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  • 1
    Online Resource
    Online Resource
    Strategies for nested and eddy-permitting state estimation
    American Geophysical Union (AGU) ; 2006
    In:  Journal of Geophysical Research Vol. 111, No. C10 ( 2006-10-11)
    Details
    In: Journal of Geophysical Research, American Geophysical Union (AGU), Vol. 111, No. C10 ( 2006-10-11)
    Type of Medium: Online Resource
    ISSN: 0148-0227
    URL: Article
    DOI: 10.1029/2005JC003094
    Language: English
    Publisher: American Geophysical Union (AGU)
    Publication Date: 2006
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    detail.hit.zdb_id: 2403298-0
    detail.hit.zdb_id: 2016800-7
    detail.hit.zdb_id: 161666-3
    detail.hit.zdb_id: 161667-5
    detail.hit.zdb_id: 2969341-X
    detail.hit.zdb_id: 161665-1
    detail.hit.zdb_id: 3094268-8
    detail.hit.zdb_id: 710256-2
    detail.hit.zdb_id: 2016804-4
    detail.hit.zdb_id: 3094181-7
    detail.hit.zdb_id: 3094219-6
    detail.hit.zdb_id: 3094167-2
    detail.hit.zdb_id: 2220777-6
    detail.hit.zdb_id: 3094197-0
    SSG: 16,13
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  • 2
    Online Resource
    Online Resource
    Timescales and regions of the sensitivity of Atlantic meridional volume and heat transport: Toward observing system design
    Elsevier BV ; 2011
    In:  Deep Sea Research Part II: Topical Studies in Oceanography Vol. 58, No. 17-18 ( 2011-9), p. 1858-1879
    Details
    In: Deep Sea Research Part II: Topical Studies in Oceanography, Elsevier BV, Vol. 58, No. 17-18 ( 2011-9), p. 1858-1879
    Type of Medium: Online Resource
    ISSN: 0967-0645
    URL: Article
    DOI: 10.1016/j.dsr2.2010.10.065
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2011
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    SSG: 14
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  • 3
    Online Resource
    Online Resource
    Potential artifacts in conservation laws and invariants inferred from sequential state estimation
    Copernicus GmbH ; 2023
    In:  Ocean Science Vol. 19, No. 4 ( 2023-08-21), p. 1253-1275
    Details
    In: Ocean Science, Copernicus GmbH, Vol. 19, No. 4 ( 2023-08-21), p. 1253-1275
    Abstract: Abstract. In sequential estimation methods often used in oceanic and general climate calculations of the state and of forecasts, observations act mathematically and statistically as source or sink terms in conservation equations for heat, salt, mass, and momentum. These artificial terms obscure the inference of the system's variability or secular changes. Furthermore, for the purposes of calculating changes in important functions of state variables such as total mass and energy or volumetric current transports, results of both filter and smoother-based estimates are sensitive to misrepresentation of a large variety of parameters, including initial conditions, prior uncertainty covariances, and systematic and random errors in observations. Here, toy models of a coupled mass–spring oscillator system and of a barotropic Rossby wave system are used to demonstrate many of the issues that arise from such misrepresentations. Results from Kalman filter estimates and those from finite interval smoothing are analyzed. In the filter (and prediction) problem, entry of data leads to violation of conservation and other invariant rules. A finite interval smoothing method restores the conservation rules, but uncertainties in all such estimation results remain. Convincing trend and other time-dependent determinations in “reanalysis-like” estimates require a full understanding of models, observations, and underlying error structures. Application of smoother-type methods that are designed for optimal reconstruction purposes alleviate some of the issues.
    Type of Medium: Online Resource
    ISSN: 1812-0792
    URL: Article
    DOI: 10.5194/os-19-1253-2023
    Language: English
    Publisher: Copernicus GmbH
    Publication Date: 2023
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  • 4
    Online Resource
    Online Resource
    Practical global oceanic state estimation
    Elsevier BV ; 2007
    In:  Physica D: Nonlinear Phenomena Vol. 230, No. 1-2 ( 2007-6), p. 197-208
    Details
    In: Physica D: Nonlinear Phenomena, Elsevier BV, Vol. 230, No. 1-2 ( 2007-6), p. 197-208
    Type of Medium: Online Resource
    ISSN: 0167-2789
    URL: Article
    DOI: 10.1016/j.physd.2006.09.040
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2007
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  • 5
    Online Resource
    Online Resource
    Linear Predictability: A Sea Surface Height Case Study
    American Meteorological Society ; 2018
    In:  Journal of Climate Vol. 31, No. 7 ( 2018-04), p. 2599-2611
    Details
    In: Journal of Climate, American Meteorological Society, Vol. 31, No. 7 ( 2018-04), p. 2599-2611
    Abstract: A benchmark of linear predictability of sea surface height (SSH) globally is presented, complementing more complicated studies of SSH predictability. Twenty years of the Estimating the Circulation and Climate of the Ocean (ECCOv4) state estimate (1992–2011) are used, fitting autoregressive moving average [ARMA([Formula: see text])] models where the order of the coefficients is chosen by the Akaike information criteria (AIC). Up to 50% of the ocean SSH variability is dominated by the seasonal signal. The variance accounted for by the nonseasonal SSH is particularly distinct in the Southern and Pacific Oceans, containing 〉 95% of the total SSH variance, and the expected prediction error growth takes a few months to reach a threshold of 1 cm. Isolated regions take 12 months or more to cross an accuracy threshold of 1 cm. Including the trend significantly increases the time taken to reach the threshold, particularly in the South Pacific. Annual averaging has expected prediction error growth of a few years to reach a threshold of 1 cm. Including the trend mainly increases the time taken to reach the threshold, but the time series is short and noisy.
