scholarly journals Observations of Bromine Monoxide Transport In the Arctic Sustained on Aerosol Particles

2017 ◽  
Author(s):  
Peter K. Peterson ◽  
Denis Pöhler ◽  
Holger Sihler ◽  
Johannes Zielcke ◽  
Stephan General ◽  
...  
Keyword(s):  
Aerosol Particles ◽  
Arctic Sea Ice ◽  
Heterogeneous Reactions ◽  
Atmospheric Composition ◽  
The Arctic ◽  
Optical Absorption Spectroscopy ◽  
Near Surface ◽  
Arctic Sea ◽  
Reactive Halogen Species ◽  
Novel Method

Abstract. The return of sunlight in the polar spring leads to production of reactive halogen species from the surface snowpack, significantly altering the chemical composition of the Arctic near-surface atmosphere and the fate of long-range transported pollutants, including mercury. Recent work has shown the initial production of reactive bromine at the Arctic surface snowpack; however, we have limited knowledge of the vertical extent of this chemistry, as well as the lifetime and possible transport of reactive bromine aloft. Here, we present bromine monoxide (BrO) and aerosol particle measurements obtained during the March 2012 BRomine Ozone Mercury EXperiment (BROMEX) near Utqiagvik (Barrow), AK. The airborne differential optical absorption spectroscopy (DOAS) measurements provided an unprecedented level of spatial resolution, over two orders of magnitude greater than satellite observations and with vertical resolution unable to be achieved by satellite methods, for BrO in the Arctic. This novel method provided quantitative identification of a BrO plume, disconnected from the surface, moving at the speed of the air mass. This lofted reactive bromine plume was transported and maintained at elevated levels through heterogeneous reactions on co-located supermicron aerosol particles, independently of surface snowpack bromine chemistry. This chemical transport mechanism significantly increases the spatial extent of this reactive bromine chemistry, impacting atmospheric composition and pollutant fate across the region, beyond the area of initial snowpack halogen production. This process must be considered in the interpretation of satellite BrO observations and examined in the context of the rapidly changing Arctic sea ice and snowpack.

scholarly journals Observations of bromine monoxide transport in the Arctic sustained on aerosol particles

2017 ◽  
Vol 17 (12) ◽  
pp. 7567-7579 ◽  
Author(s):  
Peter K. Peterson ◽  
Denis Pöhler ◽  
Holger Sihler ◽  
Johannes Zielcke ◽  
Stephan General ◽  
...  
Keyword(s):  
Aerosol Particle ◽  
Aerosol Particles ◽  
Arctic Region ◽  
Arctic Sea Ice ◽  
Heterogeneous Reactions ◽  
Atmospheric Composition ◽  
The Arctic ◽  
Optical Absorption Spectroscopy ◽  
Near Surface ◽  
Particle Measurements

Abstract. The return of sunlight in the polar spring leads to the production of reactive halogen species from the surface snowpack, significantly altering the chemical composition of the Arctic near-surface atmosphere and the fate of long-range transported pollutants, including mercury. Recent work has shown the initial production of reactive bromine at the Arctic surface snowpack; however, we have limited knowledge of the vertical extent of this chemistry, as well as the lifetime and possible transport of reactive bromine aloft. Here, we present bromine monoxide (BrO) and aerosol particle measurements obtained during the March 2012 BRomine Ozone Mercury EXperiment (BROMEX) near Utqiaġvik (Barrow), AK. The airborne differential optical absorption spectroscopy (DOAS) measurements provided an unprecedented level of spatial resolution, over 2 orders of magnitude greater than satellite observations and with vertical resolution unable to be achieved by satellite methods, for BrO in the Arctic. This novel method provided quantitative identification of a BrO plume, between 500 m and 1 km aloft, moving at the speed of the air mass. Concurrent aerosol particle measurements suggest that this lofted reactive bromine plume was transported and maintained at elevated levels through heterogeneous reactions on colocated supermicron aerosol particles, independent of surface snowpack bromine chemistry. This chemical transport mechanism explains the large spatial extents often observed for reactive bromine chemistry, which impacts atmospheric composition and pollutant fate across the Arctic region, beyond areas of initial snowpack halogen production. The possibility of BrO enhancements disconnected from the surface potentially contributes to sustaining BrO in the free troposphere and must also be considered in the interpretation of satellite BrO column observations, particularly in the context of the rapidly changing Arctic sea ice and snowpack.

