Marine Boundary Layer Cloud Feedbacks in a Constant Relative Humidity Atmosphere

Rieck, Malte; Nuijens, Louise; Stevens, Björn

doi:10.1175/jas-d-11-0203.1

Cited by 165 publications

(216 citation statements)

References 36 publications

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“…One approach is to use large-eddy simulations that resolve low-cloud processes to predict the low-cloud changes forced by the climate changes in the environment (Rieck et al 2012;Zhang et al 2012;Blossey et al 2013;Bretherton 2015). A second approach relies on observations of clouds to predict how they will respond to changes in the large-scale environment typical of climate warming.…”

Section: Seeking Observational Constraints On Low-cloud Feedbacksmentioning

confidence: 99%

Low-Cloud Feedbacks from Cloud-Controlling Factors: A Review

et al. 2017

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The response to warming of tropical low-level clouds including both marine stratocumulus and trade cumulus is a major source of uncertainty in projections of future climate. Climate model simulations of the response vary widely, reflecting the difficulty the models have in simulating these clouds. These inadequacies have led to alternative approaches to predict low-cloud feedbacks. Here, we review an observational approach that relies on the assumption that observed relationships between low clouds and the ''cloud-controlling factors'' of the large-scale environment are invariant across time-scales. With this assumption, and given predictions of how the cloud-controlling factors change with climate warming, one can predict low-cloud feedbacks without using any model simulation of low clouds. We discuss both fundamental and implementation issues with this approach and suggest steps that could reduce uncertainty in the predicted low-cloud feedback. Recent studies using this approach predict that the tropical low-cloud feedback is positive mainly due to the observation that reflection of solar radiation by low clouds decreases as temperature increases, holding all other cloud-controlling factors fixed. The positive feedback from temperature is partially offset by a negative feedback from the tendency for the inversion strength to increase in a warming world, with other cloudcontrolling factors playing a smaller role. A consensus estimate from these studies for the contribution of tropical low clouds to the global mean cloud feedback is

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Section: Seeking Observational Constraints On Low-cloud Feedbacksmentioning

confidence: 99%

Low-Cloud Feedbacks from Cloud-Controlling Factors: A Review

et al. 2017

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“…To test the hypothesis that lower-tropospheric mixing critically influences the trade-cumulus cloud fraction at cloud base (e. g., Rieck et al 2012;Gettelman et al 2012;Sherwood et al 2014;Brient et al 2016;Vial et al 2016), we will need to measure the strength of the convective mixing or quantities closely related to it. Indirect measures of convective mixing, for instance in terms of the relative humidity profile or the strength of shallow overturning circulations, are straightforward to infer from the large-scale structure of humidity field, and measurements of the large-scale vertical velocity.…”

Section: Inferring the Convective Mass Flux At The Top Of The Subcloumentioning

confidence: 99%

“…On the contrary, in large-eddy simulations (LES) and in observations the cloud-base fraction of trade-wind cumuli appears to be much more resilient to changes in environmental conditions than in climate models, both in the current (Nuijens et al 2014(Nuijens et al , 2015a and projected warmer climate (Rieck et al 2012;Bretherton 2015). Interpreting these results remains difficult.…”

Section: Introductionmentioning

confidence: 98%

EUREC4A: A Field Campaign to Elucidate the Couplings Between Clouds, Convection and Circulation

et al. 2017

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Trade-wind cumuli constitute the cloud type with the highest frequency of occurrence on Earth, and it has been shown that their sensitivity to changing environmental conditions will critically influence the magnitude and pace of future global warming. Research over the last decade has pointed out the importance of the interplay between clouds, convection and circulation in controling this sensitivity. 123Surv Geophys (2017) 38:1529-1568 https://doi.org/10.1007/s10712-017-9428-0 cumuli at cloud base is very sensitive to changes in environmental conditions, while process models suggest the opposite. To understand and resolve this contradiction, we propose to organize a field campaign aimed at quantifying the physical properties of tradecumuli (e.g., cloud fraction and water content) as a function of the large-scale environment. Beyond a better understanding of clouds-circulation coupling processes, the campaign will provide a reference data set that may be used as a benchmark for advancing the modelling and the satellite remote sensing of clouds and circulation. It will also be an opportunity for complementary investigations such as evaluating model convective parameterizations or studying the role of ocean mesoscale eddies in air-sea interactions and convective organization.

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“…A number of studies have argued that the response of tropical low clouds to warming is decisive for the determination of the cloud feedbacks. It has been hypothesized that as SSTs rise, enhanced mixing of the boundary layer air with the drier free troposphere dries out the cloud layer and results in less clouds [e.g., Rieck et al, 2012]. Brient et al [2016] showed that models with a pronounced maximum in low cloud amount at cloud base are most susceptible to convective drying, but not through a reduction of clouds throughout the cloud layer, as shown by Rieck et al [2012], rather by a reduction of cloud amount at cloud base.…”

Section: Journal Of Advances In Modeling Earth Systems 101002/2016msmentioning

confidence: 99%

Radiative convective equilibrium as a framework for studying the interaction between convection and its large‐scale environment

Silvers

Stevens

Mauritsen

et al. 2016

J Adv Model Earth Syst

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An uncertain representation of convective clouds has emerged as one of the key barriers to our understanding of climate sensitivity. The large gap in resolved spatial scales between General Circulation Models (GCMs) and high resolution models has made a systematic study of convective clouds across model configurations difficult. It is shown here that the simulated atmosphere of a GCM in Radiative Convective Equilibrium (RCE) is sufficiently similar across a range of domain sizes to justify the use of RCE to study both a GCM and a high resolution model on the same domain with the goal of improved constraints on the parameterized clouds. Simulations of RCE with parameterized convection have been analyzed on domains with areas spanning more than two orders of magnitude ( ), all having the same grid spacing of . The simulated climates on different domains are qualitatively similar in their degree of convective organization, the precipitation rates, and the vertical structure of the clouds and water vapor, with the similarity increasing as the domain size increases. Sea surface temperature perturbation experiments are used to estimate the climate feedback parameter for the differently configured experiments, and the cloud radiative effect is computed to examine the role which clouds play in the response. Despite the similar climate states between the domains the feedback parameter varies by more than a factor of two; the hydrological sensitivity parameter is better behaved, varying by a factor of 1.4. The sensitivity of the climate feedback parameter to domain size is related foremost to a nonsystematic response of low‐level clouds as well as an increasingly negative longwave feedback on larger domains.

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Marine Boundary Layer Cloud Feedbacks in a Constant Relative Humidity Atmosphere

Cited by 165 publications

References 36 publications

Low-Cloud Feedbacks from Cloud-Controlling Factors: A Review

Low-Cloud Feedbacks from Cloud-Controlling Factors: A Review

EUREC4A: A Field Campaign to Elucidate the Couplings Between Clouds, Convection and Circulation

Radiative convective equilibrium as a framework for studying the interaction between convection and its large‐scale environment

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