Pan-Arctic and regional trends of reflectance, clouds and fluxes: implications for Arctic Amplification

2021 ◽  
Author(s):  
Luca Lelli ◽  
Narges Khosravi ◽  
Marco Vountas ◽  
John Burrows
Keyword(s):  
Sea Ice ◽  
Radiative Forcing ◽  
The Arctic ◽  
Arctic Amplification ◽  
Sea Ice Extent ◽  
Simple Assumption ◽  
Spectral Reflectivity ◽  
Surface Warming ◽  
Cloud Properties ◽  
Regional Trends

<p>It is now well known that the sea ice extent in the Artic has been shrinking in the past three decades in the period known as the Arctic Amplification. A simple assumption would be that if the sea ice extent has been reduced, then the spectral reflectance at the top of the atmosphere - R<sub>TOA</sub> - would have also decreased across the Arctic. On the other hand, Arctic reflectivity also largely depends on the presence of clouds, shielding the underlying surface, and on changes of their optical and physical properties. Thus, the assessment of trends of spectral reflectivity and cloud properties are essential to understand those forcings and feedbacks considered drivers of Arctic Amplification as well as the interactions between the components of the Arctic cryosphere. In the reported study we observationally tackle the stated problem investigating changes of R<sub>TOA</sub> at selected wavelengths making use of spaceborne measurements of the Global Ozone Monitoring Experiment (GOME onboard ERS-2 and MetOp A/B/C) and of the Scanning Imaging Absorption Spectrometer for Atmospheric Chartography (SCIAMACHY onboard Envisat) for the period 1995-2018. We complement this record with cloud properties and fluxes at top of the atmosphere and at the surface, inferred from measurements of the post-meridiem orbits of the Advanced Very High Resolution Radiometer (AVHRR onboard POES). Although the Pan-Arctic reflectivity has decreased, the analysis of regional trends shows distinct areas where the reflectivity trends diverge. While darkening areas can be attributed to seasonal sea ice decline, an increase of Arctic brightness over sea ice free regions can be largely attributed to changes in the optical properties of clouds. While the multiyear mean of the radiative forcing by clouds points to a TOA cooling and a surface warming, its trends exhibit opposite tendencies. In the last two decades, the cloud radiative effect at TOA is expected to warm the lower latitudes (below 75 N) and to cool the circumpolar belt, while an opposite trend at BOA, amounting to 5 W m<sup>-2 </sup>per decade, cools the lower Arctic latitudes and warms the permanent sea ice region, this effect being more pronounced in spring months (April to June) than in summer months (July to September).</p>

Analyzing the Arctic Feedback Mechanism between Sea Ice and Low-Level Clouds Using 34 Years of Satellite Observations

2020 ◽  
Vol 33 (17) ◽  
pp. 7479-7501
Author(s):  
Daniel Philipp ◽  
Martin Stengel ◽  
Bodo Ahrens
Keyword(s):  
Sea Ice ◽  
Radiative Forcing ◽  
Large Scale ◽  
The Arctic ◽  
Turbulent Heat ◽  
Arctic Amplification ◽  
Surface Warming ◽  
Low Level ◽  
Gc Analysis ◽  
Csi Feedback

AbstractSatellite-based cloud, radiation flux, and sea ice records covering 34 years are used 1) to investigate autumn cloud cover trends over the Arctic, 2) to assess its relation with declining sea ice using Granger causality (GC) analysis, and 3) to discuss the contribution of the cloud–sea ice (CSI) feedback to Arctic amplification. This paper provides strong evidence for a positive CSI feedback with the capability to contribute to autumnal Arctic amplification. Positive low-level cloud fractional cover (CFClow) trends over the Arctic ice pack are found in October and November (ON) with magnitudes of up to about +9.6% per decade locally. Statistically significant anticorrelations between sea ice concentration (SIC) and CFClow are observed in ON over melting zones, suggesting an association. The GC analysis indicated a causal two-way interaction between SIC and CFClow. Interpreting the resulting F statistic and its spatial distribution as a relation strength proxy, the influence of SIC on CFClow is likely stronger than the reverse. ERA-Interim reanalysis data suggest that ON CFClow is impacted by sea ice melt through surface–atmosphere coupling via turbulent heat and moisture fluxes. Due to weak solar insolation in ON, net cloud radiative forcing (CRF) exerts a warming effect on the Arctic surface. Increasing CFClow induces a large-scale surface warming trend reaching magnitudes of up to about +8.3 W m−2 per decade locally. Sensitivities of total CRF to CFClow ranges between +0.22 and +0.66 W m−2 per percent CFClow. Increasing surface warming can cause a melt season lengthening and hinders formation of perennial ice.

