GLORIA

GEOMAR Library Ocean Research Information Access

X

Ihre E-Mail wurde erfolgreich gesendet. Bitte prüfen Sie Ihren Maileingang.

Leider ist ein Fehler beim E-Mail-Versand aufgetreten. Bitte versuchen Sie es erneut.

Vorgang fortführen?

Exportieren
  • 1
    Online-Ressource
    Online-Ressource
    Coupled Interannual Variability of the Hadley and Ferrel Cells
    American Meteorological Society ; 2018
    In:  Journal of Climate Vol. 31, No. 12 ( 2018-06), p. 4757-4773
    Details
    In: Journal of Climate, American Meteorological Society, Vol. 31, No. 12 ( 2018-06), p. 4757-4773
    Kurzfassung: This work investigates the covariability in the strength of the Hadley and Ferrel cells on interannual time scales using reanalysis data. A significant correlation is found in both hemispheres only during boreal winter. For other seasons, only the outermost (subtropical) part of the Hadley cell is correlated with changes in the extratropical eddy momentum fluxes, as the eddies are unable to penetrate into the deep tropics. During boreal winter, the northern Hadley cell variability is driven by extratropical planetary momentum fluxes, but the mean meridional circulation response is primarily found below the level of maximum climatological outflow. Instead, at upper levels, changes in the zonal wind dominate the response to the anomalous eddy forcing. During austral winter, the southern Hadley cell is shielded from the extratropical eddy fluxes and its variability displays some of the characteristics of the angular momentum–conserving solution.
    Materialart: Online-Ressource
    ISSN: 0894-8755 , 1520-0442
    URL: Article
    DOI: 10.1175/JCLI-D-17-0752.1
    RVK:
    UA 4548
    Sprache: Englisch
    Verlag: American Meteorological Society
    Publikationsdatum: 2018
    ZDB Id: 246750-1
    ZDB Id: 2021723-7
    Standort Signatur Einschränkungen Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Online-Ressource
  • 2
    Online-Ressource
    Online-Ressource
    On the relation between explosive cyclones affecting Europe and the North Atlantic Oscillation : Gomara et al.: Cyclones affecting Europe and the NAO
    American Geophysical Union (AGU) ; 2014
    In:  Geophysical Research Letters Vol. 41, No. 6 ( 2014-03-28), p. 2182-2190
    Details
    In: Geophysical Research Letters, American Geophysical Union (AGU), Vol. 41, No. 6 ( 2014-03-28), p. 2182-2190
    Materialart: Online-Ressource
    ISSN: 0094-8276
    URL: Article
    DOI: 10.1002/2014GL059647
    Sprache: Englisch
    Verlag: American Geophysical Union (AGU)
    Publikationsdatum: 2014
    ZDB Id: 2021599-X
    ZDB Id: 7403-2
    SSG: 16,13
    Standort Signatur Einschränkungen Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Online-Ressource
  • 3
    Online-Ressource
    Online-Ressource
    Updraft/Downdraft Constraints for Moist Baroclinic Modes and Their Implications for the Short-Wave Cutoff and Maximum Growth Rate
    American Meteorological Society ; 2005
    In:  Journal of the Atmospheric Sciences Vol. 62, No. 12 ( 2005-12-01), p. 4450-4458
    Details
    In: Journal of the Atmospheric Sciences, American Meteorological Society, Vol. 62, No. 12 ( 2005-12-01), p. 4450-4458
    Kurzfassung: This paper examines the dynamics of moist baroclinic modes, based on the idealized model of moist baroclinic instability devised by Emanuel et al. These authors found that the finite static stability along the downdraft prevents the explosive short-wave cyclogenesis of the zero stratification limit in the moist problem, and allows only moderate (order 2) changes in the growth rate and short-wave cutoff, even when the moist static stability vanishes. To understand the limiting role of the dry static stability, a constraint is derived in this paper that relates the updraft and downdraft structures. This constraint is based on continuity and implies that a bulk wavenumber (defined in the paper) scales as the relevant deformation radius in each region. Because neutral solutions are separable, the vertical structure can be encapsulated in terms of a single, equivalent wavenumber based on the downdraft width. This allows an interpretation of the results in terms of the equivalent dry mode. As the ratio between moist and dry static stability decreases, the downdraft width takes an increasingly larger fraction of the total wavelength. In the limit of moist neutrality all the wavelength is occupied by the downdraft, so that the short-wave cutoff is halved. The vertical phase tilt makes unstable solutions nonseparable, and prevents defining an equivalent wavenumber in that case. However, the constraint between the bulk wavenumbers still applies. As the moist stability is reduced, the updraft solution becomes more suboptimal; in the limit of moist neutrality, the updraft wavenumber equals the short-wave cutoff. This provides a bound to the maximum growth rate in the moist problem, which is in agreement with the results of Emanuel et al.