    Type of Medium: Online Resource
    ISSN: 0894-8755 , 1520-0442
    URL: Article
    DOI: 10.1175/JCLI-D-17-0142.1
    RVK:
    UA 4548
    Language: English
    Publisher: American Meteorological Society
    Publication Date: 2018
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  • 6
    Online Resource
    Online Resource
    Decadal Trends in Sea Level Patterns: 1993–2004
    American Meteorological Society ; 2007
    In:  Journal of Climate Vol. 20, No. 24 ( 2007-12-15), p. 5889-5911
    Details
    In: Journal of Climate, American Meteorological Society, Vol. 20, No. 24 ( 2007-12-15), p. 5889-5911
    Abstract: Estimates of regional patterns of global sea level change are obtained from a 1° horizontal resolution general circulation model constrained by least squares to about 100 million ocean observations and many more meteorological estimates during the period 1993–2004. The data include not only altimetric variability, but most of the modern hydrography, Argo float profiles, sea surface temperature, and other observations. Spatial-mean trends in altimetric data are explicitly suppressed to isolate global average long-term changes required by the in situ data alone. On large scales, some regions display strong signals although few individual points have statistically significant trends. In the regional patterns, thermal, salinity, and mass redistribution contributions are all important, showing that regional sea level change is tied directly to the general circulation. Contributions below about 900 m are significant, but not dominant, and are expected to grow with time as the abyssal ocean shifts. Estimates made here produce a global mean of about 1.6 mm yr−1, or about 60% of the pure altimetric estimate, of which about 70% is from the addition of freshwater. Interannual global variations may be dominated by the freshwater changes rather than by heating changes. The widely quoted altimetric global average values may well be correct, but the accuracies being inferred in the literature are not testable by existing in situ observations. Useful estimation of the global averages is extremely difficult given the realities of space–time sampling and model approximations. Systematic errors are likely to dominate most estimates of global average change: published values and error bars should be used very cautiously.
    Type of Medium: Online Resource
    ISSN: 1520-0442 , 0894-8755
    URL: Article
    DOI: 10.1175/2007JCLI1840.1
    RVK:
    UA 4548
    Language: English
    Publisher: American Meteorological Society
    Publication Date: 2007
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    detail.hit.zdb_id: 2021723-7
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  • 7
    Online Resource
    Online Resource
    Putting It All Together: Adding Value to the Global Ocean and Climate Observing Systems With Complete Self-Consistent Ocean State and Parameter Estimates
    Frontiers Media SA ; 2019
    In:  Frontiers in Marine Science Vol. 6 ( 2019-3-4)
    Details
    In: Frontiers in Marine Science, Frontiers Media SA, Vol. 6 ( 2019-3-4)
    Type of Medium: Online Resource
    ISSN: 2296-7745
    URL: Article
    DOI: 10.3389/fmars.2019.00055
    Language: Unknown
    Publisher: Frontiers Media SA
    Publication Date: 2019
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  • 8
    Online Resource
    Online Resource
    Estimated Decadal Changes in the North Atlantic Meridional Overturning Circulation and Heat Flux 1993–2004
    American Meteorological Society ; 2006
    In:  Journal of Physical Oceanography Vol. 36, No. 11 ( 2006-11-01), p. 2012-2024
    Details
    In: Journal of Physical Oceanography, American Meteorological Society, Vol. 36, No. 11 ( 2006-11-01), p. 2012-2024
    Abstract: Results from a global 1° model constrained by least squares to a multiplicity of datasets over the interval 1992–2004 are used to describe apparent changes in the North Atlantic Ocean meridional overturning circulation and associated heat fluxes at 26°N. The least squares fit is both stable and adequately close to the data to make the analysis worthwhile. Changes over the 12 yr are spatially and temporally complex. A weak statistically significant trend is found in net North Atlantic volume flux above about 1200 m, which drops slightly (−0.19 ± 0.05 Sv yr−1; 1 Sv ≡ 106 m3 s−1) but with a corresponding strengthening of the outflow of North Atlantic Deep Water and inflow of abyssal waters. The slight associated trend in meridional heat flux is very small and not statistically significant. The month-to-month variability implies that single-section determinations of heat and volume flux are subject to serious aliasing errors.