scholarly journals The Impact of Regional Arctic Sea Ice Loss on Atmospheric Circulation and the NAO

2016 ◽  
Vol 29 (2) ◽  
pp. 889-902 ◽  
Author(s):  
Rasmus A. Pedersen ◽  
Ivana Cvijanovic ◽  
Peter L. Langen ◽  
Bo M. Vinther
Keyword(s):  
Sea Ice ◽  
Atmospheric Circulation ◽  
General Circulation ◽  
Ice Cover ◽  
Arctic Sea Ice ◽  
The Arctic ◽  
Near Surface ◽  
Arctic Sea ◽  
The Impact ◽  
Sea Ice Reduction

Abstract Reduction of the Arctic sea ice cover can affect the atmospheric circulation and thus impact the climate beyond the Arctic. The atmospheric response may, however, vary with the geographical location of sea ice loss. The atmospheric sensitivity to the location of sea ice loss is studied using a general circulation model in a configuration that allows combination of a prescribed sea ice cover and an active mixed layer ocean. This hybrid setup makes it possible to simulate the isolated impact of sea ice loss and provides a more complete response compared to experiments with fixed sea surface temperatures. Three investigated sea ice scenarios with ice loss in different regions all exhibit substantial near-surface warming, which peaks over the area of ice loss. The maximum warming is found during winter, delayed compared to the maximum sea ice reduction. The wintertime response of the midlatitude atmospheric circulation shows a nonuniform sensitivity to the location of sea ice reduction. While all three scenarios exhibit decreased zonal winds related to high-latitude geopotential height increases, the magnitudes and locations of the anomalies vary between the simulations. Investigation of the North Atlantic Oscillation reveals a high sensitivity to the location of the ice loss. The northern center of action exhibits clear shifts in response to the different sea ice reductions. Sea ice loss in the Atlantic and Pacific sectors of the Arctic cause westward and eastward shifts, respectively.

scholarly journals Effects of Global Warming on the Poleward Heat Transport by Non-Stationary Large-Scale Atmospheric Eddies, and Feedbacks Affecting the Formation of the Arctic Climate

2021 ◽  
Vol 9 (8) ◽  
pp. 867
Author(s):  
Sergei Soldatenko
Keyword(s):  
Global Warming ◽  
Heat Transport ◽  
Large Scale ◽  
Arctic Sea Ice ◽  
Arctic Climate ◽  
The Arctic ◽  
Arctic Amplification ◽  
Near Surface ◽  
Feedback Mechanisms ◽  
Arctic Sea

It is a well-known fact that the observed rise in the Arctic near-surface temperature is more than double the increase in global mean temperature. However, the entire scientific picture of the formation of the Arctic amplification has not yet taken final shape and the causes of this phenomenon are still being discussed within the scientific community. Some recent studies suggest that the atmospheric equator-to-pole transport of heat and moisture, and also radiative feedbacks, are among the possible reasons for the Arctic amplification. In this paper, we highlight and summarize some of our research related to assessing the response of climate in the Arctic to global warming and vice versa. Since extratropical transient eddies dominate the meridional transport of sensible and latent heat from low to high latitudes, we estimated the effect of climate change on meridional heat transport by means of the β-plane model of baroclinic instability. It has been shown that the heat transport from low and middle latitudes to the Arctic by large scale transient eddies increases by about 9% due to global warming, contributing to the polar amplification—and thereby a decrease in the extent—of the Arctic sea, which, in turn, is an important factor in the formation of the Arctic climate. The main radiative feedback mechanisms affecting the formation of the Arctic climate are also considered and discussed. It was emphasized that the influence of feedbacks depends on a season since the total feedback in the winter season is negative, while in the summer season, it is positive. Thus, further research is required to diminish the uncertainty regarding the character of various feedback mechanisms in the shaping of the Artic climate and, through that, in predicting the extent of Arctic sea ice.