    Materialart: Online-Ressource
    ISSN: 1520-0469 , 0022-4928
    URL: Article
    DOI: 10.1175/JAS3630.1
    RVK:
    UA 4800
    Sprache: Englisch
    Verlag: American Meteorological Society
    Publikationsdatum: 2005
    ZDB Id: 218351-1
    ZDB Id: 2025890-2
    SSG: 16,13
    Standort Signatur Einschränkungen Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Online-Ressource
  • 4
    Online-Ressource
    Online-Ressource
    Equilibration of Baroclinic Turbulence in Primitive Equations and Quasigeostrophic Models
    American Meteorological Society ; 2009
    In:  Journal of the Atmospheric Sciences Vol. 66, No. 4 ( 2009-04-01), p. 837-863
    Details
    In: Journal of the Atmospheric Sciences, American Meteorological Society, Vol. 66, No. 4 ( 2009-04-01), p. 837-863
    Kurzfassung: This paper investigates the equilibration of baroclinic turbulence in an idealized, primitive equation, two-level model, focusing on the relation with the phenomenology of quasigeostrophic turbulence theory. Simulations with a comparable two-layer quasigeostrophic model are presented for comparison, with the deformation radius in the quasigeostrophic model being set using the stratification from the primitive equation model. Over a fairly broad parameter range, the primitive equation and quasigeostrophic results are in qualitative and, to some degree, quantitative agreement and are consistent with the phenomenology of geostrophic turbulence. The scale, amplitude, and baroclinicity of the eddies and the degree of baroclinic instability of the mean flow all vary fairly smoothly with the imposed parameters; both models are able, in some parameter ranges, to produce supercritical flows. The criticality in the primitive equation model, which does not have any convective parameterization scheme, is fairly sensitive to the external parameters, most notably the planet size (i.e., the f /β ratio), the forcing time scale, and the factors influencing the stratification. In some parameter settings of the models, although not those that are most realistic for the earth’s atmosphere, it is possible to produce eddies that are considerably larger than the deformation scales and an inverse cascade in the barotropic flow with a −5/3 spectrum. The vertical flux of heat is found to be related to the isentropic slope.
