F. W. Harrison

Langley Research Center

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E. V. Browell

Langley Research Center

J. T. Dobler

Harris Health System

S. A. Kooi

Science Systems and Applications (United States)

Amin R. Nehrir

Langley Research Center

M. D. Obland

Langley Research Center

Bing Lin

Langley Research Center

Syed Ismail

National Institute of Technology Warangal

J. F. Campbell

Langley Research Center

B. Meadows

Langley Research Center

T. Scott Zaccheo

Atmospheric and Environmental Research

Cooperative Institutions

Langley Research Center

National Aeronautics and Space Administration

Goddard Space Flight Center

Science Systems and Applications (United States)

University of Wisconsin–Madison

Bellingham Technical College

Ames Research Center

Science Applications International Corporation (United States)

Exelis (United States)

University of California, Irvine

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Tropospheric carbon monoxide and ozone measurements by geostationary imaging fourier transform spectrometer

N. S. Pougatchev William L. Smith F. W. Harrison Allen M. Larar C. P. Rinsland

Feasibility study of the atmospheric chemistry measurements potential of the Geostationary Imaging Fourier Transform Spectrometer is presented.

Fourier transform spectroscopy

Imaging spectrometer

Atmospheric chemistry

Tropospheric ozone

10.1364/ors.2001.othb2

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The Structure of Chloritoid1

Deleted Journal (1953)

G. W. Brindley F. W. Harrison

Abstract A summary is given of a structure analysis of chloritoid. The structure contains continuously linked octahedral sheets cross-linked by discrete SiO 4 units. Comparisons are made with mica structures and with corundum.

Corundum

10.1346/ccmn.1953.0020130

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Signal to Noise Ratio in Digital Lock-in Detection for Multiple Intensity-Modulated Signals in CO2 Laser Absorption Spectrometer

AGU Fall Meeting Abstracts (2013)

S. Chen Binshan Lin F. W. Harrison Amin R. Nehrir J. F. Campbell

Relative intensity noise

Intensity

SIGNAL (programming language)

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Column CO 2 Measurements with Intensity-Modulated Continuous-Wave Lidar System During the ASCENDS 2014 Summer Field Experiment

AGUFM (2014)

B. Meadows Amin R. Nehrir Bing Lin F. W. Harrison J. T. Dobler

Intensity

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Lidar Measurements of Atmospheric CO2 from Regional to Global Scales

Japan Geoscience Union (2015)

Bing Lin F. W. Harrison Amin R. Nehrir E. V. Browell J. T. Dobler

Atmospheric CO2 is a critical forcing for the Earth's climate and the knowledge on its distributions and variations influences predictions of the Earth's future climate. Large uncertainties in the predictions persist due to limited observations. This study uses the airborne Intensity-Modulated Continuous-Wave (IMCW) lidar developed at NASA Langley Research Center to measure regional atmospheric CO2 spatio-temporal variations. Further lidar development and demonstration will provide the capability of global atmospheric CO2 estimations from space, which will significantly advances our knowledge on atmospheric CO2 and reduce the uncertainties in the predictions of future climate. In this presentation, atmospheric CO2 column measurements from airborne flight campaigns and lidar system simulations for space missions will be discussed. A measurement precision of approx.0.3 ppmv for a 10-s average over desert and vegetated surfaces has been achieved. Data analysis also shows that airborne lidar CO2 column measurements over these surfaces agree well with in-situ measurements. Even when thin cirrus clouds present, consistent CO2 column measurements between clear and thin cirrus cloudy skies are obtained. Airborne flight campaigns have demonstrated that precise atmospheric column CO2 values can be measured from current IM-CW lidar systems, which will lead to use this airborne technique in monitoring CO2 sinks and sources in regional and continental scales as proposed by the NASA Atmospheric Carbon and Transport â€ America project. Furthermore, analyses of space CO2 measurements shows that applying the current IM-CW lidar technology and approach to space, the CO2 science goals of space missions will be achieved, and uncertainties in CO2 distributions and variations will be reduced.