scholarly journals Diminishing Arctic Sea Ice Promotes Stronger Surface Winds

2018 ◽  
Vol 31 (19) ◽  
pp. 8101-8119 ◽  
Author(s):  
John Mioduszewski ◽  
Stephen Vavrus ◽  
Muyin Wang
Keyword(s):  
Surface Roughness ◽  
Sea Ice ◽  
Surface Wind ◽  
Atmospheric Stability ◽  
Arctic Sea Ice ◽  
The Arctic ◽  
Near Surface ◽  
Wind Speeds ◽  
Arctic Sea ◽  
Autumn And Winter

Projections of Arctic sea ice through the end of the twenty-first century indicate the likelihood of a strong reduction in ice area and thickness in all seasons, leading to a substantial thermodynamic influence on the overlying atmosphere. This is likely to have an effect on winds over the Arctic basin because of changes in atmospheric stability, surface roughness, and/or baroclinicity. Here we identify patterns of wind changes in all seasons across the Arctic and their likely causal mechanisms, particularly those associated with sea ice loss. Output from the Community Earth System Model Large Ensemble Project (CESM-LE) was analyzed for the recent past (primarily 1971–2000) and future (2071–2100). Mean near-surface wind speeds over the Arctic Ocean are projected to increase by late century in all seasons but especially during autumn and winter, when they strengthen by up to 50% locally. The most extreme wind speeds in the 95th percentile change even more, increasing in frequency by up to 100%. The strengthened winds are closely linked to decreasing surface roughness and lower-tropospheric stability resulting from the loss of sea ice cover and consequent surface warming (exceeding 20°C warmer in the central Arctic in autumn and winter), as well as local changes in the storm track. The implications of stronger future winds include increased coastal and navigational hazards. Our findings suggest that increasing winds, along with reduction of sea ice, rising sea level, and thawing permafrost, represent another important contributor to the growing problem of Arctic coastal erosion.

scholarly journals Impacts of Arctic Sea Ice on Cold Season Atmospheric Variability and Trends Estimated from Observations and a Multi-model Large Ensemble

2021 ◽  
pp. 1-64
Author(s):  
Yu-Chiao Liang ◽  
Claude Frankignoul ◽  
Young-Oh Kwon ◽  
Guillaume Gastineau ◽  
Elisa Manzini ◽  
...  
Keyword(s):  
Sea Ice ◽  
Surface Temperature ◽  
General Circulation ◽  
Cold Season ◽  
Arctic Sea Ice ◽  
The Arctic ◽  
Atmospheric Variability ◽  
Large Ensemble ◽  
Near Surface ◽  
Arctic Sea

AbstractTo examine the atmospheric responses to Arctic sea-ice variability in the Northern Hemisphere cold season (October to following March), this study uses a coordinated set of large-ensemble experiments of nine atmospheric general circulation models (AGCMs) forced with observed daily-varying sea-ice, sea-surface temperature, and radiative forcings prescribed during the 1979-2014 period, together with a parallel set of experiments where Arctic sea ice is substituted by its climatology. The simulations of the former set reproduce the near-surface temperature trends in reanalysis data, with similar amplitude, and their multi-model ensemble mean (MMEM) shows decreasing sea-level pressure over much of the polar cap and Eurasia in boreal autumn. The MMEM difference between the two experiments allows isolating the effects of Arctic sea-ice loss, which explain a large portion of the Arctic warming trends in the lower troposphere and drives a small but statistically significant weakening of the wintertime Arctic Oscillation. The observed interannual co-variability between sea-ice extent in the Barents-Kara Seas and lagged atmospheric circulation is distinguished from the effects of confounding factors based on multiple regression, and quantitatively compared to the co-variability in MMEMs. The interannual sea-ice decline followed by a negative North Atlantic Oscillation-like anomaly found in observations is also seen in the MMEM differences, with consistent spatial structure but much smaller amplitude. This result suggests that the sea-ice impacts on trends and interannual atmospheric variability simulated by AGCMs could be underestimated, but caution is needed because internal atmospheric variability may have affected the observed relationship.

scholarly journals Comparison of ERA5 and ERA-Interim near surface air temperature and precipitation over Arctic sea ice: Effects on sea ice thermodynamics and evolution

