astrophysics Data System (ADS)

    Sanad, M. R.

    2010-12-01

    We present low resolution UV spectra of two polar systems, AM Her and QQ Vul from the observations taken by the IUE (International Ultraviolet Explorer) of the period between 1978-1996 and 1983-1996 for both systems respectively, to accomplish a large scale study of what happens to the ultraviolet flux of C IV 1550 Å spectral line during different orbital phases. Two spectra for both systems showing the variations in line fluxes and line widths at different orbital phases in high and intermediate states are presented. We concentrated on calculating the line fluxes and line widths of C IV 1550 Å emission line originating in the accretion stream. Our results show that there is spectral variability for the aformentioned physical parameters at different times, similar to that known for the light curve (Heise and Verbunt, Astron. Astrophys. 189:112, 1988; Gansicke et al., Astron. Astrophys. 303:127, 1995; Kafka and Honeycutt, Astron. J. 125:2188K, 2003). We attribute it to the variations of both density and temperature as a result of changing the mass transfer rate (Hutchings et al., Astron. J. 123:2841H, 2002; King and Lasota, Astron. Astrophys. 140L:16K, 1984) which is responsible for this spectral variability. Also we found that the line fluxes of AM Her are greater than the line fluxes of QQ Vul, while the line widths of both systems are approximately the same.

  11. System analysis of a tilted field-widened Michelson interferometer for high spectral resolution lidar.

    PubMed

    Liu, Dong; Hostetler, Chris; Miller, Ian; Cook, Anthony; Hair, Johnathan

    2012-01-16

    High spectral resolution lidars (HSRLs) have shown great value in aircraft aerosol remote sensing application and are planned for future satellite missions. A compact, robust, quasi-monolithic tilted field-widened Michelson interferometer is being developed as the spectral discrimination filter for an second-generation HSRL(HSRL-2) at NASA Langley Research Center. The Michelson interferometer consists of a cubic beam splitter, a solid arm and an air arm. Piezo stacks connect the air arm mirror to the body of the interferometer and can tune the interferometer within a small range. The whole interferometer is tilted so that the standard Michelson output and the reflected complementary output can both be obtained. In this paper, the transmission ratio is proposed to evaluate the performance of the spectral filter for HSRL. The transmission ratios over different types of system imperfections, such as cumulative wavefront error, locking error, reflectance of the beam splitter and anti-reflection coatings, system tilt, and depolarization angle are analyzed. The requirements of each imperfection for good interferometer performance are obtained.

  12. Use of high-dimensional spectral data to evaluate organic matter, reflectance relationships in soils

    NASA Technical Reports Server (NTRS)

    Henderson, T. L.; Baumgardner, M. F.; Coster, D. C.; Franzmeier, D. P.; Stott, D. E.

    1990-01-01

    Recent breakthroughs in remote sensing technology have led to the development of a spaceborne high spectral resolution imaging sensor, HIRIS, to be launched in the mid-1990s for observation of earth surface features. The effects of organic carbon content on soil reflectance over the spectral range of HIRIS, and to examine the contributions of humic and fulvic acid fractions to soil reflectance was evaluated. Organic matter from four Indiana agricultural soils was extracted, fractionated, and purified, and six individual components of each soil were isolated and prepared for spectral analysis. The four soils, ranging in organic carbon content from 0.99 percent, represented various combinations of genetic parameters such as parent material, age, drainage, and native vegetation. An experimental procedure was developed to measure reflectance of very small soil and organic component samples in the laboratory, simulating the spectral coverage and resolution of the HIRIS sensor. Reflectance in 210 narrow (10 nm) bands was measured using the CARY 17D spectrophotometer over the 400 to 2500 nm wavelength range. Reflectance data were analyzed statistically to determine the regions of the reflective spectrum which provided useful information about soil organic matter content and composition. Wavebands providing significant information about soil organic carbon content were located in all three major regions of the reflective spectrum: visible, near infrared, and middle infrared. The purified humic acid fractions of the four soils were separable in six bands in the 1600 to 2400 nm range, suggesting that longwave middle infrared reflectance may be useful as a non-destructive laboratory technique for humic acid characterization.

  13. Thermal tuning of volume Bragg gratings for spectral beam combining of high-power fiber lasers.

    PubMed

    Drachenberg, Derrek R; Andrusyak, Oleksiy; Venus, George; Smirnov, Vadim; Glebov, Leonid B

    2014-02-20

    High-radiance lasers are desired for many applications in defense and manufacturing. Spectral beam combining (SBC) by volume Bragg gratings (VBGs) is a very promising method for high-radiance lasers that need to achieve 100 kW level power. Laser-induced heating of VBGs under high-power radiation presents a challenge for maintaining Bragg resonance at various power levels without mechanical realignment. A novel thermal tuning technique and apparatus is presented that enables maintaining peak efficiency operation of the SBC system at various power levels without any mechanical adjustment. The method is demonstrated by combining two high-power ytterbium fiber lasers with high efficiency from low power to full combined power of 300 W (1.5 kW effective power), while maintaining peak combining efficiency within 0.5%.

  14. Spectral analysis of the high-energy IceCube neutrinos

    NASA Astrophysics Data System (ADS)

    Palomares-Ruiz, Sergio; Vincent, Aaron C.; Mena, Olga

    2015-05-01

    A full energy and flavor-dependent analysis of the three-year high-energy IceCube neutrino events is presented. By means of multidimensional fits, we derive the current preferred values of the high-energy neutrino flavor ratios, the normalization and spectral index of the astrophysical fluxes, and the expected atmospheric background events, including a prompt component. A crucial assumption resides on the choice of the energy interval used for the analyses, which significantly biases the results. When restricting ourselves to the ˜30 TeV - 3 PeV energy range, which contains all the observed IceCube events, we find that the inclusion of the spectral information improves the fit to the canonical flavor composition at Earth, (1 ∶1 ∶1 )⊕ , with respect to a single-energy bin analysis. Increasing both the minimum and the maximum deposited energies has dramatic effects on the reconstructed flavor ratios as well as on the spectral index. Imposing a higher threshold of 60 TeV yields a slightly harder spectrum by allowing a larger muon neutrino component, since above this energy most atmospheric tracklike events are effectively removed. Extending the high-energy cutoff to fully cover the Glashow resonance region leads to a softer spectrum and a preference for tau neutrino dominance, as none of the expected electron (anti)neutrino induced showers have been observed so far. The lack of showers at energies above 2 PeV may point to a broken power-law neutrino spectrum. Future data may confirm or falsify whether the recently discovered high-energy neutrino fluxes and the long-standing detected cosmic rays have a common origin.

  15. Airborne Multi-Spectral Minefield Survey

    DTIC Science & Technology

    2005-05-01

    Quality Control . An important methodological aspect of the selected approach is the pyramidal information structure, which is reflected in the use of...the image interpreter to manually assign ground control points. After AGM processing for each individual image the results are stored in GEOTIFF file...comply with a collection of information if it does not display a currently valid OMB control number. 1. REPORT DATE 01 MAY 2005 2. REPORT TYPE N/A

  16. Advances in High Energy Solid-State Pulsed 2-Micron Lidar Development for Ground and Airborne Wind, Water Vapor and CO2 Measurements

    NASA Technical Reports Server (NTRS)

    Singh, Upendra N.; Yu, Jirong; Petros, Mulugeta; Refaat, Tamer; Kavaya, Michael J.; Remus, Ruben

    2015-01-01

    NASA Langley Research Center has a long history of developing 2-micron lasers. From fundamental spectroscopy research, theoretical prediction of new materials, laser demonstration and engineering of lidar systems, it has been a very successful program spanning around two decades. Successful development of 2-micron lasers has led to development of a state-of-the-art compact lidar transceiver for a pulsed coherent Doppler lidar system for wind measurement with an unprecedented laser pulse energy of 250 millijoules in a rugged package. This high pulse energy is produced by a Ho:Tm:LuLiF laser with an optical amplifier. While the lidar is meant for use as an airborne instrument, ground-based tests were carried out to characterize performance of the lidar. Atmospheric measurements will be presented, showing the lidar's capability for wind measurement in the atmospheric boundary layer and free troposphere. Lidar wind measurements are compared to a balloon sonde, showing good agreement between the two sensors. Similar architecture has been used to develop a high energy, Ho:Tm:YLF double-pulsed 2-micron Integrated Differential Absorption Lidar (IPDA) instrument based on direct detection technique that provides atmospheric column CO2 measurements. This instrument has been successfully used to measure atmospheric CO2 column density initially from a ground mobile lidar trailer, and then it was integrated on B-200 plane and 20 hours of flight measurement were made from an altitude ranging 1500 meters to 8000 meters. These measurements were compared to in-situ measurements and National Oceanic and Atmospheric Administration (NOAA) airborne flask measurement to derive the dry mixing ratio of the column CO2 by reflecting the signal by various reflecting surfaces such as land, vegetation, ocean surface, snow and sand. The lidar measurements when compared showed a very agreement with in-situ and airborne flask measurement. NASA Langley Research Center is currently developing a

  17. Advances in High Energy Solid-State Pulsed 2-micron Lidar Development for Ground and Airborne Wind, Water Vapor and CO2 Measurements

    NASA Astrophysics Data System (ADS)

    Singh, Upendra; Yu, Jirong; Petros, Mulugeta; Refaat, Tamer; Kavaya, Michael; Remus, Ruben

    2015-04-01

    NASA Langley Research Center has a long history of developing 2 µm lasers. From fundamental spectroscopy research, theoretical prediction of new materials, laser demonstration and engineering of lidar systems, it has been a very successful program spanning around two decades. Successful development of 2 µm lasers has led to development of a state-of-the-art compact lidar transceiver for a pulsed coherent Doppler lidar system for wind measurement with an unprecedented laser pulse energy of 250-mJ in a rugged package. This high pulse energy is produced by a Ho:Tm:LuLiF laser with an optical amplifier. While the lidar is meant for use as an airborne instrument, ground-based tests were carried out to characterize performance of the lidar. Atmospheric measurements will be presented, showing the lidar's capability for wind measurement in the atmospheric boundary layer and free troposphere. Lidar wind measurements are compared to a balloon sonde, showing good agreement between the two sensors. Similar architecture has been used to develop a high energy, Ho:Tm:YLF double-pulsed 2 μm Integrated Differential Absorption Lidar (IPDA) instrument based on direct detection technique that provides atmospheric column CO2 measurements. This instrument has been successfully used to measure atmospheric CO2 column density initially from a ground mobile lidar trailer, and then it was integrated on B-200 plane and 20 hrs of flight measurement were made from an altitude ranging 1500 meter to 8000 meter. These measurements were compared to in-situ measurements and NOAA airborne flask measurement to derive the dry mixing ratio of the column CO2 by reflecting the signal by various reflecting surfaces such as land, vegetation, ocean surface, snow and sand. The lidar measurements when compared showed a very agreement with in-situ and airborne flask measurement. NASA Langley Research Center is currently developing a triple-pulsed 2 μm Integrated Differential Absorption Lidar (IPDA

  18. Stratocumulus Drizzle Measurements Using High Spectral Resolution Lidar and Radar Data During the MAGIC Campaign

    NASA Astrophysics Data System (ADS)

    Eloranta, E. W.

    2015-12-01

    Marine stratus clouds are an important feature of the global climate system. Drizzle plays an important role in the determining cloud lifetime. Drizzle not only removes water from the cloud but evaporation of the falling droplets cools the sub-cloud layer acting to suppress convection. Drizzle rates are often very small and difficult to measure.The ratio of millimeter radar and High Spectral Resolution Lidar (HSRL) backscatter is used to determine drizzle rates and these are compared to conventional ground based measurements. The robustly calibrated HSRL backscatter cross section provides advantages over measurements made with traditional lidars.Several investigators have used simultaneous lidar and radar observations to determine particle size. However, measurements made with conventional lidar are hampered by: 1) changes in the transmission of the output window caused by water accumulation, 2) the difficulty of correcting the backscatter signal for atmospheric extinction, 3) the effects of multiple scattering, and 4) the need to convert backscatter measurements to extinction. The use of High Spectral Resolution Lidar(HSRL) data avoids many of these problems. HSRL backscatter measurements are referenced to the known molecular scattering cross-section at each point in the profile and are thus independent of changes in window and atmospheric transmission. This study uses data collected during the US Department of Energy Atmospheric Sciences program MAGIC campaign. Instruments including a suite of conventional precipitation gages, a High Spectral Resolution Lidar, along with 3.2 mm wavelength WACR and a 8.6 mm wavelength KAZR radars, were installed on the container ship Horizon Spirit as it made repeated trips between Long Beach, CA and Honolulu, HI.

  19. Spectral Changes in Metal Halide and High-pressure Sodium Lamps Equipped with Electronic Dimming

    NASA Technical Reports Server (NTRS)

    Bubenheim, David L.; Sargis, Raman; Wilson, David

    1995-01-01

    Electronic dimming of high-intensity discharge lamps offers control of photosynthetic photon flux (PPF) but is often characterized as causing significant spectral changes. Growth chambers with 400-W metal halide (MH) and high-pressure sodium (HPS) lamps were equipped with a dimmer system using silicon-controlled rectifiers (SCR) as high-speed switches. Phase control operation turned the line power off for some period of the alternating current cycle. At full power, the electrical input to HPS and MH lamps was 480 W (root mean squared) and could be decreased to 267 W and 428 W, respectively, before the arc was extinguished. Concomitant with this decrease in input power, PPF decreased by 60% in HPS and 50% in MH. The HPS lamp has characteristic spectral peaks at 589 and 595 nm. As power to the HPS lamps was decreased, the 589-nm peak remained constant while the 595-nm peak decreased, equaling the 589-nm peak at 345-W input, and the 589-nm peak was almost absent at 270-W input. The MH lamp has a broader spectral output but also has a peak at 589 nm and another smaller peak at 545 nm. As input power to the MH lamps decreased, the peak at 589 diminished to equal the 545-nm peak. As input power approached 428 W, the 589-nm peak shifted to 570 nm. While the spectrum changed as input power was decreased in the MH and HPS lamps, the phytochrome equilibrium ratio (P(sub fr):P(sub tot)) remains unchanged for both lamp types.

