New estimates of Arctic and Antarctic sea ice extent during September 1964 from recovered Nimbus I satellite imagery

Meier, Walter N.; Gallaher, D. W.; Campbell, G. G.

doi:10.5194/tc-7-699-2013

Cited by 60 publications

(57 citation statements)

References 18 publications

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“…The polar regions have undergone major transformations over the last three decades, with satellite and in situ observations revealing a dramatic decline of Arctic summer sea ice extent and volume [Meier et al, 2013;Kwok and Rothrock, 2009], and a modest increase in winter Antarctic sea ice extent with significant spatial variability [Simpkins et al, 2013]. The magnitude and trends of such changes can only be partially captured by contemporary climate models [Stroeve et al, 2007;Jeffries et al, 2013;Tietsche et al, 2014], suggesting that important physical processes are being neglected.…”

Section: Introductionmentioning

confidence: 99%

Comparison of viscoelastic‐type models for ocean wave attenuation in ice‐covered seas

2015

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Continuum‐based models that describe the propagation of ocean waves in ice‐infested seas are considered, where the surface ocean layer (including ice floes, brash ice, etc.) is modeled by a homogeneous viscoelastic material which causes waves to attenuate as they travel through the medium. Three ice layer models are compared, namely a viscoelastic fluid layer model currently being trialed in the spectral wave model WAVEWATCH III® and two simpler viscoelastic thin beam models. All three models are two dimensional. A comparative analysis shows that one of the beam models provides similar predictions for wave attenuation and wavelength to the viscoelastic fluid model. The three models are calibrated using wave attenuation data recently collected in the Antarctic marginal ice zone as an example. Although agreement with the data is obtained with all three models, several important issues related to the viscoelastic fluid model are identified that raise questions about its suitability to characterize wave attenuation in ice‐covered seas. Viscoelastic beam models appear to provide a more robust parameterization of the phenomenon being modeled, but still remain questionable as a valid characterization of wave‐ice interactions generally.

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Section: Introductionmentioning

confidence: 99%

Comparison of viscoelastic‐type models for ocean wave attenuation in ice‐covered seas

2015

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“…The 34 year record documents the seasonal and interannual evolution in the Arctic sea ice cover. Sea ice extent has decreased for all seasons, with the strongest average decline in September (84 100 km 2 per year), and a moderate average decline during May of 33 100 km 2 per year (Meier et al, 2013). After 1999After (1999After -2010, the negative decadal trend of summer sea ice extent intensified to 154 000 km 2 per year and this period stands out as one of persistent decline, with record low September minima during 2002,2005,2007, and the latest record extent of 4.41×10 6 km 2 in September 2012.…”

Section: Sea Ice Extentmentioning

confidence: 99%

“…Reconstructions based on a limited number of local observations have been carried out, resulting for example in the HadISST2 data set (Rayner et al, 2006). Inconsistencies in the transition between traditional observations and the satellite record led to a recent correction of the sea ice extent time series before 1979 (Meier et al, 2012(Meier et al, , 2013, which brought to light a large interannual variability superimposed on a rather stable summer sea ice extent from the 1950s through to the 1970s. The overall summer sea ice extent trend for the period is estimated at −6.8 % per decade.…”

Section: Introductionmentioning

confidence: 99%

Recent advances in understanding the Arctic climate system state and change from a sea ice perspective: a review

