Ocean Prediction with the Hybrid Coordinate Ocean Model (HYCOM)

Chassignet, Eric P.; Hurlburt, Harley E.; Smedstad, Ole Martin; Halliwell, George R.; Hogan, Patrick; Wallcraft, Alan J.; Bleck, Rainer

doi:10.1007/1-4020-4028-8_16

Cited by 85 publications

(64 citation statements)

References 30 publications

(29 reference statements)

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“…It uses the hybrid coordinate ocean model (HYCOM, e.g. Bleck, 2002;Chassignet et al, 2006) coupled with a sea-ice model (Hunke and Dukowicz, 1997). Compared to TOPAZ3, TOPAZ4 has undertaken a number of substantial modifications in the DA scheme, the model, and the system configuration.…”

Section: Introductionmentioning

confidence: 99%

TOPAZ4: an ocean-sea ice data assimilation system for the North Atlantic and Arctic

et al. 2012

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Abstract. We present a detailed description of TOPAZ4, the latest version of TOPAZ -a coupled ocean-sea ice data assimilation system for the North Atlantic Ocean and Arctic. It is the only operational, large-scale ocean data assimilation system that uses the ensemble Kalman filter. This means that TOPAZ features a time-evolving, state-dependent estimate of the state error covariance. Based on results from the pilot MyOcean reanalysis for 2003-2008, we demonstrate that TOPAZ4 produces a realistic estimate of the ocean circulation in the North Atlantic and the sea-ice variability in the Arctic. We find that the ensemble spread for temperature and sea-level remains fairly constant throughout the reanalysis demonstrating that the data assimilation system is robust to ensemble collapse. Moreover, the ensemble spread for ice concentration is well correlated with the actual errors. This indicates that the ensemble statistics provide reliable state-dependent error estimates -a feature that is unique to ensemble-based data assimilation systems. We demonstrate that the quality of the reanalysis changes when different sea surface temperature products are assimilated, or when in-situ profiles below the ice in the Arctic Ocean are assimilated. We find that data assimilation improves the match to independent observations compared to a free model. Improvements are particularly noticeable for ice thickness, salinity in the Arctic, and temperature in the Fram Strait, but not for transport estimates or underwater temperature. At the same time, the pilot reanalysis has revealed several flaws in the system that have degraded its performance. Finally, we show that a simple bias estimation scheme can effectively detect the seasonal or constant bias in temperature and sea-level.

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Section: Introductionmentioning

confidence: 99%

TOPAZ4: an ocean-sea ice data assimilation system for the North Atlantic and Arctic

et al. 2012

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“…HYCOM is equipped with a suite of sequential assimilation schemes that will be used to investigate how UQ may be beneficial to data assimilation. Details about the model, its validation, and sample applications can be found in Bleck (2002); Halliwell (2004); Chassignet et al (2003Chassignet et al ( , 2006 as well as by visiting http://www.hycom.org. Below we present the main ideas of the PC expansion before we summarize our efforts since the last annual report of Sep 2012.…”

Section: Approachmentioning

confidence: 99%

Quantifying Prediction Fidelity in Ocean Circulation Models

Iskandarani¹,

Knio²,

Srinivasan³

et al. 2013

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The development, validation and application of robust uncertainty quantification methods to ocean modeling, forecasting, and parameter estimation. OBJECTIVESThis project explores the use of Polynomial Chaos (PC) expansions for improving our understanding of uncertainties in Ocean General Circulation Models (OGCM). Reliable ocean forecasts require an objective, practical and accurate methodology to assess the inherent uncertainties associated with the model and data used to produce these forecasts. OGCMs uncertainties stem from several sources that include: physical approximation of the governing equations; discretization and modeling errors; an incomplete set of sparse (and often noisy) observations to constrain the initial and boundary conditions of the model; and uncertainties in surface momentum and buoyancy fluxes.

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“…de.recherches.en.mer.phase.3.php). to the US Coast Guard. Analyses from two 1/12°high-horizontal-resolution systems were used: the PSY2V3R1 regional system (North Atlantic and Mediterranean Sea) from Mercator Océan (hereafter referred to as PSY2) and the HYbrid Coordinate Ocean Model (Bleck 2002;Chassignet et al 2006) HYCOM/NCODA global system from the NRL. These two systems are state-of-the-art operational ocean monitoring and forecasting systems (Dombrowsky et al 2009).…”

Section: Ocean Currents and Drift Forecastsmentioning

confidence: 99%

A strategy for producing refined currents in the Equatorial Atlantic in the context of the search of the AF447 wreckage

Drévillon

Greiner

Paradis³

et al. 2012

Ocean Dynamics

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On the night of 1st June 2009, a Rio-Paris Air France flight (AF447) disappeared in a highly variable and poorly observed part of the western tropical Atlantic Ocean. The first debris was located 5 days after the accident. Several reverse drift computations were conducted in order to define the likely position of the wreckage. Unfortunately, the performance of the operational ocean analyses available in the region of interest ranges from 80 to 100 km of positioning error after 5 days of inverse drift computation. In preparation of the third phase of research of the wreckage at sea, a series of numerical experiments was performed at Météo-France and Mercator Océan in an attempt to better compute the surface currents in the region and for the period of the accident of the AF447 (May and June 2009). Tailored high-resolution atmosphere and ocean reanalyses were first produced respectively at Météo-France and Mercator Océan. Several nested experiments were then performed with a small and flexible ocean model limited to the region of interest. The date of the initial conditions and the type of atmospheric forcing fields were varied in order to produce a small ensemble from which information on the sensitivity to these changes could be derived. Probabilistic and statistical combinations between model and observations were tested and a solution was finally selected by means of a comparison of drift computations with independent surface drift observations.

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Ocean Prediction with the Hybrid Coordinate Ocean Model (HYCOM)

Cited by 85 publications

References 30 publications

TOPAZ4: an ocean-sea ice data assimilation system for the North Atlantic and Arctic

TOPAZ4: an ocean-sea ice data assimilation system for the North Atlantic and Arctic

Quantifying Prediction Fidelity in Ocean Circulation Models

A strategy for producing refined currents in the Equatorial Atlantic in the context of the search of the AF447 wreckage

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