Larger Cloud Liquid Water Enhances Both Aerosol Indirect Forcing and Cloud Radiative Feedback in Two Earth System Models

Geophysical Research Letters, Journal Year: 2024, Volume and Issue: 51(2)

Published: Jan. 24, 2024

Abstract Previous studies have noticed that the Coupled Model Intercomparison Project Phase 6 (CMIP6) models with a stronger cooling from aerosol‐cloud interactions (ACI) also an enhanced warming positive cloud feedback, and these two opposing effects are counter‐balanced in simulations of historical period. However, reasons for this anti‐correlation less explored. In study, we perturb ice microphysical processes to obtain liquid varying amounts Earth System Models (ESMs). We find model larger water path (LWP) tend ACI feedback. More clouds mean‐state present more opportunities anthropogenic aerosol perturbations weaken negative feedback at middle high latitudes. This work, state perspective, emphasizes influence LWP on effective radiative forcing due (ERF ).

Language: Английский

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Cloud properties and their projected changes in CMIP models with low to high climate sensitivity

Atmospheric chemistry and physics, Journal Year: 2024, Volume and Issue: 24(3), P. 1587 - 1605

Published: Feb. 5, 2024

Abstract. Since the release of first Coupled Model Intercomparison Project version 6 (CMIP6) simulations, one most discussed topics is higher effective climate sensitivity (ECS) some models, resulting in an increased range ECS values CMIP6 compared to previous CMIP phases. An important contribution cloud feedback. Although models have continuously been developed and improved over last few decades, a realistic representation clouds remains challenging. Clouds contribute large uncertainties modeled ECS, as projected changes properties feedbacks also depend on simulated present-day fields. In this study, we investigate both physical radiative from total 51 CMIP5 models. used simple metric group warming closely related feedbacks, which turn are known ECS. Projected future scenario simulations analyzed by group. order help with interpreting changes, model results historical analyzed. The show that differences net effect reaction among three groups driven regimes rather than individual regions. polar regions, high-ECS weaker increase cooling clouds, due warming, low-ECS At same time, decrease tropical ocean subtropical stratocumulus whereas either little change or even effect. Over Southern Ocean,

Language: Английский

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A systematic evaluation of high-cloud controlling factors

Atmospheric chemistry and physics, Journal Year: 2024, Volume and Issue: 24(14), P. 8295 - 8316

Published: July 24, 2024

Abstract. Clouds strongly modulate the top-of-the-atmosphere energy budget and are a major source of uncertainty in climate projections. “Cloud controlling factor” (CCF) analysis derives relationships between large-scale meteorological drivers cloud radiative anomalies, which can be used to constrain feedback. However, choice CCFs is crucial for meaningful constraint. While there rich literature investigating ideal CCF setups low-level clouds, lack analogous research explicitly targeting high clouds. Here, we use ridge regression systematically evaluate addition five candidate previously established core within large spatial domains predict longwave high-cloud anomalies: upper-tropospheric static stability (SUT), sub-cloud moist energy, convective available potential inhibition, wind shear (ΔU300). We identify an optimal configuration predicting anomalies that includes SUT ΔU300 show domain size more important than selection predictive skill. also find discrepancy sizes required locally globally aggregated anomalies. Finally, scientifically interpret coefficients, where captures physical known feedbacks deduce inclusion into observational constraint frameworks may reduce associated with changes anvil amount as function change. Therefore, highlight clouds

Language: Английский

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Opinion: Tropical cirrus – from micro-scale processes to climate-scale impacts

Atmospheric chemistry and physics, Journal Year: 2023, Volume and Issue: 23(24), P. 15413 - 15444

Published: Dec. 18, 2023

Abstract. Tropical cirrus clouds, i.e., any type of ice cloud with tops above 400 hPa, play a critical role in the climate system and are major source uncertainty our understanding global warming. clouds involve processes spanning wide range spatial temporal scales, from microphysics on scales to mesoscale convective organization planetary wave dynamics. This complexity makes tropical notoriously difficult model has left many important questions stubbornly unanswered. At same time, their multi-scale nature them well-positioned benefit rise global, high-resolution simulations Earth's atmosphere growing abundance remotely sensed situ observations. Rapid progress requires coordinated efforts take advantage these modern computational observational abilities. In this opinion paper, we review recent studies, highlight unanswered questions, discuss promising paths forward. Significant been made life cycle convectively generated “anvil” response macrophysical properties large-scale controls. On other hand, much work remains be done fully understand how small-scale anvil climatological radiative effect will respond Thin, formed now known closely tied thermal structure humidity tropopause layer, but microphysical uncertainties prevent full link, as well precise amount water vapor entering stratosphere. Model representation ice-nucleating particles, supersaturation, depositional growth continue pose great challenges modeling. We believe that advances can through combination cross-tool synthesis cross-scale studies conducted by cross-disciplinary research teams.

