The Impact of Cloud Feedbacks on Arctic Climate under Greenhouse Forcing*

Abstract Variability in the strength of low-cloud feedbacks across climate models is the primary contributor to the spread in their estimates of equilibrium climate sensitivity (ECS). This raises the question: What are the regional implications for key features of tropical climate of globally weak versus strong low-cloud feedbacks in response to greenhouse gas–induced warming? To address this question and formalize our understanding of cloud controls on tropical climate, we perform a suite of idealized fully coupled and slab-ocean climate simulations across which we systematically scale the strength of the low-cloud-cover feedback under abrupt 2 × CO2 forcing within a single model, thereby isolating the impact of low-cloud feedback strength. The feedback strength is varied by modifying the stratus cloud fraction so that it is a function of not only local conditions but also global temperature in a series of abrupt 2 × CO2 sensitivity experiments. The unperturbed decrease in low cloud cover (LCC) under 2 × CO2 is greatest in the mid- and high-latitude oceans, and the subtropical eastern Pacific and Atlantic, a pattern that is magnified as the feedback strength is scaled. Consequently, sea surface temperature (SST) increases more in these regions as well as the Pacific cold tongue. As the strength of the low-cloud feedback increases this results in not only increased ECS, but also an enhanced reduction of the large-scale zonal and meridional SST gradients (structural climate sensitivity), with implications for the atmospheric Hadley and Walker circulations, as well as the hydrological cycle. The relevance of our results to simulating past warm climate is also discussed.

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The impact of parametrized convection on cloud feedback

Philosophical Transactions of The Royal Society A Mathematical Physical and Engineering Sciences ◽

10.1098/rsta.2014.0414 ◽

2015 ◽

Vol 373 (2054) ◽

pp. 20140414 ◽

Cited By ~ 44

Author(s):

Mark J. Webb ◽

Adrian P. Lock ◽

Christopher S. Bretherton ◽

Sandrine Bony ◽

Jason N. S. Cole ◽

...

Keyword(s):

Climate Models ◽

Correction Method ◽

Cloud Feedback ◽

Temperature Perturbation ◽

Cloud Feedbacks ◽

Stratocumulus Clouds ◽

Shallow Clouds ◽

Convection Schemes ◽

The Individual ◽

The Impact

We investigate the sensitivity of cloud feedbacks to the use of convective parametrizations by repeating the CMIP5/CFMIP-2 AMIP/AMIP + 4K uniform sea surface temperature perturbation experiments with 10 climate models which have had their convective parametrizations turned off. Previous studies have suggested that differences between parametrized convection schemes are a leading source of inter-model spread in cloud feedbacks. We find however that ‘ConvOff’ models with convection switched off have a similar overall range of cloud feedbacks compared with the standard configurations. Furthermore, applying a simple bias correction method to allow for differences in present-day global cloud radiative effects substantially reduces the differences between the cloud feedbacks with and without parametrized convection in the individual models. We conclude that, while parametrized convection influences the strength of the cloud feedbacks substantially in some models, other processes must also contribute substantially to the overall inter-model spread. The positive shortwave cloud feedbacks seen in the models in subtropical regimes associated with shallow clouds are still present in the ConvOff experiments. Inter-model spread in shortwave cloud feedback increases slightly in regimes associated with trade cumulus in the ConvOff experiments but is quite similar in the most stable subtropical regimes associated with stratocumulus clouds. Inter-model spread in longwave cloud feedbacks in strongly precipitating regions of the tropics is substantially reduced in the ConvOff experiments however, indicating a considerable local contribution from differences in the details of convective parametrizations. In both standard and ConvOff experiments, models with less mid-level cloud and less moist static energy near the top of the boundary layer tend to have more positive tropical cloud feedbacks. The role of non-convective processes in contributing to inter-model spread in cloud feedback is discussed.

