Convective Self-Aggregation in Numerical Simulations: A Review

Wing, Allison A.; Emanuel, Kerry; Holloway, Christopher E.; Muller, Caroline

doi:10.1007/s10712-017-9408-4

Cited by 189 publications

(286 citation statements)

References 72 publications

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“…As mentioned in Wing et al (2017), this kind of exponential growth will lead to much larger scales in a given amount of time when starting from larger initial clustering, as is typically found in nature. In other words, much of the time scale for selfaggregation from homogeneous initial conditions may not be especially relevant to comparisons with nature because these time periods involve spinning up mesoscale activity from extremely small initial length scales (and may also involve gestation periods before aggregation begins at all).…”

Section: Time Scales Of Self-aggregationmentioning

confidence: 80%

“…We focus on those which could be targeted in observations; a more complete review can be found in Wing et al (2017).…”

Section: Observational Perspectives On Processes Important For Idealizedmentioning

confidence: 99%

“…In the following, we briefly review the various physical processes contributing to the formation of this radiatively driven cold pool for temperatures close to current tropical atmospheric temperatures, and then we discuss the sensitivity of these processes to SST. A more complete review can be found in Wing et al (2017).…”

Section: Initiation Processesmentioning

confidence: 99%

“…As mentioned in Wing et al (2017), self-aggregation in idealized models can take 15-100 days or more to reach a relatively stable aggregated state when starting from homogeneous initial conditions (though the longer time scales likely relate to an initial gestation period in some simulations which occurs before aggregation has started at all). There is some sensitivity of this to domain size and grid scale (Muller and Held 2012).…”

Section: Time Scales Of Self-aggregationmentioning

confidence: 99%

“…Wing et al 2017), there has been a recurring question: Is this ''real''? In other words, is the intriguing clumping behavior representative of actual convective organization in nature, or is it just a model artifact?…”

Section: Introductionmentioning

confidence: 99%

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Observing Convective Aggregation

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Convective self-aggregation, the spontaneous organization of initially scattered convection into isolated convective clusters despite spatially homogeneous boundary conditions and forcing, was first recognized and studied in idealized numerical simulations. While there is a rich history of observational work on convective clustering and organization, there have been only a few studies that have analyzed observations to look specifically for processes related to self-aggregation in models. Here we review observational work in both of these categories and motivate the need for more of this work. We acknowledge that self-aggregation may appear to be far-removed from observed convective organization in terms of time scales, initial conditions, initiation processes, and mean state extremes, but we argue that these differences vary greatly across the diverse range of 123Surv Geophys (2017) 38:1199-1236 https://doi.org/10.1007/s10712-017-9419-1 model simulations in the literature and that these comparisons are already offering important insights into real tropical phenomena. Some preliminary new findings are presented, including results showing that a self-aggregation simulation with square geometry has too broad distribution of humidity and is too dry in the driest regions when compared with radiosonde records from Nauru, while an elongated channel simulation has realistic representations of atmospheric humidity and its variability. We discuss recent work increasing our understanding of how organized convection and climate change may interact, and how model discrepancies related to this question are prompting interest in observational comparisons. We also propose possible future directions for observational work related to convective aggregation, including novel satellite approaches and a groundbased observational network.

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Section: Time Scales Of Self-aggregationmentioning

confidence: 80%

“…We focus on those which could be targeted in observations; a more complete review can be found in Wing et al (2017).…”

Section: Observational Perspectives On Processes Important For Idealizedmentioning

confidence: 99%

Section: Initiation Processesmentioning

confidence: 99%

Section: Time Scales Of Self-aggregationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Observing Convective Aggregation

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Convective aggregation in realistic convective‐scale simulations

Holloway

2017

J Adv Model Earth Syst

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To investigate the real‐world relevance of idealized‐model convective self‐aggregation, five 15 day cases of real organized convection in the tropics are simulated. These include multiple simulations of each case to test sensitivities of the convective organization and mean states to interactive radiation, interactive surface fluxes, and evaporation of rain. These simulations are compared to self‐aggregation seen in the same model configured to run in idealized radiative‐convective equilibrium. Analysis of the budget of the spatial variance of column‐integrated frozen moist static energy shows that control runs have significant positive contributions to organization from radiation and negative contributions from surface fluxes and transport, similar to idealized runs once they become aggregated. Despite identical lateral boundary conditions for all experiments in each case, systematic differences in mean column water vapor (CWV), CWV distribution shape, and CWV autocorrelation length scale are found between the different sensitivity runs, particularly for those without interactive radiation, showing that there are at least some similarities in sensitivities to these feedbacks in both idealized and realistic simulations (although the organization of precipitation shows less sensitivity to interactive radiation). The magnitudes and signs of these systematic differences are consistent with a rough equilibrium between (1) equalization due to advection from the lateral boundaries and (2) disaggregation due to the absence of interactive radiation, implying disaggregation rates comparable to those in idealized runs with aggregated initial conditions and noninteractive radiation. This points to a plausible similarity in the way that radiation feedbacks maintain aggregated convection in both idealized simulations and the real world.

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A perspective on climate model hierarchies

Jeevanjee

Hassanzadeh

Hill

et al. 2017

J Adv Model Earth Syst

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To understand Earth's climate, climate modelers employ a hierarchy of climate models spanning a wide spectrum of complexity and comprehensiveness. This essay, inspired by the World Climate Research Programme's recent “Model Hierarchies Workshop,” attempts to survey and synthesize some of the current thinking on climate model hierarchies, especially as presented at the workshop. We give a few formal descriptions of the hierarchy and survey the various ways it is used to generate, test, and confirm hypotheses. We also discuss some of the pitfalls of contemporary climate modeling, and how the “elegance” advocated for by Held (2005) has (and has not) been used to address them. We conclude with a survey of current activity in hierarchical modeling, and offer suggestions for its continued fruitful development.

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Convective Self-Aggregation in Numerical Simulations: A Review

Cited by 189 publications

References 72 publications

Observing Convective Aggregation

Observing Convective Aggregation

Convective aggregation in realistic convective‐scale simulations

A perspective on climate model hierarchies

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