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Matthieu Plu

modeling. One is the bogus technique ( Heming et al. 1995 ), which consists in forcing the assimilation of pseudo-observations (wind or pressure) into the model initial state. The pseudo-observations are deduced from an idealized cyclone structure observed by satellite imagery. These specific techniques generally improve cyclone forecasts ( Heming 2009 ). Section 2 recalls the general principle of the L82 method and presents the data. Section 3 shows the results for three numerical models. Before

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Kun-Hsuan Chou, Chun-Chieh Wu, Po-Hsiung Lin, Sim D. Aberson, Martin Weissmann, Florian Harnisch, and Tetsuo Nakazawa

field campaign was to address short-range TC dynamics and forecast skill in one region and the downstream impacts of TCs on medium-range dynamics and forecast skill in another region ( Elsberry and Harr 2008 ; Parsons et al. 2008 ). This was the first time that four aircraft [the DOTSTAR Astra jet, the German Aerospace Center (DLR) Falcon 20, a U.S. Navy P-3, and a U.S. Air Force C-130] were used simultaneously to observe typhoons. DOTSTAR Astra and DLR Falcon sampled the TC environment, especially

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Sim D. Aberson

. During each mission, the G-IV released 25–30 dropwindsondes to sample the atmosphere below flight level (near 150 hPa) at 150–200-km intervals. In those cases in which one or two P-3 or Air Force C-130 aircraft supplemented the G-IV data, 20–25 dropwindsondes were released at the same horizontal resolution from around 400 (P-3) or 300 hPa (C130). The G-IV did not penetrate the inner core of any of the tropical cyclones during surveillance missions, though when the P-3s flew, at least one usually

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Sim D. Aberson

improve the manuscript. Mike Jankulak contributed his proofreading and editing expertise. The author thanks the NOAA Aircraft Operations Center (AOC) flight crews, AOC G-IV project manager, Jack Parrish, and HRD personnel who participated in the flights. Additional thanks are due to Air Force C-130 crews that provided additional surveillance data in many cases, as well as the flight crews and scientists who have run the various programs in the west Pacific (DOTSTAR, T-PaRC, TCS-08). REFERENCES Aberson

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Mu Mu, Feifan Zhou, and Hongli Wang

. , 134 , 2971 – 2988 . Barkmeijer , J. , 1996 : Constructing fast-growing perturbations for the nonlinear regime. J. Atmos. Sci. , 53 , 2838 – 2851 . Barkmeijer , J. , R. Buizza , T. N. Palmer , K. Puri , and J-F. Mahfouf , 2001 : Tropical singular vectors computed with linearized diabatic physics. Quart. J. Roy. Meteor. Soc. , 127 , 685 – 708 . Barkmeijer , J. , T. Iversen , and T. N. Palmer , 2003 : Forcing singular vectors and other sensitive model structures

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Carolyn A. Reynolds, Melinda S. Peng, and Jan-Huey Chen

index is defined as where f is the Coriolis force, V is the magnitude of the vector wind, and is the Brunt–Väisälä frequency. Here, the Eady index is calculated over the 300–1000-hPa layer. Midlatitude baroclinic instability is relatively weak in July and August during which recurving storms WP04, WP09, and WP11 have relatively small 5-day perturbation growth. Midlatitude baroclinic instability strengthens in September and October, during which recurving storms CP01, WP14, WP16, and WP21 have

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Mark Buehner, P. L. Houtekamer, Cecilien Charette, Herschel L. Mitchell, and Bin He

) approach. The vertical localization is configured to force the covariances to 0 at a distance of (a) 2, (b) 4, or (c) 100 scale heights. Fig . 2. As in Fig. 1 , but for a single observation of AMSU-A channel 10. Fig . 3. The analysis increment of temperature from assimilating either (a) the full set of AMSU-A channels (4–10) at the same location used for Figs. 1 and 2 or (b) the vertical profile of temperature observations from a

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Fuqing Zhang, Yonghui Weng, Jason A. Sippel, Zhiyong Meng, and Craig H. Bishop

same observations for a comparison with the EnKF analysis discussed above. The WRF-3DVAR method used here was developed primarily at NCAR and is now operational at the Air Force Weather Agency ( Barker et al. 2004 ). Its configuration is based on an incremental formulation, producing a multivariate analysis in the model space. Its incremental cost function is minimized in a preconditioned control variable space where the errors of different control variables are largely uncorrelated. As in any

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