    Materialart: Online-Ressource
    ISSN: 1520-0469 , 0022-4928
    URL: Article
    DOI: 10.1175/2008JAS2848.1
    RVK:
    UA 4800
    Sprache: Englisch
    Verlag: American Meteorological Society
    Publikationsdatum: 2009
    ZDB Id: 218351-1
    ZDB Id: 2025890-2
    SSG: 16,13
    Standort Signatur Einschränkungen Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Online-Ressource
  • 5
    Online-Ressource
    Online-Ressource
    Circulation Sensitivity to Heating in a Simple Model of Baroclinic Turbulence
    American Meteorological Society ; 2010
    In:  Journal of the Atmospheric Sciences Vol. 67, No. 5 ( 2010-05-01), p. 1543-1558
    Details
    In: Journal of the Atmospheric Sciences, American Meteorological Society, Vol. 67, No. 5 ( 2010-05-01), p. 1543-1558
    Kurzfassung: This paper examines the sensitivity of the circulation of an idealized primitive equation two-level model on the form and strength of the heating, aiming to understand the qualitatively different sensitivity of the isentropic slope on differential heating reported by previous idealized studies when different model formulations are used. It is argued that this contrasting behavior might arise from differences in the internal determination of the heating. To test this contention, the two-level model is forced using two different heating formulations: a standard Newtonian cooling formulation and a highly simplified formulation in which the net lower-to-upper troposphere heat transport is prescribed by construction. The results are interpreted using quasigeostrophic turbulent closures, which have previously been shown to have predictive power for the model. It is found that the strength of the circulation, as measured by eddy length and velocity scales and by the strength of the energy cycle, scales with the vertical heating (the lower-to-upper troposphere heat transport), with a weak dependence. By contrast, the isentropic slope is only sensitive to the structure of the heating, as measured by the ratio between meridional versus vertical heating, and not to the actual strength of the heating. In general the heating is internally determined, and this ratio may either increase or decrease as the circulation strengthens. It is shown that the sign of the sensitivity depends on the steepness of the relation between vertical heating and stratification for the particular heating formulation used. The quasigeostrophic limit (fixed stratification) and the prescribed heating model constrain the possible range of behaviors and provide bounds of sensitivity for the model. These results may help explain the different sensitivity of the isentropic slope on differential heating for dry and moist models and for quasigeostrophic and primitive equation models.
    Materialart: Online-Ressource
    ISSN: 1520-0469 , 0022-4928
    URL: Article
    DOI: 10.1175/2009JAS3314.1
    RVK:
    UA 4800
    Sprache: Englisch
    Verlag: American Meteorological Society
    Publikationsdatum: 2010
    ZDB Id: 218351-1
    ZDB Id: 2025890-2
    SSG: 16,13
    Standort Signatur Einschränkungen Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Online-Ressource
  • 6
    Online-Ressource
    Online-Ressource
    A Gray-Radiation Aquaplanet Moist GCM. Part II: Energy Transports in Altered Climates
    American Meteorological Society ; 2007
    In:  Journal of the Atmospheric Sciences Vol. 64, No. 5 ( 2007-05-01), p. 1680-1693
    Details
    In: Journal of the Atmospheric Sciences, American Meteorological Society, Vol. 64, No. 5 ( 2007-05-01), p. 1680-1693
    Kurzfassung: A simplified moist general circulation model is used to study changes in the meridional transport of moist static energy by the atmosphere as the water vapor content is increased. The key assumptions of the model are gray radiation, with water vapor and other constituents having no effect on radiative transfer, and mixed layer aquaplanet boundary conditions, implying that the atmospheric meridional energy transport balances the net radiation at the top of the atmosphere. These simplifications allow the authors to isolate the effect of moisture on energy transports by baroclinic eddies in a relatively simple setting. The authors investigate the partition of moist static energy transport in the model into dry static energy and latent energy transports as water vapor concentrations are increased, by varying a constant in the Clausius–Clapeyron relation. The increase in the poleward moisture flux is rather precisely compensated by a reduction in the dry static energy flux. These results are interpreted with diffusive energy balance models (EBMs). The simplest of these is an analytic model that has the property of exact invariance of total energy flux as the moisture content is changed, but the assumptions underlying this model are not accurately satisfied by the GCM. A more complex EBM that includes expressions for the diffusivity, length scale, velocity scale, and latitude of maximum baroclinic eddy activity provides a better fit to the GCM’s behavior.
