Impact of poleward heat and moisture transports on Arctic clouds and climate simulation

Abstract. Clouds play an important role in regulating the Earth's global radiation budget. Many General Circulation Models (GCMs) have difficulty in simulating Arctic clouds and climate with a large inter-model spread. In an attempt to address this issue, we compare an Atmospheric Model Inter-comparison Project (AMIP) simulation from the Community Atmosphere Model version 5 (CAM5) with that from the Seoul National University (SNU) Atmosphere Model version 0 with a Unified Convection Scheme (SAM0). Over the Arctic, it was found that SAM0 simulates more cloud fraction and cloud liquid mass than CAM5, reducing the Arctic clouds biases in CAM5. The budget analysis indicates that this improvement is associated with an enhanced net condensation rate of water vapor into the liquid condensate of the Arctic low-level stratus, which in turn is driven by enhanced poleward transports of heat and moisture by mean meridional circulation and transient eddies. The reduced Arctic cloud biases lead to improved simulations of surface radiation fluxes and near-surface air temperature over the Arctic throughout the year. The association between the enhanced poleward transports of heat and moisture and more liquid stratus over the Arctic is also evident in the multi-models analysis. Our study indicates that the proper simulation of poleward heat and moisture transport is one of the key factors necessary for improving the simulations of Arctic clouds and climate.

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Impact of poleward heat and moisture transports on Arctic clouds and climate simulation

Atmospheric Chemistry and Physics ◽

10.5194/acp-20-2953-2020 ◽

2020 ◽

Vol 20 (5) ◽

pp. 2953-2966

Author(s):

Eun-Hyuk Baek ◽

Joo-Hong Kim ◽

Sungsu Park ◽

Baek-Min Kim ◽

Jee-Hoon Jeong

Keyword(s):

General Circulation ◽

General Circulation Models ◽

Surface Radiation ◽

The Arctic ◽

Climate Simulation ◽

Near Surface ◽

Arctic Clouds ◽

Model Version ◽

Atmosphere Model ◽

Heat And Moisture

Abstract. Many general circulation models (GCMs) have difficulty simulating Arctic clouds and climate, causing substantial inter-model spread. To address this issue, two Atmospheric Model Intercomparison Project (AMIP) simulations from the Community Atmosphere Model version 5 (CAM5) and Seoul National University (SNU) Atmosphere Model version 0 (SAM0) with a unified convection scheme (UNICON) are employed to identify an effective mechanism for improving Arctic cloud and climate simulations. Over the Arctic, SAM0 produced a larger cloud fraction and cloud liquid mass than CAM5, reducing the negative Arctic cloud biases in CAM5. The analysis of cloud water condensation rates indicates that this improvement is associated with an enhanced net condensation rate of water vapor into the liquid condensate of Arctic low-level clouds, which in turn is driven by enhanced poleward transports of heat and moisture by the mean meridional circulation and transient eddies. The reduced Arctic cloud biases lead to improved simulations of surface radiation fluxes and near-surface air temperature over the Arctic throughout the year. The association between the enhanced poleward transports of heat and moisture and increase in liquid clouds over the Arctic is also evident not only in both models, but also in the multi-model analysis. Our study demonstrates that enhanced poleward heat and moisture transport in a model can improve simulations of Arctic clouds and climate.

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Arctic Clouds and Surface Radiation – a critical comparison of satellite retrievals and the ERA-Interim reanalysis

Atmospheric Chemistry and Physics ◽

10.5194/acp-12-6667-2012 ◽

2012 ◽

Vol 12 (14) ◽

pp. 6667-6677 ◽

Cited By ~ 53

Author(s):

M. Zygmuntowska ◽

T. Mauritsen ◽

J. Quaas ◽

L. Kaleschke

Keyword(s):

Surface Radiation ◽

Radiation Budget ◽

The Arctic ◽

Data Sets ◽

Radiative Effect ◽

Arctic Clouds ◽

Cloud Radiative Effect ◽

Satellite Retrievals ◽

Earth’S Radiation Budget ◽

Arctic Surface

Abstract. Clouds regulate the Earth's radiation budget, both by reflecting part of the incoming sunlight leading to cooling and by absorbing and emitting infrared radiation which tends to have a warming effect. Globally averaged, at the top of the atmosphere the cloud radiative effect is to cool the climate, while at the Arctic surface, clouds are thought to be warming. Here we compare a passive instrument, the AVHRR-based retrieval from CM-SAF, with recently launched active instruments onboard CloudSat and CALIPSO and the widely used ERA-Interim reanalysis. We find that in particular in winter months the three data sets differ significantly. While passive satellite instruments have serious difficulties, detecting only half the cloudiness of the modeled clouds in the reanalysis, the active instruments are in between. In summer, the two satellite products agree having monthly means of 70–80 percent, but the reanalysis are approximately ten percent higher. The monthly mean long- and shortwave components of the surface cloud radiative effect obtained from the ERA-Interim reanalysis are about twice that calculated on the basis of CloudSat's radar-only retrievals, while ground based measurements from SHEBA are in between. We discuss these differences in terms of instrument-, retrieval- and reanalysis characteristics, which differ substantially between the analyzed datasets.

