Theoretical investigation of the oceanic inverted barometer response

Dickman, Steven

doi:10.1029/jb093ib12p14941

Cited by 58 publications

(41 citation statements)

References 24 publications

(20 reference statements)

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“…Non-IB is the other idealized extreme, where the ocean, as if rigid, simply ignores any overriding atmospheric mass loading. The reality presumably resides somewhere in between, depending on the temporal and spatial scales of the phenomenon in question [Dickman, 1988;Ponte et al, 1991;Wunsch and Stammer, 1997]. As in usual practice we look at both cases, but also "let the data speak" to determine an optimum linear combination of the two.…”

Section: Formulation and Data Processingmentioning

confidence: 99%

Relation between length‐of‐day variation and angular momentum of geophysical fluids

Chao

Yan

2010

J. Geophys. Res.

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[1] The remarkable relation well observed between variation in the length of day (DLOD) and variation in the axial atmospheric angular momentum (DAAM) (plus the oceanic counterpart, to a much lesser extent) is a consequence of the conservation of angular momentum on planet Earth. Quantification of the exact DLOD-DAAM relation, which we seek in the present study, depends significantly on the extent to which the core participates, or is dynamically coupled with the mantle, in transmission of the axial DAAM from the mantle to the core. If, after conversion to the equivalent DLOD assuming core-mantle decoupling (as in current standard practice), the calculated axial DAAM (according to atmospheric general circulation models [GCMs]) is systematically greater than the observed DLOD, then we can conclude the presence, and, furthermore, estimate the strength, of the said dynamic core-mantle coupling. However, in this study we find the opposite instead, that the calculated DAAM (plus the small oceanic counterpart) is smaller than the observed DLOD by 10%-20% consistently across the intraseasonal and seasonal time scales. Our main logical conclusion is that the atmospheric GCMs in general underpredict the DAAM, by at least 10%-20% at the mentioned time scales, a fact of importance with respect to the assessment of GCMs. Therefore, the systematic discrepancy found between the DAAM-predicted and the observed DLOD masks the relevant information on core-mantle coupling that we seek.Citation: Chao, B. F., and H. Yan (2010), Relation between length-of-day variation and angular momentum of geophysical fluids,

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Section: Formulation and Data Processingmentioning

confidence: 99%

Relation between length‐of‐day variation and angular momentum of geophysical fluids

Chao

Yan

2010

J. Geophys. Res.

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“…At low frequency this interaction can be accounted for by the use of the inverted barometer (IB) approximation [see Dickman, 1988], but it is usually accepted that this model is far from reality for periods smaller than 20 days, as the ocean does not have time to readjust [see, e.g, Munk and MacDonald, 1960;Ponte, 1993;de Viron et al, 2001]. This model will thus not be used here.…”

Section: Introductionmentioning

confidence: 99%

Atmospheric excitation of the Earth's nutation: Comparison of different atmospheric models

et al. 2002

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[1] Using the angular momentum approach, the effect of the atmosphere on the Earth's nutation is evaluated from five atmospheric circulation models. Five nutation frequencies are considered: the annual and semiannual prograde and retrograde and the terannual prograde. The atmospheric effect on the 18.6-year nutation is also evaluated from the only model that gives a long enough homogeneous series. The results obtained from the different models and a noninverted barometer ocean model are intercompared and compared with the residuals between the observed and computed nutations. The evaluation of the atmospheric effect on the Earth's nutation is shown to be above the observation precision, particularly at the annual frequency (prograde and retrograde) and the semiannual prograde frequency but is highly dependent on the model used, strengthening the importance of having a correct estimation for the atmospheric effects on nutation. The time evolution of the atmospheric excitation of the nutation is also studied, using a wavelet analysis and a sliding-window least squares method. We show that the fluctuations of the excited amplitude are above the level of precision of the observation.

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“…As described in Dickman [1988a], additional modifications allow the loading produced by atmospheric pressure forcing to be included. The frictional terms are −Pũ and ∼Ar H 2ũ , whereũ = (u , u l ) is the horizontal current velocity, P is the bottom drag coefficient, and A is the horizontal eddy viscosity.…”

Section: Improvements To the Spherical Harmonic Ocean Tide Modelmentioning

confidence: 99%

“…[9] Alternatively [Dickman, 1988a[Dickman, , 1998], the generalized ocean tide model can be employed to compute a suite of oceanic Green's functions, each one representing the oceans' response to a fundamental scale of barometric forcing. With this approach, the heavy computation is directed toward construction of the various Green's functions, but once the latter have been determined they can easily be combined with actual pressure data for any span of time to quickly yield the oceanic DB response or the effects of that response on Earth's rotation.…”

Section: The Db Response and Ocean Tide Modelsmentioning

confidence: 99%

Rotationally acceptable ocean tide models for determining the response of the oceans to atmospheric pressure fluctuations

Dickman¹

2010

J. Geophys. Res.

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[1] Suitably generalized, ocean tide models can be used to determine the oceans' response to atmospheric pressure forcing; but the huge range of spatial and temporal scales of that forcing limits the relevance of state-of-the-art tide modeling techniques, like data assimilation, for such determinations. With an interest in its effects on Earth's rotation, in 1998 I employed a generalized but non-assimilating spherical harmonic tide model to determine the oceanic response to pressure forcing, however restricting its application to time scales exceeding a few days. This article revisits that spherical harmonic model in an attempt to improve its rotational predictions of short-period tides. We find that increasing the resolution of the model ocean does not by itself affect the tidal solution much, but varying the model's frictional parameters can produce diurnal tides whose effects on Earth's polar motion are similar to those of a variety of other ocean tide models. Such an improved model will allow our calculations of the oceans' dynamic response to pressure forcing, and the effects of that response on Earth's rotation, to be extended down to diurnal time scales.Citation: Dickman, S. R. (2010), Rotationally acceptable ocean tide models for determining the response of the oceans to atmospheric pressure fluctuations,

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Theoretical investigation of the oceanic inverted barometer response

Cited by 58 publications

References 24 publications

Relation between length‐of‐day variation and angular momentum of geophysical fluids

Relation between length‐of‐day variation and angular momentum of geophysical fluids

Atmospheric excitation of the Earth's nutation: Comparison of different atmospheric models

Rotationally acceptable ocean tide models for determining the response of the oceans to atmospheric pressure fluctuations

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