Ice-nucleating agents in sea spray aerosol identified and quantified with a holistic multimodal freezing model

Science Advances, Journal Year: 2022, Volume and Issue: 8(44)

Published: Nov. 2, 2022

Sea spray aerosol (SSA) is a widely recognized important source of ice-nucleating particles (INPs) in the atmosphere. However, composition-specific identification, nucleation processes, and ice rates SSA-INPs have not been well constrained. Microspectroscopic characterization ambient laboratory-generated SSA confirms that water-borne exudates from planktonic microorganisms composed mixture proteinaceous polysaccharidic compounds act as agents (INAs). These data previously published mesocosm wave channel studies are subsequently used to further develop stochastic freezing model (SFM) producing rate coefficients for SSA-INPs. The SFM simultaneously predicts immersion deposition homogeneous by under tropospheric conditions. Predicted INP concentrations agree with laboratory measurements. In addition, this holistic independent exact composition particles, making it suited implementation cloud climate models.

Language: Английский

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Systematic and objective evaluation of Earth system models: PCMDI Metrics Package (PMP) version 3

Geoscientific model development, Journal Year: 2024, Volume and Issue: 17(9), P. 3919 - 3948

Published: May 15, 2024

Abstract. Systematic, routine, and comprehensive evaluation of Earth system models (ESMs) facilitates benchmarking improvement across model generations identifying the strengths weaknesses different configurations. By gauging consistency between observations, this endeavor is becoming increasingly necessary to objectively synthesize thousands simulations contributed Coupled Model Intercomparison Project (CMIP) date. The Program for Climate Diagnosis (PCMDI) Metrics Package (PMP) an open-source Python software package that provides quick-look objective comparisons ESMs with one another observations. include metrics large- global-scale climatologies, tropical inter-annual intra-seasonal variability modes such as El Niño–Southern Oscillation (ENSO) Madden–Julian (MJO), extratropical variability, regional monsoons, cloud radiative feedbacks, high-frequency characteristics simulated precipitation, including its extremes. PMP comparison results are produced using all CMIP6 earlier CMIP phases. An important document performance participating in recent phases CMIP, together providing version-controlled information datasets, packages, analysis codes being used process. Among other purposes, also enables modeling groups assess changes during ESM development cycle context error distribution multi-model ensemble. Quantitative provided by can assist modelers their priorities. In paper, we provide overview PMP, latest capabilities, discuss future direction.

Language: Английский

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Weak anvil cloud area feedback suggested by physical and observational constraints

Nature Geoscience, Journal Year: 2024, Volume and Issue: 17(5), P. 392 - 397

Published: April 1, 2024

Abstract Changes in anvil clouds with warming remain a leading source of uncertainty estimating Earth’s climate sensitivity. Here we develop feedback analysis that decomposes changes and creates testable hypotheses for refining their proposed ranges observations theory. To carry out this storyline approach, derive simple but quantitative expression the area feedback, which is shown to depend on present-day measurable cloud radiative effects fractional change warming. Satellite suggest an effect about ±1 W m −2 , requires be 50% K −1 magnitude produce equal current best estimate its lower bound. We use theory show closer −4% . This constrains leads our revised 0.02 ± 0.07 many times weaker more constrained than overall feedback. In comparison, albedo much less constrained, both theoretically observationally, poses obstacle bounding

Language: Английский

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Technical note: Recommendations for diagnosing cloud feedbacks and rapid cloud adjustments using cloud radiative kernels

Atmospheric chemistry and physics, Journal Year: 2025, Volume and Issue: 25(3), P. 1477 - 1495

Published: Feb. 3, 2025

Abstract. The cloud radiative kernel method is a popular approach to quantify feedbacks and rapid adjustments increased CO2 concentrations partition contributions from changes in amount, altitude, optical depth. However, because this relies on property histograms derived passive satellite sensors or produced by simulators models, obscuration of lower-level clouds upper-level can cause apparent low-cloud adjustments, even the absence properties. Here, we provide methodology for properly diagnosing impact changing these effects across climate models. Averaged globally global accounting leads weaker positive stronger while simultaneously removing mostly artificial anti-correlation between them. Given that using kernels has evolved over several papers, have only occasionally been considered recent paper serves establish recommended best practices corresponding code base community use.

Language: Английский

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Polar amplification of orbital-scale climate variability in the early Eocene greenhouse world

Climate of the past, Journal Year: 2024, Volume and Issue: 20(6), P. 1303 - 1325

Published: June 12, 2024

Abstract. Climate variability is typically amplified towards polar regions. The underlying causes, notably albedo and humidity changes, are challenging to accurately quantify with observations or models, thus hampering projections of future amplification. Polar amplification reconstructions from the ice-free early Eocene (∼56–48 Ma) can exclude ice effects, but required tropical temperature records for resolving timescales shorter than multi-million years lacking. Here, we reconstruct sea surface by presenting an up ∼4 kyr resolution biomarker-based record Ocean Drilling Program (ODP) Site 959, located in Atlantic Ocean. This shows warming across multiple orbitally paced carbon cycle perturbations, coeval high-latitude-derived deep-ocean bottom waters, showing that these events represent transient global (hyperthermals). implies orbital forcing caused through feedbacks. Importantly, was a factor 1.7–2.3 compared ocean, corroborating available long-term estimates. fast atmospheric feedback processes controlled meridional gradients on year, as well orbital, during Eocene. Our combined have several other implications. First, our somewhat larger same metric fully coupled simulations (1.1–1.3), suggesting models slightly underestimate non-ice-related – hydrological feedbacks cause climate change. Second, even outside hyperthermals, find synchronous eccentricity-forced tropics deep ocean mean 0.7 °C, which requires significant pCO2. We hypothesize responsible independent ice, snow, frost-related might play important role Phanerozoic orbital-scale throughout geological time, including Pleistocene glacial–interglacial variability.