scholarly journals Modeled Arctic sea ice evolution through 2300 in CMIP5 extended RCPs

2014 ◽  
Vol 8 (1) ◽  
pp. 1383-1406 ◽  
Author(s):  
P. J. Hezel ◽  
T. Fichefet ◽  
F. Massonnet
Keyword(s):  
Sea Ice ◽  
Radiative Forcing ◽  
Climate Models ◽  
Global Climate ◽  
Arctic Sea Ice ◽  
Global Climate Models ◽  
The Arctic ◽  
Sea Ice Extent ◽  
Arctic Sea ◽  
Arctic Sea Ice Extent

Abstract. Almost all global climate models and Earth system models that participated in the Coupled Model Intercomparison Project 5 (CMIP5) show strong declines in Arctic sea ice extent and volume under the highest forcing scenario of the Radiative Concentration Pathways (RCPs) through 2100, including a transition from perennial to seasonal ice cover. Extended RCP simulations through 2300 were completed for a~subset of models, and here we examine the time evolution of Arctic sea ice in these simulations. In RCP2.6, the summer Arctic sea ice extent increases compared to its minimum following the peak radiative forcing in 2044 in all 9 models. RCP4.5 demonstrates continued summer Arctic sea ice decline due to continued warming on longer time scales. These two scenarios imply that summer sea ice extent could begin to recover if and when radiative forcing from greenhouse gas concentrations were to decrease. In RCP8.5 the Arctic Ocean reaches annually ice-free conditions in 7 of 9 models. The ensemble of simulations completed under the extended RCPs provide insight into the global temperature increase at which sea ice disappears in the Arctic and reversibility of declines in seasonal sea ice extent.

scholarly journals The emergence of surface-based Arctic amplification

2009 ◽  
Vol 3 (1) ◽  
pp. 11-19 ◽  
Author(s):  
M. C. Serreze ◽  
A. P. Barrett ◽  
J. C. Stroeve ◽  
D. N. Kindig ◽  
M. M. Holland
Keyword(s):  
Sea Ice ◽  
21St Century ◽  
Lower Troposphere ◽  
Cold Season ◽  
The Arctic ◽  
Arctic Amplification ◽  
Sea Ice Extent ◽  
Air Temperatures ◽  
The Arctic Ocean ◽  
Heat Transfers

Abstract. Rises in surface and lower troposphere air temperatures through the 21st century are projected to be especially pronounced over the Arctic Ocean during the cold season. This Arctic amplification is largely driven by loss of the sea ice cover, allowing for strong heat transfers from the ocean to the atmosphere. Consistent with observed reductions in sea ice extent, fields from both the NCEP/NCAR and JRA-25 reanalyses point to emergence of surface-based Arctic amplification in the last decade.

Trend analysis of aerosol particle physical properties at Villum Research Station, Northern Greenland

2021 ◽  
Author(s):  
Jakob Pernov ◽  
Henrik Skov ◽  
Daniel Thomas ◽  
Andreas Massling
Keyword(s):  
Sea Ice ◽  
Physical Properties ◽  
The Arctic ◽  
Anthropogenic Emissions ◽  
Research Station ◽  
Sea Ice Extent ◽  
Accumulation Mode ◽  
Cloud Properties ◽  
Arctic Aerosol ◽  
Increasing Trends

