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Alexander V. Ryzhkov, Terry J. Schuur, Donald W. Burgess, Pamela L. Heinselman, Scott E. Giangrande, and Dusan S. Zrnic

As part of the evolution and future enhancement of the Next Generation Weather Radars (NEXRAD), the National Severe Storms Laboratory recently upgraded the KOUN Weather Surveillance Radar-1988 Doppler (WSR-88D) to include a polarimetric capability. The proof of concept was tested in central Oklahoma during a 1-yr demonstration project referred to as the Joint Polarization Experiment (JPOLE). This paper presents an overview of polarimetric algorithms for rainfall estimation and hydrometeor classification and their performance during JPOLE. The quality of rainfall measurements is validated on a large dataset from the Oklahoma Mesonet and Agricultural Research Service Micronet rain gauge networks. The comparison demonstrates that polarimetric rainfall estimates are often dramatically superior to those provided by conventional rainfall algorithms. Using a synthetic R(Z, K DP, Z DR) polarimetric rainfall relation, rms errors are reduced by a factor of 1.7 for point measurements and 3.7 for areal estimates [when compared to results from a conventional R(Z) relation]. Radar data quality improvement, hail identification, rain/snow discrimination, and polarimetric tornado detection are also illustrated for selected events.

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E. E. Clothiaux, G. G. Mace, T. P. Ackerman, T. J. Kane, J. D. Spinhirne, and V. S. Scott

Abstract

A cloud detection algorithm for a low power micropulse lidar is presented that attempts to identify all of the significant power returns from the vertical column above the lidar at all times. The main feature of the algorithm is construction of lidar power return profiles during periods of clear sky against which cloudy-sky power returns are compared. This algorithm supplements algorithms designed to detect cloud-base height in that the tops of optically thin clouds are identified and it provides an alternative approach to algorithms that identify significant power returns by analysis of changes in the slope of the backscattered powers with height. The cloud-base heights produced by the current algorithm during nonprecipitating periods are comparable with the results of a cloud-base height algorithm applied to the same data. Although an objective validation of algorithm performance on high, thin cirrus is lacking because of no truth data, the current algorithm produces few false positive and false negative classifications as determined through manual comparison of the original photoelectron count data to the final cloud mask image.

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Ronald J. Ferek, Timothy Garrett, Peter V. Hobbs, Scott Strader, Doug Johnson, Jonathan P. Taylor, Kurt Nielsen, Andrew S. Ackerman, Yefim Kogan, Qingfu Liu, Bruce A. Albrecht, and David Babb

Abstract

Although drizzle was a relatively infrequent occurrence during the Monterey Area Ship Track study, diverse measurements from several sources produced data signals consistent with a reduction in drizzle drops in stratus clouds affected by ship effluents. Concurrent increases in liquid water in the cloud droplet size range, due to redistribution from the drizzle mode, were not always observed, possibly because of the relatively small and often negligible amounts of water in the drizzle mode. Significant changes in cloud droplet size distribution, as well as reductions in drizzle flux and concentrations of drops >50-μm radius, were observed in ship tracks when drizzle was more uniformly present in the ambient cloud.

Radiometric measurements showed that increased droplet concentrations in ship tracks, which resulted in reduced droplet sizes, can significantly alter the liquid water path. Radar observations indicated that the reduced reflectivities of ship tracks compared with ambient clouds may be due to reductions in the concentrations of larger drops and/or reductions in the sizes of these drops. Two independent modeling studies showed decreases in drizzle in ship tracks due to the presence of smaller cloud droplets that reduced the efficiency of drop growth by collisions.

