The Experts below are selected from a list of 62583 Experts worldwide ranked by ideXlab platform
Samantha Blair - One of the best experts on this subject based on the ideXlab platform.
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LCROSS (Lunar Crater Observation and Sensing Satellite) Observation Campaign: Strategies, Implementation, and Lessons Learned
Space Science Reviews, 2011Co-Authors: Jennifer Heldmann, Anthony Colaprete, Diane H. Wooden, R. F. Ackermann, David Acton, Peter Backus, Vanessa P. Bailey, Jesse G. Ball, William C. Barott, Samantha BlairAbstract:NASA’s LCROSS (Lunar Crater Observation and Sensing Satellite) mission was designed to explore the nature of previously detected enhanced levels of hydrogen near the lunar poles. The LCROSS mission impacted the spent upper stage of the launch vehicle into a permanently shadowed region of the lunar surface to create an ejecta plume. The resultant impact crater and plume were then observed by the LCROSS Shepherding Spacecraft as well as a cadre of telescopes on the Earth and in space to determine the nature of the materials contained within the permanently shadowed region. The Shepherding Spacecraft then became a second impactor which was also observed by multiple assets.
Hajime Okamoto - One of the best experts on this subject based on the ideXlab platform.
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vertical grid spacing necessary for simulating tropical cirrus clouds with a high resolution atmospheric general circulation model
Geophysical Research Letters, 2015Co-Authors: Tatsuya Seiki, Chihiro Kodama, Masaki Satoh, Tempei Hashino, Yuichiro Hagihara, Hajime OkamotoAbstract:The distribution of simulated cirrus clouds over the tropics is affected by the particular model's vertical grid spacing. To examine this effect, we use a high-resolution atmospheric general circulation model with 28 km and 14 km horizontal meshes. We show that a vertical grid spacing of 400 m or less is necessary to resolve the bulk structure of cirrus clouds. As one reduces the vertical grid spacing below about 1000 m, the visible cirrus cloud fraction decreases, the cloud thins (optically and geometrically), the cloud top height lowers, and consequently, the outgoing longwave radiation increases. These effects are stronger over the tropics. When using a vertical grid spacing of 400 m or less, the vertical profiles of effective radii and ice water content converge toward measurements (CloudSat Satellite and Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation).
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global analysis of cloud phase and ice crystal orientation from cloud aerosol lidar and infrared pathfinder Satellite Observation calipso data using attenuated backscattering and depolarization ratio
Journal of Geophysical Research, 2010Co-Authors: Yuichiro Hagihara, Hajime Okamoto, Ryo Yoshida, Hiroshi IshimotoAbstract:[1] A method for discriminating cloud particle types was developed using lidar backscattering copolarization and cross-polarization channel measurements from Cloud-Aerosol Lidar With Orthogonal Polarization (CALIOP) on board Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO). In spaceborne lidar measurements, significant multiple scattering effects discriminate between cloud water and ice difficult using the depolarization ratio (δ). We theoretically estimated the relationship between δ and cloud extinction on the basis of the backward Monte Carlo method. Cloud particle type was determined by the combined use of δ and the ratio of attenuated backscattering coefficients for two vertically consecutive layers. Ice particles were further classified into two categories: randomly oriented ice crystals (3-D ice) and horizontally oriented plates (2-D plate). The method was applied to CALIOP data for September–November 2006. We found that 3-D ice generally occurred colder than −20°C, whereas 2-D plate occurred between −10°C and −20°C, with high-occurrence frequency in high-latitude regions. We compared the results to those obtained using the vertical feature mask (VFM). The VFM tended to show a homogeneous cloud type through the entire cloud layer in vertical directions and misclassified 2-D plate as water. The ratio of water particles relative to ice particles decreased with decreasing temperature. By the proposed method, water cloud occurrence in subtropical and high-latitude regions was greater (up to 20%) than in the other regions below −10°C; however, the VFM results did not show such dependence on latitude. Comparison of ice and water cloud between our results and Moderate Resolution Imaging Spectroradiometer (MODIS) products showed better agreement for water cloud than for ice cloud.
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testing iwc retrieval methods using radar and ancillary measurements with in situ data
Journal of Applied Meteorology and Climatology, 2008Co-Authors: Andrew J Heymsfield, Hajime Okamoto, Alain Protat, Richard T Austin, Dominique Bouniol, Robin J Hogan, Julien Delanoe, Kaori Sato, Gerd Jan Van Zadelhoff, David DonovanAbstract:Abstract Vertical profiles of ice water content (IWC) can now be derived globally from spaceborne cloud Satellite radar (CloudSat) data. Integrating these data with Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) data may further increase accuracy. Evaluations of the accuracy of IWC retrieved from radar alone and together with other measurements are now essential. A forward model employing aircraft Lagrangian spiral descents through mid- and low-latitude ice clouds is used to estimate profiles of what a lidar and conventional and Doppler radar would sense. Radar reflectivity Ze and Doppler fall speed at multiple wavelengths and extinction in visible wavelengths were derived from particle size distributions and shape data, constrained by IWC that were measured directly in most instances. These data were provided to eight teams that together cover 10 retrieval methods. Almost 3400 vertically distributed points from 19 clouds were used. Approximate cloud optical depths ranged from...
Jennifer Heldmann - One of the best experts on this subject based on the ideXlab platform.
