Long-term Arctic Ice Variability Records AvailablePosted By Dave Snope |
Long-Term Ice Variability in Arctic Marginal Seas
IGOR V. POLYAKOV,* GENRIKH V. ALEKSEEV,1 ROMAN V. BEKRYAEV,*1 UMA S. BHATT,* ROGER COLONY,*
MARK A. JOHNSON,# VALERII P. KARKLIN,1 DAVID WALSH,* AND ALEXANDER V. YULIN1
*International Arctic Research Center, University of Alaska Fairbanks, Fairbanks, Alaska
1Arctic and Antarctic Research Institute, St. Petersburg, Russia
#Institute of Marine Science, University of Alaska Fairbanks, Fairbanks, Alaska
(Manuscript received 6 August 2002, in final form 2 December 2002)
ABSTRACT
Examination of records of fast ice thickness (1936–2000) and ice extent (1900–2000) in the Kara, Laptev, East Siberian, and Chukchi Seas provide evidence that long-term ice thickness and extent trends are small and generally not statistically significant, while trends for shorter records are not indicative of the long-term tendencies due to large-amplitude low-frequency variability.
Conclusions
In recent decades, large-scale changes have been observed
throughout the Arctic atmosphere–ice–ocean
system, sparking discussion as to whether these changes
are episodic events, or long-term shifts in the Arctic
environment. The lack of long-term observations in the
Arctic makes it impossible to reach a definitive conclusion.
Long-term records are now available due to recently
released Russian ice observations from the Siberian
marginal-ice zone.
Examination of records of fast ice thickness and ice
extent from four Arctic marginal seas (Kara, Laptev,
East Siberian, and Chukchi) indicates that long-term
trends are small and generally statistically insignificant,
while trends for shorter records are not indicative of the
long-term tendencies due to strong low-frequency variability
in these time series, which places a strong limitation
on our ability to resolve long-term trends. Ice
variability in the Arctic marginal-ice zone is dominated
by the multidecadal LFO and, to a lesser degree, by
decadal fluctuations. This variability is complicated by
geographical differences: the LFO signal decays eastward,
and is strongest in the Kara Sea, whereas in the
Chukchi Sea, ice-extent and fast ice variability is dominated
by decadal fluctuations, and there is no evidence
of the LFO. This is consistent with the Arctic SAT/NAO
index correlation pattern, which shows maximum correlation
in the near-Atlantic region, decaying toward the
North Pacific.
Correlation analysis shows that dynamical forcing
(wind or surface currents) is at least of the same order
of importance as thermodynamical forcing for the iceextent
variability in the Laptev, East Siberian, and
Chukchi Seas. Prevailing easterly winds over the Chukchi
Sea cannot contribute much to ice advection across
the open boundary, but surface currents provide an effective
mechanism of ice transport from the sea into the
central Arctic Ocean. In the Kara Sea, thermodynamical
factors outweigh dynamical factors in controlling iceextent
variability. This analysis implies that deficiencies
of present-day models, such as the oversimplification of
ice dynamics, make simulation of fundamental ice–albedo
feedback most difficult.
Acknowledgments. This project was supported by
grants from the International Arctic Research Center,
University of Alaska, Fairbanks, and the National Science
Foundation’s Office Of Polar Programs
(#9806926). We thank the Frontier Research System for
Global Change (FRSGC) for financial support.
http://www.frontier.iarc.uaf.edu/~igor/research/pdf/ice.pdf
IGOR V. POLYAKOV,* GENRIKH V. ALEKSEEV,1 ROMAN V. BEKRYAEV,*1 UMA S. BHATT,* ROGER COLONY,*
MARK A. JOHNSON,# VALERII P. KARKLIN,1 DAVID WALSH,* AND ALEXANDER V. YULIN1
*International Arctic Research Center, University of Alaska Fairbanks, Fairbanks, Alaska
1Arctic and Antarctic Research Institute, St. Petersburg, Russia
#Institute of Marine Science, University of Alaska Fairbanks, Fairbanks, Alaska
(Manuscript received 6 August 2002, in final form 2 December 2002)
ABSTRACT
Examination of records of fast ice thickness (1936–2000) and ice extent (1900–2000) in the Kara, Laptev, East Siberian, and Chukchi Seas provide evidence that long-term ice thickness and extent trends are small and generally not statistically significant, while trends for shorter records are not indicative of the long-term tendencies due to large-amplitude low-frequency variability.
Conclusions
In recent decades, large-scale changes have been observed
throughout the Arctic atmosphere–ice–ocean
system, sparking discussion as to whether these changes
are episodic events, or long-term shifts in the Arctic
environment. The lack of long-term observations in the
Arctic makes it impossible to reach a definitive conclusion.
Long-term records are now available due to recently
released Russian ice observations from the Siberian
marginal-ice zone.
Examination of records of fast ice thickness and ice
extent from four Arctic marginal seas (Kara, Laptev,
East Siberian, and Chukchi) indicates that long-term
trends are small and generally statistically insignificant,
while trends for shorter records are not indicative of the
long-term tendencies due to strong low-frequency variability
in these time series, which places a strong limitation
on our ability to resolve long-term trends. Ice
variability in the Arctic marginal-ice zone is dominated
by the multidecadal LFO and, to a lesser degree, by
decadal fluctuations. This variability is complicated by
geographical differences: the LFO signal decays eastward,
and is strongest in the Kara Sea, whereas in the
Chukchi Sea, ice-extent and fast ice variability is dominated
by decadal fluctuations, and there is no evidence
of the LFO. This is consistent with the Arctic SAT/NAO
index correlation pattern, which shows maximum correlation
in the near-Atlantic region, decaying toward the
North Pacific.
Correlation analysis shows that dynamical forcing
(wind or surface currents) is at least of the same order
of importance as thermodynamical forcing for the iceextent
variability in the Laptev, East Siberian, and
Chukchi Seas. Prevailing easterly winds over the Chukchi
Sea cannot contribute much to ice advection across
the open boundary, but surface currents provide an effective
mechanism of ice transport from the sea into the
central Arctic Ocean. In the Kara Sea, thermodynamical
factors outweigh dynamical factors in controlling iceextent
variability. This analysis implies that deficiencies
of present-day models, such as the oversimplification of
ice dynamics, make simulation of fundamental ice–albedo
feedback most difficult.
Acknowledgments. This project was supported by
grants from the International Arctic Research Center,
University of Alaska, Fairbanks, and the National Science
Foundation’s Office Of Polar Programs
(#9806926). We thank the Frontier Research System for
Global Change (FRSGC) for financial support.
http://www.frontier.iarc.uaf.edu/~igor/research/pdf/ice.pdf