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W. C. Thacker

for irregular computational grids are presented. Successful simulations oftransient normal mode oscillations in shallow circular basins, where analytic solutions are known, demonstrate that these techniques can yield accurate results, even in situations involving a curved boundary.These techniques should prove to be quite useful for numerically forecasting storm surges in bays andestuaries where calculations are complicated by the curving coastline.1. Introduction Numerical forecasts of storm

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Francesco Fedele

.3 × 10 6 waves. In contrast, the Andrea and WACSIS events would occur less often being both unexpected and rogue, that is, on average once every 3 × 10 6 and 0.6 × 10 6 , respectively. Finally, we point out that our statistical model for unexpected waves supports and goes beyond the analysis by Gemmrich and Garrett (2008) based on Monte Carlo simulations. In particular, our statistical approach can be used in operational wave forecast models to predict the unexpectedness of ocean waves

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Francesco Barbariol, Alvise Benetazzo, Sandro Carniel, and Mauro Sclavo

formulas are exact) the analytical and numerical estimates were exact within a few per thousand difference, which is the error introduced by the numerical integration technique. For JON+cos 2 , in the range of γ between 1 and 7, we obtained differences between numerical and analytical results within 5% for spectral parameters of Eq. (2) and the significant wave height, H s being the most affected parameter, since the JON approximation mostly affects the zeroth moment (i.e., m 000 ). Hence

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Allan R. Robinson, James A. Carton, Nadia Pinardi, and Christopher N. K. Mooers

eddies have merged and formed asingle eddy. Even the forecast with incorrect boundary conditions demonstrates the internal dynamical processesinvolved in the merger event. Two examples are given of four-dimensional data assimilation: direct insertion and a backward-forwardcombination technique. These results justify the use of the dynamical forecasts as synoptic time series. Parametersensitivity experiments were performed to determine the sensitivity of the model to physical parameters suchas

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Leonard J. Walstad and Allan R. Robinson

.Model studies also demonstrate that hindcast quality improves after being degraded by a period of poor boundaryconditions, topographic forcing is relatively important in improving the accuracy of the hindcasts, and idealizednumerical resolution studies are applicable to the assimilation of oceanic data sets. Methods for forecasting are examined and intercompared for several periods during the POLYMODE experiment. Forecast accuracy is found to be highest when statistical techniques are used to forecast

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Arthur J. Miller, Pierre-Marie Poulain, Alex Warn-Varnas, Hernan G. Arango, Allan R. Robinson, and Wayne G. Leslie

level of no motion, 3) the effects of surrounding mesoscale activity, 4) variations in the boundaryconditions, and 5 ) simple assimilation of newly acquired data into the forecasts are carded out. Using a feature validation technique, which incorporates a 1 ) validating hydrocast survey, 2) satellite SSTimages, and 3 ) surface drifter observations, most of the forecasts are found to perform well in capturing the keyevents of the validation strategy, particularly the development of the cold tongue

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Lee-Lueng Fu, Jorge Vazquez, and Claire Perigaud

linear model on an equatorial beta plane are usedto fit the Geosat altimetric sea level observations in the Tropical Pacific Ocean. The Kalman filter technique isused to estimate the wave amplitude and phase from the data. The estimation is performed at each time stepby combining the model forecast with the observation in an optimal fashion utilizing the respective errorcovariances. The model error covariance is determined such that the performance of the model forecast isoptimized. It is found that

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James A. Carton

) ABSTRACT POLYMODE data is used to produce a new gridded analysis of multilevel streamfunctions in a (500 kin)2 domain during July 1977-August 1978. The analysis is used to define initial and lateral boundary conditions, and verification fields for six predictability experiments. These experiments are designed to determine the accuracy of current techniques of forecasting and hindcasting the circulation in a limited domain and to define the sources of error. A forecast based on

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Andrew M. Moore and Arthur J. Mariano

1. Introduction In recent years there has been an increasing interest in the prediction of ocean currents and the ocean circulation. These efforts have focused primarily on coastal and nearshore circulations because of their impact on marine operations and fisheries. In meteorology, numerical weather prediction (NWP) techniques have evolved rapidly during the last 30 years or so, and much of the experience gained in NWP is directly applicable to ocean prediction. Based on the experience of NWP

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Russell L. Elsberry and Larry L. Warrenfelt

AUGUST 1982 RUSSELL L. ELSBERRY AND LARRY L. WARRENFELTZ 839Data Assimilation Tests with an Oceanic Mixed-Layer ModelRUSSELL L. ELSBERRY AND LARRY L. WARRENFELTZIDepartment of Meteorology, Naval Postgraduate School, Monterey, CA 93940(Manuscript received 16 November 1981, in final form 12 April 1982)ABSTRACT A data assimilation technique using a one-dimensional, ocean mixed-layer model to advance the

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