<p><strong>Introduction</strong></p><p>The Arctic region is particularly sensitive to global climate change, experiencing warming at twice the rate of the global average. Anthropogenic pollution (e.g. aerosols, black carbon, ozone, and greenhouse gases), which to a large extent originates from the mid-latitudes, is suspected to be partly responsible for this warming. Atmospheric aerosols can alter the planetary radiation balance directly through scattering and absorption and indirectly through modification of cloud properties. These interactions depend on aerosol physicochemical properties. The Arctic cryosphere and atmosphere has undergone significant changes in recent decades, accompanied by reductions in anthropogenic emissions, especially in Europe and North America. These changes have important ramifications for the ambient Arctic aerosol. Understanding the direction and magnitude of recent changes in the Arctic aerosol population is key to elucidating the implications for the changing Arctic, although this remains a scientific challenge. Here we report recent trends for aerosol particle physical properties, which will aid in this understanding of the changing Arctic.</p><p><strong>Measurement Site</strong><strong> & Methods</strong></p><p>All measurements were obtained at Villum Research Station (Villum, N 81<sup>o</sup>36’ W 16<sup>o</sup>39’ 24 m a.s.l) in northeastern Greenland. Particle number size distributions (PNSD) were measured using a Scanning Mobility Particle Sizer (SMPS) from 2010–2018.</p><p>We have utilized mode fitting on daily averaged PNSDs to characterize three distinct modes (Nucleation, Aitken, and Accumulation) along with geometric mean diameters (GMD) and number concentrations (PN) for each mode.</p><p>The trends in these parameters were identified and quantified using the Mann-Kendal test and Theil Sen slope on the 90<sup>th</sup> % confidence interval. Trends in different months were analyzed using daily modal parameters.</p><p><strong>Results</strong></p><p>Statistically significant (s.s.) decreasing trends were detected for the Nucleation and Aitken modes GMDs in the winter, spring, and summer, with the only s.s. increasing trends occurring in the autumn. The Accumulation mode GMD showed a s.s. decrease in the spring and s.s. increase in the summer. For the PN of each mode, large s.s. increasing trends were detected for Nucleation and Aitken mode PN in the spring and summer. The Accumulation mode PN showed a small s.s. increase in the summer and a large s.s. decrease in the autumn.</p><p>            These results show that ultrafine modes (Nucleation and Aitken) are decreasing in diameter while simultaneously increasing in number concentration. These trends are most likely related to changes in sea ice extent, as previous research has indicated a negative correlation between new particle formation and sea ice extent. The decrease in Accumulation mode GMD in spring (during the peak of the Arctic Haze) is possibly related to decreases in anthropogenic emissions, while the increase PN during summer could signal an increase in primary biogenic aerosol emissions from the ocean surface. The large decrease in Accumulation mode PN during autumn requires further investigation. </p><p>            This work will help confirm trends of other aerosol components observed at other High Arctic sites and can offer insight into the climatic implications (i.e., radiative balance and cloud properties) for a future Arctic climate.</p>

scholarly journals The emergence of surface-based Arctic amplification

2008 ◽  
Vol 2 (4) ◽  
pp. 601-622 ◽  
Author(s):  
M. C. Serreze ◽  
A. P. Barrett ◽  
J. C. Stroeve ◽  
D. N. Kindig ◽  
M. M. Holland
Keyword(s):  
Sea Ice ◽  
21St Century ◽  
Lower Troposphere ◽  
Cold Season ◽  
The Arctic ◽  
Arctic Amplification ◽  
Sea Ice Extent ◽  
Air Temperatures ◽  
The Arctic Ocean ◽  
Heat Transfers

Abstract. Rises in surface and lower troposphere air temperatures through the 21st century are projected to be especially pronounced over the Arctic Ocean during the cold season. This Arctic amplification is largely driven by loss of the sea ice cover, allowing for strong heat transfers from the ocean to the atmosphere. Consistent with observed reductions in sea ice extent, fields from the NCEP/NCAR reanalysis suggest emergence of surface-based Arctic amplification in the last decade.

scholarly journals The early twentieth century warming and winter Arctic sea ice

2012 ◽  
Vol 6 (3) ◽  
pp. 2037-2057 ◽  
Author(s):  
V. A. Semenov ◽  
M. Latif
Keyword(s):  
Twentieth Century ◽  
Sea Ice ◽  
Surface Temperature ◽  
Strong Dependence ◽  
Arctic Sea Ice ◽  
The Arctic ◽  
Sea Ice Extent ◽  
Surface Warming ◽  
Early Twentieth Century ◽  
Arctic Sea