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Climate Changes and the Imperatives of All Round-a-Year Human Activity in the Arctic

Journal of International Analytics ◽

10.46272/2587-8476-2015-0-1-9-18 ◽

2015 ◽

pp. 9-18

Author(s):

L. Voronkov

Keyword(s):

Energy Supply ◽

Climate Changes ◽

Climatic Changes ◽

Arctic Climate ◽

The Arctic ◽

Financial Resources ◽

Human Society ◽

Human Beings ◽

Earth’S Climate ◽

The Impact

The author questions the indisputability of the Arctic’s existing climate change assessments and insists on the need to adjust the Arctic strategies of states to different scenarios of such changes. While not denying the impact of human society on the Earth’s climate, the author believes to be important not to limit research on its changes by exclusively natural-scientific aspects, but to include considerations concerning the influence of peculiarities of human society’s development on the climate. He thinks it is important to take into account the combine impact of the changing nature of contemporary industrial activity, of sources for energy supply, the on-going processes of building of “smart” economy and its innovative development, demographic changes, improvement of human capital as well as the impact of increased environmental consciousness of human beings on the global and Arctic climate. Despite the observed climatic changes in the Arctic, it remains ice-covered the major part of the year. Any commercially justified human activities in the Arctic must be based on the need to maintain a year-round exploitation of its resources and possibilities and to create the appropriate infrastructure, machinery and equipment. The author comes to the conclusion that the need to resolve these problems requires considerable financial resources and time.

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Aircraft observations of enhancement and depletion of black carbon mass in the springtime Arctic

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-10-15167-2010 ◽

2010 ◽

Vol 10 (6) ◽

pp. 15167-15196

Author(s):

J. R. Spackman ◽

R. S. Gao ◽

W. D. Neff ◽

J. P. Schwarz ◽

L. A. Watts ◽

...

Keyword(s):

Boundary Layer ◽

Black Carbon ◽

Biomass Burning ◽

Boundary Layer Transition ◽

Arctic Climate ◽

The Arctic ◽

Vertical Profiles ◽

Free Troposphere ◽

Air Mass ◽

The Impact

Abstract. Understanding the processes controlling black carbon (BC) in the Arctic is crucial for evaluating the impact of anthropogenic and natural sources of BC on Arctic climate. Vertical profiles of BC mass were observed from the surface to near 7-km altitude in April 2008 using a Single-Particle Soot Photometer (SP2) during flights on the NOAA WP-3D research aircraft from Fairbanks, Alaska. These measurements were conducted during the NOAA-sponsored Aerosol, Radiation, and Cloud Processes affecting Arctic Climate (ARCPAC) project as part of POLARCAT, an International Polar Year (IPY) activity. In the free troposphere, the Arctic air mass was influenced by long-range transport from biomass-burning and anthropogenic source regions at lower latitudes especially during the latter part of the campaign. Maximum average BC mass loadings of 150 ng kg−1 were observed near 5.5-km altitude in the aged Arctic air mass. In biomass-burning plumes, BC was enhanced from near the top of the Arctic boundary layer (ABL) to 5.5 km compared to the aged Arctic air mass. At the bottom of some of the profiles, positive vertical gradients in BC were observed in the vicinity of open leads in the sea-ice. BC mass loadings increased by about a factor of two across the boundary layer transition in the ABL in these cases while carbon monoxide (CO) remained constant, evidence for depletion of BC in the ABL. BC mass loadings were positively correlated with O3 in ozone depletion events (ODEs) for all the observations in the ABL suggesting that BC was removed by dry deposition of BC on the snow or ice because molecular bromine, Br2, which photolyzes and catalytically destroys O3, is thought to be released near the open leads in regions of ice formation. We estimate the deposition flux of BC mass to the snow using a box model constrained by the vertical profiles of BC in the ABL. The open leads may increase vertical mixing in the ABL and entrainment of pollution from the free troposphere possibly enhancing the deposition of BC to the snow.

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Case study of an Arctic atmospheric river with the ICON model

10.5194/egusphere-egu21-1344 ◽

2021 ◽

Author(s):

Hélène Bresson ◽

Annette Rinke ◽

Vera Schemann ◽

Mario Mech ◽

Susanne Crewell ◽

...

