Can general circulation models be assessed and their output enhanced with drifter data?

Toner, M.; Kirwan, A. D.; Kantha, Lakshmi; Choi, Jei-Kook

doi:10.1029/2000jc000587

Cited by 37 publications

(23 citation statements)

References 25 publications

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“…The present study utilizes the same drifter observations and numerical model. However, in comparing with Toner et al (2001) and Kuznetsov et al (2002) the primary focus of our study is on statistical laws of the model prediction error growth.…”

Section: Statictics Of the Lagrangian Predictabilitymentioning

confidence: 99%

“…Second, other sources of prediction errors are unresolved motions which are either parameterized in the model or neglected. Comparison between the drifter trajectories and modeled synthetic particle trajectories (Toner at al., 2001) demonstrates that after filtrating the effect of 30-hour tides, individual drifter trajectories are reproduced by the model with reasonable accuracy within 10 days. The present study utilizes the same drifter observations and numerical model.…”

Section: Statictics Of the Lagrangian Predictabilitymentioning

confidence: 99%

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Lagrangian predictability of high-resolution regional models: the special case of the Gulf of Mexico

Chu

Ivanov

Kantha

et al. 2004

Nonlin. Processes Geophys.

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Abstract. The Lagrangian prediction skill (model ability to reproduce Lagrangian drifter trajectories) of the nowcast/forecast system developed for the Gulf of Mexico at the University of Colorado at Boulder is examined through comparison with real drifter observations. Model prediction error (MPE), singular values (SVs) and irreversible-skill time (IT) are used as quantitative measures of the examination. Divergent (poloidal) and nondivergent (toroidal) components of the circulation attractor at 50 m depth are analyzed and compared with the Lagrangian drifter buoy data using the empirical orthogonal function (EOF) decomposition and the measures, respectively. Irregular (probably, chaotic) dynamics of the circulation attractor reproduced by the nowcast/forecast system is analyzed through Lyapunov dimension, global entropies, toroidal and poloidal kinetic energies. The results allow assuming exponential growth of prediction error on the attractor. On the other hand, the q-th moment of MPE grows by the power law with exponent of 3q/4. The probability density function (PDF) of MPE has a symmetrical but nonGaussian shape for both the short and long prediction times and for spatial scales ranging from 20 km to 300 km. The phenomenological model of MPE based on a diffusion-like equation is developed. The PDF of IT is non-symmetric with a long tail stretched towards large ITs. The power decay of the tail was faster than 2 for long prediction times.

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Section: Statictics Of the Lagrangian Predictabilitymentioning

confidence: 99%

Section: Statictics Of the Lagrangian Predictabilitymentioning

confidence: 99%

Lagrangian predictability of high-resolution regional models: the special case of the Gulf of Mexico

Chu

Ivanov

Kantha

et al. 2004

Nonlin. Processes Geophys.

Self Cite

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“…Two criteria are available for quantitative assessment. These are the Lagrangian error metrics proposed by Toner et al (2001), and the accuracy of advective pathways predicted by inflowing and outflowing manifolds associated with hyperbolic trajectories.…”

Section: Approachmentioning

confidence: 99%

Model Assessment and Deployment Strategies for Drifting Instruments

Kirwan¹,

Lipphardt²

2006

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LONG-TERM GOALSThis is part of a collaborative program Optimal Deployment of Drifting Acoustic Sensors, ODDAS, which involves academic, private sector, and Navy scientists. The long-term goal of ODDAS is to develop strategies for the deployment of drifting sensors that maximize the amount of environmental information collected with the fewest sensors. The primary long-term goal of our component is to quantify oceanic submesoscale stirring and advective transport processes and to assess their roles in the deployment strategies. The secondary goal is to develop novel and quantitative assessments of the ability of predictive models and real-time observations to determine the movement of sensors and the location of material boundaries or advective pathways in the ocean. OBJECTIVESTwo objectives were pursued during FY06:• Locate hyperbolic trajectories and calculate associated inflowing and outflowing manifolds in EAS16 hindcasts for the region around Taiwan.• Assess the ability of EAS16 to predict the movement of drifting sensors. APPROACHAs documented in publications and previous progress reports we have developed a variety of Lagrangian methods that quantify advective processes from synoptic velocity archives. These methods are used in this project to configure deployment schemes of drifting sensors so as to maximize data return from drifting sensor arrays with a minimum number of units. This requires meeting three diverse, and occassionally contradictory, user requirements. One is to maximize the spatial coverage for regions of interest. Another requirement is maintain array coherence for a specified time period. The third requirement is to sample denied areas. To meet these requirements it is also important to decide whether to deploy all sensors at one time or to use a time staggered strategy.The key of our approach is the capability to locate critical regions from the synoptic velocity archives. These are usually found in regions where the velocity is small. However, small velocity regions in the

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“…Toner et al (2001a) directly compared near surface drifter trajectories within a large Loop Current ring with numerical trajectories from the CUPOM. Near surface drifters were also used by Kuznetsov et al (2002) in conjunction with Lagrangian boundaries of coherent features in the model to verify complicated interactions of the Loop Current and adjacent cyclones and anti-cyclones.…”

mentioning

confidence: 99%

“…where (u, v) are the zonal and meridional velocity components given by the model at 50 m. This depth is representative of the near surface flow and is a typical drifter drogue depth (Toner et al, 2001a;Kuznetsov et al, 2002). Trajectory integration is performed with the LSODA routine from the public domain library ODEPACK using bicubic spatial and linear temporal interpolation of the gridded daily model velocities.…”

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confidence: 99%

Lagrangian velocity statistics of directed launch strategies in a Gulf of Mexico model

Toner

Poje

2004

Nonlin. Processes Geophys.

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Abstract. The spatial dependence of Lagrangian displacement and velocity statistics is studied in the context of a data assimilating numerical model of the Gulf Mexico. In the active eddy region of the Western Gulf, a combination of Eulerian and Lagrangian measures are used to locate strongly hyperbolic regions of the flow. The statistics of the velocity field sampled by sets of drifters launched specifically in these hyperbolic regions are compared to those produced by randomly chosen launch sites. The results show that particle trajectories initialized in hyperbolic regions preferentially sample a broader range of Eulerian velocities than do members of ensembles of randomly launched drifters. The velocity density functions produced by the directed launches compare well with Eulerian velocity pdfs. Implications for the development of launch strategies to improve Eulerian velocity field reconstruction from drifter data are discussed.

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Can general circulation models be assessed and their output enhanced with drifter data?

Cited by 37 publications

References 25 publications

Lagrangian predictability of high-resolution regional models: the special case of the Gulf of Mexico

Lagrangian predictability of high-resolution regional models: the special case of the Gulf of Mexico

Model Assessment and Deployment Strategies for Drifting Instruments

Lagrangian velocity statistics of directed launch strategies in a Gulf of Mexico model

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