A simple model of convection with memory

Davies, Laura; Plant, Robert S.; Derbyshire, S. H.

doi:10.1029/2008jd011653

Cited by 19 publications

(28 citation statements)

References 27 publications

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“…Davies et al (2009) considered an idealized analytic model of convection for an atmosphere being radiatively cooled at a prescribed constant rate above a surface with a prescribed, time‐varying temperature. The functional form of the time variation was chosen as an idealization of the diurnal cycle over land.…”

Section: Characterizing Convection With Memorymentioning

confidence: 99%

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Departures from convective equilibrium with a rapidly varying surface forcing

Davies

Plant

Derbyshire

2013

Quart J Royal Meteoro Soc

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Convective equilibrium is a long-standing and useful concept for understanding many aspects of the behaviour of deep moist convection. For example, it is often invoked in developing parametrizations for large-scale models. However, the equilibrium assumption may begin to break down as models are increasingly used with shorter time steps and finer resolutions. Here we perform idealized cloud-system resolving model simulations of deep convection with imposed time variations in the surface forcing. A range of rapid forcing time-scales from 1 to 36 h are used, in order to induce systematic departures from equilibrium. For the longer forcing time-scales, the equilibrium assumption remains valid, in at least the limited sense that cycle-integrated measures of convective activity are very similar from cycle to cycle. For shorter forcing time-scales, cycle-integrated convection becomes more variable, with enhanced activity on one cycle being correlated with reduced activity on the next, suggesting a role for convective memory. Further investigation shows that the memory does not appear to be carried by the domain-mean thermodynamic fields but rather by structures on horizontal scales of 5-20 km. Such structures are produced by the convective clouds and can persist beyond the lifetime of the cloud, even through to the next forcing cycle.

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Section: Characterizing Convection With Memorymentioning

confidence: 99%

“…Davies et al (2009) investigated a simple dynamical system which may provide an idealized model of convection with memory effects. The system is essentially a reinterpretation of the prognostic system of Pan and Randall (1998) but with its response studied for an imposed periodic forcing.…”

Section: Introductionmentioning

confidence: 99%

Departures from convective equilibrium with a rapidly varying surface forcing

Davies

Plant

Derbyshire

2013

Quart J Royal Meteoro Soc

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“… Davies et al [2009]explicitly demonstrate the importance of time scale separation in order to establish CQE. They consider a dynamical system consisting of a fixed periodic large‐scale forcing and a convective relaxation time scale.…”

Section: Interpretations Of Cqementioning

confidence: 99%

Convective quasi‐equilibrium

Yano

Plant

2012

Reviews of Geophysics

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[1] The concept of convective quasi-equilibrium (CQE) is a key ingredient in order to understand the role of deep moist convection in the atmosphere. It has been used as a guiding principle to develop almost all convective parameterizations and provides a basic theoretical framework for large-scale tropical dynamics. The CQE concept as originally proposed by Arakawa and Schubert (1974) is systematically reviewed from wider perspectives. Various interpretations and extensions of Arakawa and Schubert's CQE are considered both in terms of a thermodynamic analogy and as a dynamical balance. The thermodynamic interpretations can be more emphatically embraced as a homeostasis. The dynamic balance interpretations can be best understood by analogy with the slow manifold. Various criticisms of CQE can be avoided by taking the dynamic balance interpretation. Possible limits of CQE are also discussed, including the importance of triggering in many convective situations, as well as the possible self-organized criticality of tropical convection. However, the most intriguing aspect of the CQE concept is that in spite of many observational tests supporting and interpreting it in many different senses, it has never been established in a robust manner based on a systematic analysis of the cloud work function budget by observations as was originally defined.

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“…Complementary to the approach in Mapes and Neale (2011), the two‐dimensional CA field in the present study is acting on the subgrid of the numerical model, such that one CA cell aims to represent the horizontal scale of individual convective plumes; furthermore, it contains stochastic elements and has self‐organizational properties. The importance of convective memory has also been explored by Frank and Cohen (1987), Pan and Randall (1998), Piriou et al (2007) and Davies et al (2009).…”

Section: Introductionmentioning

confidence: 99%

Electrochemistry of Carbon Nanotubes: Reactive Processes, Dual Sensing–Actuating Properties and Devices

Martínez

Sugino²,

Asaka³

et al. 2012

ChemPhysChem

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Single-walled carbon nanotubes (SWCNT) embedded in a non-electroactive polymer are electrochemically characterized. The increasing voltammetric maximums obtained with rising temperature or electrolyte concentration point to a chemical nature of the processes. The chemical kinetic control of the processes is corroborated by its empirical chemical kinetics: the initial reaction rates are obtained from the chronoamperometric responses to potential steps. The activation energy of the reaction includes information about the structural state of the SWCNT before the potential step. Under constant current the potential evolution (chronopotentiometric response) and consumed electrical energy at any time change as a function of (are sensors of) the experimental temperature or the electrolyte concentration. The reactive material, or any device based on this material, senses these working variables, and shows dual and simultaneous actuating-sensing properties.

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A simple model of convection with memory

Cited by 19 publications

References 27 publications

Departures from convective equilibrium with a rapidly varying surface forcing

Departures from convective equilibrium with a rapidly varying surface forcing

Convective quasi‐equilibrium

Electrochemistry of Carbon Nanotubes: Reactive Processes, Dual Sensing–Actuating Properties and Devices

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