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J. K. Andersen, Liss M. Andreassen, Emily H. Baker, Thomas J. Ballinger, Logan T. Berner, Germar H. Bernhard, Uma S. Bhatt, Jarle W. Bjerke, Jason E. Box, L. Britt, R. Brown, David Burgess, John Cappelen, Hanne H. Christiansen, B. Decharme, C. Derksen, D. S. Drozdov, Howard E. Epstein, L. M. Farquharson, Sinead L. Farrell, Robert S. Fausto, Xavier Fettweis, Vitali E. Fioletov, Bruce C. Forbes, Gerald V. Frost, Sebastian Gerland, Scott J. Goetz, Jens-Uwe Grooß, Edward Hanna, Inger Hanssen-Bauer, Stefan Hendricks, Iolanda Ialongo, K. Isaksen, Bjørn Johnsen, L. Kaleschke, A. L. Kholodov, Seong-Joong Kim, Jack Kohler, Zachary Labe, Carol Ladd, Kaisa Lakkala, Mark J. Lara, Bryant Loomis, Bartłomiej Luks, K. Luojus, Matthew J. Macander, G. V. Malkova, Kenneth D. Mankoff, Gloria L. Manney, J. M. Marsh, Walt Meier, Twila A. Moon, Thomas Mote, L. Mudryk, F. J. Mueter, Rolf Müller, K. E. Nyland, Shad O’Neel, James E. Overland, Don Perovich, Gareth K. Phoenix, Martha K. Raynolds, C. H. Reijmer, Robert Ricker, Vladimir E. Romanovsky, E. A. G. Schuur, Martin Sharp, Nikolai I. Shiklomanov, C. J. P. P. Smeets, Sharon L. Smith, Dimitri A. Streletskiy, Marco Tedesco, Richard L. Thoman, J. T. Thorson, X. Tian-Kunze, Mary-Louise Timmermans, Hans Tømmervik, Mark Tschudi, Dirk van As, R. S. W. van de Wal, Donald A. Walker, John E. Walsh, Muyin Wang, Melinda Webster, Øyvind Winton, Gabriel J. Wolken, K. Wood, Bert Wouters, and S. Zador
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Richard L. Thoman, Matthew L. Druckenmiller, Twila A. Moon, L. M. Andreassen, E. Baker, Thomas J. Ballinger, Logan T. Berner, Germar H. Bernhard, Uma S. Bhatt, Jarle W. Bjerke, L.N. Boisvert, Jason E. Box, B. Brettschneider, D. Burgess, Amy H. Butler, John Cappelen, Hanne H. Christiansen, B. Decharme, C. Derksen, Dmitry Divine, D. S. Drozdov, Chereque A. Elias, Howard E. Epstein, Sinead L. Farrell, Robert S. Fausto, Xavier Fettweis, Vitali E. Fioletov, Bruce C. Forbes, Gerald V. Frost, Sebastian Gerland, Scott J. Goetz, Jens-Uwe Grooß, Christian Haas, Edward Hanna, -Bauer Inger Hanssen, M. M. P. D. Heijmans, Stefan Hendricks, Iolanda Ialongo, K. Isaksen, C. D. Jensen, Bjørn Johnsen, L. Kaleschke, A. L. Kholodov, Seong-Joong Kim, J. Kohler, Niels J. Korsgaard, Zachary Labe, Kaisa Lakkala, Mark J. Lara, Simon H. Lee, Bryant Loomis, B. Luks, K. Luojus, Matthew J. Macander, R. Í Magnússon, G. V. Malkova, Kenneth D. Mankoff, Gloria L. Manney, Walter N. Meier, Thomas Mote, Lawrence Mudryk, Rolf Müller, K. E. Nyland, James E. Overland, F. Pálsson, T. Park, C. L. Parker, Don Perovich, Alek Petty, Gareth K. Phoenix, J. E. Pinzon, Robert Ricker, Vladimir E. Romanovsky, S. P. Serbin, G. Sheffield, Nikolai I. Shiklomanov, Sharon L. Smith, K. M. Stafford, A. Steer, Dimitri A. Streletskiy, Tove Svendby, Marco Tedesco, L. Thomson, T. Thorsteinsson, X. Tian-Kunze, Mary-Louise Timmermans, Hans Tømmervik, Mark Tschudi, C. J. Tucker, Donald A. Walker, John E. Walsh, Muyin Wang, Melinda Webster, A. Wehrlé, Øyvind Winton, G. Wolken, K. Wood, B. Wouters, and D. Yang
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Matthew L. Druckenmiller, Twila A. Moon, Richard L. Thoman, Thomas J. Ballinger, Logan T. Berner, Germar H. Bernhard, Uma S. Bhatt, Jarle W. Bjerke, Jason E. Box, R. Brown, John Cappelen, Hanne H. Christiansen, B. Decharme, C. Derksen, Dmitry Divine, D. S. Drozdov, A. Elias Chereque, Howard E. Epstein, L. M. Farquharson, Sinead L. Farrell, Robert S. Fausto, Xavier Fettweis, Vitali E. Fioletov, Bruce C. Forbes, Gerald V. Frost, Emily Gargulinski, Sebastian Gerland, Scott J. Goetz, Z. Grabinski, Jens-Uwe Grooß, Christian Haas, Edward Hanna, Inger Hanssen-Bauer, Stefan Hendricks, Robert M. Holmes, Iolanda Ialongo, K. Isaksen, Piyush Jain, Bjørn Johnsen, L. Kaleschke, A. L. Kholodov, Seong-Joong Kim, Niels J. Korsgaard, Zachary Labe, Kaisa Lakkala, Mark J. Lara, Bryant Loomis, K. Luojus, Matthew J. Macander, G. V. Malkova, Kenneth D. Mankoff, Gloria L. Manney, James W. McClelland, Walter N. Meier, Thomas Mote, L. Mudryk, Rolf Müller, K. E. Nyland, James E. Overland, T. Park, Olga Pavlova, Don Perovich, Alek Petty, Gareth K. Phoenix, Martha K. Raynolds, C. H. Reijmer, Jacqueline Richter-Menge, Robert Ricker, Vladimir E. Romanovsky, Lindsay Scott, Hazel Shapiro, Alexander I. Shiklomanov, Nikolai I. Shiklomanov, C. J. P. P. Smeets, Sharon L. Smith, Amber Soja, Robert G. M. Spencer, Sandy Starkweather, Dimitri A. Streletskiy, Anya Suslova, Tove Svendby, Suzanne E. Tank, Marco Tedesco, X. Tian-Kunze, Mary-Louise Timmermans, Hans Tømmervik, Mikhail Tretiakov, Mark Tschudi, Sofia Vakhutinsky, Dirk van As, R. S. W. van de Wal, Sander Veraverbeke, Donald A. Walker, John E. Walsh, Muyin Wang, Melinda Webster, Øyvind Winton, K. Wood, Alison York, and Robert Ziel
Free access