  20. On shifted Jacobi spectral method for high-order multi-point boundary value problems

    NASA Astrophysics Data System (ADS)

    Doha, E. H.; Bhrawy, A. H.; Hafez, R. M.

    2012-10-01

    This paper reports a spectral tau method for numerically solving multi-point boundary value problems (BVPs) of linear high-order ordinary differential equations. The construction of the shifted Jacobi tau approximation is based on conventional differentiation. This use of differentiation allows the imposition of the governing equation at the whole set of grid points and the straight forward implementation of multiple boundary conditions. Extension of the tau method for high-order multi-point BVPs with variable coefficients is treated using the shifted Jacobi Gauss-Lobatto quadrature. Shifted Jacobi collocation method is developed for solving nonlinear high-order multi-point BVPs. The performance of the proposed methods is investigated by considering several examples. Accurate results and high convergence rates are achieved.

  1. Human tissue color as viewed in high dynamic range optical spectral transmission measurements.

    PubMed

    Petrov, Georgi I; Doronin, Alexander; Whelan, Harry T; Meglinski, Igor; Yakovlev, Vladislav V

    2012-09-01

    High dynamic range optical-to-near-infrared transmission measurements for different parts of human body in the spectral range from 650 to 950 nm have been performed. Experimentally measured spectra are correlated with Monte Carlo simulations using chromaticity coordinates in CIE 1976 L*a*b* color space. Both a qualitative and a quantitative agreement have been found, paving a new way of characterizing human tissues in vivo. The newly developed experimental and computational platform for assessing tissue transmission spectra is anticipated to have a considerable impact on identifying favorable conditions for laser surgery and optical diagnostics, while providing supplementary information about tissue properties.

  2. Paired SSB optical OFDM channels for high spectral efficient signal transmission over DWDM networks

    NASA Astrophysics Data System (ADS)

    Chicharro, Francisco I.; Ortega, Beatriz; Mora, José

    2016-07-01

    A new high spectral efficient SSB-OOFDM DWDM transmission system has been experimentally demonstrated. The proposed transmitter employs paired optical channels consisting of two SSB modulated OFDM signals using opposite sidebands in order to allow an efficient use of the spectrum with optical carriers separation under 10 GHz. Moreover, different paired channels are multiplexed into the 25 GHz grid DWDM fiber transmission link. Optical carrier spacing of 8.75 GHz in paired channels has been demonstrated allowing 40.8 Gb/s signal transmission rate over a 25 GHz paired channel bandwidth.

  3. High Spectral Resolution Lidar Measurements Using an I2 Absorption Filter

    NASA Technical Reports Server (NTRS)

    Eloranta, E. W.; Piironen, P.

    1996-01-01

    The University of Wisconsin high spectral resolution lidar (HSRL) measures optical properties of the atmosphere by separating the Doppler-broadened molecular backscatter return from the unbroadened aerosol return. The HSRL was modified to use an I2 absorption cell The modified HSRL transmitter uses a continuously pumped, Q-switched, injection seeded, frequency doubled Nd:YAG laser operating at a 4 kHz pulse repetition rate. This laser is tunable over a 124 GHz frequency range by temperature tuning the seed laser under computer control.

  4. SWIFTS and SWIFTS-LA: two concepts for high spectral resolution static micro-imaging spectrometers

    NASA Astrophysics Data System (ADS)

    Le Coarer, E.; Schmitt, B.; Guerineau, N.; Martin, G.; Rommeluere, S.; Ferrec, Y.; Simon, F.; Thomas, F.

    2014-04-01

    SWIFTS (Stationary-Wave Integrated Fourier Transform Spectrometer) represents a family of very compact spectrometers based on detection of standing waves for which detectors play itself a role in the interferential detection mechanism. The aim of this paper is to illustrate how these spectrometers can be used to build efficient imaging spectrometers for planetary exploration inside dm3 instrumental volume. The first mode (SWIFTS) is devoted to high spectral resolving power imaging (R~10000-50000) for 40x40 pixels field of view. The second mode (SWIFTS-LA) is optimized for its luminosity with a resolving power up to R~2000.

  5. Spectral Analyses of High-Frequency Pn, Sn Phases from Very Shallow Focus Earthquakes.

    DTIC Science & Technology

    1983-09-01

    off at about -24 diB/octave over 1971). the range of 0.3 to 6 Is. Between 3 and 15 R . . 62 McCreary et al.: P and Noise Spectra on Wake Hydrophones...D., C. McCreary . G. Sutton, and F. western Pacific: Structure of oceanic litho- Duennebier, Spectral analyses of high-frequency sphere revealed by...received. The time, in Julian days through milliseconds, is output in parallel BCD format through 45 pins of a 50 pin connector. This connector also

  6. Development of a high spectral resolution surface albedo product for the ARM Southern Great Plains Central Facility

    SciTech Connect

    McFarlane, Sally A.; Gaustad, Krista L.; Mlawer, Eli J.; Long, Charles N.; Delamere, Jennifer

    2011-09-01

    We present a method for identifying dominant surface type and estimating high spectral resolution surface albedo at the Atmospheric Radiation Measurement (ARM) facility at the Southern Great Plains (SGP) site in Oklahoma for use in radiative transfer calculations. Given a set of 6-channel narrowband visible and near-infrared irradiance measurements from upward and downward looking multi-filter radiometers (MFRs), four different surface types (snow-covered, green vegetation, partial vegetation, non-vegetated) can be identified. A normalized difference vegetation index (NDVI) is used to distinguish between vegetated and non-vegetated surfaces, and a scaled NDVI index is used to estimate the percentage of green vegetation in partially vegetated surfaces. Based on libraries of spectral albedo measurements, a piecewise continuous function is developed to estimate the high spectral resolution surface albedo for each surface type given the MFR albedo values as input. For partially vegetated surfaces, the albedo is estimated as a linear combination of the green vegetation and non-vegetated surface albedo values. The estimated albedo values are evaluated through comparison to high spectral resolution albedo measurements taken during several Intensive Observational Periods (IOPs) and through comparison of the integrated spectral albedo values to observed broadband albedo measurements. The estimated spectral albedo values agree well with observations for the visible wavelengths constrained by the MFR measurements, but have larger biases and variability at longer wavelengths. Additional MFR channels at 1100 nm and/or 1600 nm would help constrain the high resolution spectral albedo in the near infrared region.

  7. The use of high spectral resolution bands for estimating absorbed photosynthetically active radiation (A par)

    NASA Technical Reports Server (NTRS)

    Kim, Moon S.; Daughtry, C. S. T.; Chappelle, E. W.; Mcmurtrey, J. E.; Walthall, C. L.

    1994-01-01

    Most remote sensing estimations of vegetation variables such as Leaf Area Index (LAI), Absorbed Photosynthetically Active Radiation (APAR), and phytomass are made using broad band sensors with a bandwidth of approximately 100 nm. However, high resolution spectrometers are available and have not been fully exploited for the purpose of improving estimates of vegetation variables. A study directed to investigate the use of high spectral resolution spectroscopy for remote sensing estimates of APAR in vegetation canopies in the presence of nonphotosynthetic background materials such as soil and leaf litter is presented. A high spectral resolution method defined as the Chlorophyll Absorption Ratio Index (CARI) was developed for minimizing the effects of nonphotosynthetic materials in the remote estimates of APAR. CARI utilizes three bands at 550, 670, and 700 nm with bandwidth of 10 nm. Simulated canopy reflectance of a range of LAI were generated with the SAIL model using measurements of 42 different soil types as canopy background. CARI obtained from the simulated canopy reflectance was compared with the broad band vegetation indices (Normalized Difference Vegetation Index (NDVI), Soil Adjusted Vegetation Index (SAVI), and Simple Ratio (SR)). CARI reduced the effect of nonphotosynthetic background materials in the assessment of vegetation canopy APAR more effectively than broad band vegetation indices.

  8. Improved global high resolution precipitation estimation using multi-satellite multi-spectral information

    NASA Astrophysics Data System (ADS)

    Behrangi, Ali

    In respond to the community demands, combining microwave (MW) and infrared (IR) estimates of precipitation has been an active area of research since past two decades. The anticipated launching of NASA's Global Precipitation Measurement (GPM) mission and the increasing number of spectral bands in recently launched geostationary platforms will provide greater opportunities for investigating new approaches to combine multi-source information towards improved global high resolution precipitation retrievals. After years of the communities' efforts the limitations of the existing techniques are: (1) Drawbacks of IR-only techniques to capture warm rainfall and screen out no-rain thin cirrus clouds; (2) Grid-box- only dependency of many algorithms with not much effort to capture the cloud textures whether in local or cloud patch scale; (3) Assumption of indirect relationship between rain rate and cloud-top temperature that force high intensity precipitation to any cold cloud; (4) Neglecting the dynamics and evolution of cloud in time; (5) Inconsistent combination of MW and IR-based precipitation estimations due to the combination strategies and as a result of above described shortcomings. This PhD dissertation attempts to improve the combination of data from Geostationary Earth Orbit (GEO) and Low-Earth Orbit (LEO) satellites in manners that will allow consistent high resolution integration of the more accurate precipitation estimates, directly observed through LEO's PMW sensors, into the short-term cloud evolution process, which can be inferred from GEO images. A set of novel approaches are introduced to cope with the listed limitations and is consist of the following four consecutive components: (1) starting with the GEO part and by using an artificial-neural network based method it is demonstrated that inclusion of multi-spectral data can ameliorate existing problems associated with IR-only precipitating retrievals; (2) through development of Precipitation Estimation

  9. Processing of High Resolution, Multiparametric Radar Data for the Airborne Dual-Frequency Precipitation Radar APR-2

    NASA Technical Reports Server (NTRS)

    Tanelli, Simone; Meagher, Jonathan P.; Durden, Stephen L.; Im, Eastwood

    2004-01-01

    Following the successful Precipitation Radar (PR) of the Tropical Rainfall Measuring Mission, a new airborne, 14/35 GHz rain profiling radar, known as Airborne Precipitation Radar - 2 (APR-2), has been developed as a prototype for an advanced, dual-frequency spaceborne radar for a future spaceborne precipitation measurement mission. . This airborne instrument is capable of making simultaneous measurements of rainfall parameters, including co-pol and cross-pol rain reflectivities and vertical Doppler velocities, at 14 and 35 GHz. furthermore, it also features several advanced technologies for performance improvement, including real-time data processing, low-sidelobe dual-frequency pulse compression, and dual-frequency scanning antenna. Since August 2001, APR-2 has been deployed on the NASA P3 and DC8 aircrafts in four experiments including CAMEX-4 and the Wakasa Bay Experiment. Raw radar data are first processed to obtain reflectivity, LDR (linear depolarization ratio), and Doppler velocity measurements. The dataset is then processed iteratively to accurately estimate the true aircraft navigation parameters and to classify the surface return. These intermediate products are then used to refine reflectivity and LDR calibrations (by analyzing clear air ocean surface returns), and to correct Doppler measurements for the aircraft motion. Finally, the the melting layer of precipitation is detected and its boundaries and characteristics are identifIed at the APR-2 range resolution of 30m. The resulting 3D dataset will be used for validation of other airborne and spaceborne instruments, development of multiparametric rain/snow retrieval algorithms and melting layer characterization and statistics.

  10. Inference of Ice Cloud Properties from High-spectral Resolution Infrared Observations. Appendix 4

    NASA Technical Reports Server (NTRS)

    Huang, Hung-Lung; Yang, Ping; Wei, Heli; Baum, Bryan A.; Hu, Yongxiang; Antonelli, Paolo; Ackerman, Steven A.

    2005-01-01

    The theoretical basis is explored for inferring the microphysical properties of ice crystal from high-spectral resolution infrared observations. A radiative transfer model is employed to simulate spectral radiances to address relevant issues. The extinction and absorption efficiencies of individual ice crystals, assumed as hexagonal columns for large particles and droxtals for small particles, are computed from a combination of the finite- difference time-domain (FDTD) technique and a composite method. The corresponding phase functions are computed from a combination of FDTD and an improved geometric optics method (IGOM). Bulk scattering properties are derived by averaging the single- scattering properties of individual particles for 30 particle size distributions developed from in situ measurements and for additional four analytical Gamma size distributions for small particles. The non-sphericity of ice crystals is shown to have a significant impact on the radiative signatures in the infrared (IR) spectrum; the spherical particle approximation for inferring ice cloud properties may result in an overest&ation of the optical thickness and an inaccurate retrieval of effective particle size. Furthermore, we show that the error associated with the use of the Henyey-Greenstein phase function can be as larger as 1 K in terms of brightness temperature for larger particle effective size at some strong scattering wavenumbers. For small particles, the difference between the two phase functions is much less, with brightness temperatures generally differing by less than 0.4 K. The simulations undertaken in this study show that the slope of the IR brightness temperature spectrum between 790-960/cm is sensitive to the effective particle size. Furthermore, a strong sensitivity of IR brightness temperature to cloud optical thickness is noted within the l050-1250/cm region. Based on this spectral feature, a technique is presented for the simultaneous retrieval of the visible

  11. The use of Airborne Imaging Spectrometer (AIS) data to differentiate marsh vegetation

    NASA Technical Reports Server (NTRS)

    Gross, M. F.; Klemas, V.

    1986-01-01

    The Airborne Imaging Spectrometer (AIS) is a high spectral resolution (9.6-nm-wide bands between 0.9 and 2.4 microns) instrument. Analysis of AIS data revealed significant differences in characteristics of the spectral radiance curves of four types of wetland vegetation canopies (trees, broadleaf herbaceous, Spartina alterniflora, and S. patens/Distichlis spicata) in Delaware, enabling them to be distinguished. The single most useful spectral region was that between 1.40 and 1.90 microns. Differences in radiance values at various wavelengths between samples of the same vegetation type could potentially be used to estimate biomass. Thus, high spectral resolution spectrometry appears to have significant value for remote sensing studies of wetland vegetation.

  12. Airborne Visible Laser Optical Communications Program (AVLOC)

    NASA Technical Reports Server (NTRS)

    Ward, J. H.

