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Raymond F. Toll Jr. and William M. Clune

to identify systematic pressure, displacement, and directional errorsin the 48-hour surface pressure forecast of extmtropical cyclones by the Navy Operational Global AtmosphericPrediction System (NOGAPS) has been completed for the 1983 Northern Hemisphere winter season (5 January31 March). All available NOGAPS 0000 and 1200 GMT forecast cycles are verified for the Western Pacific,Eastern Pacific, and Atlantic Oceans north of the equator. NOGAPS generally underforecasts the intensity of

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C. Lemcke and S. Kruizinga

MAY 1988 C. LEMCKE AND S. KRUIZINGA 1077Model Output Statistics Forecasts: Three Years of Operational Experience in the Netherlands C. LEMCKE AND S. KRUIZINGARoyal Netherlands Meteorological Institute (KNMI), de Bilt, The Netherlands(Manuscript received 20 July 1987, in final form 5 November 1987)ABSTRACT In the Netherlands, one to five day Model Output Statistics

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Ryan D. Torn and Gregory J. Hakim

) for reviews of the EnKF. Progress on EnKF systems has reached the point where several groups have applied it to global NWP models in operational settings. Houtekamer et al. (2005) used an EnKF to assimilate all available observations with the Canadian Meteorological Center (CMC) Global Environmental Multiscale (GEM) model. Their results show that the error in EnKF-initialized forecasts is similar to those in the CMC operational three-dimensional variations data assimilation (3DVAR) scheme. This

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Kathy Pegion and Arun Kumar

conditional to average. 3. ENSO as a predictor of perfect-model forecast skill We evaluate ENSO as a predictor of variations in forecast skill by exploring the linear relationship between two ENSO indices and perfect-model forecast skill of 2-m temperature and precipitation over the United States. The first index is Niño-3.4, a commonly used index of ENSO ( Trenberth 1997 ). The index used by CPC in preparing operational seasonal forecasts, the oceanic Niño index, is a 3-month running mean of Niño-3

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Joseph R. Bocchieri and Harry R. Glahn

JUNE1976 JOSEPH R. BOCCHIERI AND HARRY R. GLAHN 691Verification and Further Development of an Operational Model for Forecasting the Probability of Frozen Precipitation JOSEPH R. BOCCHIERI AND HARRY R. GLAHNTechniques Development Laboratory, National Weather Service, NOAA, Silver Spring, Md. 20910(Manuscript recieved 10 November 1975, in revised form 24 February 1976)ABSTRACT An

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Pieter De Meutter, Luc Gerard, Geert Smet, Karim Hamid, Rafiq Hamdi, Daan Degrauwe, and Piet Termonia

-Aire Limitée Adaptation Dynamique Développement International (ARPEGE-ALADIN) operational limited area model with a revised and modular structure of the physical parameterizations] of the Royal Meteorological Institute (RMI) of Belgium that was running with a horizontal grid spacing of 4 km operationally that time. However, the operationally forecasted precipitation rates were an order of magnitude smaller than the observed values. Inspecting the values of the subgrid downdraft velocities, it was found

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James A. Renwick and Craig S. Thompson

1. Introduction Variations in the skill of operational numerical weather prediction (NWP) models arise in two main ways. First, technological improvements (faster computers, better models) have led to substantial and relatively steady improvements in skill over the last several decades ( Kalnay et al. 1998 ). Second, overlaid on the general upward trend in forecast skill are shorter-term variations related to the predictability of the atmospheric circulation. The chaotic nature of the

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Martin Charron, Saroja Polavarapu, Mark Buehner, P. A. Vaillancourt, Cécilien Charette, Michel Roch, Josée Morneau, Louis Garand, Josep M. Aparicio, Stephen MacPherson, Simon Pellerin, Judy St-James, and Sylvain Heilliette

observations of the stratosphere were becoming available for operational assimilation by weather forecasting centers. Indeed, the Advanced Microwave Sounding Unit (AMSU-A) instrument—a microwave sounder that provides global coverage in 6 h because of its presence on several concurrent polar orbiting satellites—is now an important component of the current operational observing system ( Cardinali et al. 2004 ; Langland and Baker 2004 ). Though its horizontal coverage is excellent, vertically, the

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Milija Zupanski

2396 MONTHLY WEATHER REVIEW VOLUME 121Regional Four-Dimensional Variational Data Assimilationin a Quasi-Operational Forecasting Environment MILIJA ZUPANSKIUC,4R Visiting Research Program, National Meteorological Center, Washington, D.C.Manuscript received 31 August 1992, in final form 20 January 1993) Four-dimensional variational data assimilation is applied to a o

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Peter D. Düben, Martin Leutbecher, and Peter Bauer

variable such that the overall number of bits that are stored for ensemble forecast data can be reduced. We test the approach for storage of model output of an operational ensemble forecast with the Integrated Forecast System (IFS) at ECMWF and investigate savings and errors for data that are stored in GRIB format. It is not the focus of this paper to show that the new methods for data storage can compete with existing methods for lossy data compression in terms of the potential reduction of data

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