Reductions in Arctic sea ice cover no longer limited to summer

Meier, Walter N.; Stroeve, Julienne; Fetterer, F.; Knowles, Ken

doi:10.1029/2005eo360003

Cited by 47 publications

(30 citation statements)

References 2 publications

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“…Recently, sea ice 6 coverage has strongly decreased in the northern hemisphere, in summer and winter 7 (Meier et al, 2005;Stroeve et al, 2005). However, little is known about ice thickness 8…”

Section: Below) 18mentioning

confidence: 99%

Helicopter-borne measurements of sea ice thickness, using a small and lightweight, digital EM system

Haas

Lobach²,

Hendricks

et al. 2009

Journal of Applied Geophysics

195

223

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Sea ice is an important climate variable and is also an obstacle for marine operations in polar regions. We have developed a small and lightweight, digital frequency-domain electromagnetic-induction (EM) system, a so-called EM bird, dedicated for measurements of sea ice thickness. 3.5 m long and weighing only 105 kg, it can easily be shipped to remote places and can be operated from icebreakers and small helicopters. Here, we describe the technical design of the bird operating at two frequencies of f1 = 3.68 kHz and f2 = 112 kHz, and study its technical performance. On average, noise amounts to ±8.5 ppm and ±17.5 ppm for f1 and f2, respectively. Electrical drift amounts to 200 ppm/h and 2000 ppm/h for f1 and f2, during the first 0.5 h of operation. It is reduced by 75% after two hours. Calibration of the Inphase and Quadrature ppm signals varies by 2 to 3%. A sensitivity study shows that all these signal variations do affect the accuracy of the ice thickness retrieval, but that it remains better than ±0.1 m over level ice in most cases.This accuracy is also confirmed by means of comparisons of the helicopter EM data with other thickness measurements. The paper also presents the ice thickness retrieval from single component Sea ice is an important climate variable and is also an obstacle for marine operations 3 in polar regions. We have developed a small and lightweight, digital frequency-4 domain electromagnetic-induction (EM) system, a so-called EM bird, dedicated for 5 measurements of sea ice thickness. 3.5 m long and weighing only 105 kg, it can 6 easily be shipped to remote places and can be operated from icebreakers and small 7 helicopters. Here, we describe the technical design of the bird operating at two 8 frequencies of f1 = 3.68 kHz and f2 = 112 kHz, and study its technical performance. 9On average, noise amounts to ±8.5 ppm and ±17.5 ppm for f1 and f2, respectively. 10Electrical drift amounts to 200 ppm/h and 2000 ppm/h for f1 and f2, during the first 11 0.5 h of operation. It is reduced by 75% after two hours. Calibration of the Inphase 12and Quadrature ppm signals varies by 2 to 3%. A sensitivity study shows that all 13 these signal variations do affect the accuracy of the ice thickness retrieval, but that it 14 remains better than ±0.1 m over level ice in most cases. This accuracy is also 15 confirmed by means of comparisons of the helicopter EM data with other thickness 16 measurements. The paper also presents the ice thickness retrieval from single

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Section: Below) 18mentioning

confidence: 99%

Helicopter-borne measurements of sea ice thickness, using a small and lightweight, digital EM system

Haas

Lobach²,

Hendricks

et al. 2009

Journal of Applied Geophysics

195

223

View full text Add to dashboard Cite

show abstract

“…If enough ice is lost to allow sufficient extra heat into the Arctic Ocean, such that some can remain through the winter and reduce ice thickness the following spring, the so-called ice-albedo feedback will accelerate the loss of ice [e.g., Serreze and Francis, 2006]. Recent accelerat ing declines in summer and winter ice extent [Meier et al, 2005] suggest this thresh old has been crossed.…”

Section: Pages 509-511mentioning

confidence: 99%

New insight into the disappearing Arctic sea ice

Francis¹,

Hunter²

2006

EoS Transactions

174

136

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The dramatic loss of Arctic sea ice is ringing alarm bells in the minds of climate scientists, policy makers, and the public. The extent of perennial sea ice—ice that has survived a summer melt season—has declined 20% since the mid‐1970s [Stroeue et al., 2005]. Its retreat varies regionally, driven by changes in winds and heating from the atmosphere and ocean. Limited data have hampered attempts to identify which culprits are to blame, but new satellite‐derived information provides insight into the drivers of change. A clear message emerges. The location of the summer ice edge is strongly correlated to variability in longwave (infrared) energy emitted by the atmosphere (downward longwave flux; DLF), particularly during the most recent decade when losses have been most rapid. Increasing DLF, in turn, appears to be driven by more clouds and water vapor in spring over the Arctic.

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“…For the past 100 years, the Arctic has warmed twice as much as the global average (Trenberth et al, 2007). This warming has been associated with a substantial diminution of sea ice thickness (Serreze et al, 2000) and extent (Meier et al, 2005).…”

Section: Introductionmentioning

confidence: 99%

The 15th century Arctic warming in coupled model simulations with data assimilation

et al. 2009

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Abstract. An ensemble of simulations of the climate of the past millennium conducted with a three-dimensional climate model of intermediate complexity are constrained to follow temperature histories obtained from a recent compilation of well-calibrated surface temperature proxies using a simple data assimilation technique. Those simulations provide a reconstruction of the climate of the Arctic that is compatible with the model physics, the forcing applied and the proxy records. Available observational data, proxybased reconstructions and our model results suggest that the Arctic climate is characterized by substantial variations in surface temperature over the past millennium. Though the most recent decades are likely to be the warmest of the past millennium, we find evidence for substantial past warming episodes in the Arctic. In particular, our model reconstructions show a prominent warm event during the period 1470-1520. This warm period is likely related to the internal variability of the climate system, that is the variability present in the absence of any change in external forcing. We examine the roles of competing mechanisms that could potentially produce this anomaly. This study leads us to conclude that changes in atmospheric circulation, through enhanced southwesterly winds towards northern Europe, Siberia and Canada, are likely the main cause of the late 15th/early 16th century Arctic warming.

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Reductions in Arctic sea ice cover no longer limited to summer

Cited by 47 publications

References 2 publications

Helicopter-borne measurements of sea ice thickness, using a small and lightweight, digital EM system

Helicopter-borne measurements of sea ice thickness, using a small and lightweight, digital EM system

New insight into the disappearing Arctic sea ice

The 15th century Arctic warming in coupled model simulations with data assimilation

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