    1975-01-01

    The design, development, and operation of airborne and ground-based laser communications and laser radar hardware is described in support of the Airborne Visible Laser Optical Communication program. The major emphasis is placed on the development of a highly flexible test bed for the evaluation of laser communications systems techniques and components in an operational environment.

  13. Using high spectral resolution spectrophotometry to study broad mineral absorption features on Mars

    NASA Technical Reports Server (NTRS)

    Blaney, D. L.; Crisp, D.

    1993-01-01

    Traditionally telescopic measurements of mineralogic absorption features have been made using relatively low to moderate (R=30-300) spectral resolution. Mineralogic absorption features tend to be broad so high resolution spectroscopy (R greater than 10,000) does not provide significant additional compositional information. Low to moderate resolution spectroscopy allows an observer to obtain data over a wide wavelength range (hundreds to thousands of wavenumbers) compared to the several wavenumber intervals that are collected using high resolution spectrometers. However, spectrophotometry at high resolution has major advantages over lower resolution spectroscopy in situations that are applicable to studies of the Martian surface, i.e., at wavelengths where relatively weak surface absorption features and atmospheric gas absorption features both occur.

  14. Speckle noise reduction in high speed polarization sensitive spectral domain optical coherence tomography

    PubMed Central

    Götzinger, Erich; Pircher, Michael; Baumann, Bernhard; Schmoll, Tilman; Sattmann, Harald; Leitgeb, Rainer A.; Hitzenberger, Christoph K.

    2015-01-01

    We present a high speed polarization sensitive spectral domain optical coherence tomography system based on polarization maintaining fibers and two high speed CMOS line scan cameras capable of retinal imaging with up to 128 k A-lines/s. This high imaging speed strongly reduces motion artifacts and therefore averaging of several B-scans is possible, which strongly reduces speckle noise and improves image quality. We present several methods for averaging retardation and optic axis orientation, the best one providing a 5 fold noise reduction. Furthermore, a novel scheme of calculating images of degree of polarization uniformity is presented. We quantitatively compare the noise reduction depending on the number of averaged frames and discuss the limits of frame numbers that can usefully be averaged. PMID:21934820

  15. Spectral Dimensionality and Scale of Urban Radiance

    NASA Technical Reports Server (NTRS)

    Small, Christopher

    2001-01-01

    Characterization of urban radiance and reflectance is important for understanding the effects of solar energy flux on the urban environment as well as for satellite mapping of urban settlement patterns. Spectral mixture analyses of Landsat and Ikonos imagery suggest that the urban radiance field can very often be described with combinations of three or four spectral endmembers. Dimensionality estimates of Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) radiance measurements of urban areas reveal the existence of 30 to 60 spectral dimensions. The extent to which broadband imagery collected by operational satellites can represent the higher dimensional mixing space is a function of both the spatial and spectral resolution of the sensor. AVIRIS imagery offers the spatial and spectral resolution necessary to investigate the scale dependence of the spectral dimensionality. Dimensionality estimates derived from Minimum Noise Fraction (MNF) eigenvalue distributions show a distinct scale dependence for AVIRIS radiance measurements of Milpitas, California. Apparent dimensionality diminishes from almost 40 to less than 10 spectral dimensions between scales of 8000 m and 300 m. The 10 to 30 m scale of most features in urban mosaics results in substantial spectral mixing at the 20 m scale of high altitude AVIRIS pixels. Much of the variance at pixel scales is therefore likely to result from actual differences in surface reflectance at pixel scales. Spatial smoothing and spectral subsampling of AVIRIS spectra both result in substantial loss of information and reduction of apparent dimensionality, but the primary spectral endmembers in all cases are analogous to those found in global analyses of Landsat and Ikonos imagery of other urban areas.

  16. Real-time remote detection and measurement for airborne imaging spectroscopy: a case study with methane

    NASA Astrophysics Data System (ADS)

    Thompson, D. R.; Leifer, I.; Bovensmann, H.; Eastwood, M.; Fladeland, M.; Frankenberg, C.; Gerilowski, K.; Green, R. O.; Kratwurst, S.; Krings, T.; Luna, B.; Thorpe, A. K.

    2015-06-01

    Localized anthropogenic sources of atmospheric CH4 are highly uncertain and temporally variable. Airborne remote measurement is an effective method to detect and quantify these emissions. In a campaign context, the science yield can be dramatically increased by real-time retrievals that allow operators to coordinate multiple measurements of the most active areas. This can improve science outcomes for both single- and multiple-platform missions. We describe a case study of the NASA/ESA CO2 and Methane Experiment (COMEX) campaign in California during June and August/September 2014. COMEX was a multi-platform campaign to measure CH4 plumes released from anthropogenic sources including oil and gas infrastructure. We discuss principles for real-time spectral signature detection and measurement, and report performance on the NASA Next Generation Airborne Visible Infrared Spectrometer (AVIRIS-NG). AVIRIS-NG successfully detected CH4 plumes in real-time at Gb s-1 data rates, characterizing fugitive releases in concert with other in situ and remote instruments. The teams used these real-time CH4 detections to coordinate measurements across multiple platforms, including airborne in situ, airborne non-imaging remote sensing, and ground-based in situ instruments. To our knowledge this is the first reported use of real-time trace gas signature detection in an airborne science campaign, and presages many future applications.

  17. VCM-OFDM technique for advanced space communications system with high spectral efficiency

    NASA Astrophysics Data System (ADS)

    Li, Jionghui; Zhou, Qing; Xiong, Weiming; Zhang, Ying; Yao, Chen

    2016-11-01

    The development of precise scientific payloads brings higher demand on the efficiency of space communications system to transmit the increasing volume of scientific data. Aiming to this issue, Orthogonal Frequency Division Multiplexing (OFDM) is chosen for its inherent capability of high-rate data transmission. Further, considering the dynamic link condition due to satellite orbital motion, we propose a new technique which combines Variable Coding Modulation (VCM) with OFDM to enhance the communication link spectral efficiency with required transmission reliability. With VCM-OFDM technique, the channel coding and modulation mode can be variable with time according to the link conditions, in order to fit the link budget curve and maintain a relatively fixed link margin. Hence, link resource waste can be reduced and throughput can be remarkably improved. Considering that OFDM-based systems are sensitive to Doppler shifts/spread, the coding and modulation mode (CODMOD) selection should be optimized subject to this scenario. This paper introduces the architecture of near-earth space data transmission system based on VCM-OFDM technique. The Doppler influence is analyzed through simulation and the CODMOD selection algorithm is discussed. The results prove the high performance on spectral efficiency enhancement of VCM-OFDM by comparison with several existing alternative methods.

  18. A high temperature hybrid photovoltaic-thermal receiver employing spectral beam splitting for linear solar concentrators

    NASA Astrophysics Data System (ADS)

    Mojiri, Ahmad; Stanley, Cameron; Rosengarten, Gary

    2015-09-01

    Hybrid photovoltaic/thermal (PV-T) solar collectors are capable of delivering heat and electricity concurrently. Implementing such receivers in linear concentrators for high temperature applications need special considerations such as thermal decoupling of the photovoltaic (pv) cells from the thermal receiver. Spectral beam splitting of concentrated light provides an option for achieving this purpose. In this paper we introduce a relatively simple hybrid receiver configuration that spectrally splits the light between a high temperature thermal fluid and silicon pv cells using volumetric light filtering by semi-conductor doped glass and propylene glycol. We analysed the optical performance of this device theoretically using ray tracing and experimentally through the construction and testing of a full scale prototype. The receiver was mounted on a commercial parabolic trough concentrator in an outdoor experiment. The prototype receiver delivered heat and electricity at total thermal efficiency of 44% and electrical efficiency of 3.9% measured relative to the total beam energy incident on the primary mirror.

  19. A geomorphologist's dream come true: synoptic high resolution river bathymetry with the latest generation of airborne dual wavelength lidar

    NASA Astrophysics Data System (ADS)

    Lague, Dimitri; Launeau, Patrick; Michon, Cyril; Gouraud, Emmanuel; Juge, Cyril; Gentile, William; Hubert-Moy, Laurence; Crave, Alain

    2016-04-01

    Airborne, terrestrial lidar and Structure From Motion have dramatically changed our approach of geomorphology, from low density/precision data, to a wealth of data with a precision adequate to actually measure topographic change across multiple scales, and its relation to vegetation. Yet, an important limitation in the context of fluvial geomorphology has been the inability of these techniques to penetrate water due to the use of NIR laser wavelengths or to the complexity of accounting for water refraction in SFM. Coastal bathymetric systems using a green lidar can penetrate clear water up to 50 m but have a resolution too coarse and deployment costs that are prohibitive for fluvial research and management. After early prototypes of narrow aperture green lidar (e.g., EEARL NASA), major lidar manufacturer are now releasing dual wavelength laser system that offer water penetration consistent with shallow fluvial bathymetry at very high resolution (> 10 pts/m²) and deployment costs that makes the technology, finally accessible. This offers unique opportunities to obtain synoptic high resolution, high precision data for academic research as well as for fluvial environment management (flood risk mapping, navigability,…). In this presentation, we report on the deployment of the latest generation Teledyne-Optech Titan dual-wavelength lidar (1064 nm + 532 nm) owned by the University of Nantes and Rennes. The instrument has been deployed over several fluvial and lacustrine environments in France. We present results and recommendation on how to optimize the bathymetric cover as a function of aerial and aquatic vegetation cover and the hydrology regime of the river. In the surveyed rivers, the penetration depth varies from 0.5 to 4 m with discrete echoes (i.e., onboard detection), heavily impacted by water clarity and bottom reflectance. Simple post-processing of the full waveform record allows to recover an additional 20 % depth. As for other lidar techniques, the main

  20. Infrared to x-ray spectral energy distributions of high redshift quasars

    NASA Technical Reports Server (NTRS)

    Bechtold, Jill; Elvis, Martin; Fiore, Fabrizio; Kuhn, Olga; Cutri, Roc M.; Mcdowell, Jonathan C.; Rieke, Marcia; Siemiginowska, Aneta; Wilkes, Belinda J.

    1994-01-01

    We have observed 14 quasars with z greater than 2.8 with the ROSAT-PSPC, and detected 12 of them, including the z=4.11 quasar 0000-263. We present the first x-ray spectrum of a radio quiet quasar with z greater than 3, 1946+768. Its x-ray spectrum is consistent with a power law with spectral index alpha(sub E)=1.8(sup +2.1, sub -1.4) and no evidence for absorption in excess of the galactic column (alpha(sub E)=1.00(sup +0.28, sub -0.32) assuming N(sub H)=N(sub H)(Gal)). A Position Sensitive Proportional Counter (PSPC) hardness ratio is used to constrain the x-ray spectral properties of the quasars for which there were less than 100 photons detected. For the radio quiet quasars, (alpha(sub E)) approximately equals 1.2, if one assumes that there is no absorption in excess of the galactic column. We combine the x-ray data with new ground based optical and near-IR spectrophotometry obtained at the Steward 2.3 m and Multiple Mirror Telescope, and data from the literature. The spectral energy distributions are compared to those of low redshift objects. For the radio quiet quasars with z greater than 2.5, the mean (alpha(sub ox)) is approximately 1.8. This is larger than the mean for quasars with z less than 2.5, but consistent with the expected value for quasars with the high optical luminosities of the objects in this sample. For the radio-loud quasars, (alpha(sub ox)) is approximately 1.4, independent of redshift. This is smaller than the expected value for the optically luminous, high redshift objects in this sample, if they are mostly GHz peaked radio sources and hence comparable to steep-spectrum, compact radio sources at lower redshift. Finally, we compare the spectral energy distributions of two representative objects to the predicted spectrum of a thin accretion disk in the Kerr geometry, and discuss the uncertainties in deriving black hole masses and mass accretion rates.

  1. Retrieval of effective leaf area index (LAIe) and leaf area density (LAD) profile at individual tree level using high density multi-return airborne LiDAR

    NASA Astrophysics Data System (ADS)

    Lin, Yi; West, Geoff

    2016-08-01

    As an important canopy structure indicator, leaf area index (LAI) proved to be of considerable implications for forest ecosystem and ecological studies, and efficient techniques for accurate LAI acquisitions have long been highlighted. Airborne light detection and ranging (LiDAR), often termed as airborne laser scanning (ALS), once was extensively investigated for this task but showed limited performance due to its low sampling density. Now, ALS systems exhibit more competing capacities such as high density and multi-return sampling, and hence, people began to ask the questions like-"can ALS now work better on the task of LAI prediction?" As a re-examination, this study investigated the feasibility of LAI retrievals at the individual tree level based on high density and multi-return ALS, by directly considering the vertical distributions of laser points lying within each tree crown instead of by proposing feature variables such as quantiles involving laser point distribution modes at the plot level. The examination was operated in the case of four tree species (i.e. Picea abies, Pinus sylvestris, Populus tremula and Quercus robur) in a mixed forest, with their LAI-related reference data collected by using static terrestrial laser scanning (TLS). In light of the differences between ALS- and TLS-based LAI characterizations, the methods of voxelization of 3D scattered laser points, effective LAI (LAIe) that does not distinguish branches from canopies and unified cumulative LAI (ucLAI) that is often used to characterize the vertical profiles of crown leaf area densities (LADs) was used; then, the relationships between the ALS- and TLS-derived LAIes were determined, and so did ucLAIs. Tests indicated that the tree-level LAIes for the four tree species can be estimated based on the used airborne LiDAR (R2 = 0.07, 0.26, 0.43 and 0.21, respectively) and their ucLAIs can also be derived. Overall, this study has validated the usage of the contemporary high density multi

  2. A Cryogenic, Insulating Suspension System for the High Resolution Airborne Wideband Camera (HAWC)and Submillemeter And Far Infrared Experiment (SAFIRE) Adiabatic Demagnetization Refrigerators (ADRs)

    NASA Technical Reports Server (NTRS)

    Voellmer, George M.; Jackson, Michael L.; Shirron, Peter J.; Tuttle, James G.

    2002-01-01

    The High Resolution Airborne Wideband Camera (HAWC) and the Submillimeter And Far Infrared Experiment (SAFIRE) will use identical Adiabatic Demagnetization Refrigerators (ADR) to cool their detectors to 200mK and 100mK, respectively. In order to minimize thermal loads on the salt pill, a Kevlar suspension system is used to hold it in place. An innovative, kinematic suspension system is presented. The suspension system is unique in that it consists of two parts that can be assembled and tensioned offline, and later bolted onto the salt pill.