Keyword(s):

Temporal Structure ◽

Horizontal Resolution ◽

Added Value ◽

Arctic Climate ◽

The Arctic ◽

Limited Area ◽

Polar Regions ◽

Relative Role ◽

The Impact

The Arctic climate changes faster than the ones of other regions, but the relative role of the individual feedback mechanisms contributing to Arctic amplification is still unclear. Atmospheric Rivers (ARs) are narrow and transient river-style moisture flows from the sub-polar regions. The integrated water vapour transport associated with ARs can explain up to 70% of the precipitation variance north of 70&#176;N. However, there are still uncertainties regarding the specific role and the impact of ARs on the Arctic climate variability.&#160;For the first time, the high-resolution ICON modelling framework is used over the Arctic region. Pan Arctic simulations (from 13 km down to ca. 6 and 3 km) are performed to investigate processes related with anomalous moisture transport into the Arctic. Based on a case study over the Nordic Seas, the representation of the atmospheric circulation and the spatio-temporal structure of water vapor, temperature and precipitation within the limited-area mode (LAM) of the ICON model is assessed, and compared with reanalysis and in-situ datasets. Preliminary results show that the moisture intrusion is relatively well represented in the ICON-LAM simulations. The study also shows added value in increasing the model horizontal resolution on the AR representation.

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Quantifying Emerging Local Anthropogenic Emissions in the Arctic Region: The ACCESS Aircraft Campaign Experiment

Bulletin of the American Meteorological Society ◽

10.1175/bams-d-13-00169.1 ◽

2015 ◽

Vol 96 (3) ◽

pp. 441-460 ◽

Cited By ~ 40

Author(s):

A. Roiger ◽

J.-L. Thomas ◽

H. Schlager ◽

K. S. Law ◽

J. Kim ◽

...

Keyword(s):

Oil And Gas ◽

Anthropogenic Activities ◽

Arctic Region ◽

Arctic Sea Ice ◽

Arctic Climate ◽

The Arctic ◽

Local Pollution ◽

Arctic Climate Change ◽

The Impact ◽

Pollution Plumes

Abstract Arctic sea ice has decreased dramatically in the past few decades and the Arctic is increasingly open to transit shipping and natural resource extraction. However, large knowledge gaps exist regarding composition and impacts of emissions associated with these activities. Arctic hydrocarbon extraction is currently under development owing to the large oil and gas reserves in the region. Transit shipping through the Arctic as an alternative to the traditional shipping routes is currently underway. These activities are expected to increase emissions of air pollutants and climate forcers (e.g., aerosols, ozone) in the Arctic troposphere significantly in the future. The authors present the first measurements of these activities off the coast of Norway taken in summer 2012 as part of the European Arctic Climate Change, Economy, and Society (ACCESS) project. The objectives include quantifying the impact that anthropogenic activities will have on regional air pollution and understanding the connections to Arctic climate. Trace gas and aerosol concentrations in pollution plumes were measured, including emissions from different ship types and several offshore extraction facilities. Emissions originating from industrial activities (smelting) on the Kola Peninsula were also sampled. In addition, pollution plumes originating from Siberian biomass burning were probed in order to put the emerging local pollution within a broader context. In the near future these measurements will be combined with model simulations to quantify the influence of local anthropogenic activities on Arctic composition. Here the authors present the scientific objectives of the ACCESS aircraft experiment and the the meteorological conditions during the campaign, and they highlight first scientific results from the experiment.

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Simulating aerosol–radiation–cloud feedbacks on meteorology and air quality over eastern China under severe haze conditions in winter

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-14-26085-2014 ◽

2014 ◽

Vol 14 (19) ◽

pp. 26085-26125 ◽

Cited By ~ 2

Author(s):

B. Zhang ◽

Y. X. Wang ◽

J. M. Hao

Keyword(s):