    Materialart: Online-Ressource
    ISSN: 1520-0469 , 0022-4928
    URL: Article
    DOI: 10.1175/JAS3913.1
    RVK:
    UA 4800
    Sprache: Englisch
    Verlag: American Meteorological Society
    Publikationsdatum: 2007
    ZDB Id: 218351-1
    ZDB Id: 2025890-2
    SSG: 16,13
    Standort Signatur Einschränkungen Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Online-Ressource
  • 7
    Online-Ressource
    Online-Ressource
    Baroclinic Equilibration and the Maintenance of the Momentum Balance.Part II: 3D Results
    American Meteorological Society ; 2004
    In:  Journal of the Atmospheric Sciences Vol. 61, No. 13 ( 2004-07), p. 1483-1499
    Details
    In: Journal of the Atmospheric Sciences, American Meteorological Society, Vol. 61, No. 13 ( 2004-07), p. 1483-1499
    Materialart: Online-Ressource
    ISSN: 0022-4928 , 1520-0469
    URL: Article
    DOI: 10.1175/1520-0469(2004)061〈1483:BEATMO〉2.0.CO;2
    RVK:
    UA 4800
    Sprache: Englisch
    Verlag: American Meteorological Society
    Publikationsdatum: 2004
    ZDB Id: 218351-1
    ZDB Id: 2025890-2
    SSG: 16,13
    Standort Signatur Einschränkungen Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Online-Ressource
  • 8
    Online-Ressource
    Online-Ressource
    The Impact of Zonal Propagation and Seeding on the Eddy–Mean Flow Equilibrium of a Zonally Varying Two-Layer Model
    American Meteorological Society ; 2005
    In:  Journal of the Atmospheric Sciences Vol. 62, No. 7 ( 2005-07-01), p. 2261-2273
    Details
    In: Journal of the Atmospheric Sciences, American Meteorological Society, Vol. 62, No. 7 ( 2005-07-01), p. 2261-2273
    Kurzfassung: This paper investigates the role of zonal propagation for the equilibration of zonally varying flow. It is hypothesized that there exist two ideal limits, for very small or very large group speed. In the first limit the eddies equilibrate locally with the forcing, while in the second limit the equilibration can only be understood in a global sense. To understand these two limits and to assess which is more relevant for the extratropical troposphere, a series of idealized experiments that involves changing the magnitude of the uniform zonal wind is performed. The results of the idealized model experiments suggest that the actual troposphere is likely to be in a transition regime between the two limits, but perhaps closer to the global than the local limit. Near the global limit, both the eddy amplitude and local baroclinicity over the baroclinic zone are strongly affected by the amount of upstream seeding. When the propagation speed is reduced relative to the control run, the zonal mean eddy activity decreases because the residence time increases more over the stable part of the channel than along the baroclinic zone. With the decrease in upstream seeding, the local supercriticality along the baroclinic zone increases, although the increase is moderate. The decrease in seeding and increase in baroclinicity partially offset the effects of each other, leading to only small changes in the maximum eddy amplitude downstream of the baroclinic zone. Changes in upstream seeding can also be achieved by enhanced damping. When the eddies are locally damped, the baroclinicity is also enhanced downstream of the damping region due to reduced eddy fluxes. For typical parameters, the recovery of the eddy amplitude occurs over very long distances. Based on these idealized results, it is argued that the coexistence of enhanced baroclinicity and weaker eddy amplitude over the Pacific storm track, as compared to the Atlantic storm track, is consistent with the effects of strong eddy damping over Asia.