Language: Английский

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Multi-objective observational constraint of tropical Atlantic and Pacific low-cloud variability narrows uncertainty in cloud feedback

Nature Communications, Journal Year: 2025, Volume and Issue: 16(1)

Published: Jan. 2, 2025

Tropical marine low cloud feedback is key to the uncertainty in climate sensitivity, and it depends on warming pattern of sea surface temperatures (SSTs). Here, we empirically constrain this two major regions, tropical Pacific Atlantic, using interannual variability. Low sensitivities local SST remote SST, represented by lower-troposphere temperature, are poorly captured many models latest global model ensemble, especially less-studied Atlantic. The Atlantic favors large positive that appears difficult reconcile with Pacific—we apply a Pareto optimization approach elucidate trade-offs between conflicting observational constraints. Examining ~200,000 possible combinations subensembles, multi-objective constraint narrows among models, nearly eliminates possibility negative shortwave CO2-induced warming, suggests 71% increase feedback. low-cloud variability simultaneously capture models. reconciles feedbacks basins, constraining toward higher values.

Language: Английский

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Understanding equilibrium climate sensitivity changes from CMIP5 to CMIP6: Feedback, AMOC, and precipitation responses

Atmospheric Research, Journal Year: 2025, Volume and Issue: unknown, P. 107917 - 107917

Published: Jan. 1, 2025

Language: Английский

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Aerosol trends dominate over global warming-induced cloud feedback in driving recent changes in marine low clouds

Research Square (Research Square), Journal Year: 2025, Volume and Issue: unknown

Published: Feb. 13, 2025

Over the past two decades, anthropogenic emission reductions and global warming have impacted marine low clouds through aerosol-cloud interactions (ACI) cloud feedback, yet their quantitative contributions remain unclear. This study employs a deep learning model (CNN_Met−Nd) Community Earth System Model version 2 (CESM2) to disentangle these effects. CNN_Met−Nd reveals that aerosol-driven changes in droplet number concentration dominate near-global shortwave radiative effect (ΔCRE), contributing 0.42 ± 0.08 Wm⁻² per 20 years, compared 0.05 0.37 from feedback. CESM2 effectively reproduces predominant influence of aerosol on ΔCRE by CNN_Met−Nd, lending us confidence for stronger estimate effective forcing due ACI (ERF_aci) -1.29 since preindustrial era. These findings highlight critical role shaping trends its broader climate implications, especially under ongoing reduction efforts.

Language: Английский

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Insights on Tropical High‐Cloud Radiative Effect From a New Conceptual Model

Journal of Advances in Modeling Earth Systems, Journal Year: 2025, Volume and Issue: 17(2)

Published: Feb. 1, 2025

Abstract The new capabilities of global storm‐resolving models to resolve individual clouds allow for a more physical perspective on the tropical high‐cloud radiative effect and how it might change with warming. In this study, we develop conceptual model as function cloud thickness measured by ice water path. We use atmospheric profiles from ICON simulation horizontal grid spacing calculate radiation offline ARTS line‐by‐line transfer model. reveals that is sufficient approximate high single layer characterized an albedo, emissivity temperature, which vary increase short‐wave path solely explained albedo. long‐wave governed below , decrease temperature increasing above threshold. mean simulations chosen day run closely matched our . Because depends assumed alternative, assumptions low make substantial difference. predicts doubling fraction roughly doubles positive effect.

Language: Английский

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Assessing Cloud Fraction in the Canadian Regional Climate Model Over North America Using Satellite Data and a Satellite Simulator Package

Journal of Geophysical Research Atmospheres, Journal Year: 2025, Volume and Issue: 130(7)

Published: March 27, 2025

Abstract Clouds are crucial to Earth's climate system, influencing radiation and contributing projection uncertainties. Here, the simulated cloud fraction by sixth version of Canadian Regional Climate Model (CRCM6‐GEM5) was evaluated using CALIPSO lidar retrievals second Cloud Feedback Intercomparison Project (CFMIP) Observation Simulator Package (COSP2) for years 2014 2015. Horizontal vertical distributions clouds in CRCM6‐GEM5 model were profiles four categories (total, high‐, mid‐, low‐level clouds) derived directly from treated COSP2 satellite simulator. A seasonal analysis conducted across specific regions North America. Results showed that use is essential comparing outputs against data account variable definitions signal attenuation active instruments (e.g., Cloud‐Aerosol Lidar with Orthogonal Polarization: CALIOP). Spatial patterns generally well represented both winter (December–February) summer (June–August). High‐ particularly well‐represented, especially winter. The demonstrated some difficulty producing enough accurately represent those at mid‐level. representation systematically better during than summer. performed over whole American domain confirmed help mitigate discrepancies definitions. These results contribute a understanding representations high‐resolution models.

Language: Английский

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Climate Models Underestimate Global Decreases in High‐Cloud Amount With Warming

Geophysical Research Letters, Journal Year: 2025, Volume and Issue: 52(7)

Published: April 9, 2025

Abstract Cloud feedback has prevailed as a leading source of uncertainty in climate model projections under increasing atmospheric carbon dioxide. Cloud‐controlling factor (CCF) analysis is an approach used to observationally constrain cloud feedback, and subsequently the sensitivity. Although high clouds contribute significantly toward uncertainty, they have received comparatively little attention CCF other observational analyses. Here we use for first time ‐cloud radiative focusing on amount component owing its dominant contribution high‐cloud feedback. Globally, observations indicate larger decreases cloudiness than state‐of‐the‐art models suggest. In fact, half 16 considered here predict feedbacks inconsistent with observations, likely due misrepresenting stability iris mechanism. Despite suggested strong warming, point near‐neutral net almost canceling longwave shortwave contributions.

Language: Английский

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