New estimates of the large‐scale Arctic atmospheric energy budget

Porter, D. F.; Cassano, John J.; Kindig, David N.

doi:10.1029/2009jd012653

Cited by 36 publications

(50 citation statements)

References 34 publications

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“…North Pacific and North Atlantic warm water intrusions (e.g., Shimada et al 2006;Zhang et al 2008b;Polyakov et al 2010) and atmospheric forcings are also believed to play an important role on the Arctic sea-ice variation. The atmospheric forcing parameters include large-scale atmospheric circulation patterns (Zhang et al 2008b;Ogi et al 2008;Deser et al 2000;Overland and Wang 2010), atmospheric transport of heat and moisture (Zhang et al 2008b;Graversen et al 2008Graversen et al , 2011, wind stress (Ogi et al 2008;Haas and Eicken 2001), and surface radiative and turbulent fluxes (Francis and Hunter 2006;Graversen et al 2011;Porter et al 2010Porter et al , 2011. The relative importance of each parameter and the underlying causes of Arctic sea-ice variation has, however, not been well evaluated, in particular for the two opposing extreme events in 2007 and 1996. For the past 30 years, passive microwave sensors have monitored sea-ice and provided an important tool for investigating its seasonal and inter-annual variability over the Arctic.…”

Section: Introductionmentioning

confidence: 99%

“…A warming Arctic is undergoing significant environmental change, mostly evidenced by the reduction of Arctic sea-ice extent (SIE) during summer. Sea-ice plays a major role in the Arctic climate system by regulating the amount of insolation received at the surface (Porter et al 2010 and and the salinity of sea surface water, which is one of the keys for thermohaline circulations (Levermann et al 2007). Changes in location and extent of sea-ice lead to perturbations of surface albedo and ocean-atmosphere interactions that in turn impact the climate system (Deser et al 2000;Donohoe and Battisti 2011).…”

Section: Introductionmentioning

confidence: 99%

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Critical mechanisms for the formation of extreme arctic sea-ice extent in the summers of 2007 and 1996

Dong

Zib

et al. 2013

Clim Dyn

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Along with significant changes in the Arctic climate system, the largest year-to-year variation in sea-ice extent (SIE) has occurred in the Laptev, East Siberian, and Chukchi seas (defined here as the area of focus, AOF), among which the two highly contrasting extreme events were observed in the summers of 2007 and 1996 during the period 1979-2012. Although most efforts have been devoted to understanding the 2007 low, a contrasting high September SIE in 1996 might share some related but opposing forcing mechanisms. In this study, we investigate the mechanisms for the formation of these two extremes and quantitatively estimate the cloud-radiation-water vapor feedback to the sea-ice-concentration (SIC) variation utilizing satellite-observed sea-ice products and the NASA MERRA reanalysis. The low SIE in 2007 was associated with a persistent anticyclone over the Beaufort Sea coupled with low pressure over Eurasia, which induced anomalous southerly winds. Ample warm and moist air from the North Pacific was transported to the AOF and resulted in positive anomalies of cloud fraction (CF), precipitable water vapor (PWV), surface LWnet (down-up), total surface energy and temperature. In contrast, the high SIE event in 1996 was associated with a persistent low pressure over the central Arctic coupled with high pressure along the Eastern Arctic coasts, which generated anomalous northerly winds and resulted in negative anomalies of above mentioned atmospheric parameters. In addition to their immediate impacts on sea ice reduction, CF, PWV and radiation can interplay to lead to a positive feedback loop among them, which plays a critical role in reinforcing sea ice to a great low value in 2007. During the summer of 2007, the minimum SIC is 31 % below the climatic mean, while the maximum CF, LWnet and PWV can be up to 15 %, 20 Wm -2 , and 4 kg m -3 above. The high anti-correlations (-0.79, -0.61, -0.61) between the SIC and CF, PWV, and LWnet indicate that CF, PWV and LW radiation are indeed having significant impacts on the SIC variation. A new record low occurred in the summer of 2012 was mainly triggered by a super storm over the central Arctic Ocean in early August that caused substantial mechanical ice deformation on top of the long-term thinning of an Arctic ice pack that had become more dominated by seasonal ice.Keywords Trigger and cause of Arctic sea ice retreat Á Cloud-radiation-water vapor feedback to the sea-ice-concentration variation Á Extreme Arctic seaice extent formation mechanisms Á Triggered by atmospheric forcings Á Enhanced clouds-radiation-PWV feedback