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Arctic clouds and surface radiation – a critical comparison of satellite retrievals and the ERA-interim reanalysis

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-11-31495-2011 ◽

2011 ◽

Vol 11 (11) ◽

pp. 31495-31522 ◽

Cited By ~ 2

Author(s):

M. Zygmuntowska ◽

T. Mauritsen ◽

J. Quaas ◽

L. Kaleschke

Keyword(s):

Reanalysis Data ◽

Surface Radiation ◽

Radiation Budget ◽

The Arctic ◽

Data Sets ◽

Radiative Effect ◽

Central Arctic Ocean ◽

Arctic Clouds ◽

Cloud Radiative Effect ◽

Earth’S Radiation Budget

Abstract. Clouds regulate Earth's radiation budget, both by reflecting part of the incoming sunlight leading to cooling and by absorbing and emitting infrared radiation which tends to have a warming effect. Globally averaged, at the top of the atmosphere the cloud radiative effect is to cool the climate, while at the Arctic surface, clouds are thought to be warming. Ground-based observations of central Arctic Ocean cloudiness are limited to sporadic field campaigns. Therefore many studies rely on satellite- or reanalysis data. Here we compare a passive instrument, the AVHRR-based retrieval from CM-SAF, with recently launched active instruments onboard CloudSat and CALIPSO and the widely used ERA-Interim reanalysis. We find that the three data sets differ significantly. In summer, the two satellite products agree having monthly means of 70–80 percent, but the reanalysis are approximately ten percent higher. In winter passive satellite instruments have serious difficulties, detecting only half the cloudiness of the reanalysis, active instruments being in between. The monthly mean long- and shortwave components of the surface cloud radiative effect obtained from the ERA-Interim reanalysis are about twice that calculated on the basis of CloudSat retrievals. We discuss these discrepancies in terms of instrument-, retrieval- and reanalysis characteristics.

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The Influence of Cloud and Surface Properties on the Arctic Ocean Shortwave Radiation Budget in Coupled Models*

Journal of Climate ◽

10.1175/2007jcli1614.1 ◽

2008 ◽

Vol 21 (5) ◽

pp. 866-882 ◽

Cited By ~ 44

Author(s):

Irina V. Gorodetskaya ◽

L-Bruno Tremblay ◽

Beate Liepert ◽

Mark A. Cane ◽

Richard I. Cullather

Keyword(s):

Sea Ice ◽

Arctic Ocean ◽

Liquid Water ◽

Surface Albedo ◽

Liquid Water Content ◽

Radiation Budget ◽

The Arctic ◽

Coupled Models ◽

Arctic Clouds ◽

The Arctic Ocean

Abstract The impact of Arctic sea ice concentrations, surface albedo, cloud fraction, and cloud ice and liquid water paths on the surface shortwave (SW) radiation budget is analyzed in the twentieth-century simulations of three coupled models participating in the Intergovernmental Panel on Climate Change Fourth Assessment Report. The models are the Goddard Institute for Space Studies Model E-R (GISS-ER), the Met Office Third Hadley Centre Coupled Ocean–Atmosphere GCM (UKMO HadCM3), and the National Center for Atmosphere Research Community Climate System Model, version 3 (NCAR CCSM3). In agreement with observations, the models all have high Arctic mean cloud fractions in summer; however, large differences are found in the cloud ice and liquid water contents. The simulated Arctic clouds of CCSM3 have the highest liquid water content, greatly exceeding the values observed during the Surface Heat Budget of the Arctic Ocean (SHEBA) campaign. Both GISS-ER and HadCM3 lack liquid water and have excessive ice amounts in Arctic clouds compared to SHEBA observations. In CCSM3, the high surface albedo and strong cloud SW radiative forcing both significantly decrease the amount of SW radiation absorbed by the Arctic Ocean surface during the summer. In the GISS-ER and HadCM3 models, the surface and cloud effects compensate one another: GISS-ER has both a higher summer surface albedo and a larger surface incoming SW flux when compared to HadCM3. Because of the differences in the models’ cloud and surface properties, the Arctic Ocean surface gains about 20% and 40% more solar energy during the melt period in the GISS-ER and HadCM3 models, respectively, compared to CCSM3. In twenty-first-century climate runs, discrepancies in the surface net SW flux partly explain the range in the models’ sea ice area changes. Substantial decrease in sea ice area simulated during the twenty-first century in CCSM3 is associated with a large drop in surface albedo that is only partly compensated by increased cloud SW forcing. In this model, an initially high cloud liquid water content reduces the effect of the increase in cloud fraction and cloud liquid water on the cloud optical thickness, limiting the ability of clouds to compensate for the large surface albedo decrease. In HadCM3 and GISS-ER, the compensation of the surface albedo and cloud SW forcing results in negligible changes in the net SW flux and is one of the factors explaining moderate future sea ice area trends. Thus, model representations of cloud properties for today’s climate determine the ability of clouds to compensate for the effect of surface albedo decrease on the future shortwave radiative budget of the Arctic Ocean and, as a consequence, the sea ice mass balance.