  3. Variation in airborne 137Cs peak levels with altitude from high-altitude locations across Europe after the arrival of Fukushima-labeled air masses

    NASA Astrophysics Data System (ADS)

    Masson, Olivier; Bieringer, Jacqueline; Dalheimer, Axel; Estier, Sybille; Evrard, Olivier; Penev, Ilia; Ringer, Wolfgang; Schlosser, Clemens; Steinkopff, Thomas; Tositti, Laura; de Vismes-Ott, Anne

    2015-04-01

    During the Fukushima Daiichi nuclear power plant (FDNPP) accident, a dozen of high-altitude aerosol sampling stations, located between 850 and 3,454 m above sea level (a.s.l.), provided airborne activity levels across Europe (Fig. 1). This represents at most 5% of the total number of aerosol sampling locations that delivered airborne activity levels (at least one result) in Europe, in connection with this nuclear accident. High altitude stations are typically equipped with a high volume sampler that collects aerosols on filters. The Fukushima-labeled air mass arrival and the peak of airborne cesium-137 (137Cs) activity levels were registered in Europe at different dates depending on the location, with differences up to a factor of six on a regional scale. Besides this statement related to lowland areas, we have compared the maximum airborne levels registered at high-altitude European locations (850 m < altitudes < 3450 m) with what was observed at the closest lowland location. The vertical distribution of 137Cs peak level was not uniform even after a long travel time/distance from Japan. This being true at least in the atmospheric boundary layer and in the lower free troposphere. Moreover the relation '137Csmax vs. altitude' shows a decreasing trend (Fig. 2). Results and discussion : Comparison of 137Cs and 7Be levels shows simultaneous increases at least when the 137Cs airborne level rose for the first time (Fig. 3). Zugspitze and Jungfraujoch stations attest of a time shift between 7Be and 137Cs peak that can be due to the particular dynamic of air movements at such high altitudes. After the 137Cs peak value, the plume concentration decreased whatever the 7Be level. Due to the cosmogenic origin of 7Be, its increase in the ground-level air is usually associated with downwind air movements, i.e. stratospheric air intrusions or at least air from high-tropospheric levels, into lower atmospheric layers. This means that Fukushima-labeled air masses registered at ground

  4. Adaptive uniform grayscale coded aperture design for high dynamic range compressive spectral imaging

    NASA Astrophysics Data System (ADS)

    Diaz, Nelson; Rueda, Hoover; Arguello, Henry

    2016-05-01

    Imaging spectroscopy is an important area with many applications in surveillance, agriculture and medicine. The disadvantage of conventional spectroscopy techniques is that they collect the whole datacube. In contrast, compressive spectral imaging systems capture snapshot compressive projections, which are the input of reconstruction algorithms to yield the underlying datacube. Common compressive spectral imagers use coded apertures to perform the coded projections. The coded apertures are the key elements in these imagers since they define the sensing matrix of the system. The proper design of the coded aperture entries leads to a good quality in the reconstruction. In addition, the compressive measurements are prone to saturation due to the limited dynamic range of the sensor, hence the design of coded apertures must consider saturation. The saturation errors in compressive measurements are unbounded and compressive sensing recovery algorithms only provide solutions for bounded noise or bounded with high probability. In this paper it is proposed the design of uniform adaptive grayscale coded apertures (UAGCA) to improve the dynamic range of the estimated spectral images by reducing the saturation levels. The saturation is attenuated between snapshots using an adaptive filter which updates the entries of the grayscale coded aperture based on the previous snapshots. The coded apertures are optimized in terms of transmittance and number of grayscale levels. The advantage of the proposed method is the efficient use of the dynamic range of the image sensor. Extensive simulations show improvements in the image reconstruction of the proposed method compared with grayscale coded apertures (UGCA) and adaptive block-unblock coded apertures (ABCA) in up to 10 dB.

  5. Toward a High-Efficient Utilization of Solar Radiation by Quad-Band Solar Spectral Splitting.

    PubMed

    Cao, Feng; Huang, Yi; Tang, Lu; Sun, Tianyi; Boriskina, Svetlana V; Chen, Gang; Ren, Zhifeng

    2016-12-01

    The promising quad-band solar spectral splitter incorporates the properties of the optical filter and the spectrally selective solar thermal absorber can direct PV band to PV modules and absorb thermal band energy for thermal process with low thermal losses. It provides a new strategy for spectral splitting and offers potential ways for hybrid PVT system design.

  6. Unidentified Spectral Lines between 4800 and 8100 Å in High-Resolution Spectra of Comets

    NASA Astrophysics Data System (ADS)

    Sim, Chaekyung; Hwang, S.; Kim, S.

    2010-10-01

    Visible spectrum of Comet Machholz (C/2004Q2) was obtained in the wavelength range of 2800 8100 Å with a resolution of 30,000 using BOES (BOao Echelle Spectograph) at Bohyunsan Observatory on January 4, 2005. It was found that emission lines of Machholz spectra were mostly originate from C2, NH2, CN, and H2O+. A list of unidentified spectral lines was compared with high-resolution visible spectra of other comets in literature: Swift-Tuttle, Brorsen-Metcalf, Austin, and 122P/de Vico. We will present identified molecular lines, which are previously unknown; and these identifications will be useful information for studying high-resolution spectra of future comets.

  7. High resolution Thomson Parabola Spectrometer for full spectral capture of multi-species ion beams

    NASA Astrophysics Data System (ADS)

    Alejo, A.; Kar, S.; Tebartz, A.; Ahmed, H.; Astbury, S.; Carroll, D. C.; Ding, J.; Doria, D.; Higginson, A.; McKenna, P.; Neumann, N.; Scott, G. G.; Wagner, F.; Roth, M.; Borghesi, M.

    2016-08-01

    We report on the experimental characterisation of laser-driven ion beams using a Thomson Parabola Spectrometer (TPS) equipped with trapezoidally shaped electric plates, proposed by Gwynne et al. [Rev. Sci. Instrum. 85, 033304 (2014)]. While a pair of extended (30 cm long) electric plates was able to produce a significant increase in the separation between neighbouring ion species at high energies, deploying a trapezoidal design circumvented the spectral clipping at the low energy end of the ion spectra. The shape of the electric plate was chosen carefully considering, for the given spectrometer configuration, the range of detectable ion energies and species. Analytical tracing of the ion parabolas matches closely with the experimental data, which suggests a minimal effect of fringe fields on the escaping ions close to the wedged edge of the electrode. The analytical formulae were derived considering the relativistic correction required for the high energy ions to be characterised using such spectrometer.

  8. Polarization maintaining fiber based ultra-high resolution spectral domain polarization sensitive optical coherence tomography

    PubMed Central

    2010-01-01

    We present a new ultra high resolution spectral domain polarization sensitive optical coherence tomography (PS-OCT) system based on polarization maintaining (PM) fibers. The method transfers the principles of our previous bulk optic PS-OCT systems to a fiberized setup. The phase shift between the orthogonal polarization states travelling in the two orthogonal modes of the PM fiber is compensated by software in post processing. Thereby, the main advantage of our bulk optics setups, i.e. the use of only a single input polarization state to simultaneously acquire reflectivity, retardation, optic axis orientation, and Stokes vector, is maintained. The use of a broadband light source of 110 nm bandwidth provides improved depth resolution and smaller speckle size. The latter is important for improved resolution of depolarization imaging. We demonstrate our instrument for high-resolution PS-OCT imaging of the healthy human retina. PMID:20052196

  9. Airborne Astronomy with a 150 micron - 400 micron Heterodyne Spectrometer

    NASA Technical Reports Server (NTRS)

    Betz, A. L.

    1995-01-01

    This report summarizes work done under NASA Grant NAG2-753 awarded to the University of Colorado. The project goal was to build a far-infrared heterodyne spectrometer for NASA's Kuiper Airborne Observatory, and to use this instrument to observe atomic and molecular spectral lines from the interstellar medium. This goal was successfully achieved. Detections of particular note have been the 370 micron line of neutral atomic carbon, the 158 micron transition of ionized carbon, many of the high-J rotational lines of CO-12 and CO-13 between J=9-8 and J=22-21, the 119 micron and 163 micron rotational lines of OH, the 219 micron ground-state rotational line of H2D(+), and the 63 microns fine structure line of neutral atomic oxygen. All of these lines were observed at spectral resolutions exceeding 1 part in 10(exp 6), thereby allowing accurate line shapes and Doppler velocities to be measured.

  10. Airborne Astronomy with a 150 microns - 400 microns Heterodyne Spectrometer

    NASA Technical Reports Server (NTRS)

    Betz, A. L.

    1995-01-01

    This report summarizes work done under NASA Grant NAG2-753 awarded to the University of Colorado. The project goal was to build a far-infrared heterodyne spectrometer for NASA's Kuiper Airborne Observatory, and to use this instrument to observe atomic and molecular spectral lines from the interstellar medium. This goal was successfully achieved. Detections of particular note have been the 370 micron line of neutral atomic carbon, the 158 micron transition of ionized carbon, many of the high-J rotational lines of CO-12 and CO-13 between J=9-8 and J=22-21, the 119 micron and 163 micron rotational lines of OH, the 219 micron ground-state rotational line of H2D(+), and the 63 micron fine structure line of neutral atomic oxygen. All of these lines were observed at spectral resolutions exceeding 1 part in 10(exp 6) thereby allowing accurate line shapes and Doppler velocities to be measured.

  11. Airborne astronomy with a 150 micrometer - 500 micrometer heterodyne spectrometer

    NASA Technical Reports Server (NTRS)

    Betz, A. L.

    1991-01-01

    This report summarizes work done under NASA Grant NAG2-254 awarded to the University of California. The project goal was to build a far-infrared heterodyne spectrometer for NASA's Kuiper Airborne Observatory (KAO), and to use this instrument to observe atomic and molecular spectral lines from the interstellar medium. This goal was successfully achieved; the spectrometer is now in routine use aboard the KAO. Detections of particular note have been the 370 micrometers line of neutral atomic carbon, the 158 micrometers transition of ionized carbon, many of the high-J rotational lines of 12CO and 13CO between J=9-8 and J=22-21, the 119 micron ground-state rotational line of OH, and the 219 micron ground-state rotational line of H2D(+). All of these lines were observed at spectral resolutions exceeding 1 part in 10(exp 6), thereby allowing accurate line shapes and Doppler velocities to be measured.

  12. High spectral resolution studies of gamma ray bursts on new missions

    SciTech Connect

    Desai, U. D.; Acuna, M. H.; Cline, T. L.; Dennis, B. R.; Orwig, L. E.; Trombka, J. I.; Starr, R. D.

    1996-08-01

    Two new missions will be launched in 1996 and 1997, each carrying X-ray and gamma ray detectors capable of high spectral resolution at room temperature. The Argentine Satelite de Aplicaciones Cientificas (SAC-B) and the Small Spacecraft Technology Initiative (SSTI) Clark missions will each carry several arrays of X-ray detectors primarily intended for the study of solar flares and gamma-ray bursts. Arrays of small (1 cm{sup 2}) cadmium zinc telluride (CZT) units will provide x-ray measurements in the 10 to 80 keV range with an energy resolution of {approx_equal}6 keV. Arrays of both silicon avalanche photodiodes (APD) and P-intrinsic-N (PIN) photodiodes (for the SAC-B mission only) will provide energy coverage from 2-25 keV with {approx_equal}1 keV resolution. For SAC-B, higher energy spectral data covering the 30-300 keV energy range will be provided by CsI(Tl) scintillators coupled to silicon APDs, resulting in similar resolution but greater simplicity relative to conventional CsI/PMT systems. Because of problems with the Pegasus launch vehicle, the launch of SAC-B has been delayed until 1997. The launch of the SSTI Clark mission is scheduled for June 1996.

  13. ISIS: An Interactive Spectral Interpretation System for High Resolution X-Ray Spectroscopy

    NASA Astrophysics Data System (ADS)

    Houck, J. C.; Denicola, L. A.

    The Interactive Spectral Interpretation System (ISIS) is designed to facilitate the interpretation and analysis of high resolution X-ray spectra like those obtained using the grating spectrographs on Chandra and XMM and the microcalorimeter on Astro-E. It is being developed as an interactive tool for studying the physics of X-ray spectrum formation, supporting measurement and identification of spectral features, and interaction with a database of atomic structure parameters and plasma emission models. The current version uses the atomic data and collisional ionization equilibrium models in the Astrophysical Plasma Emission Database (APED) of Brickhouse et.al., and also provides access to earlier plasma emission models including Raymond-Smith and MEKAL. Although the current version focuses on collisional ionization equilibrium plasmas, the system is designed to allow use of other databases to provide better support for studies of non-equilibrium and photoionized plasmas. To maximize portability between Unix operating systems, ISIS is being written entirely in ANSI C using free-software components (CFITSIO, PGPLOT and S-Lang).

  14. Fast spectral coherent anti-Stokes Raman scattering microscopy with high-speed tunable picosecond laser.

    PubMed

    Cahyadi, Harsono; Iwatsuka, Junichi; Minamikawa, Takeo; Niioka, Hirohiko; Araki, Tsutomu; Hashimoto, Mamoru

    2013-09-01

    We develop a coherent anti-Stokes Raman scattering (CARS) microscopy system equipped with a tunable picosecond laser for high-speed wavelength scanning. An acousto-optic tunable filter (AOTF) is integrated in the laser cavity to enable wavelength scanning by varying the radio frequency waves applied to the AOTF crystal. An end mirror attached on a piezoelectric actuator and a pair of parallel plates driven by galvanometer motors are also introduced into the cavity to compensate for changes in the cavity length during wavelength scanning to allow synchronization with another picosecond laser. We demonstrate fast spectral imaging of 3T3-L1 adipocytes every 5  cm-1 in the Raman spectral region around 2850  cm-1 with an image acquisition time of 120 ms. We also demonstrate fast switching of Raman shifts between 2100 and 2850  cm-1, corresponding to CD2 symmetric stretching and CH2 symmetric stretching vibrations, respectively. The fast-switching CARS images reveal different locations of recrystallized deuterated and nondeuterated stearic acid.