2018 ◽  
Author(s):  
Caixin Wang ◽  
Robert M. Graham ◽  
Keguang Wang ◽  
Sebastian Gerland ◽  
Mats A. Granskog
Keyword(s):  
Sea Ice ◽  
Air Temperature ◽  
Cold Season ◽  
Arctic Sea Ice ◽  
The Arctic ◽  
Near Surface ◽  
Warm Bias ◽  
Ice Growth ◽  
Arctic Sea ◽  
Ice Model

Abstract. Rapid changes are occurring in the Arctic, including a reduction in sea ice thickness and coverage and a shift towards younger and thinner sea ice. Snow and sea ice models are often used to study these ongoing changes in the Arctic, and are typically forced by atmospheric reanalyses in absence of observations. ERA5 is a new global reanalysis that will replace the widely used ERA-Interim (ERA-I). In this study, we compare the 2 m air temperature (T2M) and precipitation between ERA I and ERA5, and evaluate these products using buoy observations from Arctic sea ice. We further assess how biases in reanalyses influence the snow and sea ice evolution in the Arctic, when used to force a thermodynamic sea ice model. We find that both reanalyses have a warm bias over Arctic sea ice in relation to the buoy observations. The warm bias is smaller in the warm season, and larger in the cold season, especially when the T2M is lower than −25 °C. Interestingly, the warm bias in the new ERA5 is on average 2.1 °C (daily mean) larger than ERA-I during the cold season. While ERA-I is drier than most modern reanalyses in the Arctic, the total precipitation along the buoy trajectories is often lower in ERA5 than in ERA-I. Nonetheless, the snowfall products are broadly similar for both ERA I and ERA5. ERA-I had substantial anomalous Arctic rainfall, which is greatly reduced in ERA5. Simulations with a freezing degree days (FDD) model and a 1D thermodynamic sea ice model demonstrate that the warm bias in ERA5 acts to reduce thermodynamic ice growth. However, the lower precipitation in ERA5 results in a thinner snow pack that allows more heat loss to the atmosphere. Thus, the larger warm bias and lower precipitation in ERA5, compared with ERA I, compensate in terms of the effect on winter ice growth. Ultimately, we find slightly thicker ice at the end of growth season when using ERA5 forcing, compared with ERA-I. Thus differences in the precipitation fields of the two reanalyses have a larger influence on the sea ice evolution than the T2M.

scholarly journals Comparison of ERA5 and ERA-Interim near-surface air temperature, snowfall and precipitation over Arctic sea ice: effects on sea ice thermodynamics and evolution

2019 ◽  
Vol 13 (6) ◽  
pp. 1661-1679 ◽  
Author(s):  
Caixin Wang ◽  
Robert M. Graham ◽  
Keguang Wang ◽  
Sebastian Gerland ◽  
Mats A. Granskog
Keyword(s):  
Sea Ice ◽  
Air Temperature ◽  
Arctic Sea Ice ◽  
The Arctic ◽  
Ice Thickness ◽  
Atlantic Sector ◽  
Near Surface ◽  
Warm Bias ◽  
Arctic Sea ◽  
Ice Model