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An Evaluation of Surface Atmospheric Changes over the Arctic Ocean for 2000–09 Using Recent Reanalyses

Earth Interactions ◽

10.1175/ei-d-14-0012.1 ◽

2015 ◽

Vol 19 (2) ◽

pp. 1-18 ◽

Cited By ~ 1

Author(s):

Ayan H. Chaudhuri ◽

Rui M. Ponte

Keyword(s):

Arctic Ocean ◽

Extreme Event ◽

Longwave Radiation ◽

Remotely Sensed ◽

Surface Radiation ◽

Shortwave Radiation ◽

The Arctic ◽

Near Surface ◽

The Arctic Ocean ◽

Ice Retreat

Abstract The authors examine five recent reanalysis products [NCEP Climate Forecast System Reanalysis (CFSR), Modern-Era Retrospective Analysis for Research and Applications (MERRA), Japanese 25-year Reanalysis Project (JRA-25), Interim ECMWF Re-Analysis (ERA-Interim), and Arctic System Reanalysis (ASR)] for 1) trends in near-surface radiation fluxes, air temperature, and humidity, which are important indicators of changes within the Arctic Ocean and also influence sea ice and ocean conditions, and 2) fidelity of these atmospheric fields and effects for an extreme event: namely, the 2007 ice retreat. An analysis of trends over the Arctic for the past decade (2000–09) shows that reanalysis solutions have large spreads, particularly for downwelling shortwave radiation. In many cases, the differences in significant trends between the five reanalysis products are comparable to the estimated trend within a particular product. These discrepancies make it difficult to establish a consensus on likely changes occurring in the Arctic solely based on results from reanalyses fields. Regarding the 2007 ice retreat event, comparisons with remotely sensed estimates of downwelling radiation observations against these reanalysis products present an ambiguity. Remotely sensed observations from a study cited herewith suggest a large increase in downwelling summertime shortwave radiation and decrease in downwelling summertime longwave radiation from 2006 and 2007. On the contrary, the reanalysis products show only small gains in summertime shortwave radiation, if any; however, all the products show increases in downwelling longwave radiation. Thus, agreement within reanalysis fields needs to be further checked against observations to assess possible biases common to all products.

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Clouds damp the radiative impacts of polar sea ice loss

The Cryosphere ◽

10.5194/tc-14-2673-2020 ◽

2020 ◽

Vol 14 (8) ◽

pp. 2673-2686 ◽

Cited By ~ 1

Author(s):

Ramdane Alkama ◽

Patrick C. Taylor ◽

Lorea Garcia-San Martin ◽

Herve Douville ◽

Gregory Duveiller ◽

...

Keyword(s):