Cirrus

Atmospheric research

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Airborne Laser CO 2 Column Measurements: Evaluation of Precision and Accuracy Under a Wide Range of Surface and Atmospheric Conditions

AGUFM (2011)

E. V. Browell J. T. Dobler S. A. Kooi Marta A. Fenn Yunsoo Choi

Accuracy and precision

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Lidar Observations of Atmospheric CO2 Column During 2014 Summer Flight Campaigns

Bing Lin F. W. Harrison Tai-Fang Fan

Advanced knowledge in atmospheric CO2 is critical in reducing large uncertainties in predictions of the Earth' future climate. Thus, Active Sensing of CO2 Emissions over Nights, Days, and Seasons (ASCENDS) from space was recommended by the U.S. National Research Council to NASA. As part of the preparation for the ASCENDS mission, NASA Langley Research Center (LaRC) and Exelis, Inc. have been collaborating in development and demonstration of the Intensity-Modulated Continuous-Wave (IM-CW) lidar approach for measuring atmospheric CO2 column from space. Airborne laser absorption lidars such as the Multi-Functional Fiber Laser Lidar (MFLL) and ASCENDS CarbonHawk Experiment Simulator (ACES) operating in the 1.57 micron CO2 absorption band have been developed and tested to obtain precise atmospheric CO2 column measurements using integrated path differential absorption technique and to evaluate the potential of the space ASCENDS mission. This presentation reports the results of our lidar atmospheric CO2 column measurements from 2014 summer flight campaign. Analysis shows that for the 27 Aug OCO-2 under flight over northern California forest regions, significant variations of CO2 column approximately 2 ppm) in the lower troposphere have been observed, which may be a challenge for space measurements owing to complicated topographic condition, heterogeneity of surface reflection and difference in vegetation evapotranspiration. Compared to the observed 2011 summer CO2 drawdown (about 8 ppm) over mid-west, 2014 summer drawdown in the same region measured was much weak (approximately 3 ppm). The observed drawdown difference could be the results of the changes in both meteorological states and the phases of growing seasons. Individual lidar CO2 column measurements of 0.1-s integration were within 1-2 ppm of the CO2 estimates obtained from on-board in-situ sensors. For weak surface reflection conditions such as ocean surfaces, the 1- s integrated signal-to-noise ratio (SNR) of lidar measurements at 11 km altitude reached 376, which was equivalent to a 10-s CO2 error 0.33 ppm. For the entire processed 2014 summer flight campaign data, the mean differences between lidar remote sensed and in-situ estimated CO2 values were about -0.013 ppm. These results indicate that current laser absorption lidar approach could meet space measurement requirements for CO2 science goals.

Atmospheric research

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Preparation, characterization, and some magnetic properties of Eu3VTa2O9 and Sr3VTa2O9 — New perovskites containing vanadium(II)

Materials Research Bulletin (1977)

John E. Greedan F. W. Harrison

Ionic radius

Supercell

Oxidation state

Characterization

10.1016/0025-5408(77)90035-6

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Systems simulations supporting NASA telerobotics

F. W. Harrison J. E. Pennington

Two simulation and analysis environments have been developed to support telerobotics research at the Langley Research Center. One is a high-fidelity, nonreal-time, interactive model called ROBSIM, which combines user-generated models of workspace environment, robots, and loads into a working system and simulates the interaction among the system components. Models include user-specified actuator, sensor, and control parameters, as well as kinematic and dynamic characteristics. Kinematic, dynamic, and response analyses can be selected, with system configuration, task trajectories, and arm states displayed using computer graphics. The second environment is a real-time, manned Telerobotic Systems Simulation (TRSS) which uses the facilities of the Intelligent Systems Research Laboratory (ISRL). It utilizes a hierarchical structure of functionally distributed computers communicating over both parallel and high-speed serial data paths to enable studies of advanced telerobotic systems. Multiple processes perform motion planning, operator communications, forward and inverse kinematics, control/sensor fusion, and I/O processing while communicating via common memory. This paper describes both ROBSIM and TRSS, including their capability, status, and future plans. Also described is the architecture of ISRL and recent telerobotic system studies in ISRL.

Work space

Telerobotics

Teleoperation

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Advancements for Active Remote Sensing of Carbon Dioxide from Space using the ASCENDS CarbonHawk Experiment Simulator: First Results

2014 AGU Fall Meeting (2014)

M. D. Obland Amin R. Nehrir Benjamin Lin F. W. Harrison S. A. Kooi

Active carbon

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