Abstract. The Arctic featured the strongest surface warming over the globe during the recent decades, and the temperature increase was accompanied by a rapid decline in sea ice extent. However, little is known about Arctic sea ice change during the Early Twentieth Century Warming (ETCW) during 1920–1940, also a period of a strong surface warming, both globally and in the Arctic. Here, we investigate the sensitivity of Arctic winter surface air temperature (SAT) to sea ice during 1875–2008 by means of simulations with an atmospheric general circulation model (AGCM) forced by estimates of the observed sea surface temperature (SST) and sea ice concentration. The Arctic warming trend since the 1960s is very well reproduced by the model. In contrast, ETCW in the Arctic is hardly captured. This is consistent with the fact that the sea ice extent in the forcing data does not strongly vary during ETCW. AGCM simulations with observed SST but fixed sea ice reveal a strong dependence of winter SAT on sea ice extent. In particular, the warming during the recent decades is strongly underestimated by the model, if the sea ice extent does not decline and varies only seasonally. This suggests that a significant reduction of Arctic sea ice extent may have also accompanied the Early Twentieth Century Warming, pointing toward an important link between anomalous sea ice extent and Arctic surface temperature variability.

scholarly journals Dynamic and Thermodynamic Impacts of the Winter Arctic Oscillation on Summer Sea Ice Extent

2018 ◽  
Vol 31 (4) ◽  
pp. 1483-1497 ◽  
Author(s):  
Hyo-Seok Park ◽  
Andrew L. Stewart ◽  
Jun-Hyeok Son
Keyword(s):  
Sea Ice ◽  
Radiative Forcing ◽  
Arctic Oscillation ◽  
Reanalysis Data ◽  
Heat Fluxes ◽  
The Arctic ◽  
Ice Thickness ◽  
Sea Ice Extent ◽  
The Pacific ◽  
Basin Scale

Arctic summer sea ice extent exhibits substantial interannual variability, as is highlighted by the remarkable recovery in sea ice extent in 2013 following the record minimum in the summer of 2012. Here, the mechanism via which Arctic Oscillation (AO)-induced ice thickness changes impact summer sea ice is explored, using observations and reanalysis data. A positive AO weakens the basin-scale anticyclonic sea ice drift and decreases the winter ice thickness by 15 and 10 cm in the Eurasian and the Pacific sectors of the Arctic, respectively. Three reanalysis datasets show that the upward surface heat fluxes are reduced over wide areas of the Arctic, suppressing the ice growth during the positive AO winters. The winter dynamic and thermodynamic thinning preconditions the ice for enhanced radiative forcing via the ice–albedo feedback in late spring–summer, leading to an additional 10 cm of thinning over the Pacific sector of the Arctic. Because of these winter AO-induced dynamic and thermodynamics effects, the winter AO explains about 22% ( r = −0.48) of the interannual variance of September sea ice extent from 1980 to 2015.

scholarly journals Whither Arctic sea ice? A clear signal of decline regionally, seasonally and extending beyond the satellite record

2007 ◽  
Vol 46 ◽  
pp. 428-434 ◽  
Author(s):  
Walter N. Meier ◽  
Julienne Stroeve ◽  
Florence Fetterer
Keyword(s):  
Time Series ◽  
Sea Ice ◽  
Arctic Sea Ice ◽  
Passive Microwave ◽  
The Arctic ◽  
Sea Ice Extent ◽  
The Past ◽  
Regional Trends ◽  
Arctic Sea ◽  
Derived Data

AbstractThe Arctic sea ice has been pointed to as one of the first and clearest indicators of climate change. Satellite passive microwave observations from 1979 through 2005 now indicate a significant –8.4±1.5% decade–1 trend (99% confidence level) in September sea-ice extent, a larger trend than earlier estimates due to acceleration of the decline over the past 41 years. There are differences in regional trends, with some regions more stable than others; not all regional trends are significant. The largest trends tend to occur in months where melt is at or near its peak for a given region. A longer time series of September extents since 1953 was adjusted to correct biases and extended through 2005. The trend from the longer time series is –7.7±0.6% decade–1 (99%), slightly less than from the satellite-derived data that begin in 1979, which is expected given the recent acceleration in the decline.