Abstract. Rapid changes are occurring in the Arctic, including a reduction in sea ice thickness and coverage and a shift towards younger and thinner sea ice. Snow and sea ice models are often used to study these ongoing changes in the Arctic, and are typically forced by atmospheric reanalyses in absence of observations. ERA5 is a new global reanalysis that will replace the widely used ERA-Interim (ERA-I). In this study, we compare the 2 m air temperature (T2M), snowfall (SF) and total precipitation (TP) from ERA-I and ERA5, and evaluate these products using buoy observations from Arctic sea ice for the years 2010 to 2016. We further assess how biases in reanalyses can influence the snow and sea ice evolution in the Arctic, when used to force a thermodynamic sea ice model. We find that ERA5 is generally warmer than ERA-I in winter and spring (0–1.2 ∘C), but colder than ERA-I in summer and autumn (0–0.6 ∘C) over Arctic sea ice. Both reanalyses have a warm bias over Arctic sea ice relative to buoy observations. The warm bias is smaller in the warm season, and larger in the cold season, especially when the T2M is below −25 ∘C in the Atlantic and Pacific sectors. Interestingly, the warm bias for ERA-I and new ERA5 is on average 3.4 and 5.4 ∘C (daily mean), respectively, when T2M is lower than −25 ∘C. The TP and SF along the buoy trajectories and over Arctic sea ice are consistently higher in ERA5 than in ERA-I. Over Arctic sea ice, the TP in ERA5 is typically less than 10 mm snow water equivalent (SWE) greater than in ERA-I in any of the seasons, while the SF in ERA5 can be 50 mm SWE higher than in ERA-I in a season. The largest increase in annual TP (40–100 mm) and SF (100–200 mm) in ERA5 occurs in the Atlantic sector. The SF to TP ratio is larger in ERA5 than in ERA-I, on average 0.6 for ERA-I and 0.8 for ERA5 along the buoy trajectories. Thus, the substantial anomalous Arctic rainfall in ERA-I is reduced in ERA5, especially in summer and autumn. Simulations with a 1-D thermodynamic sea ice model demonstrate that the warm bias in ERA5 acts to reduce thermodynamic ice growth. The higher precipitation and snowfall in ERA5 results in a thicker snowpack that allows less heat loss to the atmosphere. Thus, the larger winter warm bias and higher precipitation in ERA5, compared with ERA-I, result in thinner ice thickness at the end of the growth season when using ERA5; however the effect is small during the freezing period.

scholarly journals Arctic Tropospheric Warming: Causes and Linkages to Lower Latitudes

2015 ◽  
Vol 28 (6) ◽  
pp. 2154-2167 ◽  
Author(s):  
Judith Perlwitz ◽  
Martin Hoerling ◽  
Randall Dole
Keyword(s):  
Sea Ice ◽  
Causal Chain ◽  
Arctic Sea Ice ◽  
The Arctic ◽  
Physical Factors ◽  
Climate Trends ◽  
Near Surface ◽  
The North ◽  
Arctic Sea ◽  
Arctic Sea Ice Loss

Abstract Arctic temperatures have risen dramatically relative to those of lower latitudes in recent decades, with a common supposition being that sea ice declines are primarily responsible for amplified Arctic tropospheric warming. This conjecture is central to a hypothesis in which Arctic sea ice loss forms the beginning link of a causal chain that includes weaker westerlies in midlatitudes, more persistent and amplified midlatitude waves, and more extreme weather. Through model experimentation, the first step in this chain is examined by quantifying contributions of various physical factors to October–December (OND) mean Arctic tropospheric warming since 1979. The results indicate that the main factors responsible for Arctic tropospheric warming are recent decadal fluctuations and long-term changes in sea surface temperatures (SSTs), both located outside the Arctic. Arctic sea ice decline is the largest contributor to near-surface Arctic temperature increases, but it accounts for only about 20% of the magnitude of 1000–500-hPa warming. These findings thus disconfirm the hypothesis that deep tropospheric warming in the Arctic during OND has resulted substantially from sea ice loss. Contributions of the same factors to recent midlatitude climate trends are then examined. It is found that pronounced circulation changes over the North Atlantic and North Pacific result mainly from recent decadal ocean fluctuations and internal atmospheric variability, while the effects of sea ice declines are very small. Therefore, a hypothesized causal chain of hemisphere-wide connections originating from Arctic sea ice loss is not supported.

scholarly journals Cloud and boundary layer interactions over the Arctic sea ice in late summer

2013 ◽  
Vol 13 (18) ◽  
pp. 9379-9399 ◽  
Author(s):  
M. D. Shupe ◽  
P. O. G. Persson ◽  
I. M. Brooks ◽  
M. Tjernström ◽  
J. Sedlar ◽  
...  
Keyword(s):  
Sea Ice ◽  
Mixed Layer ◽  
Late Summer ◽  
Arctic Sea Ice ◽  
Cloud Formation ◽  
The Arctic ◽  
Mixing Processes ◽  
Near Surface ◽  
Air Masses ◽  
Arctic Sea

