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Munehiko Yamaguchi, Ryota Sakai, Masayuki Kyoda, Takuya Komori, and Takashi Kadowaki

%, 20%, and 23% at 24, 48, and 72 h, respectively. Furthermore, Komori et al. (2007) have verified the ensemble mean track of three global models from operational NWP centers, the European Centre for Medium-Range Weather Forecasts (ECMWF), JMA, and UKMO. In the verification of 48- and 96-h predictions for the western North Pacific basin from 1991 to 2005, and for the Atlantic basin from 1999 to 2005, the ensemble mean has the best performance with respect to the best of the individual models with

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Ryan D. Torn and Gregory J. Hakim

Hurricane Rainband and Intensity Change Experiment (RAINEX; Houze et al. 2006 ) provide an opportunity to test the performance of an EnKF for TC forecasting with an unusually rich set of observations. Ensemble analyses and forecasts are generated on a coarse-resolution outer domain, and on a nested, higher-resolution inner domain. We begin with an overview of the model setup and data assimilation system in section 2 . Results for the coarse outer domain are presented in section 3 , and the nested

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Mu Mu, Feifan Zhou, and Hongli Wang

. Currently, several strategies have been applied to identify the sensitive areas. One strategy is based on the adjoint technique, such as singular vectors (SVs; Palmer et al. 1998 ), adjoint sensitivities ( Ancell and Mass 2006 ), and the adjoint-derived sensitivity steering vector (ADSSV; Wu et al. 2007 ). The adjoint of the forward tangent propagator of the numerical model is required for their calculation, so they are also named adjoint-based senstitivities ( Kim et al. 2004 ). Another strategy is

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

tropics: An evaluation of model performance during the 1995 hurricane season . Mon. Wea. Rev. , 126 , 1287 – 1305 . Weissmann , M. , and Coauthors , 2011 : The influence of assimilating dropsonde data on typhoon track and midlatitude forecasts . Mon. Wea. Rev. , 139 , 908 – 920 . Woollen , J. R. , 1991 : New NMC operational OI quality control . Preprints, Ninth Conf. on Numerical Weather Prediction, Denver, CO, Amer. Meteor. Soc., 24–27 . Wu , C.-C. , and Coauthors , 2005

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Sim D. Aberson

. Surgi , N. , H-L. Pan , and S. J. Lord , 1998 : Improvement of the NCEP global model over the tropics: An evaluation of model performance during the 1995 hurricane season. Mon. Wea. Rev. , 126 , 1287 – 1305 . Woollen , J. R. , 1991 : New NMC operational OI quality control. Preprints, Ninth

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Matthieu Plu

(upper bound on predictability) is the maximum error reduction that may be expected from future model improvements. The bold curves show that IFS performs as the best model, followed by UM and then by ARPEGE. At 48- and 72-h forecast terms, the total mean error of the IFS model is 160 and 225 km, respectively. The inherent predictability estimated by Leslie et al. (1998) is approximately 150 km at 48 h and 220 km at 72 h. The IFS performance is therefore very close to the estimated predictability

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

complex weather phenomena exhibiting different scales of motion [moving beyond a single supercell storm examined in Dowell et al. (2004) ]. The following section will introduce the forecast model, the EnKF technique, and the processing of the observations to be assimilated. Section 3 presents the use of the EnKF for this storm in terms of analysis quality, and deterministic and ensemble forecasts. Comparison to the performance of data assimilation with a 3-dimensional variational method that

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Munehiko Yamaguchi, Takeshi Iriguchi, Tetsuo Nakazawa, and Chun-Chieh Wu

sensitive regions, statistically have better performance with respect to those that includes all observations. Following the previous studies, this study aims to evaluate the following two issues: Impact of selected DOTSTAR observations on the track forecast of Conson at 1200 UTC 8 June 2004; Feasibility of the JMA SV method as a sensitivity analysis technique. For these purposes, two sets of Observing System Experiments (OSEs) are performed. In the first OSE (OSE-1), two initial conditions are created

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

1. Introduction Variational data assimilation approaches are used at many numerical weather prediction (NWP) centers for operationally assimilating meteorological observations to provide a single “best” estimate of the current atmospheric state (e.g., Parrish and Derber, 1992 ; Rabier et al. 2000 ; Gauthier et al. 2007 ; Rawlins et al. 2007 ). The resulting analysis is used to initialize deterministic forecast models to produce short- and medium-range forecasts. Observations

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Hyun Mee Kim and Byoung-Joo Jung

for typhoon forecasters. Geophys. Res. Lett. , 32 , L02810 . doi:10.1029/2004GL021680 . Peng , M. S. , and C. A. Reynolds , 2006 : Sensitivity of tropical cyclone forecasts as revealed by singular vectors. J. Atmos. Sci. , 63 , 2508 – 2528 . Pu , Z-X. , and E. Kalnay , 1999 : Targeting observations with the quasi-inverse linear and adjoint NCEP global models: Performance during FASTEX. Quart. J. Roy. Meteor. Soc. , 125 , 3329 – 3337 . Reynolds , C. A. , R. Gelaro , and

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