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Critical mechanisms for the formation of extreme arctic sea-ice extent in the summers of 2007 and 1996

Dong

Zib

et al. 2013

Clim Dyn

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“…Figure 5f shows the energy budget of the polar region (averaged north of 708N). Polar ASR is quantized into in the present-day Arctic (Overland and Turet 1994;Serreze et al 2007;Porter et al 2010). This decrease occurs in spite of increased AHT at its midlatitude peak (Figs.…”

Section: Ridgementioning

confidence: 99%

The Role of Oceans and Sea Ice in Abrupt Transitions between Multiple Climate States

2013

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The coupled climate dynamics underlying large, rapid, and potentially irreversible changes in ice cover are studied. A global atmosphere-ocean-sea ice general circulation model with idealized aquaplanet geometry is forced by gradual multi-millennial variations in solar luminosity. The model traverses a hysteresis loop between warm ice-free conditions and cold glacial conditions in response to 65 W m 22 variations in global,annual-mean insolation. Comparison of several model configurations confirms the importance of polar ocean processes in setting the sensitivity and time scales of the transitions. A ''sawtooth'' character is found with faster warming and slower cooling, reflecting the opposing effects of surface heating and cooling on upper-ocean buoyancy and, thus, effective heat capacity. The transition from a glacial to warm, equable climate occurs in about 200 years. In contrast to the ''freshwater hosing'' scenario, transitions are driven by radiative forcing and sea ice feedbacks. The ocean circulation, and notably the meridional overturning circulation (MOC), does not drive the climate change. The MOC (and associated heat transport) collapses poleward of the advancing ice edge, but this is a purely passive response to cooling and ice expansion. The MOC does, however, play a key role in setting the time scales of the transition and contributes to the asymmetry between warming and cooling.

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“…In the polar regions the energy budget and its variability are frequently used as a diagnostic for 34 understanding rapidly changing conditions including glacial mass balance and perennial sea ice 35 reduction (e.g., Porter et al, 2010). As noted in Cullather and Bosilovich (2010), numerical 36 reanalyses are widely used in polar research for evaluating polar processes, as boundary 37 conditions for limited area atmosphere and ocean-sea ice models, and as a first-order validation 38 for climate models.…”

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confidence: 99%

The Energy Budget of the Polar Atmosphere in MERRA

Cullather

Bosilovich

2012

Journal of Climate

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Components of the atmospheric energy budget from the Modern-Era Retrospective Analysis for Research and Applications (MERRA) are evaluated in polar regions for the period 1979–2005 and compared with previous estimates, in situ observations, and contemporary reanalyses. Closure of the budget is reflected by the analysis increments term, which indicates an energy surplus of 11 W m−2 over the North Polar cap (70°–90°N) and 22 W m−2 over the South Polar cap (70°–90°S). Total atmospheric energy convergence from MERRA compares favorably with previous studies for northern high latitudes but exceeds the available previous estimate for the South Polar cap by 46%. Discrepancies with the Southern Hemisphere energy transport are largest in autumn and may be related to differences in topography with earlier reanalyses. For the Arctic, differences between MERRA and other sources in top of atmosphere (TOA) and surface radiative fluxes are largest in May. These differences are concurrent with the largest discrepancies between MERRA parameterized and observed surface albedo. For May, in situ observations of the upwelling shortwave flux in the Arctic are 80 W m−2 larger than MERRA, while the MERRA downwelling longwave flux is underestimated by 12 W m−2 throughout the year. Over grounded ice sheets, the annual mean net surface energy flux in MERRA is erroneously nonzero. Contemporary reanalyses from the Climate Forecast Center (CFSR) and the Interim Re-Analyses of the European Centre for Medium-Range Weather Forecasts (ERA-I) are found to have better surface parameterizations; however, these reanalyses also disagree with observed surface and TOA energy fluxes. Discrepancies among available reanalyses underscore the challenge of reproducing credible estimates of the atmospheric energy budget in polar regions.

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New estimates of the large‐scale Arctic atmospheric energy budget

Cited by 36 publications

References 34 publications

Critical mechanisms for the formation of extreme arctic sea-ice extent in the summers of 2007 and 1996

Critical mechanisms for the formation of extreme arctic sea-ice extent in the summers of 2007 and 1996

The Role of Oceans and Sea Ice in Abrupt Transitions between Multiple Climate States

The Energy Budget of the Polar Atmosphere in MERRA

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