Abstract. Observations from the Arctic Summer Cloud Ocean Study (ASCOS), in the central Arctic sea-ice pack in late summer 2008, provide a detailed view of cloud–atmosphere–surface interactions and vertical mixing processes over the sea-ice environment. Measurements from a suite of ground-based remote sensors, near-surface meteorological and aerosol instruments, and profiles from radiosondes and a helicopter are combined to characterize a week-long period dominated by low-level, mixed-phase, stratocumulus clouds. Detailed case studies and statistical analyses are used to develop a conceptual model for the cloud and atmosphere structure and their interactions in this environment. Clouds were persistent during the period of study, having qualities that suggest they were sustained through a combination of advective influences and in-cloud processes, with little contribution from the surface. Radiative cooling near cloud top produced buoyancy-driven, turbulent eddies that contributed to cloud formation and created a cloud-driven mixed layer. The depth of this mixed layer was related to the amount of turbulence and condensed cloud water. Coupling of this cloud-driven mixed layer to the surface boundary layer was primarily determined by proximity. For 75% of the period of study, the primary stratocumulus cloud-driven mixed layer was decoupled from the surface and typically at a warmer potential temperature. Since the near-surface temperature was constrained by the ocean–ice mixture, warm temperatures aloft suggest that these air masses had not significantly interacted with the sea-ice surface. Instead, back-trajectory analyses suggest that these warm air masses advected into the central Arctic Basin from lower latitudes. Moisture and aerosol particles likely accompanied these air masses, providing necessary support for cloud formation. On the occasions when cloud–surface coupling did occur, back trajectories indicated that these air masses advected at low levels, while mixing processes kept the mixed layer in equilibrium with the near-surface environment. Rather than contributing buoyancy forcing for the mixed-layer dynamics, the surface instead simply appeared to respond to the mixed-layer processes aloft. Clouds in these cases often contained slightly higher condensed water amounts, potentially due to additional moisture sources from below.

scholarly journals Cloud and boundary layer interactions over the Arctic sea-ice in late summer

2013 ◽  
Vol 13 (5) ◽  
pp. 13191-13244 ◽  
Author(s):  
M. D. Shupe ◽  
P. O. G. Persson ◽  
I. M. Brooks ◽  
M. Tjernström ◽  
J. Sedlar ◽  
...  
Keyword(s):  
Sea Ice ◽  
Mixed Layer ◽  
Late Summer ◽  
Arctic Sea Ice ◽  
Cloud Formation ◽  
The Arctic ◽  
Mixing Processes ◽  
Near Surface ◽  
Air Masses ◽  
Arctic Sea

Abstract. Observations from the Arctic Summer Cloud Ocean Study (ASCOS), in the central Arctic sea-ice pack in late summer 2008, provide a detailed view of cloud-atmosphere-surface interactions and vertical mixing processes over the sea–ice environment. Measurements from a suite of ground-based remote sensors, near surface meteorological and aerosol instruments, and profiles from radiosondes and a helicopter are combined to characterize a week-long period dominated by low-level, mixed-phase, stratocumulus clouds. Detailed case studies and statistical analyses are used to develop a conceptual model for the cloud and atmosphere structure and their interactions in this environment. Clouds were persistent during the period of study, having qualities that suggest they were sustained through a combination of advective influences and in-cloud processes, with little contribution from the surface. Radiative cooling near cloud top produced buoyancy-driven, turbulent eddies that contributed to cloud formation and created a cloud-driven mixed layer. The depth of this mixed layer was related to the amount of turbulence and condensed cloud water. Coupling of this cloud-driven mixed layer to the surface boundary layer was primarily determined by proximity. For 75% of the period of study, the primary stratocumulus cloud-driven mixed layer was decoupled from the surface and typically at a warmer potential temperature. Since the near-surface temperature was constrained by the ocean–ice mixture, warm temperatures aloft suggest that these air masses had not significantly interacted with the sea–ice surface. Instead, back trajectory analyses suggest that these warm airmasses advected into the central Arctic Basin from lower latitudes. Moisture and aerosol particles likely accompanied these airmasses, providing necessary support for cloud formation. On the occasions when cloud-surface coupling did occur, back trajectories indicated that these air masses advected at low levels, while mixing processes kept the mixed layer in equilibrium with the near-surface environment. Rather than contributing buoyancy forcing for the mixed-layer dynamics, the surface instead simply appeared to respond to the mixed-layer processes aloft. Clouds in these cases often contained slightly higher condensed water amounts, potentially due to additional moisture sources from below.

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