  15. Soft X-ray spectral observations of quasars and high X-ray luminosity Seyfert galaxies

    NASA Technical Reports Server (NTRS)

    Petre, R.; Mushotzky, R. F.; Krolik, J. H.; Holt, S. S.

    1983-01-01

    Results of the analysis of 28 Einstein SSS observations of 15 high X-ray luminosity (L(x) 10 to the 435 power erg/s) quasars and Seyfert type 1 nuclei are presented. The 0.75-4.5 keV spectra are in general well fit by a simple model consisting of a power law plus absorption by cold gas. The averager spectral index alpha is 0.66 + or - .36, consistent with alpha for the spectrum of these objects above 2 keV. In all but one case, no evidence was found for intrinsic absorption, with an upper limit of 2 x 10 to the 21st power/sq cm. Neither was evidence found for partial covering of the active nucleus by dense, cold matter (N(H) 10 to the 22nd power/sq cm; the average upper limit on the partial covering fraction is 0.5. There is no obvious correlation between spectral index and 0175-4.5 keV X-ray luminosity (which ranges from 3 x 10 to the 43rd to 47th powers erg/s or with other source properties. The lack of intrinsic X-ray absorption allows us to place constraints on the density and temperature of the broad-line emission region, and narrow line emission region, and the intergalactic medium.

  16. Polarized high-spectral-resolution lidar based on field-widened Michelson interferometer

    NASA Astrophysics Data System (ADS)

    Liu, Dong; Cheng, Zhongtao; Luo, Jing; Yang, Yongying; Zhang, Yupeng; Zhou, Yudi; Bai, Jian; Liu, Chong; Shen, Yibing

    2016-05-01

    A polarized high-spectral-resolution lidar (HSRL) based on a field-widened Michelson interferometer (FWMI) is developed in Zhejiang University, China, which is intended to profile various atmospheric aerosol optical properties simultaneously, such as the backscatter coefficient, the extinction coefficient, depolarization ratio, lidar ratio, etc. Due to the enlarged field-of-view (FOV) of the FWMI spectroscopic filter compared with the conventional Fabry-Perot interferometer (FPI) filter, we can expand the angular acceptable angle of the HSRL system to about 1 degree yet without any degradation of the spectral discrimination, enhancing the photon efficiency considerably. In this paper, we describe the developed FWMI-based polarized HSRL system comprehensively. The instrument configuration parameters and overall systematic structure are first presented. Then the FWMI subsystem, as the core apparatus of this HSRL, is particularly focused on. Instrumental calibration approach and the data retrieval are also discussed in detail. To our knowledge, this HSRL system is the first new generation of lidar which employs the FWMI spectroscopic filter in China, and great potential will be shown with the gradually improved engineering design in near future.

  17. Spectral anomalies in high intensity stimulated Raman backscattering in laser plasmas

    SciTech Connect

    Skoric, M.M.; Jovanovic, M.S.

    1995-12-31

    A large amount of effort is put into studies of fascinating new physics that is observed as one moves into a regime for collective effects with ultra short pulse high intensity laser plasmas. Recently, a Livermore-UCLA collaboration has observed a sub-psec version of classic laser plasma stimulated Raman backscattering (SRBS) instability. The backscattered light displays novel spectral signatures that depend on laser intensity. Broad and modulated frequency spectrum that spreads to the blue side of the incident wavelength; that is obviously different from classic SRBS which downshifts the incident frequency by approximately the electron plasma frequency (EPW). The authors study anomalous SRBS signatures in the 1-D model of underdense uniform weakly collisional plasma Layer. The set of three coupled equations, that account for pump depletion and relativistic detuning of EPW is simulated in space-time. By increasing a laser pump, a generic route via steady state periodic and quasi-periodic regime with an intermittent transition to spatio-temporal chaos is discovered. This type of intermittency in which quasi-periodic oscillations are interrupted by chaotic bursts displays modulated spectra with many peaks immersed in a broad band chaotic background. The picture reveals patches of turbulence inside the coherent state; the continuous transition amounts to a progressive increase of turbulence through the increase of the pump strength. Features, such as spiky burst-like reflectivity, anomalous broadening and blue shifted SRBS spectra are obtained and compared with recent experiments. Consistency, with observed anomalous spectral data is outlined.

  18. 16 W output power by high-efficient spectral beam combining of DBR-tapered diode lasers.

    PubMed

    Müller, André; Vijayakumar, Deepak; Jensen, Ole Bjarlin; Hasler, Karl-Heinz; Sumpf, Bernd; Erbert, Götz; Andersen, Peter E; Petersen, Paul Michael

    2011-01-17

    Up to 16 W output power has been obtained using spectral beam combining of two 1063 nm DBR-tapered diode lasers. Using a reflecting volume Bragg grating, a combining efficiency as high as 93.7% is achieved, resulting in a single beam with high spatial coherence. The result represents the highest output power achieved by spectral beam combining of two single element tapered diode lasers. Since spectral beam combining does not affect beam propagation parameters, M2-values of 1.8 (fast axis) and 3.3 (slow axis) match the M2-values of the laser with lowest spatial coherence. The principle of spectral beam combining used in our experiments can be expanded to combine more than two tapered diode lasers and hence it is expected that the output power may be increased even further in the future.

  19. Three-Dimensional High-Order Spectral Finite Volume Method for Unstructured Grids

    NASA Technical Reports Server (NTRS)

    Liu, Yen; Vinokur, Marcel; Wang, Z. J.; Kwak, Dochan (Technical Monitor)

    2002-01-01

    Many areas require a very high-order accurate numerical solution of conservation laws for complex shapes. This paper deals with the extension to three dimensions of the Spectral Finite Volume (SV) method for unstructured grids, which was developed to solve such problems. We first summarize the limitations of traditional methods such as finite-difference, and finite-volume for both structured and unstructured grids. We then describe the basic formulation of the spectral finite volume method. What distinguishes the SV method from conventional high-order finite-volume methods for unstructured triangular or tetrahedral grids is the data reconstruction. Instead of using a large stencil of neighboring cells to perform a high-order reconstruction, the stencil is constructed by partitioning each grid cell, called a spectral volume (SV), into 'structured' sub-cells, called control volumes (CVs). One can show that if all the SV cells are partitioned into polygonal or polyhedral CV sub-cells in a geometrically similar manner, the reconstructions for all the SVs become universal, irrespective of their shapes, sizes, orientations, or locations. It follows that the reconstruction is reduced to a weighted sum of unknowns involving just a few simple adds and multiplies, and those weights are universal and can be pre-determined once for all. The method is thus very efficient, accurate, and yet geometrically flexible. The most critical part of the SV method is the partitioning of the SV into CVs. In this paper we present the partitioning of a tetrahedral SV into polyhedral CVs with one free parameter for polynomial reconstructions up to degree of precision five. (Note that the order of accuracy of the method is one order higher than the reconstruction degree of precision.) The free parameter will be determined by minimizing the Lebesgue constant of the reconstruction matrix or similar criteria to obtain optimized partitions. The details of an efficient, parallelizable code to solve

  20. High spectral and spatial resolution spectroscopy of YSOs with a silicon grism and adaptive optics

    NASA Astrophysics Data System (ADS)

    Ge, J.; Lloyd, J. P.; Gavel, D.; Macintosh, B.; Max, C. E.; Ciarlo, D.; Kuzmenko, P.; Graham, J. R.

    2000-12-01

    We have obtained complete K band spectra of a total of 6 T Tauri and Ae/Be stars and their close companions at a spectral resolution of R ≈ 5000 using a silicon grism at the Lick 3m telescope. These results represent our first scientific observations conducted by the high resolution silicon grisms. Coupled with the LLNL adaptive optics system, a spatial resolution of 0.2 arcsec was achieved to allow observations of the companions with separations between 0.3-1.3 arcsec. The complete wavelength coverage was achieved by placing 16 cross-dispersed echelle orders on a 256x256 HgCdTe array with the silicon grism operating on high diffraction orders and a low dispersing CaF2 grism as a cross-disperser. High spectral resolution observations allow us to characterize each of the companions. Analysis of the spectra of these YSOs will be reported. The observations also allow us to measure the optical performance of the second generation of silicon grisms made with the techniques developed in early 2000. The new silicon grism has a peak efficiency of 45% and scattered light of ~ 8% in the K band. New techniques have been developed at Penn State to further reduce scattered light in the K band (Bernecker et al. this meeting) and are being applied in fabricating the third generation of silicon grisms for scientific observations. Fabrication of the silicon grisms and work on the Lick adaptive optics system was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract W-7405-ENG-48. Graham and Lloyd were also supported by the Center for Adaptive Optics under the STC Program of the National Science Foundation, Agreement No. AST-9876783

  1. Design and test of a new facility for assessing spectral normal emittance of solid materials at high temperature

    NASA Astrophysics Data System (ADS)

    Mercatelli, L.; Meucci, M.; Sani, E.

    2016-02-01

    The measurement of spectral emittance is a key topic in the study of new compositions, depositions and mechanical machining of materials for solar absorption and for renewable energies. In this work we report on the realization and testing of a new experimental facility for the measurement of directional spectral emittance which provides emittance spectral information in a controlled environment at medium-high temperatures up to 1300 K. The device is composed by a vacuum chamber with electrical heater optically connected with a visible and an FT-IR spectrometer. A split mirror permits to calibrate the system as it directs toward the detector the signal deriving from a calibrated blackbody. A ZnSe window allows to measure normal radiance in 0.6-17 μm spectral range. In this device the first test were carried out comparing the results obtained for HfC and TaB2 ultra-refractory ceramic samples to previous monochromatic measurements performed in a research solar furnace, obtaining a good agreement. Then, in order to confirm the reliability of the acquired spectral emittance curve, we compared it to that calculated from the room temperature spectrum in 2.5-17 μm spectral range, showing a similar spectral trend.

  2. Acquisition, calibration, and performance of airborne high-resolution ADS40 SH52 sensor data for monitoring the Colorado River below Glen Canyon Dam

    NASA Astrophysics Data System (ADS)

    Davis, P. A.; Cagney, L. E.; Kohl, K. A.; Gushue, T. M.; Fritzinger, C.; Bennett, G. E.; Hamill, J. F.; Melis, T. S.

    2010-12-01

    Periodically, the Grand Canyon Monitoring and Research Center of the U.S. Geological Survey collects and interprets high-resolution (20-cm), airborne multispectral imagery and digital surface models (DSMs) to monitor the effects of Glen Canyon Dam operations on natural and cultural resources of the Colorado River in Grand Canyon. We previously employed the first generation of the ADS40 in 2000 and the Zeiss-Imaging Digital Mapping Camera (DMC) in 2005. Data from both sensors displayed band-image misregistration owing to multiple sensor optics and image smearing along abrupt scarps due to errors in image rectification software, both of which increased post-processing time, cost, and errors from image classification. Also, the near-infrared gain on the early, 8-bit ADS40 was not properly set and its signal was saturated for the more chlorophyll-rich vegetation, which limited our vegetation mapping. Both sensors had stereo panchromatic capability for generating a DSM. The ADS40 performed to specifications; the DMC failed. In 2009, we employed the new ADS40 SH52 to acquire 11-bit multispectral data with a single lens (20-cm positional accuracy), as well as stereo panchromatic data that provided a 1-m cell DSM (40-cm root-mean-square vertical error at one sigma). Analyses of the multispectral data showed near-perfect registration of its four band images at our 20-cm resolution, a linear response to ground reflectance, and a large dynamic range and good sensitivity (except for the blue band). Data were acquired over a 10-day period for the 450-km-long river corridor in which acquisition time and atmospheric conditions varied considerably during inclement weather. We received 266 orthorectified flightlines for the corridor, choosing to calibrate and mosaic the data ourselves to ensure a flawless mosaic with consistent, realistic spectral information. A linear least-squares cross-calibration of overlapping flightlines for the corridor showed that the dominate factors in

  3. Evolution of a highly dilatant fault zone in the grabens of Canyonlands National Park, Utah/USA - integrating field work, ground penetrating radar and airborne imagery analysis

    NASA Astrophysics Data System (ADS)

    Kettermann, M.; Grützner, C.; van Gent, H. W.; Urai, J. L.; Reicherter, K.; Mertens, J.

    2015-03-01

    The grabens of the Canyonlands National Park are a young and active system of sub-parallel, arcuate grabens, whose evolution is the result of salt movement in the subsurface and a slight regional tilt of the faulted strata. We present results of ground penetrating radar surveys in combination with field observations and analysis of high resolution airborne imagery. GPR data show intense faulting of the Quaternary sediments at the flat graben floors, implying a more complex fault structure than visible at the surface. Direct measurements of heave and throw at several locations to infer fault dips at depth, combined with observations of primary joint surfaces in the upper 100 m suggest a model of the highly dilatant fault geometry in profile. Sinkholes observed in the field as well as in airborne imagery give insights in local massive dilatancy and show where water and sediments are transported underground. Based on correlations of paleosols observed in outcrops and GPR profiles, we argue that the grabens in Canyonlands National Park are either older than previously assumed, or that sedimentation rates were much higher in the Pleistocene.

  4. Evolution of a highly dilatant fault zone in the grabens of Canyonlands National Park, Utah, USA - integrating fieldwork, ground-penetrating radar and airborne imagery analysis

    NASA Astrophysics Data System (ADS)

    Kettermann, M.; Grützner, C.; van Gent, H. W.; Urai, J. L.; Reicherter, K.; Mertens, J.

    2015-07-01

    The grabens of Canyonlands National Park are a young and active system of sub-parallel, arcuate grabens, whose evolution is the result of salt movement in the subsurface and a slight regional tilt of the faulted strata. We present results of ground-penetrating radar (GPR) surveys in combination with field observations and analysis of high-resolution airborne imagery. GPR data show intense faulting of the Quaternary sediments at the flat graben floors, implying a more complex fault structure than visible at the surface. Direct measurements of heave and throw at several locations to infer fault dips at depth, combined with observations of primary joint surfaces in the upper 100 m, suggest a highly dilatant fault geometry. Sinkholes observed in the field as well as in airborne imagery give insights in local dilatancy and show where water and sediments are transported underground. Based on correlations of paleosols observed in outcrops and GPR profiles, we argue that either the grabens in Canyonlands National Park are older than previously assumed or that sedimentation rates were much higher in the Pleistocene.