2014

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Abstract. Sea ice is the central component and most sensitive indicator of the Arctic climate system. Both the depletion and areal decline of the Arctic sea ice cover, observed since the 1970s, have accelerated since the millennium. While the relationship of global warming to sea ice reduction is evident and underpinned statistically, it is the connecting mechanisms that are explored in detail in this review.Sea ice erodes both from the top and the bottom. Atmospheric, oceanic and sea ice processes interact in nonlinear ways on various scales. Feedback mechanisms lead to an Arctic amplification of the global warming system: the amplification is both supported by the ice depletion and, at the same time, accelerates ice reduction. Knowledge of the mechanisms of sea ice decline grew during the 1990s and This article reviews recent progress in understanding the sea ice decline. Processes are revisited from atmospheric, oceanic and sea ice perspectives. There is strong evidence that decisive atmospheric changes are the major driver of sea ice change. Feedbacks due to reduced ice concentration, surface albedo, and ice thickness allow for additional local atmospheric and oceanic influences and self-supporting feedbacks. Large-scale ocean influences on Arctic Ocean hydrology and circulation are highly evident. Northward heat fluxes in the ocean are clearly impacting the ice margins, especially in the Atlantic sector of the Arctic. There is little indication of a direct and decisive influence of the warming ocean on the overall sea ice cover, due to an isolating layer of cold and fresh water underneath the sea ice.

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“…(Sea ice area is nominally different from SIE in that it includes regions of 0-15% sea ice concentration, but tests comparing the SIE and sea ice area data reveal no noticeable difference for the season of interest.) Additionally, point estimates of SIE from the Nimbus 1, 2, and 3 satellite missions [Meier et al, 2013a;Gallaher et al, 2014] were used. The Nimbus 1 mission covered a 3 week period in September 1964, Nimbus 2 was operational from May to August 1966, and Nimbus 3 data are available for the entire May 1969 to January 1970.…”

Section: Sie Datamentioning

confidence: 99%

“…Studies have suggested that multidecadal variability may explain some of the observed trends [Fan et al, 2014], with a particular role for atmospheric teleconnections to the tropical Pacific [Ding et al, 2011], but this is hard to test in the satellite record, and useful insight may be gained from extending the sea ice record further back than 1979. Estimates of sea ice areal cover from the early NIMBUS satellite missions now provide Southern Ocean SIE as far back as 1964 [Meier et al, 2013a;Gallaher et al, 2014]. Gagne et al [2015] compared the NIMBUS 1 estimate of September 1964 Southern Ocean SIE with both models and passive microwave data and found that although there has been a slight decrease over the 50 year period, the change was not significant in the context of simulated internal variability.…”

Section: Introductionmentioning

confidence: 99%

Century‐scale perspectives on observed and simulated Southern Ocean sea ice trends from proxy reconstructions

et al. 2016

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Since 1979 when continuous satellite observations began, Southern Ocean sea ice cover has increased, whilst global coupled climate models simulate a decrease over the same period. It is uncertain whether the observed trends are anthropogenically forced or due to internal variability, or whether the apparent discrepancy between models and observations can be explained by internal variability. The shortness of the satellite record is one source of this uncertainty, and a possible solution is to use proxy reconstructions, which extend the analysis period but at the expense of higher observational uncertainty. In this work, we evaluate the utility for change detection of 20th century Southern Ocean sea ice proxies. We find that there are reliable proxies for the East Antarctic, Amundsen, Bellingshausen and Weddell sectors in late winter, and for the Weddell Sea in late autumn. Models and reconstructions agree that sea ice extent in the East Antarctic, Amundsen and Bellingshausen Seas has decreased since the early 1970s, consistent with an anthropogenic response. However, the decrease is small compared to internal variability, and the change is not robustly detectable. We also find that optimal fingerprinting filters out much of the uncertainty in proxy reconstructions. The Ross Sea is a confounding factor, with a significant increase in sea ice since 1979 that is not captured by climate models; however, existing proxy reconstructions of this region are not yet sufficiently reliable for formal change detection.

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New estimates of Arctic and Antarctic sea ice extent during September 1964 from recovered Nimbus I satellite imagery

Cited by 60 publications

References 18 publications

Comparison of viscoelastic‐type models for ocean wave attenuation in ice‐covered seas

Comparison of viscoelastic‐type models for ocean wave attenuation in ice‐covered seas

Recent advances in understanding the Arctic climate system state and change from a sea ice perspective: a review

Century‐scale perspectives on observed and simulated Southern Ocean sea ice trends from proxy reconstructions

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