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Yong-Fei Zhang, Cecilia M. Bitz, Jeffrey L. Anderson, Nancy Collins, Jonathan Hendricks, Timothy Hoar, Kevin Raeder, and François Massonnet

1. Introduction Significant changes have been observed in the Arctic sea ice extent during the past few decades. Decreasing trends of the total Arctic sea ice extent have been identified in all seasons, and the strongest decline appears in summer ( Comiso 2002 ; Meier et al. 2007 ; Serreze et al. 2007 ). While large regional variations exist, most regions have experienced significant declining trends in sea ice extent ( Meier et al. 2007 ). Although the causes of such trends are varied

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Yi-Ching Chung, Stéphane Bélair, and Jocelyn Mailhot

fluxes, and rate due to blowing snow in the boundary layer, but very few have distinguished the effect of blowing snow on the seasonal evolution of snow and sea ice. Meanwhile, the significance of blowing snow sublimation has been argued in some studies (e.g., Steffen and DeMaria 1996 ; Papakyriakou 1999 ; Pomeroy and Essery 1999 ; Pomeroy and Li 2000 ; Persson et al. 2002 ; Savelyev et al. 2006 ). The main objective of this study is to investigate the effect of blowing snow on the simulation

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Casey J. Wall, Tsubasa Kohyama, and Dennis L. Hartmann

1. Introduction Sea ice, low clouds, and the atmospheric boundary layer modulate the climate of the Southern Ocean by influencing surface heat fluxes. During winter, sea ice insulates the ocean from the cold atmosphere above, reducing the rate of ocean heat loss at the surface by a factor of 10 to 100 ( Gordon 1991 ). Low clouds and moisture emit longwave (LW) radiation downward and heat the surface, and low-level winds control the surface turbulent heat and moisture fluxes. When sea ice forms

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Hiroshi Sumata, Frank Kauker, Michael Karcher, and Rüdiger Gerdes

1. Introduction Sea ice plays an important role in the Arctic climate system. It reflects larger amounts of solar radiation than the open ocean and it substantially modulates the exchange of heat, freshwater, and momentum between the ocean and the atmosphere (e.g., Wadhams 2002 ; McPhee 2008 ; Thomas and Dieckmann 2009 ). Well-adjusted sea ice models are thus necessary for climate studies ( Budikova 2009 ; Overland 2016 ), and for the further development of climate models ( Notz 2015

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Ruibo Lei, Zhijun Li, Yanfeng Cheng, Xin Wang, and Yao Chen

1. Introduction Sea ice plays an important role in the global climate system ( Vavrus and Harrison 2003 ) and also is the most sensitive indicator of local and global climate change ( Vinnikov et al. 1999 ; Heil 2006 ). Sea ice thickness is the most fundamentally integrative and crucially important parameter for describing ice conditions. The uncertainty of ice thickness measurements is the major difficulty in setting the ocean heat flux from ice mass and temperature measurements ( Heil et al

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Jan Sedláček, Reto Knutti, Olivia Martius, and Urs Beyerle

1. Introduction The Arctic sea ice area and thickness have been decreasing steadily over the last few decades ( Maslanik et al. 2007 ; Nghiem et al. 2007 ; Serreze et al. 2007 ; Comiso et al. 2008 ). Serreze et al. (2007) reported that the decrease occurred throughout the year. However, the summer months experienced a larger decrease than the winter months. During summer 2007 the Arctic sea ice area was reduced substantially. The minimum sea ice area in September was 28% lower than the

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Ana C. Ordoñez, Cecilia M. Bitz, and Edward Blanchard-Wrigglesworth

1. Introduction Sea ice predictability studies have focused mainly on the Arctic or Antarctic, with few comparative studies of Arctic and Antarctic differences, especially at the regional scale. Johnson et al. (1985) is the only paper to the authors’ knowledge that makes comparisons of predictability between the pan-Arctic and pan-Antarctic and among their subdivided regions, but their study relies on observational data from a short time period and considers only a limited set of sea ice

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Laura Landrum, Marika M. Holland, David P. Schneider, and Elizabeth Hunke

1. Introduction The Antarctic sea ice cover undergoes a large seasonal range from a climatological maximum of approximately 19 million km 2 in extent in September to a minimum of 3 million km 2 in February (e.g., Cavalieri and Parkinson 2008 ) ( Fig. 1 ). The seasonal cycle of ice advance and retreat is influenced by the dominant seasonality in the atmosphere and the semiannual oscillation (SAO)—a biannual (spring and autumn) strengthening and poleward migration of the circumpolar trough (e

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James Williams, Bruno Tremblay, Robert Newton, and Richard Allard

1. Introduction There has been a negative trend in the Arctic Ocean sea ice extent since the late 1970s, when satellite observations became available on a consistent basis ( Parkinson et al. 1999 ). This trend is present in all months and ranges from −0.30 to −0.87 × 10 6 km 2 decade −1 (from −2.3% to −13.6% decade −1 ) in May and September, respectively ( Fetterer et al. 2002 , updated daily). The rate of decline in the September minimum sea ice extent (SIE) accelerated in recent decades

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Yuyan Li and Zhicong Yin

1. Introduction Since the beginning of the satellite-observed sea ice era, record-breaking minimum values of sea ice cover have been observed in 2007 and 2012 ( Polyakov et al. 2017 ), which might be connected to the trends of sea level pressure (SLP) in Arctic in summer ( Simmonds 2015 ). The dramatic reduction of the summer Arctic sea ice (ASI) extent in recent years has fundamentally changed the nature of the ice ( Maslanik et al. 2011 ) including the trend of thinning ( Kwok and Rothrock

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