Language: Английский

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Model spread in tropical low cloud feedback tied to overturning circulation response to warming

Nature Communications, Journal Year: 2022, Volume and Issue: 13(1)

Published: Nov. 19, 2022

Among models participating in the Coupled Model Intercomparison Project phase 6 (CMIP6), here we show that magnitude of tropical low cloud feedback, which contributes considerably to uncertainty estimates climate sensitivity, is intimately linked deep convection and its effects on atmospheric overturning circulation. First, a reduction ascent area an increased frequency heavy precipitation result high upper-tropospheric drying, increases longwave cooling reduces subsidence weakening, favoring (Radiation-Subsidence Pathway). Second, decreases tropospheric stability, also weakening cloudiness (Stability-Subsidence In summary, greater drying (negative feedback) lead more positive feedback among CMIP6 by contributing (positive shortwave feedback). Varying strengths two pathways contribute intermodel spread sensitivity.

Language: Английский

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Evaluating Cloud Feedback Components in Observations and Their Representation in Climate Models

Journal of Geophysical Research Atmospheres, Journal Year: 2024, Volume and Issue: 129(2)

Published: Jan. 22, 2024

Abstract This study quantifies the contribution of individual cloud feedbacks to total short‐term feedback in satellite observations over period 2002–2014 and evaluates how they are represented climate models. The observed positive is primarily due high‐cloud altitude, extratropical high‐ low‐cloud optical depth, land amount partially offset by negative tropical marine feedback. Seventeen models from Atmosphere Model Intercomparison Project sixth Coupled analyzed. generally reproduce moderate However, compared estimates, systematically high‐biased low‐biased altitude depth feedbacks. Errors modeled components identified this analysis highlight need for improvements model simulations response high clouds low clouds. Our results suggest that skill simulating interannual may not indicate long‐term components.

Language: Английский

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Causes of Reduced Climate Sensitivity in E3SM from Version 1 to Version 2

Authorea (Authorea), Journal Year: 2023, Volume and Issue: unknown

Published: June 14, 2023

The effective climate sensitivity in the Department of Energy’s Energy Exascale Earth System Model (E3SM) has decreased from 5.3 K version 1 to 4.0 2. This reduction is mainly due a weaker positive cloud feedback that leads stronger negative radiative feedback. Present-day atmosphere-only experiments with uniform 4 sea surface temperature warming are used separate contributions individual model modifications reduced We find mostly driven by changes over tropical marine low regime, related new trigger function for deep convection scheme and microphysics scheme. helps weaken increasing water detrainment at levels under warming. Changes formula autoconversion rate liquid rain an introduced minimum droplet number concentration threshold microphysical calculations help sustain clouds against dissipation suppressing precipitation generation In midlatitudes, increased Wegener-Bergeron-Findeisen (WBF) efficiency strongly reduces present-day optical depth trade cumulus v2 closer estimates recent observational large-eddy modeling studies but might not be right physical reasons. mid-latitude may more plausible because realistic mixed-phase produced through change WBF efficiency.

Language: Английский

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Machine learning of cloud types in satellite observations and climate models

Atmospheric chemistry and physics, Journal Year: 2023, Volume and Issue: 23(1), P. 523 - 549

Published: Jan. 13, 2023

Abstract. Uncertainty in cloud feedbacks climate models is a major limitation projections of future climate. Therefore, evaluation and improvement simulation are essential to ensure the accuracy models. We analyse biases change with respect global mean near-surface temperature (GMST) relative satellite observations relate them equilibrium sensitivity, transient response feedback. For this purpose, we develop supervised deep convolutional artificial neural network for determination types from low-resolution (2.5∘×2.5∘) daily top-of-atmosphere shortwave longwave radiation fields, corresponding World Meteorological Organization (WMO) genera recorded by human observers Global Telecommunication System (GTS). train on retrieved Clouds Earth’s Radiant Energy (CERES) GTS apply it Coupled Model Intercomparison Project Phase 5 6 (CMIP5 CMIP6) model output European Centre Medium-Range Weather Forecasts (ECMWF) Reanalysis version (ERA5) Modern-Era Retrospective Analysis Research Applications 2 (MERRA-2) reanalyses. compare between observations. link sensitivity identify negative linear relationship root square error type occurrence derived (ECS), (TCR) This statistical ensemble favours higher ECS, TCR However, could be due relatively small size used or decoupling present-day projected change. Using abrupt-4×CO2 CMIP5 CMIP6 experiments, show that simulating decreasing stratiform increasing cumuliform clouds tend have ECS than clouds, also partially explain association ECS.

Language: Английский

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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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