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LCROSS (Lunar Crater Observation and Sensing Satellite) Observation Campaign: Strategies, Implementation, and Lessons Learned
Space Science Reviews, 2011Co-Authors: Jennifer Heldmann, Anthony Colaprete, Diane H. Wooden, R. F. Ackermann, David Acton, Peter Backus, Vanessa P. Bailey, Jesse G. Ball, William C. Barott, Samantha BlairAbstract:NASA’s LCROSS (Lunar Crater Observation and Sensing Satellite) mission was designed to explore the nature of previously detected enhanced levels of hydrogen near the lunar poles. The LCROSS mission impacted the spent upper stage of the launch vehicle into a permanently shadowed region of the lunar surface to create an ejecta plume. The resultant impact crater and plume were then observed by the LCROSS Shepherding Spacecraft as well as a cadre of telescopes on the Earth and in space to determine the nature of the materials contained within the permanently shadowed region. The Shepherding Spacecraft then became a second impactor which was also observed by multiple assets.
Byungju Sohn - One of the best experts on this subject based on the ideXlab platform.
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two heavy rainfall types over the korean peninsula in the humid east asian summer environment a Satellite Observation study
Monthly Weather Review, 2015Co-Authors: Hwanjin Song, Byungju SohnAbstract:AbstractA total of 10 years (2002–11) of Tropical Rainfall Measuring Mission (TRMM) Precipitation Radar (PR) reflectivities, signaling heavy rainfall (>10 mm h−1), were objectively classified by applying the K-means clustering method in order to obtain typical reflectivity profiles associated with heavy rainfall over East Asia. Two types of heavy rainfall emerged as the most important rain processes over East Asia: type 1 (cold type) characterized by high storm height and abundant ice water under convectively unstable conditions, developing mostly over inland China; and type 2 (warm type) associated with a lower storm height and lower ice water content, developing mostly over the ocean. These two types also show sharp contrasts in relation to their seasonal changes and in the diurnal variation of frequency maxima, in addition to other contrasting meteorological parameters. The PR-derived heavy rain events were observed over the Korean peninsula and their spatiotemporal evolution was examined using 10-yr c...
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two heavy rainfall types over the korean peninsula in the humid east asian summer environment a Satellite Observation study
Monthly Weather Review, 2015Co-Authors: Hwanjin Song, Byungju SohnAbstract:AbstractA total of 10 years (2002–11) of Tropical Rainfall Measuring Mission (TRMM) Precipitation Radar (PR) reflectivities, signaling heavy rainfall (>10 mm h−1), were objectively classified by applying the K-means clustering method in order to obtain typical reflectivity profiles associated with heavy rainfall over East Asia. Two types of heavy rainfall emerged as the most important rain processes over East Asia: type 1 (cold type) characterized by high storm height and abundant ice water under convectively unstable conditions, developing mostly over inland China; and type 2 (warm type) associated with a lower storm height and lower ice water content, developing mostly over the ocean. These two types also show sharp contrasts in relation to their seasonal changes and in the diurnal variation of frequency maxima, in addition to other contrasting meteorological parameters. The PR-derived heavy rain events were observed over the Korean peninsula and their spatiotemporal evolution was examined using 10-yr c...
Yuichiro Hagihara - One of the best experts on this subject based on the ideXlab platform.
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vertical grid spacing necessary for simulating tropical cirrus clouds with a high resolution atmospheric general circulation model
Geophysical Research Letters, 2015Co-Authors: Tatsuya Seiki, Chihiro Kodama, Masaki Satoh, Tempei Hashino, Yuichiro Hagihara, Hajime OkamotoAbstract:The distribution of simulated cirrus clouds over the tropics is affected by the particular model's vertical grid spacing. To examine this effect, we use a high-resolution atmospheric general circulation model with 28 km and 14 km horizontal meshes. We show that a vertical grid spacing of 400 m or less is necessary to resolve the bulk structure of cirrus clouds. As one reduces the vertical grid spacing below about 1000 m, the visible cirrus cloud fraction decreases, the cloud thins (optically and geometrically), the cloud top height lowers, and consequently, the outgoing longwave radiation increases. These effects are stronger over the tropics. When using a vertical grid spacing of 400 m or less, the vertical profiles of effective radii and ice water content converge toward measurements (CloudSat Satellite and Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation).
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global analysis of cloud phase and ice crystal orientation from cloud aerosol lidar and infrared pathfinder Satellite Observation calipso data using attenuated backscattering and depolarization ratio
Journal of Geophysical Research, 2010Co-Authors: Yuichiro Hagihara, Hajime Okamoto, Ryo Yoshida, Hiroshi IshimotoAbstract:[1] A method for discriminating cloud particle types was developed using lidar backscattering copolarization and cross-polarization channel measurements from Cloud-Aerosol Lidar With Orthogonal Polarization (CALIOP) on board Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO). In spaceborne lidar measurements, significant multiple scattering effects discriminate between cloud water and ice difficult using the depolarization ratio (δ). We theoretically estimated the relationship between δ and cloud extinction on the basis of the backward Monte Carlo method. Cloud particle type was determined by the combined use of δ and the ratio of attenuated backscattering coefficients for two vertically consecutive layers. Ice particles were further classified into two categories: randomly oriented ice crystals (3-D ice) and horizontally oriented plates (2-D plate). The method was applied to CALIOP data for September–November 2006. We found that 3-D ice generally occurred colder than −20°C, whereas 2-D plate occurred between −10°C and −20°C, with high-occurrence frequency in high-latitude regions. We compared the results to those obtained using the vertical feature mask (VFM). The VFM tended to show a homogeneous cloud type through the entire cloud layer in vertical directions and misclassified 2-D plate as water. The ratio of water particles relative to ice particles decreased with decreasing temperature. By the proposed method, water cloud occurrence in subtropical and high-latitude regions was greater (up to 20%) than in the other regions below −10°C; however, the VFM results did not show such dependence on latitude. Comparison of ice and water cloud between our results and Moderate Resolution Imaging Spectroradiometer (MODIS) products showed better agreement for water cloud than for ice cloud.
