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Edward N. Rappaport, Jiann-Gwo Jiing, Christopher W. Landsea, Shirley T. Murillo, and James L. Franklin

The Joint Hurricane Testbed (JHT) is reviewed at the completion of its first decade. Views of the program by hurricane forecasters at the National Hurricane Center, the test bed's impact on forecast accuracy, and highlights of the top-rated projects are presented. Key concerns encountered by the test bed are identified as possible “lessons learned” for future research-to-operations efforts. The paper concludes with thoughts on the potential changing role of the JHT.

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Shirley T. Murillo, Wen-Chau Lee, Michael M. Bell, Gary M. Barnes, Frank D. Marks Jr., and Peter P. Dodge

Abstract

A plausible primary circulation and circulation center of a tropical cyclone (TC) can be deduced from a coastal Doppler radar using the ground-based velocity track display (GBVTD) technique and the GBVTD-simplex algorithm. The quality of the retrieved primary circulation is highly sensitive to the accuracy of the circulation center that can only be estimated from the degree of scattering of all possible centers obtained in GBVTD-simplex analyses from a single radar in real TCs. This study extends previous work to examine the uncertainties in the GBVTD-simplex-derived circulation centers and the GBVTD-derived primary circulations in Hurricane Danny (1997) sampled simultaneously from two Doppler radars [Weather Surveillance Radar-1988 Dopplers (WSR-88Ds) in Mobile, Alabama, and Slidell, Louisiana] for 5 h.

It is found that the mean difference between the individually computed GBVTD-simplex-derived centers is 2.13 km, similar to the estimates in previous studies. This value can be improved to 1.59 km by imposing time continuity in the radius of maximum wind, maximum mean tangential wind, and the center position in successive volumes. These additional physical criteria, not considered in previous work, stabilized the GBVTD-simplex algorithm and paved the way for automating the center finding and wind retrieval procedures in the future.

Using the improved set of centers, Danny’s axisymmetric tangential wind structures retrieved from each radar showed general agreement with systematic differences (up to 6 m s−1) in certain periods. The consistency in the wavenumber-1 tangential winds was not as good as their axisymmetric counterparts. It is suspected that the systematic differences in the axisymmetric tangential winds were caused by the unresolved wavenumber-2 sine components rather than from the relatively small cross-beam mean wind components in Danny.

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Rajul E. Pandya, David R. Smith, Donna J. Charlevoix, Genene M. Fisher, Shirley T. Murillo, Kathleen A. Murphy, Diane M. Stanitski, and Thomas M. Whittaker
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Paul R. Harasti, Colin J. McAdie, Peter P. Dodge, Wen-Chau Lee, John Tuttle, Shirley T. Murillo, and Frank D. Marks Jr.

Abstract

The NOAA/NWS/NCEP/Tropical Prediction Center/National Hurricane Center has sought techniques that use single-Doppler radar data to estimate the tropical cyclone wind field. A cooperative effort with NOAA/Atlantic Oceanographic and Meteorological Laboratory/Hurricane Research Division and NCAR has resulted in significant progress in developing a method whereby radar display data are used as a proxy for a full-resolution base data and in improving and implementing existing wind retrieval and center-finding techniques. These techniques include the ground-based velocity track display (GBVTD), tracking radar echoes by correlation (TREC), GBVTD- simplex, and the principal component analysis (PCA) methods.

The GBVTD and TREC algorithms are successfully applied to the Weather Surveillance Radar-1988 Doppler (WSR-88D) display data of Hurricane Bret (1999) and Tropical Storm Barry (2001). GBVTD analyses utilized circulation center estimates provided by the GBVTD-simplex and PCA methods, whereas TREC analyses utilized wind center estimates provided by radar imagery and aircraft measurements. GBVTD results demonstrate that the use of the storm motion as a proxy for the mean wind is not always appropriate and that results are sensitive to the accuracy of the circulation center estimate. TREC results support a previous conjecture that the use of polar coordinates would produce improved wind retrievals for intense tropical cyclones. However, there is a notable effect in the results when different wind center estimates are used as the origin of coordinates. The overall conclusion is that GBVTD and TREC have the ability to retrieve the intensity of a tropical cyclone with an accuracy of ∼2 m s−1 or better if the wind intensity estimates from individual analyses are averaged together.

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Rajul E. Pandya, David R. Smith, Donna J. Charlevoix, Wayne Hart, Marianne J. Hayes, Shirley T. Murillo, Kathleen A. Murphy, Diane M. Stanitski, and Thomas M. Whittaker
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Rajul Pandya, David Smith, Steven A. Ackerman, Priti P. Brahma, Donna J. Charlevoix, Susan Q. Foster, Volker Karl Gaertner, Thomas F. Lee, Marianne J. Hayes, Anthony Mostek, Shirley T. Murillo, Kathleen A. Murphy, Lola Olsen, Diane M. Stanitski, and Thomas Whittaker

Abstract

No Abstract available.

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Rajul E. Pandya, David R. Smith, Donna J. Charlevoix, Susan Q. Foster, Robert Hart, Marianne J. Hayes, Marjorie McGuirk, Shirley T. Murillo, Kathleen A. Murphy, Diane M. Stanitski, and Thomas M. Whittaker
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Jonathan Zawislak, Robert F. Rogers, Sim D. Aberson, Ghassan J. Alaka Jr., George R. Alvey III, Altug Aksoy, Lisa Bucci, Joseph Cione, Neal Dorst, Jason Dunion, Michael Fischer, John Gamache, Sundararaman Gopalakrishnan, Andrew Hazelton, Heather M. Holbach, John Kaplan, Hua Leighton, Frank Marks, Shirley T. Murillo, Paul Reasor, Kelly Ryan, Kathryn Sellwood, Jason A. Sippel, and Jun A. Zhang

Abstract

Since 2005, NOAA has conducted the annual Intensity Forecasting Experiment (IFEX), led by scientists from the Hurricane Research Division at NOAA’s Atlantic Oceanographic and Meteorological Laboratory. They partner with NOAA’s Aircraft Operations Center, who maintain and operate the WP-3D and Gulfstream IV-SP (G-IV) Hurricane Hunter aircraft, and NCEP’s National Hurricane Center and Environmental Modeling Center, who task airborne missions to gather data used by forecasters for analysis and forecasting and for ingest into operational numerical weather prediction models. The goal of IFEX is to improve tropical cyclone (TC) forecasts using an integrated approach of analyzing observations from aircraft, initializing and evaluating forecast models with those observations, and developing new airborne instrumentation and observing strategies targeted at filling observing gaps and maximizing the data’s impact in model forecasts. This summary article not only highlights recent IFEX contributions toward improved TC understanding and prediction, but also reflects more broadly on the accomplishments of the program during the 16 years of its existence. It describes how IFEX addresses high-priority forecast challenges, summarizes recent collaborations, describes advancements in observing systems monitoring structure and intensity, as well as in assimilation of aircraft data into operational models, and emphasizes key advances in understanding of TC processes, particularly those that lead to rapid intensification. The article concludes by laying the foundation for the next generation of IFEX as it broadens its scope to all TC hazards, particularly rainfall, storm-surge inundation, and tornadoes, that have gained notoriety during the last few years after several devastating landfalling TCs.

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