  5. High fidelity remote sensing of snow properties from MODIS and the Airborne Snow Observatory: Snowflakes to Terabytes

    NASA Astrophysics Data System (ADS)

    Painter, T.; Mattmann, C. A.; Brodzik, M.; Bryant, A. C.; Goodale, C. E.; Hart, A. F.; Ramirez, P.; Rittger, K. E.; Seidel, F. C.; Zimdars, P. A.

    2012-12-01

    The response of the cryosphere to climate forcings largely determines Earth's climate sensitivity. However, our understanding of the strength of the simulated snow albedo feedback varies by a factor of three in the GCMs used in the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, mainly caused by uncertainties in snow extent and the albedo of snow-covered areas from imprecise remote sensing retrievals. Additionally, the Western US and other regions of the globe depend predominantly on snowmelt for their water supply to agriculture, industry and cities, hydroelectric power, and recreation, against rising demand from increasing population. In the mountains of the Upper Colorado River Basin, dust radiative forcing in snow shortens snow cover duration by 3-7 weeks. Extended to the entire upper basin, the 5-fold increase in dust load since the late-1800s results in a 3-week earlier peak runoff and a 5% annual loss of total runoff. The remotely sensed dynamics of snow cover duration and melt however have not been factored into hydrological modeling, operational forecasting, and policymaking. To address these deficiencies in our understanding of snow properties, we have developed and validated a suite of MODIS snow products that provide accurate fractional snow covered area and radiative forcing of dust and carbonaceous aerosols in snow. The MODIS Snow Covered Area and Grain size (MODSCAG) and MODIS Dust Radiative Forcing in Snow (MODDRFS) algorithms, developed and transferred from imaging spectroscopy techniques, leverage the complete MODIS surface reflectance spectrum. The two most critical properties for understanding snowmelt runoff and timing are the spatial and temporal distributions of snow water equivalent (SWE) and snow albedo. We have created the Airborne Snow Observatory (ASO), an imaging spectrometer and scanning LiDAR system, to quantify SWE and snow albedo, generate unprecedented knowledge of snow properties, and provide complete

  6. High spectral resolution observations of fluorescent molecular hydrogen in molecular clouds

    NASA Technical Reports Server (NTRS)

    Burton, Michael G.; Geballe, T. R.; Brand, P. W. J. L.; Moorhouse, A.

    1990-01-01

    The 1-0 S(1) line of molecular hydrogen has been observed at high spectral resolution in several sources where the emission was suspected of being fluorescent. In NGC 2023, the Orion Bar, and Parsamyan 18, the S(1) line is unresolved, and the line center close to the rest velocity of the ambient molecular cloud. Such behavior is expected for UV-excited line emission. The H2 line widths in molecular clouds thus can serve as diagnostic for shocked and UV-excitation mechanisms. If the lines are broader than several km/s or velocity shifts are observed across a source it is likely that shocks are responsible for the excitation of the gas.

  7. PEAK FLUX DISTRIBUTIONS OF SOLAR RADIO TYPE-I BURSTS FROM HIGHLY RESOLVED SPECTRAL OBSERVATIONS

    SciTech Connect

    Iwai, K.; Masuda, S.; Miyoshi, Y.; Tsuchiya, F.; Morioka, A.; Misawa, H.

    2013-05-01

    Solar radio type-I bursts were observed on 2011 January 26 by high resolution observations with the radio telescope AMATERAS in order to derive their peak flux distributions. We have developed a two-dimensional auto burst detection algorithm that can distinguish each type-I burst element from complex noise storm spectra that include numerous instances of radio frequency interference (RFI). This algorithm removes RFI from the observed radio spectra by applying a moving median filter along the frequency axis. Burst and continuum components are distinguished by a two-dimensional maximum and minimum search of the radio dynamic spectra. The analysis result shows that each type-I burst element has one peak flux without double counts or missed counts. The peak flux distribution of type-I bursts derived using this algorithm follows a power law with a spectral index between 4 and 5.

  8. Spectral response of atmospheric electric field measurements near AC high voltage power lines

    NASA Astrophysics Data System (ADS)

    Silva, H. G.; Matthews, J. C.; Wright, M. D.; Shallcross, D. E.

    2015-10-01

    To understand the influence of corona ion emission on the atmospheric electrical field, measurements were made near to two AC high voltage power lines. A JCI 131 field-mill recorded the atmospheric electric field over one year. Meteorological measurements were also taken. The data series is divided in four zones (dependent on wind direction): whole zones, Z0; zone 1, Z1; zone 2, Z2; zone 3, Z3. Z3 is the least affected by corona ion emission and for that reason it is used as a reference against Z1 and Z2, which are strongly influenced by this phenomena. Analysis was undertaken for all weather days and dry days only. The Lomb-Scargle strategy developed for unevenly spaced time-series is used to calculate the spectral response of the aforementioned zones. Only frequencies above 1 minute are considered.

  9. Adaptation of the University of Wisconsin High Spectral Resolution Lidar for Polarization and Multiple Scattering Measurements

    NASA Technical Reports Server (NTRS)

    Eloranta, E. W.; Piironen, P. K.

    1996-01-01

    Quantitative lidar measurements of aerosol scattering are hampered by the need for calibrations and the problem of correcting observed backscatter profiles for the effects of attenuation. The University of Wisconsin High Spectral Resolution Lidar (HSRL) addresses these problems by separating molecular scattering contributions from the aerosol scattering; the molecular scattering is then used as a calibration target that is available at each point in the observed profiles. While the HSRl approach has intrinsic advantages over competing techniques, realization of these advantages requires implementation of a technically demanding system which is potentially very sensitive to changes in temperature and mechanical alignments. This paper describes a new implementation of the HSRL in an instrumented van which allows measurements during field experiments. The HSRL was modified to measure depolarization. In addition, both the signal amplitude and depolarization variations with receiver field of view are simultaneously measured. This allows for discrimination of ice clouds from water clouds and observation of multiple scattering contributions to the lidar return.

  10. Design Of A Low Cost Diode-Laser-Based High Spectral Resolution Lidar (HSRL)

    NASA Astrophysics Data System (ADS)

    Hayman, Matthew; Spuler, Scott; Morley, Bruce; Eloranta, Edwin W.

    2016-06-01

    A concept for an eye-safe, semiconductor-based high spectral resolution lidar has been developed at the National Center for Atmospheric Research. The lidar operates at a wavelength of 780 nm near several rubidium absorption peaks. A rubidium vapor cell is used to block aerosol backscatter in one channel to provide a molecular backscatter measurement for calculating extinction and backscatter ratio (calibrated backscatter). Laser and optical components around 780 nm are widely developed due to the large growth in atomic cooling and trapping of rubidium. Thus this instrument can be built largely using mature commercial-off-the-shelf parts. The simulation of the conceptual design shown here uses known commercial products and suggests that such an instrument could be used for quantitative profiling of the lower troposphere.

  11. Identification of Stratospheric Waves in Ozone in the Tropics from OMI High Spectral Resolution Measurements

    NASA Technical Reports Server (NTRS)

    Ziemke, J. R.; Liu, X.; Bhartia, P. K.

    2007-01-01

    Previous studies using Total Ozone Mapping Spectrometer (TOMS) measurements have identified several types of tropical waves in the stratosphere. These waves include Kelvin waves, mixed Rossby-gravity waves, equatorial Rossby waves, and global normal modes. All of these detected waves occur when their zonal phase speeds are opposite the zonal winds in the low-mid stratosphere associated with the Quasi-biennial Oscillation (QBO). Peak-to-peak amplitudes in all cases are typically 5 DU. While total ozone data from TOMS is sensitive in detecting these tropical waves, they provide each day only a single horizontal cross-sectional map. The high spatial and spectral resolution of the Aura Ozone Monitoring Instrument (OMI) provides a unique means to evaluate 3D structure in these waves including their propagation characteristics. Ozone profiles retrieved from OMI radiances for wavelengths 270-310 nm are utilized to examine the nature of these wave disturbances extending from the lower to upper stratosphere.

  12. Iodine-filter-based high spectral resolution lidar for atmospheric temperature measurements.

    PubMed

    Liu, Zhi-Shen; Bi, De-Cang; Song, Xiao-Quan; Xia, Jin-Bao; Li, Rong-Zhong; Wang, Zhang-Jun; She, Chiao-Yao

    2009-09-15

    This paper presents a method for measuring atmosphere temperature profile using a single iodine filter as frequency discriminator. This high spectral resolution lidar (HSRL) is a system reconfigured with the transmitter of a mobile Doppler wind lidar and with a receiving subsystem redesigned to pass the backscattering optical signal through the iodine cell twice to filter out the aerosol scattering signal and to allow analysis of the molecular scattering spectrum, thus measuring temperatures. We report what are believed to be the first results of vertical temperature profiling from the ground to 16 km altitude by this lidar system (power-aperture product=0.35 Wm(2)). Concurrent observations of an L band radiosonde were carried out on June 14 and August 3, 2008, in good agreement with HSRL temperature profiles.

  13. Laser measurement of the spectral extinction coefficients of fluorescent, highly absorbing liquids. [crude petroleum oils

    NASA Technical Reports Server (NTRS)

    Hoge, F. E.

    1982-01-01

    A conceptual method is developed to deduce rapidly the spectral extinction coefficient of fluorescent, highly absorbing liquids, such as crude or refined petroleum oils. The technique offers the advantage of only requiring one laser wavelength and a single experimental assembly and execution for any specific fluorescent liquid. The liquid is inserted into an extremely thin wedge-shaped cavity for stimulation by a laser from one side and flurescence measurement on the other side by a monochromator system. For each arbitrarily selected extinction wavelength, the wedge is driven slowly to increasing thicknesses until the fluorescence extinguishes. The fluorescence as a function of wedge thickness permits a determination of the extinction coefficient using an included theoretical model. When the monochromator is set to the laser emission wavelength, the extinction coefficient is determined using the usual on-wavelength signal extinction procedure.

  14. Theoretical computation of trace gases retrieval random error from measurements of high spectral resolution infrared sounder

    NASA Technical Reports Server (NTRS)

    Huang, Hung-Lung; Smith, William L.; Woolf, Harold M.; Theriault, J. M.

    1991-01-01

    The purpose of this paper is to demonstrate the trace gas profiling capabilities of future passive high spectral resolution (1 cm(exp -1) or better) infrared (600 to 2700 cm(exp -1)) satellite tropospheric sounders. These sounders, such as the grating spectrometer, Atmospheric InfRared Sounders (AIRS) (Chahine et al., 1990) and the interferometer, GOES High Resolution Interferometer Sounder (GHIS), (Smith et al., 1991) can provide these unique infrared spectra which enable us to conduct this analysis. In this calculation only the total random retrieval error component is presented. The systematic error components contributed by the forward and inverse model error are not considered (subject of further studies). The total random errors, which are composed of null space error (vertical resolution component error) and measurement error (instrument noise component error), are computed by assuming one wavenumber spectral resolution with wavenumber span from 1100 cm(exp -1) to 2300 cm(exp -1) (the band 600 cm(exp -1) to 1100 cm(exp -1) is not used since there is no major absorption of our three gases here) and measurement noise of 0.25 degree at reference temperature of 260 degree K. Temperature, water vapor, ozone and mixing ratio profiles of nitrous oxide, carbon monoxide and methane are taken from 1976 US Standard Atmosphere conditions (a FASCODE model). Covariance matrices of the gases are 'subjectively' generated by assuming 50 percent standard deviation of gaussian perturbation with respect to their US Standard model profiles. Minimum information and maximum likelihood retrieval solutions are used.

  15. THE SPECTRAL AMPLITUDE OF STELLAR CONVECTION AND ITS SCALING IN THE HIGH-RAYLEIGH-NUMBER REGIME

    SciTech Connect

    Featherstone, Nicholas A.; Hindman, Bradley W.

    2016-02-10

    Convection plays a central role in the dynamics of any stellar interior, and yet its operation remains largely hidden from direct observation. As a result, much of our understanding concerning stellar convection necessarily derives from theoretical and computational models. The Sun is, however, exceptional in that regard. The wealth of observational data afforded by its proximity provides a unique test bed for comparing convection models against observations. When such comparisons are carried out, surprising inconsistencies between those models and observations become apparent. Both photospheric and helioseismic measurements suggest that convection simulations may overestimate convective flow speeds on large spatial scales. Moreover, many solar convection simulations have difficulty reproducing the observed solar differential rotation owing to this apparent overestimation. We present a series of three-dimensional stellar convection simulations designed to examine how the amplitude and spectral distribution of convective flows are established within a star’s interior. While these simulations are nonmagnetic and nonrotating in nature, they demonstrate two robust phenomena. When run with sufficiently high Rayleigh number, the integrated kinetic energy of the convection becomes effectively independent of thermal diffusion, but the spectral distribution of that kinetic energy remains sensitive to both of these quantities. A simulation that has converged to a diffusion-independent value of kinetic energy will divide that energy between spatial scales such that low-wavenumber power is overestimated and high-wavenumber power is underestimated relative to a comparable system possessing higher Rayleigh number. We discuss the implications of these results in light of the current inconsistencies between models and observations.

  16. Characterizing riverbed sediment using high-frequency acoustics 1: spectral properties of scattering

    USGS Publications Warehouse

    Buscombe, Daniel D.; Grams, Paul E.; Kaplinski, Matt A.

