Changing Degree of Convective Organization as a Mechanism for Dynamic Changes in Extreme Precipitation

Pendergrass, Angeline G.

doi:10.1007/s40641-020-00157-9

Cited by 26 publications

(21 citation statements)

References 70 publications

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“…In this case, synoptic scale processes usually trigger, organize, steer and amplify mesoscale processes [101,102]. The role of changes in convective organization in the response of extreme precipitation to climate change remains uncertain and is an important avenue for future research [103]. It is possible that there may be a difference, too, arising from the dominance of different microphysical mechanisms: e.g.…”

Section: Towards Understanding Mechanisms Of Changementioning

confidence: 99%

Towards advancing scientific knowledge of climate change impacts on short-duration rainfall extremes

Fowler

Ali

Allan

et al. 2021

Phil. Trans. R. Soc. A.

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A large number of recent studies have aimed at understanding short-duration rainfall extremes, due to their impacts on flash floods, landslides and debris flows and potential for these to worsen with global warming. This has been led in a concerted international effort by the INTENSE Crosscutting Project of the GEWEX (Global Energy and Water Exchanges) Hydroclimatology Panel. Here, we summarize the main findings so far and suggest future directions for research, including: the benefits of convection-permitting climate modelling; towards understanding mechanisms of change; the usefulness of temperature-scaling relations; towards detecting and attributing extreme rainfall change; and the need for international coordination and collaboration. Evidence suggests that the intensity of long-duration (1 day+) heavy precipitation increases with climate warming close to the Clausius–Clapeyron (CC) rate (6–7% K −1 ), although large-scale circulation changes affect this response regionally. However, rare events can scale at higher rates, and localized heavy short-duration (hourly and sub-hourly) intensities can respond more strongly (e.g. 2 × CC instead of CC). Day-to-day scaling of short-duration intensities supports a higher scaling, with mechanisms proposed for this related to local-scale dynamics of convective storms, but its relevance to climate change is not clear. Uncertainty in changes to precipitation extremes remains and is influenced by many factors, including large-scale circulation, convective storm dynamics andstratification. Despite this, recent research has increased confidence in both the detectability and understanding of changes in various aspects of intense short-duration rainfall. To make further progress, the international coordination of datasets, model experiments and evaluations will be required, with consistent and standardized comparison methods and metrics, and recommendations are made for these frameworks. This article is part of a discussion meeting issue ‘Intensification of short-duration rainfall extremes and implications for flash flood risks’.

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Section: Towards Understanding Mechanisms Of Changementioning

confidence: 99%

Towards advancing scientific knowledge of climate change impacts on short-duration rainfall extremes

Fowler

Ali

Allan

et al. 2021

Phil. Trans. R. Soc. A.

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show abstract

“…The large inter-model differences in the response in the tropics [4] arise partly because of parameterizations of deep convection which are known to strongly affect the intensity distribution of precipitation [5]. Furthermore, the inability of coarse global climate models to represent mesoscale organization of convection calls into question their ability to correctly simulate the response of precipitation extremes to climate change [6], and the role of convective organization in this response is an active area of research [7–9]. A number of studies have analysed precipitation extremes in regional simulations at high resolution run without a convective parameterization of deep convection [10–12], but because of their regional focus it is difficult to use the results to understand the global response and the role of large-scale dynamics in shaping this response.…”

Section: Introductionmentioning

confidence: 99%

Response of extreme precipitation to uniform surface warming in quasi-global aquaplanet simulations at high resolution

O’Gorman

Boos

Yuval

2021

Phil. Trans. R. Soc. A.

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Projections of precipitation extremes in simulations with global climate models are very uncertain in the tropics, in part because of the use of parameterizations of deep convection and model deficiencies in simulating convective organization. Here, we analyse precipitation extremes in high-resolution simulations that are run without a convective parameterization on a quasi-global aquaplanet. The frequency distributions of precipitation rates and precipitation cluster sizes in the tropics of a control simulation are similar to the observed distributions. In response to climate warming, 3 h precipitation extremes increase at rates of up to 9 % K − 1 in the tropics because of a combination of positive thermodynamic and dynamic contributions. The dynamic contribution at different latitudes is connected to the vertical structure of warming using a moist static stability. When the precipitation rates are first averaged to a daily timescale and coarse-grained to a typical global climate-model resolution prior to calculating the precipitation extremes, the response of the precipitation extremes to warming becomes more similar to what was found previously in coarse-resolution aquaplanet studies. However, the simulations studied here do not exhibit the high rates of increase of tropical precipitation extremes found in projections with some global climate models. This article is part of a discussion meeting issue ‘Intensification of short-duration rainfall extremes and implications for flash flood risks’.

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“…One of the debates in these studies is whether precipitation extreme increases with convective organisation with the definition of extreme varying from instantaneous to short time‐scale (e.g. daily), and spatially considering an area‐specific extreme or only that within deep convection (see review in Pendergrass, 2020). So far the result of β ∼ 4/3 from both observations and our current model analysis suggests that the extreme part of the within‐cluster rainfall intensity ( R / A ∼ A 1/3 ) likely would increase with the degree of organisation, at least for those mesoscale convective clusters or smaller.…”

Section: Resultsmentioning

confidence: 99%

Scaling characteristics of modelled tropical oceanic rain clusters

Teo

Koh

Cheung

et al. 2021

Quart J Royal Meteoro Soc

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The scaling exponents of the distributions of cluster rain amount, R, and cluster size, A, for oceanic rain clusters over the Indian and Pacific warm pools, and the intertropical convergence zones over the eastern Pacific and the tropical Atlantic, were obtained from a set of regional climate model downscaling products. The main aim of the investigation is to compare the model cluster's scaling characteristics with those obtained from observations that have been reported previously. The scaling exponents for the model were found to be different across the ocean basins indicating the lack of universality in the modelled rain cluster distributions. The scaling exponent for the conditional mean of R given A = a, E(R|a), was found to be the same across the different ocean basins, and the estimated value of the exponent agrees with that obtained from satellite‐observed rain clusters. However, no crossover in the scaling of E(R|a) in the model for cluster size larger than mesoscale was seen, unlike those reported elsewhere based on observations. The implication is that in the model the intensification of rain with cluster size continues up to synoptic scale. Through simple scaling arguments it is believed that before the break in scaling that has been identified from an observational study elsewhere, the model simulates the fundamental mesoscale dynamics well and thus estimated the E(R|a) in agreement with observations. Whether such a difference in transition of scaling between the modelled and observed rain cluster scaling behaviour depends on the model details, for example the convection parametrization, needs further clarification.

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Changing Degree of Convective Organization as a Mechanism for Dynamic Changes in Extreme Precipitation

Cited by 26 publications

References 70 publications

Towards advancing scientific knowledge of climate change impacts on short-duration rainfall extremes

Towards advancing scientific knowledge of climate change impacts on short-duration rainfall extremes

Response of extreme precipitation to uniform surface warming in quasi-global aquaplanet simulations at high resolution

Scaling characteristics of modelled tropical oceanic rain clusters

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