Sea Ice ◽

Climate Models ◽

Surface Radiation ◽

Radiation Budget ◽

The Arctic ◽

Cloud Properties ◽

Surface Radiation Budget ◽

Cloud Radiative Effect ◽

Radiative Impact ◽

The Impact

Abstract. Clouds play an important role in the climate system: (1) cooling Earth by reflecting incoming sunlight to space and (2) warming Earth by reducing thermal energy loss to space. Cloud radiative effects are especially important in polar regions and have the potential to significantly alter the impact of sea ice decline on the surface radiation budget. Using CERES (Clouds and the Earth's Radiant Energy System) data and 32 CMIP5 (Coupled Model Intercomparison Project) climate models, we quantify the influence of polar clouds on the radiative impact of polar sea ice variability. Our results show that the cloud short-wave cooling effect strongly influences the impact of sea ice variability on the surface radiation budget and does so in a counter-intuitive manner over the polar seas: years with less sea ice and a larger net surface radiative flux show a more negative cloud radiative effect. Our results indicate that 66±2% of this change in the net cloud radiative effect is due to the reduction in surface albedo and that the remaining 34±1 % is due to an increase in cloud cover and optical thickness. The overall cloud radiative damping effect is 56±2 % over the Antarctic and 47±3 % over the Arctic. Thus, present-day cloud properties significantly reduce the net radiative impact of sea ice loss on the Arctic and Antarctic surface radiation budgets. As a result, climate models must accurately represent present-day polar cloud properties in order to capture the surface radiation budget impact of polar sea ice loss and thus the surface albedo feedback.

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Process-model simulations of cloud albedo enhancement by aerosols in the Arctic

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

10.1098/rsta.2014.0052 ◽

2014 ◽

Vol 372 (2031) ◽

pp. 20140052 ◽

Cited By ~ 11

Author(s):

Ben Kravitz ◽

Hailong Wang ◽

Philip J. Rasch ◽

Hugh Morrison ◽

Amy B. Solomon

Keyword(s):

Boundary Layer ◽

Process Model ◽

Current Knowledge ◽

Global Radiation ◽

Mixed Phase ◽

Radiation Budget ◽

The Arctic ◽

Pure Liquid ◽

Cloud Albedo ◽

Mixed Phase Clouds

A cloud-resolving model is used to simulate the effectiveness of Arctic marine cloud brightening via injection of cloud condensation nuclei (CCN), either through geoengineering or other increased sources of Arctic aerosols. An updated cloud microphysical scheme is employed, with prognostic CCN and cloud particle numbers in both liquid and mixed-phase marine low clouds. Injection of CCN into the marine boundary layer can delay the collapse of the boundary layer and increase low-cloud albedo. Albedo increases are stronger for pure liquid clouds than mixed-phase clouds. Liquid precipitation can be suppressed by CCN injection, whereas ice precipitation (snow) is affected less; thus, the effectiveness of brightening mixed-phase clouds is lower than for liquid-only clouds. CCN injection into a clean regime results in a greater albedo increase than injection into a polluted regime, consistent with current knowledge about aerosol–cloud interactions. Unlike previous studies investigating warm clouds, dynamical changes in circulation owing to precipitation changes are small. According to these results, which are dependent upon the representation of ice nucleation processes in the employed microphysical scheme, Arctic geoengineering is unlikely to be effective as the sole means of altering the global radiation budget but could have substantial local radiative effects.

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A characterization of Arctic aerosols on the basis of aerosol optical depth and black carbon measurements

Elem Sci Anth ◽

10.12952/journal.elementa.000027 ◽

2014 ◽

Vol 2 ◽

Cited By ~ 40

Author(s):

R. S. Stone ◽

S. Sharma ◽

A. Herber ◽

K. Eleftheriadis ◽

D. W. Nelson

Keyword(s):

Black Carbon ◽

Aerosol Optical Depth ◽

Optical Depth ◽

Atmospheric Aerosols ◽

Surface Radiation ◽

Radiation Budget ◽

The Arctic ◽

Carbonaceous Particles ◽

Surface Warming ◽

Soot Deposition

Abstract Aerosols, transported from distant source regions, influence the Arctic surface radiation budget. When deposited on snow and ice, carbonaceous particles can reduce the surface albedo, which accelerates melting, leading to a temperature-albedo feedback that amplifies Arctic warming. Black carbon (BC), in particular, has been implicated as a major warming agent at high latitudes. BC and co-emitted aerosols in the atmosphere, however, attenuate sunlight and radiatively cool the surface. Warming by soot deposition and cooling by atmospheric aerosols are referred to as “darkening” and “dimming” effects, respectively. In this study, climatologies of spectral aerosol optical depth AOD (2001–2011) and Equivalent BC (EBC) (1989–2011) from three Arctic observatories and from a number of aircraft campaigns are used to characterize Arctic aerosols. Since the 1980s, concentrations of BC in the Arctic have decreased by more than 50% at ground stations where in situ observations are made. AOD has increased slightly during the past decade, with variations attributed to changing emission inventories and source strengths of natural aerosols, including biomass smoke and volcanic aerosol, further influenced by deposition rates and airflow patterns.