    2014-01-01

    Bed-sediment classification using high-frequency hydro-acoustic instruments is challenging when sediments are spatially heterogeneous, which is often the case in rivers. The use of acoustic backscatter to classify sediments is an attractive alternative to analysis of topography because it is potentially sensitive to grain-scale roughness. Here, a new method is presented which uses high-frequency acoustic backscatter from multibeam sonar to classify heterogeneous riverbed sediments by type (sand, gravel,rock) continuously in space and at small spatial resolution. In this, the first of a pair of papers that examine the scattering signatures from a heterogeneous riverbed, methods are presented to construct spatially explicit maps of spectral properties from geo-referenced point clouds of geometrically and radiometrically corrected echoes. Backscatter power spectra are computed to produce scale and amplitude metrics that collectively characterize the length scales of stochastic measures of riverbed scattering, termed ‘stochastic geometries’. Backscatter aggregated over small spatial scales have spectra that obey a power-law. This apparently self-affine behavior could instead arise from morphological- and grain-scale roughnesses over multiple overlapping scales, or riverbed scattering being transitional between Rayleigh and geometric regimes. Relationships exist between stochastic geometries of backscatter and areas of rough and smooth sediments. However, no one parameter can uniquely characterize a particular substrate, nor definitively separate the relative contributions of roughness and acoustic impedance (hardness). Combinations of spectral quantities do, however, have the potential to delineate riverbed sediment patchiness, in a data-driven approach comparing backscatter with bed-sediment observations (which is the subject of part two of this manuscript).

  17. High-speed spectral calibration by complex FIR filter in phase-sensitive optical coherence tomography

    PubMed Central

    Kim, Sangmin; Raphael, Patrick D.; Oghalai, John S.; Applegate, Brian E.

    2016-01-01

    Swept-laser sources offer a number of advantages for Phase-sensitive Optical Coherence Tomography (PhOCT). However, inter- and intra-sweep variability leads to calibration errors that adversely affect phase sensitivity. While there are several approaches to overcoming this problem, our preferred method is to simply calibrate every sweep of the laser. This approach offers high accuracy and phase stability at the expense of a substantial processing burden. In this approach, the Hilbert phase of the interferogram from a reference interferometer provides the instantaneous wavenumber of the laser, but is computationally expensive. Fortunately, the Hilbert transform may be approximated by a Finite Impulse-Response (FIR) filter. Here we explore the use of several FIR filter based Hilbert transforms for calibration, explicitly considering the impact of filter choice on phase sensitivity and OCT image quality. Our results indicate that the complex FIR filter approach is the most robust and accurate among those considered. It provides similar image quality and slightly better phase sensitivity than the traditional FFT-IFFT based Hilbert transform while consuming fewer resources in an FPGA implementation. We also explored utilizing the Hilbert magnitude of the reference interferogram to calculate an ideal window function for spectral amplitude calibration. The ideal window function is designed to carefully control sidelobes on the axial point spread function. We found that after a simple chromatic correction, calculating the window function using the complex FIR filter and the reference interferometer gave similar results to window functions calculated using a mirror sample and the FFT-IFFT Hilbert transform. Hence, the complex FIR filter can enable accurate and high-speed calibration of the magnitude and phase of spectral interferograms. PMID:27446666

  18. High Average Power Diode Pumped Solid State Lasers: Power Scaling With High Spectral and Spatial Coherence

    DTIC Science & Technology

    2009-03-30

    thulium upper laser level through cross-relaxation [5, 6]. Phosphate glass is also an attractive host for high-power single-frequency 2-µm Tm3+- doped...12, (8), p. 512 (1976) [4] D. G. Lancaster, A. Sabella, A. Hemming, S. Bennetts, S.D. Jackson, “Power-scalable thulium and holmium fibre lasers...efficient high-power thulium -doped germanate glass fiber laser,” Optics Letters, 32, (6), p. 638 (2007) [6] S. Jackson, “Power scaling method for 2-μm

  19. Nanoscale characterization of PM2.5 airborne pollutants reveals high adhesiveness and aggregation capability of soot particles

    PubMed Central

    Shi, Yuanyuan; Ji, Yanfeng; Sun, Hui; Hui, Fei; Hu, Jianchen; Wu, Yaxi; Fang, Jianlong; Lin, Hao; Wang, Jianxiang; Duan, Huiling; Lanza, Mario

    2015-01-01

    In 2012 air pollutants were responsible of seven million human death worldwide, and among them particulate matter with an aerodynamic diameter of 2.5 micrometers or less (PM2.5) are the most hazardous because they are small enough to invade even the smallest airways and penetrate to the lungs. During the last decade the size, shape, composition, sources and effect of these particles on human health have been studied. However, the noxiousness of these particles not only relies on their chemical toxicity, but particle morphology and mechanical properties affect their thermodynamic behavior, which has notable impact on their biological activity. Therefore, correlating the physical, mechanical and chemical properties of PM2.5 airborne pollutants should be the first step to characterize their interaction with other bodies but, unfortunately, such analysis has never been reported before. In this work, we present the first nanomechanical characterization of the most abundant and universal groups of PM2.5 airborne pollutants and, by means of atomic force microscope (AFM) combined with other characterization tools, we observe that fluffy soot aggregates are the most sticky and unstable. Our experiments demonstrate that such particles show strong adhesiveness and aggregation, leading to a more diverse composition and compiling all possible toxic chemicals. PMID:26177695

  20. Nanoscale characterization of PM2.5 airborne pollutants reveals high adhesiveness and aggregation capability of soot particles.

    PubMed

    Shi, Yuanyuan; Ji, Yanfeng; Sun, Hui; Hui, Fei; Hu, Jianchen; Wu, Yaxi; Fang, Jianlong; Lin, Hao; Wang, Jianxiang; Duan, Huiling; Lanza, Mario

    2015-07-16

    In 2012 air pollutants were responsible of seven million human death worldwide, and among them particulate matter with an aerodynamic diameter of 2.5 micrometers or less (PM2.5) are the most hazardous because they are small enough to invade even the smallest airways and penetrate to the lungs. During the last decade the size, shape, composition, sources and effect of these particles on human health have been studied. However, the noxiousness of these particles not only relies on their chemical toxicity, but particle morphology and mechanical properties affect their thermodynamic behavior, which has notable impact on their biological activity. Therefore, correlating the physical, mechanical and chemical properties of PM2.5 airborne pollutants should be the first step to characterize their interaction with other bodies but, unfortunately, such analysis has never been reported before. In this work, we present the first nanomechanical characterization of the most abundant and universal groups of PM2.5 airborne pollutants and, by means of atomic force microscope (AFM) combined with other characterization tools, we observe that fluffy soot aggregates are the most sticky and unstable. Our experiments demonstrate that such particles show strong adhesiveness and aggregation, leading to a more diverse composition and compiling all possible toxic chemicals.

  1. High-speed and high-sensitivity parallel spectral-domain optical coherence tomography using a supercontinuum light source.

    PubMed

    Barrick, Jessica; Doblas, Ana; Gardner, Michael R; Sears, Patrick R; Ostrowski, Lawrence E; Oldenburg, Amy L

    2016-12-15

    The three most important metrics in optical coherence tomography (OCT) are resolution, speed, and sensitivity. Because there is a complex interplay between these metrics, no previous work has obtained the best performance in all three metrics simultaneously. We demonstrate that a high-power supercontinuum source, in combination with parallel spectral-domain OCT, achieves an unparalleled combination of resolution, speed, and sensitivity. This system captures cross-sectional images spanning 4  mm×0.5  mm at 1,024,000 lines/s with 2×14  μm resolution (axial×transverse) at a sensitivity of 113 dB. Imaging using the proposed system is demonstrated on highly differentiated human bronchial epithelial cells to capture and spatially localize ciliary dynamics.

  2. Satellite imagery and airborne geophysics for geologic mapping of the Edembo area, Eastern Hoggar (Algerian Sahara)

    NASA Astrophysics Data System (ADS)

    Lamri, Takfarinas; Djemaï, Safouane; Hamoudi, Mohamed; Zoheir, Basem; Bendaoud, Abderrahmane; Ouzegane, Khadidja; Amara, Massinissa

    2016-03-01

    Satellite imagery combined with airborne geophysical data and field observations were employed for new geologic mapping of the Edembo area in the Eastern Hoggar (Tuareg Shield, Sahara). Multi-spectral band fusion, filtering, and transformation techniques, i.e., band combination, band-rationing and principal component analysis of ETM+ and ASTER data are used for better spectral discrimination of the different rocks units. A thematic map assessed by field data and available geologic information is compiled by supervised classification of satellite data with high overall accuracy (>90%). The automated extraction technique efficiently aided the detection of the structural lineaments, i.e., faults, shear zones, and joints. Airborne magnetic and Gamma-ray spectrometry data showed the pervasiveness of the large structures beneath the Paleozoic sedimentary cover and aeolian sands. The aeroradiometric K-range is used for discrimination of the high-K granitoids of Djanet from the peralumineous granites of Edembo, and to verify the Silurian sediments with their high K-bearing minerals. The new geological map is considered to be a high resolution improvement on all pre-existing maps of this hardly accessible area in the Tuareg Shield. Integration of the airborne geophysical and space-borne imagery data can hence provide a rapid means of geologically mapping areas hitherto poorly known or difficult to access.

  3. The Effects of High Frequency ULF Wave Activity on the Spectral Characteristics of Coherent HF Radar Returns

    NASA Astrophysics Data System (ADS)

    Wright, D. M.; Yeoman, T. K.; Woodfield, E. E.

    2003-12-01

    It is now a common practice to employ ground-based radars in order to distinguish between those regions of the Earth's upper atmosphere which are magnetically conjugate to open and closed field lines. Radar returns from ionospheric irregularities inside the polar cap and cusp regions generally exhibit large spectral widths in contrast to those which exist on closed field lines at lower latitudes. It has been suggested that the so-called Spectral Width Boundary (SWB) might act as a proxy for the open-closed field line boundary (OCFLB), which would then be an invaluable tool for investigating reconnection rates in the magnetosphere. The exact cause of the increased spectral widths observed at very high latitudes is still subject to considerable debate. Several mechanisms have been proposed. This paper compares a dusk-sector interval of coherent HF radar data with measurements made by an induction coil magnetometer located at Tromso, Norway (66° N geomagnetic). On this occasion, a series of transient regions of radar backscatter exhibiting large spectral widths are accompanied by increases in spectral power of ULF waves in the Pc1-2 frequency band. These observations would then, seem to support the possibility that high frequency magnetospheric wave activity at least contribute to the observed spectral characteristics and that such wave activity might play a significant role in the cusp and polar cap ionospheres.

  4. Energy gain and spectral tailoring of ion beams using ultra-high intensity laser beams

    NASA Astrophysics Data System (ADS)

    Prasad, Rajendra; Swantusch, Marco; Cerchez, Mirela; Spickermann, Sven; Auorand, Bastian; Wowra, Thomas; Boeker, Juergen; Willi, Oswald

    2015-11-01

    The field of laser driven ion acceleration over the past decade has produced a huge amount of research. Nowadays, several multi-beam facilities with high rep rate system, e.g. ELI, are being developed across the world for different kinds of experiments. The study of interaction dynamics of multiple beams possessing ultra-high intensity and ultra-short pulse duration is of vital importance. Here, we present the first experimental results on ion acceleration using two ultra-high intensity beams. Thanks to the unique capability of Arcturus laser at HHU Düsseldorf, two almost identical, independent beams in laser parameters such as intensity (>1020 W/cm2), pulse duration (30 fs) and contrast (>1010), could be accessed. Both beams are focused onto a 5 μm thin Ti target. While ensuring spatial overlap of the two beams, at relative temporal delay of ~ 50 ps (optimum delay), the proton and carbon ion energies were enhanced by factor of 1.5. Moreover, strong modulation in C4+ions near the high energy cut-off is observed later than the optimum delay for the proton enhancement. This offers controlled tailoring of the spectral content of heavy ions.

  5. Realization of Ultra-High Spectral Purity with the Opto-Electronic Oscillator

    NASA Technical Reports Server (NTRS)

    Yao, Steve; Maleki, Lute; Ji, Yu; Dick, John

    2000-01-01

    Recent results with the Opto-Electronic Oscillator (OEO) have led to the realization of very high spectral purity. Experimental results have produced a performance characterized by a noise as low as by -50 dBc/Hz at 10 Hz for a 10 GHz OEO. The unit was built in a compact package containing an integrated DFB laser and the modulator. This performance is significant because the oscillator is free running, and since the noise in an OEO is independent of the oscillation frequency, the same result can also be obtained at higher frequencies. The result also demonstrates that high frequency, high performance, low cost, and miniature OEO can be realized with the integrated photonic technology. We have also developed a novel carrier suppression technique to reduce the 1/f phase noise of the oscillator even further. The technique is based on the use of a long fiber delay, in place of the high Q cavity, to implement carrier suppression. Our preliminary experimental results indicate an extra 10 to 20 dB phase noise reduction of the OEO with this novel technique. Further noise reduction beyond this value is expected with improved circuit design and longer reference fiber.

  6. Extension of least squares spectral resolution algorithm to high-resolution lipidomics data.

    PubMed

    Zeng, Ying-Xu; Mjøs, Svein Are; David, Fabrice P A; Schmid, Adrien W

    2016-03-31

    Lipidomics, which focuses on the global study of molecular lipids in biological systems, has been driven tremendously by technical advances in mass spectrometry (MS) instrumentation, particularly high-resolution MS. This requires powerful computational tools that handle the high-throughput lipidomics data analysis. To address this issue, a novel computational tool has been developed for the analysis of high-resolution MS data, including the data pretreatment, visualization, automated identification, deconvolution and quantification of lipid species. The algorithm features the customized generation of a lipid compound library and mass spectral library, which covers the major lipid classes such as glycerolipids, glycerophospholipids and sphingolipids. Next, the algorithm performs least squares resolution of spectra and chromatograms based on the theoretical isotope distribution of molecular ions, which enables automated identification and quantification of molecular lipid species. Currently, this methodology supports analysis of both high and low resolution MS as well as liquid chromatography-MS (LC-MS) lipidomics data. The flexibility of the methodology allows it to be expanded to support more lipid classes and more data interpretation functions, making it a promising tool in lipidomic data analysis.

  7. Linear-wavenumber spectrometer for high-speed spectral-domain optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Gelikonov, V. M.; Gelikonov, G. V.; Shilyagin, P. A.

    2009-03-01

    An equidistant (in the wavenumber) spectrometer based on a diffraction grating, a compensation prism, and a CCD linear array is developed and implemented for spectral-domain optical coherence tomography. A criterion is introduced for estimating the level of residual nonequidistance. This criterion allows one to determine the threshold compensation level necessary for obtaining the spectrally limited spatial resolution. The method is tested in spectral-domain optical coherent tomography systems at wavelengths of 1270 and 830 nm.

