Dr. Ralph Kahn Profile

Dr. Ralph Kahn

Senior Research Scientist at NASA Goddard Space Flight Ctr

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Author

Publications (8)

Proceedings Article | 26 October 2011 Paper

Capabilities and limitations of MISR aerosol products in dust-laden regions

Olga Kalashnikova, Michael Garay, Irina Sokolik, David Diner, Ralph Kahn, John Martonchik, Jae Lee, Omar Torres, Weidong Yang, Alexander Marshak, Sero Kassabian, Mark Chodas

Proceedings Volume 8177, 81770O (2011) https://doi.org/10.1117/12.897773

KEYWORDS: Aerosols, Climatology, Atmospheric particles, Atmospheric modeling, Scattering, Satellites, Environmental sensing, Aluminum, Spherical lenses, Cameras

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Proceedings Article | 27 August 2008 Paper

Quantitative studies of wildfire smoke injection heights with the Terra Multi-angle Imaging SpectroRadiometer

David Diner, David Nelson, Yang Chen, Ralph Kahn, Jennifer Logan, Fok-Yan Leung, Maria Val Martin

Proceedings Volume 7089, 708908 (2008) https://doi.org/10.1117/12.795215

KEYWORDS: Cameras, Aerosols, Atmospheric modeling, Climatology, Satellites, LIDAR, Clouds, MODIS, Data modeling, Troposphere

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Proceedings Article | 27 August 2008 Paper

Example applications of the MISR INteractive eXplorer (MINX) software tool to wildfire smoke plume analyses

David Nelson, Yang Chen, Ralph Kahn, David Diner, Dominic Mazzoni

Proceedings Volume 7089, 708909 (2008) https://doi.org/10.1117/12.795087

KEYWORDS: Cameras, Clouds, MODIS, Atmospheric modeling, Aerosols, Visualization, Data modeling, Algorithm development, Feature extraction, Climatology

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Proceedings Article | 20 August 2008 Paper

WindCam and MSPI: two cloud and aerosol instrument concepts derived from Terra/MISR heritage

David Diner, Michael Mischna, Russell Chipman, Ab Davis, Brian Cairns, Roger Davies, Ralph Kahn, Jan-Peter Muller, Omar Torres

Proceedings Volume 7081, 70810T (2008) https://doi.org/10.1117/12.795146

KEYWORDS: Cameras, Aerosols, Clouds, Sensors, Polarization, Imaging systems, Polarimetry, Modulation, Signal detection, Ultraviolet radiation

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Proceedings Article | 8 December 2006 Paper

Current and future advances in optical multiangle remote sensing of aerosols and clouds based on Terra/MISR experience

David Diner, Roger Davies, Ralph Kahn, John Martonchik, Barbara Gaitley, Ab Davis

Proceedings Volume 6408, 640801 (2006) https://doi.org/10.1117/12.698008

KEYWORDS: Aerosols, Clouds, Cameras, Atmospheric particles, Climatology, Calibration, Remote sensing, Sensors, Spatial resolution, Polarization

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Proceedings Article | 27 September 2006 Paper

Analysis of calibration difference between MODIS and MISR

A. Lyapustin, Y. Wang, R. Kahn, J. Xiong, A. Ignatov, R. Wolfe, A. Wu, C. Bruegge

Proceedings Volume 6298, 62980X (2006) https://doi.org/10.1117/12.680896

KEYWORDS: MODIS, Calibration, Clouds, Reflectivity, Near infrared, Sensors, Radiative transfer, Atmospheric modeling, Aerosols, Cameras

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Proceedings Article | 30 December 2004 Paper

Dust aerosol retrieval results from MISR

Olga Kalashnikova, David Diner, Ralph Kahn, Barbara Gaitley

Proceedings Volume 5652, (2004) https://doi.org/10.1117/12.606657

KEYWORDS: Aerosols, Atmospheric modeling, Atmospheric particles, Ocean optics, Cameras, Climatology, Optical properties, Scattering, Spherical lenses, RGB color model

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Proceedings Article | 30 December 2004 Paper

Refinements to MISR’s radiometric calibration and implications for establishing a climate-quality aerosol observing system

David Diner, Ralph Kahn, Carol Bruegge, John Martonchik, Wedad Abdou, Barbara Gaitley, Mark Helmlinger, Olga Kalashnikova, Wen-Hao Li

Proceedings Volume 5652, (2004) https://doi.org/10.1117/12.579041

KEYWORDS: Aerosols, Calibration, Cameras, Atmospheric modeling, MODIS, Clouds, Atmospheric particles, Climatology, Radiometry, Sensors

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A number of factors affect the accuracy of aerosol retrievals from satellite imaging radiometers, including algorithm assumptions, the quality of the associated cloud masks, the prescribed aerosol optical and microphysical models, and calibration uncertainties. In this paper, we highlight a concerted effort by the Terra Multi-angle Imaging SpectroRadiometer (MISR) team to evaluate the accuracy and stability of the instrument's radiometric calibration, with the twofold objective of (1) making improvements in the absolute and relative calibration where supported by multiple lines of evidence, and (2) evaluating the effect of those calibration refinements on aerosol retrievals. Aspects of the instrument's on-board calibrator design, including careful pre-flight handling of the Spectralon diffusers and the novel use of detector-based standards, have contributed to excellent long-term radiometric stability. In addition, multiple methodologies, including comparisons with other Terra sensors, in-flight and laboratory tests involving AirMISR (the airborne counterpart to MISR), lunar observations, camera-to-camera radiometric comparisons at specialized viewing geometries, and investigations using surface-based radiometer data over dark water sites have provided a detailed picture of radiometric performance at the low light levels typical of a large fraction of global aerosol observations. We examine the sensitivity of aerosol property retrievals to small band-to-band and camera-to-camera calibration adjustments, and demonstrate the importance of calibration in meeting climate-quality accuracy requirements. Because combining downward-looking (satellite-based) and upward-looking (surface-based) radiometers can constrain the optical properties of an aerosol column to a greater extent than possible from either vantage point by itself, achieving radiometric consistency, or “closure” between them is essential to establishing a long-term aerosol/climate observing system.

Showing 5 of 8 publications

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