Air Quality ◽

Indirect Effects ◽

Eastern China ◽

River Delta ◽

Central China ◽

Meteorological Variables ◽

Cloud Feedbacks ◽

The Impact ◽

Aerosol Radiative ◽

Mass Concentrations

Abstract. The aerosol–radiation–cloud feedbacks on meteorology and air quality over eastern China under severe winter haze conditions during January~2013 are simulated using the fully coupled on-line Weather Research and Forecasting/Chemistry (WRF-Chem) model. Three simulation scenarios including different aerosol configurations are undertaken to distinguish the impact of aerosol radiative (direct and semi-direct) and indirect effects on meteorological variables and air quality. Simulated spatial and temporal variations of PM2.5 are generally consistent with surface observations, with a mean bias of −18.9 μg m−3 (−15.0%) averaged over 71 big cities in China. Comparisons between different scenarios reveal that aerosol radiative effects (direct effect and semi-direct effects) result in reductions of downward shortwave flux at the surface, 2 m temperature, 10 m wind speed and planetary boundary layer (PBL) height by up to 84.0 W m−2, 3.2 °C, 0.8 m s−1, and 268 m, respectively. The simulated impact of the aerosol indirect effects is comparatively smaller. Through reducing the PBL height and wind speeds, the aerosol effects lead to increases in surface concentrations of primary pollutants (CO and SO2) and PM2.5. The aerosol feedbacks on secondary pollutants such as surface ozone and PM2.5 mass concentrations show some spatial variations. Surface O3 mixing ratio is reduced by up to 6.9 ppb due to reduced incoming solar radiation and lower temperature. Comparisons of model results with observations show that inclusion of aerosol feedbacks in the model significantly improves model's performances in simulating meteorological variables and improves simulations of PM2.5 temporal distributions over the North China Plain, the Yangtze River Delta, the Pearl River Delta, and Central China. Although the aerosol–radiation–cloud feedbacks on aerosol mass concentrations are subject to uncertainties, this work demonstrates the significance of aerosol–radiation–cloud feedbacks for real-time air quality forecasting under haze conditions.

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Impacts of Stratospheric Ozone Extremes on Arctic High Cloud

10.5194/egusphere-egu21-3239 ◽

2021 ◽

Author(s):

Karen Smith ◽

Sarah Maleska ◽

John Virgin

Keyword(s):

Northern Hemisphere ◽

Ozone Depletion ◽

Climate Model ◽

Stratospheric Ozone ◽

Global Climate Models ◽

Arctic Climate ◽

The Arctic ◽

Stratospheric Ozone Depletion ◽

High Cloud ◽

The Impact

Stratospheric ozone depletion in the Antarctic is well known to cause changes in Southern Hemisphere tropospheric climate; however, because of its smaller magnitude in the Arctic, the effects of stratospheric ozone depletion on Northern Hemisphere tropospheric climate are not as obvious or well understood. Recent research using both global climate models and observational data has determined that the impact of ozone depletion on ozone extremes can affect interannual variability in tropospheric circulation in the Northern Hemisphere in spring. To further this work, we use a coupled chemistry&#8211;climate model to examine the difference in high cloud between years with anomalously low and high Arctic stratospheric ozone concentrations. We find that low ozone extremes during the late twentieth century, when ozone-depleting substances (ODS) emissions are higher, are related to a decrease in upper tropospheric stability and an increase in high cloud fraction, which may contribute to enhanced Arctic surface warming in spring through a positive longwave cloud radiative effect. A better understanding of how Arctic climate is affected by ODS emissions, ozone depletion, and ozone extremes will lead to improved predictions of Arctic climate and its associated feedbacks with atmospheric fields as ozone levels recover.

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The impact of orbital forcing on the Arctic climate during the Last Interglacial simulated by the IPSL-CM6A-LR model

10.5194/egusphere-egu2020-16044 ◽

2020 ◽

Author(s):

Marie Sicard ◽

Masa Kageyama ◽

Pascale Braconnot ◽

Sylvie Charbit

Keyword(s):

Solar Radiation ◽

Sea Ice ◽

Arctic Sea Ice ◽

Arctic Climate ◽

The Arctic ◽

Orbital Forcing ◽

Last Interglacial ◽

Arctic Sea ◽

The Impact

The Last Interglacial (129 &#8211; 116 ka BP) is a time period with a strong orbital forcing which leads to a different seasonal and latitudinal distribution of insolation compared to the present. In particular, these changes amplify the Arctic climate seasonality. They induce warmer summers and colder winters in the high latitudes of the Northern Hemisphere. Such surface conditions favour a huge retreat of the arctic sea ice cover. In this study, we try to understand how this solar radiation anomaly spreads through the surface and impacts the seasonal arctic sea ice. Using IPSL-CM6A-LR model outputs, we decompose the surface energy budget to identify the role of atmospheric and oceanic key processes beyond 60&#176;N and its changes compared to pre-industrial. We show that solar radiation anomaly is greatly reduced when it reaches the Earth&#8217;s surface, which emphasizes the role of clouds and water vapor transport. The results are also compared to other PMIP4-CMIP6 model simulations. We would like to thank PMIP participants for producing and making available their model outputs.

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