Modes of Tropical Variability under Convective Adjustment and the Madden–Julian Oscillation. Part I: Analytical Theory

Neelin, J. David; Yu, Jia‐Yuh

doi:10.1175/1520-0469(1994)051<1876:motvuc>2.0.co;2

Cited by 208 publications

(249 citation statements)

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“…For humidity, the reference profile q ref is a constant relative humidity (RH SBM ) with respect to this moist adiabat. This form of humidity reference profile, also used in Neelin and Yu (1994), is simplified compared with the original Betts-Miller profile. The simplified Betts-Miller scheme is called whenever there is convective available potential energy (CAPE).…”

Section: Model Descriptions and Experimental Designmentioning

confidence: 99%

“…In these two studies, the changes in circulation strength and CCEW speed are interpreted with the concept of ''gross moist stability'' (Neelin and Held 1987;Emanuel et al 1994;Neelin 2007). When the gross moist stability is smaller, theoretical work suggests a stronger and narrower precipitating region (Bretherton and Sobel 2002;Chou and Neelin 2004), slower CCEWs (Neelin et al 1987;Neelin and Yu 1994;Frierson et al 2004), and a larger response to perturbations (Neelin and Su 2005;Chou et al 2006). Thus, in this section, we study the response of the model to the convection scheme parameter RH SBM , which changes the tropical gross moist stability.…”

Section: B Sensitivity To the Convection Schemementioning

confidence: 99%

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The Tropical Response to Extratropical Thermal Forcing in an Idealized GCM: The Importance of Radiative Feedbacks and Convective Parameterization

Kang

Frierson

Held

2009

Journal of the Atmospheric Sciences

298

410

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The response of tropical precipitation to extratropical thermal forcing is reexamined using an idealized moist atmospheric GCM that has no water vapor or cloud feedbacks, simplifying the analysis while retaining the aquaplanet configuration coupled to a slab ocean from the authors' previous study. As in earlier studies, tropical precipitation in response to high-latitude forcing is skewed toward the warmed hemisphere. Comparisons with a comprehensive GCM in an identical aquaplanet, mixed-layer framework reveal that the tropical responses tend to be much larger in the comprehensive GCM as a result of positive cloud and water vapor feedbacks that amplify the imposed extratropical thermal forcing.The magnitude of the tropical precipitation response in the idealized model is sensitive to convection scheme parameters. This sensitivity as well as the tropical precipitation response can be understood from a simple theory with two ingredients: the changes in poleward energy fluxes are predicted using a onedimensional energy balance model and a measure of the ''total gross moist stability'' [Dm, which is defined as the total (mean plus eddy) atmospheric energy transport per unit mass transport] of the model tropics converts the energy flux change into a mass flux and a moisture flux change. The idealized model produces a low level of compensation of about 25% between the imposed oceanic flux and the resulting response in the atmospheric energy transport in the tropics regardless of the convection scheme parameter. Because Geophysical Fluid Dynamics Laboratory Atmospheric Model 2 (AM2) with prescribed clouds and water vapor exhibits a similarly low level of compensation, it is argued that roughly 25% of the compensation is dynamically controlled through eddy energy fluxes. The sensitivity of the tropical response to the convection scheme in the idealized model results from different values of Dm: smaller Dm leads to larger tropical precipitation changes for the same response in the energy transport.

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Section: Model Descriptions and Experimental Designmentioning

confidence: 99%

Section: B Sensitivity To the Convection Schemementioning

confidence: 99%

The Tropical Response to Extratropical Thermal Forcing in an Idealized GCM: The Importance of Radiative Feedbacks and Convective Parameterization

Kang

Frierson

Held

2009

Journal of the Atmospheric Sciences

298

410

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“…The present model is equivalent to the linear EWF model of Neelin and Yu (1994) using the BettsMiller scheme, except that the present model explicitly expresses the prognostic-adjustment process in terms of large-scale forcing. Their model allows "propagating deep convective mode" that corresponds to Mode I, but does not allow Modes J and K, since their model has either a lid or radiation condition at the top of the convective layer.…”