    Materialart: Online-Ressource
    ISSN: 1520-0469 , 0022-4928
    URL: Article
    DOI: 10.1175/JAS3473.1
    RVK:
    UA 4800
    Sprache: Englisch
    Verlag: American Meteorological Society
    Publikationsdatum: 2005
    ZDB Id: 218351-1
    ZDB Id: 2025890-2
    SSG: 16,13
    Standort Signatur Einschränkungen Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Online-Ressource
  • 9
    Online-Ressource
    Online-Ressource
    The Sensitivity of the Isentropic Slope in a Primitive Equation Dry Model
    American Meteorological Society ; 2008
    In:  Journal of the Atmospheric Sciences Vol. 65, No. 1 ( 2008-01-01), p. 43-65
    Details
    In: Journal of the Atmospheric Sciences, American Meteorological Society, Vol. 65, No. 1 ( 2008-01-01), p. 43-65
    Kurzfassung: This paper discusses the sensitivity of the isentropic slope in a primitive equation dry model forced with Newtonian cooling when the heating is varied. This is done in two different ways, changing either the radiative equilibrium baroclinicity or the diabatic time scale for the zonal-mean flow. When the radiative equilibrium baroclinicity is changed, the isentropic slope remains insensitive against changes in the forcing, in agreement with previous results. However, the isentropic slope steepens when the diabatic heating rate is accelerated for the zonal-mean flow. Changes in the ratio between the interior and the boundary diffusivities as the diabatic heating rate is varied appear to be responsible for the violation of the constant criticality constraint in this model. Theoretical arguments are used to relate the sensitivity of the isentropic slope to that of the isentropic mass flux, which also remains constant when the radiative-equilibrium baroclinicity is changed. The sensitivity of the isentropic mass flux on the heating depends on how the gross stability changes. Bulk stabilities calculated from isobaric averages and gross stabilities estimated from isentropic diagnostics are not necessarily equivalent because a significant part of the return flow occurs at potential temperatures colder than the mean surface temperature.
    Materialart: Online-Ressource
    ISSN: 1520-0469 , 0022-4928
    URL: Article
    DOI: 10.1175/2007JAS2284.1
    RVK:
    UA 4800
    Sprache: Englisch
    Verlag: American Meteorological Society
    Publikationsdatum: 2008
    ZDB Id: 218351-1
    ZDB Id: 2025890-2
    SSG: 16,13
    Standort Signatur Einschränkungen Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Online-Ressource
  • 10
    Online-Ressource
    Online-Ressource
    Nonlinear generation of long waves and the reversal of eddy momentum fluxes in a two-layer quasi-geostrophic model
    American Meteorological Society ; 2021
    In:  Journal of the Atmospheric Sciences ( 2021-08-30)
    Details
    In: Journal of the Atmospheric Sciences, American Meteorological Society, ( 2021-08-30)
    Kurzfassung: Although classical theories of midlatitude momentum fluxes focus on the wave-mean flow interaction, wave-wave interactions may be important for generating long waves. It is shown in this study that this nonlinear generation has implications for eddy momentum fluxes in some regimes. Using a two-layer quasi-geostrophic model of a baroclinic jet on a β -plane, statistically steady states are explored in which the vertically integrated eddy momentum flux is divergent at the center of the jet, rather than convergent as in Earth-like climates. One moves towards this less familiar climate from more Earth-like settings by reducing either β , frictional drag, or the width of the baroclinic zone, or by increasing the upper bound of resolvable wavelengths by lengthening the zonal channel. Even in Earth-like settings, long waves diverge momentum from the jet, but they are too weak to compete with short unstable waves that converge momentum. We argue that long waves are generated by breaking of short unstable waves near their critical latitudes, where long waves converge momentum while diverging momentum at the center of the jet. Quasi-linear models with no wave-wave interaction can qualitatively capture the Earth-like regime but not the regime with momentum flux divergence at the center of the jet, because the nonlinear wave breaking and long wave generation processes are missing. Therefore, a more comprehensive theory of atmospheric eddy momentum fluxes should take into account the nonlinear dynamics of long waves.
    Materialart: Online-Ressource
    ISSN: 0022-4928 , 1520-0469
    URL: Article
    DOI: 10.1175/JAS-D-20-0368.1
    RVK:
    UA 4800
    Sprache: Unbekannt
    Verlag: American Meteorological Society
    Publikationsdatum: 2021
    ZDB Id: 218351-1
    ZDB Id: 2025890-2
    SSG: 16,13
    Standort Signatur Einschränkungen Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Online-Ressource
Schließen ⊗
Diese Webseite nutzt Cookies und das Analyse-Tool Matomo. Weitere Informationen finden Sie hier...