scholarly journals Ocean surface warming in Krossfjorden, Svalbard, during the last 60 years

2020 ◽  
Author(s):  
Harikrishnan Guruvayoorappan ◽  
Arto Miettinen ◽  
Dmitry Divine ◽  
Matthias Moros ◽  
Lisa Orme ◽  
...  
Keyword(s):  
Sea Ice ◽  
Arctic Region ◽  
Ocean Surface ◽  
Warming Trend ◽  
Sea Surface ◽  
The Arctic ◽  
Arctic Water ◽  
Sea Ice Extent ◽  
Surface Warming ◽  
Instrumental Records

<p>A high-resolution marine sediment core NP16-Kro1-MCB from Krossfjorden, Western Svalbard is studied to investigate changes in sea surface conditions in the fjord during the last 60 years (1953-2014). The diatom-based reconstruction of August sea surface temperature (aSST) demonstrates a clear warming trend of 0.6 °C through the record. As inferred from Marginal Ice Zone (MIZ) diatoms, surface warming occurs in parallel with a decline in sea ice extent (SIE) during recent decades. Factor analysis identified variations in diatom assemblages representing different water masses, showing a dominance of Arctic water diatoms throughout the period and decadal variations in the sea ice assemblage during periods of peak sea ice extent. The strong dominance of Arctic water diatoms along with increasing aSST suggest prolonged open water conditions and increased sea ice melting in the region throughout the observed period. The reconstructed ocean surface changes are in line with the background warming occurring over the Arctic region. A comparison with instrumental records from neighboring regions supports the quality of the reconstructions, including the average reconstructed aSST and the magnitude of the warming trend. We suggest that increased CO<sub>2</sub> forcing together with ocean-atmospheric interaction have caused the increasing SST trend and decreasing sea ice presence in Krossfjorden rather than an increasing influence from Atlantic Water, which has amplified changes in many regions of Svalbard. </p>

scholarly journals The Role of Springtime Arctic Clouds in Determining Autumn Sea Ice Extent

2016 ◽  
Vol 29 (18) ◽  
pp. 6581-6596 ◽  
Author(s):  
Christopher J. Cox ◽  
Taneil Uttal ◽  
Charles N. Long ◽  
Matthew D. Shupe ◽  
Robert S. Stone ◽  
...  
Keyword(s):  
Sea Ice ◽  
Arctic Ocean ◽  
Radiative Forcing ◽  
Cloud Cover ◽  
Arctic Sea Ice ◽  
The Arctic ◽  
Sea Ice Extent ◽  
Radiative Processes ◽  
Arctic Sea

Abstract Recent studies suggest that the atmosphere conditions arctic sea ice properties in spring in a way that may be an important factor in predetermining autumn sea ice concentrations. Here, the role of clouds in this system is analyzed using surface-based observations from Barrow, Alaska. Barrow is a coastal location situated adjacent to the region where interannual sea ice variability is largest. Barrow is also along a main transport pathway through which springtime advection of atmospheric energy from lower latitudes to the Arctic Ocean occurs. The cloud contribution is quantified using the observed surface radiative fluxes and cloud radiative forcing (CRF) derived therefrom, which can be positive or negative. In low sea ice years enhanced positive CRF (increased cloud cover enhancing longwave radiative forcing) in April is followed by decreased negative CRF (decreased cloud cover allowing a relative increase in shortwave radiative forcing) in May and June. The opposite is true in high sea ice years. In either case, the combination and timing of these early and late spring cloud radiative processes can serve to enhance the atmospheric preconditioning of sea ice. The net CRF (April and May) measured at Barrow from 1993 through 2014 is negatively correlated with sea ice extent in the following autumn (r2 = 0.33; p < 0.01). Reanalysis data appear to capture the general timing and sign of the observed CRF anomalies at Barrow and suggest that the anomalies occur over a large region of the central Arctic Ocean, which supports the link between radiative processes observed at Barrow and the broader arctic sea ice extent.

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