Section: Interpretations Of the Resultsmentioning

confidence: 99%

“…In the linearized Betts-Miller scheme theoretically studied by Neelin and Yu (1994), the effect of diagnostic adjustment can be represented by "fast modes" which quickly decay with time. When slow and fast modes initially cancel each other and the fast modes decay, the sum of these modes grow through the transient nonmodal growth mechanism (see Farrell,1989;Farrell and Iaonnou,1996a,b;Trefethen et al, 1993).…”

Section: Comparison With Other Schemesmentioning

confidence: 99%

United Mechanisms for the Generation of Low- and High-Frequency Tropical Waves. Part II

Hayashi¹,

Golder²

1997

Journal of the Meteorological Society of Japan

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It is assumed that low-and high-frequency tropical waves are generated by the united mechanisms consisting of the evaporation-wind feedback (EWF), saturation-triggering (ST), and lateral-triggering mechanisms. Through the EWF mechanism, some waves become unstable owing to evaporation-wind feedback. Through the ST mechanism, other waves are triggered by the intermittent onset of moist convection, upon saturation, to neutralize any pre-existing conditionally unstable stratification. These mechanisms are theoretically interpreted by partitioning moist connective adjustment into two consecutive processes of diagnostic and prognostic adjustments. The two processes respectively restore and maintain convective equilibrium, and are crucial to the ST and EWF mechanisms.As a step to toward a unified theory, EWF instability is examined by the use of a theoretical Kelvin-wave model, which incorporates only the prognostic-adjustment process in the linearized perturbation equations, thereby excluding the ST mechanism. The solutions indicate that wave instability results from the EWF mechanism and not from the wave-CISK mechanism. For a plausible choice of adjustable parameters, one strongly unstable mode corresponds to the observed 40-50-day oscillation, while two weakly unstable modes correspond to the observed 25-30-day and 10-20-day oscillations.These results are compared with those from the numerical experiments conducted in Part I, using a nonlinear model incorporating the original moist convective adjustment scheme. It is then speculated that the 40-50-and 25-30-day modes can strongly grow through the linear and nonlinear EWF mechanisms respectively, while the 10-20-day mode can strongly amplify through the ST mechanism.

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“…As a result, in addition to conventional equatorial-wave modes, another mode called "moisture mode" arises. The moisture mode is, as the name suggests, typically characterized by a dominance of the moisture field relative to the temperature field (Neelin and Yu, 1994;Sugiyama, 2009a,b;Fuchs et al, 2012).…”

Section: Perspective From the Tropical Large-scale Dynamicsmentioning

confidence: 99%

Phenomenology of convection-parameterization closure

et al. 2013

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Closure is a problem of defining the convective intensity in a given parameterization. In spite of many years of efforts and progress, it is still considered an overall unresolved problem. The present article reviews this problem from phenomenological perspectives.

The physical variables that may contribute in defining the convective intensity are listed, and their statistical significances identified by observational data analyses are reviewed. A possibility is discussed for identifying a correct closure hypothesis by performing a linear stability analysis of tropical convectively coupled waves with various different closure hypotheses. Various individual theoretical issues are considered from various different perspectives. The review also emphasizes that the dominant physical factors controlling convection differ between the tropics and extra-tropics, as well as between oceanic and land areas.

Both observational as well as theoretical analyses, often focused on the tropics, do not necessarily lead to conclusions consistent with our operational experiences focused on midlatitudes. Though we emphasize the importance of the interplays between these observational, theoretical and operational perspectives, we also face challenges for establishing a solid research framework that is universally applicable. An energy cycle framework is suggested as such a candidate

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Modes of Tropical Variability under Convective Adjustment and the Madden–Julian Oscillation. Part I: Analytical Theory

Cited by 208 publications

References 0 publications

The Tropical Response to Extratropical Thermal Forcing in an Idealized GCM: The Importance of Radiative Feedbacks and Convective Parameterization

The Tropical Response to Extratropical Thermal Forcing in an Idealized GCM: The Importance of Radiative Feedbacks and Convective Parameterization

United Mechanisms for the Generation of Low- and High-Frequency Tropical Waves. Part II

Phenomenology of convection-parameterization closure

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