    Type of Medium: Online Resource
    ISSN: 1520-0485 , 0022-3670
    URL: Article
    DOI: 10.1175/JPO2957.1
    Language: English
    Publisher: American Meteorological Society
    Publication Date: 2006
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  • 9
    Online Resource
    Online Resource
    An Eddy-Permitting Southern Ocean State Estimate
    American Meteorological Society ; 2010
    In:  Journal of Physical Oceanography Vol. 40, No. 5 ( 2010-05-01), p. 880-899
    Details
    In: Journal of Physical Oceanography, American Meteorological Society, Vol. 40, No. 5 ( 2010-05-01), p. 880-899
    Abstract: An eddy-permitting general circulation model of the Southern Ocean is fit by constrained least squares to a large observational dataset during 2005–06. Data used include Argo float profiles, CTD synoptic sections, Southern Elephant Seals as Oceanographic Samplers (SEaOS) instrument-mounted seal profiles, XBTs, altimetric observations [Envisat, Geosat, Jason-1, and Ocean Topography Experiment (TOPEX)/Poseidon], and infrared and microwave radiometer observed sea surface temperature. An adjoint model is used to determine descent directions in minimizing a misfit function, each of whose elements has been weighted by an estimate of the observational plus model error. The model is brought into near agreement with the data by adjusting its control vector, here consisting of initial and meteorological boundary conditions. Although total consistency has not yet been achieved, the existing solution is in good agreement with the great majority of the 2005 and 2006 Southern Ocean observations and better represents these data than does the World Ocean Atlas 2001 (WOA01) climatological product. The estimate captures the oceanic temporal variability and in this respect represents a major improvement upon earlier static inverse estimates. During the estimation period, the Drake Passage volume transport is 153 ± 5 Sv (1 Sv ≡ 106 m3 s−1). The Ross and Weddell polar gyre transports are 20 ± 5 Sv and 40 ± 8 Sv, respectively. Across 32°S there is a surface meridional overturning cell of 12 ± 12 Sv, an intermediate cell of 17 ± 12 Sv, and an abyssal cell of 13 ± 6 Sv. The northward heat and freshwater anomaly transports across 30°S are −0.3 PW and 0.7 Sv, with estimated uncertainties of 0.5 PW and 0.2 Sv. The net rate of wind work is 2.1 ± 1.1 TW. Southern Ocean theories involving short temporal- and spatial-scale dynamics may now be tested with a dynamically and thermodynamically realistic general circulation model solution that is known to be compatible with the modern observational datasets.
    Type of Medium: Online Resource
    ISSN: 1520-0485 , 0022-3670
    URL: Article
    DOI: 10.1175/2009JPO4236.1
    Language: English
    Publisher: American Meteorological Society
    Publication Date: 2010
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  • 10
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    Online Resource
    Change of the Global Ocean Vertical Heat Transport over 1993–2010
    American Meteorological Society ; 2017
    In:  Journal of Climate Vol. 30, No. 14 ( 2017-07), p. 5319-5327
    Details
    In: Journal of Climate, American Meteorological Society, Vol. 30, No. 14 ( 2017-07), p. 5319-5327
    Abstract: A dynamically and data-consistent ocean state estimate during 1993–2010 is analyzed for bidecadal changes in the mechanisms of heat exchange between the upper and lower oceans. Many patterns of change are consistent with prior studies. However, at various levels above 1800 m the global integral of the change in ocean vertical heat flux involves the summation of positive and negative regional contributions and is not statistically significant. The nonsignificance of change in the global ocean vertical heat transport from an ocean state estimate that provides global coverage and regular sampling, spatially and temporally, raises the question of whether an adequate observational database exists to assess changes in the upper ocean heat content over the past few decades. Also, whereas the advective term largely determines the spatial pattern of the change in ocean vertical heat flux, its global integral is not significantly different from zero. In contrast, the diffusive term, although regionally weak except in high-latitude oceans, produces a statistically significant extra downward heat flux during the 2000s. This result suggests that besides ocean advection, ocean mixing processes, including isopycnal and diapycnal as well as convective mixing, are important for the decadal variation of the heat exchange between upper and deep oceans as well. Furthermore, the analyses herein indicate that focusing on any particular region in explaining changes of the global ocean heat content is misleading.
    Type of Medium: Online Resource
    ISSN: 0894-8755 , 1520-0442
    URL: Article
    DOI: 10.1175/JCLI-D-16-0569.1
    RVK:
    UA 4548
    Language: English
    Publisher: American Meteorological Society
    Publication Date: 2017
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    detail.hit.zdb_id: 2021723-7
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