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Global Climate Simulated by the Seoul National University Atmosphere Model Version 0 with a Unified Convection Scheme (SAM0-UNICON)

Journal of Climate ◽

10.1175/jcli-d-18-0796.1 ◽

2019 ◽

Vol 32 (10) ◽

pp. 2917-2949 ◽

Cited By ~ 20

Author(s):

Sungsu Park ◽

Jihoon Shin ◽

Siyun Kim ◽

Eunsil Oh ◽

Yoonjae Kim

Keyword(s):

Sea Ice ◽

Global Climate ◽

The Arctic ◽

Convection Scheme ◽

Model Version ◽

National University ◽

Atmosphere Model ◽

Mean Climate ◽

Seoul National University ◽

Ice Fraction

Abstract As a contribution to phase 6 of the Coupled Model Intercomparison Project (CMIP6), the global climate simulated by an atmospheric general circulation model (GCM), the Seoul National University Atmosphere Model version 0 with a Unified Convection Scheme (SAM0-UNICON), is compared with observation and climates simulated by the Community Atmosphere Model version 5 (CAM5) and Community Earth System Model version 1 (CESM1), on which SAM0-UNICON is based. Both SAM0-UNICON and CESM1 successfully reproduce observed global warming after 1970. The global mean climate simulated by SAM0-UNICON is roughly similar to that of CAM5/CESM1. However, SAM0-UNICON improves the simulations of the double intertropical convergence zone, shortwave cloud forcing, near-surface air temperature, aerosol optical depth, sea ice fraction, and sea surface temperature (SST), but is slightly poorer for the simulation of tropical relative humidity, Pacific surface wind stress, and ocean rainfall. Two important biases in the simulated mean climate in both models are a set of horseshoe-shaped biases of SST, sea level pressure, precipitation, and cloud radiative forcings in the central equatorial Pacific and a higher sea ice fraction in the Arctic periphery and Southern Hemispheric circumpolar regions. Both SAM0-UNICON and CESM1 simulate the observed El Niño–Southern Oscillation (ENSO) reasonably well. However, compared with CAM5/CESM1, SAM0-UNICON performs better in simulating the Madden–Julian oscillation (MJO), diurnal cycle of precipitation, and tropical cyclones. The aerosol indirect effect (AIE) simulated by SAM0-UNICON is similar to that from CAM5 but the magnitudes of the individual shortwave and longwave AIEs are substantially reduced.

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Antarctic Peninsula warming and precipitation phase transition during atmospheric river events

10.5194/dach2022-309 ◽

2021 ◽

Author(s):

Irina Gorodetskaya ◽

Penny Rowe ◽

Xun Zou ◽

Anastasia Chyhareva ◽

Svitlana Krakovska ◽

...

Keyword(s):

Phase Transition ◽

Antarctic Peninsula ◽

Moisture Transport ◽

Large Scale ◽

The Arctic ◽

Polar Regions ◽

Near Surface ◽

Depth Analysis ◽

Heat And Moisture ◽

Precipitation Phase

Polar amplification has been pronounced in the Arctic with near-surface air temperatures increasing at more than twice the global warming rate during the last several decades. At the same time, over Antarctica temperature trends have exhibited a large regional variability. In particular, the Antarctic Peninsula (AP) stands out as having a warming rate much higher than the rest of the Antarctic ice sheet and other land areas in the Southern Hemisphere (SH). Future projections indicate that warming and ice loss will intensify in both polar regions with important impacts globally. In addition to the warming amplification, there has been also an enhancement of the polar water cycle with increases in poleward moisture transport and precipitation in both polar regions. An important process linking warming and precipitation enhancement is a shift towards more frequent rainfall compared to snowfall. Future projections show that the rain fraction will significantly increase in coastal Antarctica, especially in the AP. Atmospheric rivers (ARs), long corridors of intense moisture transport from subtropical and mid-latitude regions poleward, are known for their prominent role in both heat and moisture transport with impacts ranging from intense precipitation to temperature records and major melt events in Antarctica. Limited observations have hampered process understanding and correct representation of these extreme events in models. This presentation will give an overview of the enhanced observations targeting ARs in the AP (including surface meteorology, radiosonde, cloud and precipitation remote sensing, and radiative fluxes) as part of the Year of Polar Prediction (YOPP)-SH international collaborative effort. In-depth analysis of transport of heat and moisture, atmospheric vertical structure, cloud properties and precipitation phase transition from snowfall to rainfall during selected AR cases will be presented and compared with ERA5 reanalysis and high-resolution Polar-WRF model simulations. We will highlight three different local regimes around the AP: large-scale precipitation over the Southern Ocean north of the AP, orographic enhancement of precipitation in the western AP and the role of foehn, cloud/precipitation clearing and temperature increase in the northeastern AP.

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