  8. Geologic mapping in Death Valley, California/Nevada using NASA/JPL airborne systems (AVIRIS, TIMS, and AIRSAR)

    NASA Technical Reports Server (NTRS)

    Kruse, Fred A.; Dietz, John B.; Kiereinyoung, Kathryn S.

    1991-01-01

    A multi-sensor aircraft campaign called the Geologic Remote Sensing Field Experiment (GRSFE) conducted during 1989 resulted in acquisition of high quality multispectral images in the visible, near infrared, shortwave infrared, thermal infrared, and microwave regions of the electromagnetic spectrum. The airborne data sets include the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS), the Thermal Infrared Multispectral Scanner (TIMS), and the Airborne Synthetic Aperture Radar (SAR). Ancillary data include Landsat Thematic Mapper, laboratory and field spectral measurements, and traditional geologic mapping. The GRSFE data for a site in the northern Death Valley, (California and Nevada) region were calibrated to physical units and geometrically registered to a map base. Various aspects of this experiment are briefly discussed.

  9. An infrared remote sensor with high integration and multi-spectral bands

    NASA Astrophysics Data System (ADS)

    Zhang, Lisha; Liu, Zhaojun; Ma, Wenpo; Tang, Shaofan; Hu, Bin

    2014-11-01

    Along with the further application of optical remote sensing, it becomes main trend to realize high spatial resolution, high time resolution, high spectrum resolution and high irradiance sensitivity simultaneously. We present a new satellite-based imaging system that will provide images with these high performances. The structure of the system is compact with small size and light weight. The IR imager, a new generation of high resolution optical remote sensing, is universally acknowledged as the most effective approach to surveil dynamic changes in the environment on the earth. Pushbroom imaging fashion with high efficiency and long-array focal plane detector with passive cooling are adopted to realize area imaging relevant to the flight direction of satellite. The instrument is a dual-optical-path system with long-wave infrared (LWIR) and mid-short-wave infrared (MW-SWIR) bands - which has 4 narrow spectrum bands respectively. An IR dichroic beam-splitter is use to divide wideband incident infrared into LWIR and MW-SWIR. Then two pieces of joint filters, which are integrated in front of detectors and then enveloped by IR Dewars, are used to divide the LWIR and MWIR into 4 spectral bands separately. The focal plane arrays (FPA) are fixed on the optical imaging plane of the lens. The LWIR and MW-SWIR FPA are cooled around 80K or even below. For cooled FPA, optical system must provide a real, accessible exit pupil coupled with a fast f/number refractive component in a Dewar and very close to the FPA. Compared to traditional infrared instruments, high spatial resolution and spectrum resolution can be obtained simultaneously within mass, volume and performance constraints.

  10. High-Order Moving Overlapping Grid Methodology in a Spectral Element Method

    NASA Astrophysics Data System (ADS)

    Merrill, Brandon E.

    A moving overlapping mesh methodology that achieves spectral accuracy in space and up to second-order accuracy in time is developed for solution of unsteady incompressible flow equations in three-dimensional domains. The targeted applications are in aerospace and mechanical engineering domains and involve problems in turbomachinery, rotary aircrafts, wind turbines and others. The methodology is built within the dual-session communication framework initially developed for stationary overlapping meshes. The methodology employs semi-implicit spectral element discretization of equations in each subdomain and explicit treatment of subdomain interfaces with spectrally-accurate spatial interpolation and high-order accurate temporal extrapolation, and requires few, if any, iterations, yet maintains the global accuracy and stability of the underlying flow solver. Mesh movement is enabled through the Arbitrary Lagrangian-Eulerian formulation of the governing equations, which allows for prescription of arbitrary velocity values at discrete mesh points. The stationary and moving overlapping mesh methodologies are thoroughly validated using two- and three-dimensional benchmark problems in laminar and turbulent flows. The spatial and temporal global convergence, for both methods, is documented and is in agreement with the nominal order of accuracy of the underlying solver. Stationary overlapping mesh methodology was validated to assess the influence of long integration times and inflow-outflow global boundary conditions on the performance. In a turbulent benchmark of fully-developed turbulent pipe flow, the turbulent statistics are validated against the available data. Moving overlapping mesh simulations are validated on the problems of two-dimensional oscillating cylinder and a three-dimensional rotating sphere. The aerodynamic forces acting on these moving rigid bodies are determined, and all results are compared with published data. Scaling tests, with both methodologies

  11. NASA COAST and OCEANIA Airborne Missions Support Ecosystem and Water Quality Research in the Coastal Zone

    NASA Astrophysics Data System (ADS)

    Guild, L. S.; Kudela, R. M.; Hooker, S. B.; Morrow, J. H.; Russell, P. B.; Palacios, S. L.; Livingston, J. M.; Negrey, K.; Torres-Perez, J. L.; Broughton, J.

    2014-12-01

    NASA has a continuing requirement to collect high-quality in situ data for the vicarious calibration of current and next generation ocean color satellite sensors and to validate the algorithms that use the remotely sensed observations. Recent NASA airborne missions over Monterey Bay, CA, have demonstrated novel above- and in-water measurement capabilities supporting a combined airborne sensor approach (imaging spectrometer, microradiometers, and a sun photometer). The results characterize coastal atmospheric and aquatic properties through an end-to-end assessment of image acquisition, atmospheric correction, algorithm application, plus sea-truth observations from state-of-the-art instrument systems. The primary goal is to demonstrate the following in support of calibration and validation exercises for satellite coastal ocean color products: 1) the utility of a multi-sensor airborne instrument suite to assess the bio-optical properties of coastal California, including water quality; and 2) the importance of contemporaneous atmospheric measurements to improve atmospheric correction in the coastal zone. The imaging spectrometer (Headwall) is optimized in the blue spectral domain to emphasize remote sensing of marine and freshwater ecosystems. The novel airborne instrument, Coastal Airborne In-situ Radiometers (C-AIR) provides measurements of apparent optical properties with high dynamic range and fidelity for deriving exact water leaving radiances at the land-ocean boundary, including radiometrically shallow aquatic ecosystems. Simultaneous measurements supporting empirical atmospheric correction of image data are accomplished using the Ames Airborne Tracking Sunphotometer (AATS-14). Flight operations are presented for the instrument payloads using the CIRPAS Twin Otter flown over Monterey Bay during the seasonal fall algal bloom in 2011 (COAST) and 2013 (OCEANIA) to support bio-optical measurements of phytoplankton for coastal zone research.

  12. High sensitivity mass spectral characterization of glycosphingolipids from bovine erythrocytes, mouse kidney and fetal calf brain

    NASA Astrophysics Data System (ADS)

    Perreault, H.; Hronowski, X. L.; Koul, O.; Street, J.; McCluer, R. H.; Costello, C. E.

    1997-12-01

    Stage-specific embryonic antigen (SSEA) glycosphingolipids (GSLs) found in the central nervous system are implicated in regulating cell-cell recognition, targeting and migration of cells during development. Through the action of fucosyltransferase enzymes, SSEA-1 (Lewisx) glycolipids are biosynthesized in the brain by fucosylation of lipid substrates with the neolacto series glycolipid core structure [Gal[beta]1 --> 4GlcNAc[beta]1 --> 3Gal[beta]1 --> 4Glc[beta]1 --> 1'Cer] (originally termed paragloboside) or its higher analogs. In order to optimize methodology for high sensitivity structural determinations of SSEA-1 type glycolipids from fetal calf brain, potential precursors and SSEA-1 glycolipids of previously established structure were first isolated from bovine erythrocytes and beige mutant mouse kidney, purified by column chromatography and characterized by matrix-assisted laser desorption/ionisation time-of-flight (MALDI-TOF) MS, liquid secondary ionization mass spectrometry (LSIMS), and tandem mass spectrometry (MS/MS), among other techniques. Peracetylated derivatives were detected at the low femtomole level by MALDI-TOF MS and the subnanomole level by LSIMS. MALDI-TOF MS produced mainly [M + Na] + and [M + K]+ species. On the basis of the direct and tandem mass spectral analyses of peracetylated and permethylated derivatives, the carbohydrate sequences in the selected bovine erythrocyte and mouse kidney GSL fractions were found to be consistent with those of glycolipids previously-reported from larger-scale studies of these sources. Their heterogeneous ceramide moieties were characterized by collision induced decomposition (CID) MS/MS of abundant Z0-type ions in the LSI mass spectra of the permethylated GSLs. MALDI-PSD-TOF mass spectral analyses of low and subpicomole amounts of derivatized GSL fractions from fetal calf brain provided carbohydrate sequence information that indicates the presence of mono- and difucosylated SSEA-1 neolacto series

  13. Uncovering the Spectral Energy Distribution in Active Galaxies Using High Ionization Mid-Infrared Emission Lines

    NASA Technical Reports Server (NTRS)

    Melendez, M.; Kraemer, S. B.; Weaver, K. A.; Mushotzky, R. F.

    2011-01-01

    The shape of the spectral energy distribution of active galaxies in the EUV soft X-ray band (13.6 eV to 1 keV) is uncertain because obscuration by dust and gas can hamper our view of the continuum. To investigate the shape of the spectral energy distribution in this energy band, we have generated a set of photoionization models which reproduce the small dispersion found in correlations between high-ionization mid-infrared emission lines in a sample of hard X-ray selected AGN. Our calculations show that a broken power-law continuum model is sufficient to reproduce the [Ne V]14.32 microns/[Ne III], [Ne V]24.32 microns/[O IV]25.89 micron and [O IV] 25.89 microns/[Ne III] ratios, and does not require the addition of a "big bump" EUV model component. We constrain the EUV-soft X-ray slope, alpha(sub i), to be between 1.5 - 2.0 and derive a best fit of alpha(sub i) approx. 1.9 for Seyfert 1 galaxies, consistent with previous studies of intermediate redshift quasars. If we assume a blue bump model, most sources in our sample have derived temperatures between T(sub BB) = 10(exp 5.18) K to 10(exp 5.7) K, suggesting that the peak of this component spans a large range of energies extending from approx. (Lambda)600 A to > (Lambda)1900 A. In this case, the best fitting peak energy that matches the mid-infrared line ratios of Seyfert 1 galaxies occurs between approx. (Lambda)700-(Lambda)1000 A. Despite the fact that our results do not rule out the presence of an EUV bump, we conclude that our power-law model produces enough photons with energies > 4 Ry to generate the observed amount of mid-infrared emission in our sample of BAT AGN.

  14. Spectral Evolution in High Redshift Quasars from the Final Baryon Oscillation Spectroscopic Survey Sample

    NASA Astrophysics Data System (ADS)

    Jensen, Trey W.; Vivek, M.; Dawson, Kyle S.; Anderson, Scott F.; Bautista, Julian; Bizyaev, Dmitry; Brandt, William N.; Brownstein, Joel R.; Green, Paul; Harris, David W.; Kamble, Vikrant; McGreer, Ian D.; Merloni, Andrea; Myers, Adam; Oravetz, Daniel; Pan, Kaike; Pâris, Isabelle; Schneider, Donald P.; Simmons, Audrey; Suzuki, Nao

    2016-12-01

    We report on the diversity in quasar spectra from the Baryon Oscillation Spectroscopic Survey. After filtering the spectra to mitigate selection effects and Malmquist bias associated with a nearly flux-limited sample, we create high signal-to-noise ratio composite spectra from 58,656 quasars (2.1≤slant z≤slant 3.5), binned by luminosity, spectral index, and redshift. With these composite spectra, we confirm the traditional Baldwin effect (BE, i.e., the anti-correlation of C iv equivalent width (EW) and luminosity) that follows the relation {W}λ \\propto {L}{β w} with slope {β }w=-0.35+/- 0.004, -0.35 ± 0.005, and -0.41 ± 0.005 for z = 2.25, 2.46, and 2.84, respectively. In addition to the redshift evolution in the slope of the BE, we find redshift evolution in average quasar spectral features at fixed luminosity. The spectroscopic signature of the redshift evolution is correlated at 98% with the signature of varying luminosity, indicating that they arise from the same physical mechanism. At a fixed luminosity, the average C iv FWHM decreases with increasing redshift and is anti-correlated with C iv EW. The spectroscopic signature associated with C iv FWHM suggests that the trends in luminosity and redshift are likely caused by a superposition of effects that are related to black hole mass and Eddington ratio. The redshift evolution is the consequence of a changing balance between these two quantities as quasars evolve toward a population with lower typical accretion rates at a given black hole mass.

  15. Quantification of gully volume using very high resolution DSM generated through 3D reconstruction from airborne and field digital imagery

    NASA Astrophysics Data System (ADS)

    Castillo, Carlos; Zarco-Tejada, Pablo; Laredo, Mario; Gómez, Jose Alfonso

    2013-04-01

    Major advances have been made recently in automatic 3D photo-reconstruction techniques using uncalibrated and non-metric cameras (James and Robson, 2012). However, its application on soil conservation studies and landscape feature identification is currently at the outset. The aim of this work is to compare the performance of a remote sensing technique using a digital camera mounted on an airborne platform, with 3D photo-reconstruction, a method already validated for gully erosion assessment purposes (Castillo et al., 2012). A field survey was conducted in November 2012 in a 250 m-long gully located in field crops on a Vertisol in Cordoba (Spain). The airborne campaign was conducted with a 4000x3000 digital camera installed onboard an aircraft flying at 300 m above ground level to acquire 6 cm resolution imagery. A total of 990 images were acquired over the area ensuring a large overlap in the across- and along-track direction of the aircraft. An ortho-mosaic and the digital surface model (DSM) were obtained through automatic aerial triangulation and camera calibration methods. For the field-level photo-reconstruction technique, the gully was divided in several reaches to allow appropriate reconstruction (about 150 pictures taken per reach) and, finally, the resulting point clouds were merged into a unique mesh. A centimetric-accuracy GPS provided a benchmark dataset for gully perimeter and distinguishable reference points in order to allow the assessment of measurement errors of the airborne technique and the georeferenciation of the photo-reconstruction 3D model. The uncertainty on the gully limits definition was explicitly addressed by comparison of several criteria obtained by 3D mode