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Daryl T. Kleist and Kayo Ide

local maxima ( Fig. 4 , top right), associated with the extratropical jets and consistent with the background error variance specification. Two secondary maxima are also noted in the near-surface extratropics, with larger amplitude in the Southern Hemisphere consistent with the season for which the observations are assimilated. Fig . 4. Time mean zonally averaged standard deviation of the 3DVar analysis increment for a (left) real observation experiment and (right) an OSSE experiment for (top) zonal

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Andrew C. Lorenc, Neill E. Bowler, Adam M. Clayton, Stephen R. Pring, and David Fairbairn

. Diagnosing the 4D covariances a. Experimental setup We diagnose the behavior of the 4D covariances using single-observation experiments. We chose two different cases: a strong midlatitude jet stream—a good test of strong advection, and a hurricane—a good test of complex nonlinear physics, including moist processes. The same configurations are used for each case, except that a 44-member ensemble is used for the jet stream, whereas only a 22-member ensemble is available for Hurricane Sandy—this was the

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Hailing Zhang and Zhaoxia Pu

. Before data assimilation, all NCEP ADP data passed through a complex quality control procedure. The QuikSCAT ocean surface wind vectors used here are retrieved products (wind speed and direction at 10-m height at 25-km horizontal resolution) produced by the National Aeronautics and Space Administration (NASA) Jet Propulsion Laboratory (JPL) from the SeaWinds scatterometer sensors on board the QuikSCAT satellite with quality flags ( Hoffman and Leidner 2005 ). Observations with low- and high

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Ting-Chi Wu, Christopher S. Velden, Sharanya J. Majumdar, Hui Liu, and Jeffrey L. Anderson

representation of the tropical cyclone inner core, the operational use of AMVs would require a long-term evaluation. The appropriate treatment of correlated errors and biases in data assimilation, and significant improvements on AMV height assignment are of primary concern. Acknowledgments The authors gratefully acknowledge the support from National Oceanographic Partnership Program under ONR Marine Meteorology Program Award N00014-10-1-0123. The access to the NOAA T-Jet supercomputer was essential in

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Daisuke Hotta, Tse-Chun Chen, Eugenia Kalnay, Yoichiro Ota, and Takemasa Miyoshi

lead times and in the upper troposphere where the westerly jet prevails. This explains why the impact from aircraft, for example, weakens more quickly than does that from surface observations. In assessing the accuracy of EFSO impact estimation, it is useful to check the consistency between the actual forecast error reduction [Δ e 2 as in (4) ] and the sum of the EFSO impacts over all observations. The means and the correlation coefficient of these two quantities over the verification period are

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