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. 2013 ). The decreasing areal coverage of Arctic sea ice is in line with Arctic warming (e.g., ACIA 2005 ; Walsh 2013 ; Hartmann et al. 2013 ) and produces feedbacks that tend to enhance that warming (e.g., Screen and Simmonds 2010 ). It is also in line with an observed thinning of the ice cover ( Yu et al. 2004 ; Kwok and Rothrock 2009 ; Laxon et al. 2013 ) and a full suite of additional changes in the Arctic, such as thawing permafrost, increasing coastal erosion, greening tundra, and
. 2013 ). The decreasing areal coverage of Arctic sea ice is in line with Arctic warming (e.g., ACIA 2005 ; Walsh 2013 ; Hartmann et al. 2013 ) and produces feedbacks that tend to enhance that warming (e.g., Screen and Simmonds 2010 ). It is also in line with an observed thinning of the ice cover ( Yu et al. 2004 ; Kwok and Rothrock 2009 ; Laxon et al. 2013 ) and a full suite of additional changes in the Arctic, such as thawing permafrost, increasing coastal erosion, greening tundra, and
arctic Alaska, provides a store of latent heat that can significantly delay the cooling of the soil in the early part of the winter, directly affecting the snow–ground interface temperature. Organic layers, especially the mosses found in tundra, provide insulation that can, when dry, equal that of the overlying snowpack [compare results from Hinzman et al. (1991 , their Fig. 12) with those of Sturm et al. (1997 , their Fig. 6)]. While this fine insulation does not directly affect the interface
arctic Alaska, provides a store of latent heat that can significantly delay the cooling of the soil in the early part of the winter, directly affecting the snow–ground interface temperature. Organic layers, especially the mosses found in tundra, provide insulation that can, when dry, equal that of the overlying snowpack [compare results from Hinzman et al. (1991 , their Fig. 12) with those of Sturm et al. (1997 , their Fig. 6)]. While this fine insulation does not directly affect the interface
Sturm 1998 ; M. Sturm and G. E. Liston 2001, unpublished manuscript, hereafter SL; Taras et al. 2002 ). It was tantalizing to realize that if we could account for blowing-snow redistribution and sublimation, then these snow-depth measurements could be converted into a measure of the winter solid precipitation. This became possible with the development of a blowing-snow model (SnowTran-3D; Liston and Sturm 1998 ) that simulates snow-transport and sublimation processes ( Fig. 1 ). Arctic tundra snow
Sturm 1998 ; M. Sturm and G. E. Liston 2001, unpublished manuscript, hereafter SL; Taras et al. 2002 ). It was tantalizing to realize that if we could account for blowing-snow redistribution and sublimation, then these snow-depth measurements could be converted into a measure of the winter solid precipitation. This became possible with the development of a blowing-snow model (SnowTran-3D; Liston and Sturm 1998 ) that simulates snow-transport and sublimation processes ( Fig. 1 ). Arctic tundra snow
-s (~1 km) resolution version (G. E. Liston and M. Sturm 2011, unpublished manuscript) of Sturm et al.’s (1995) global snow classification, regridded to the pan-Arctic SnowModel simulation grid ( Fig. 2 ), shows the land area of this domain contains 10% ice (i.e., glaciers and ice sheets), 39% tundra, 34% taiga, 7% warm forests (alpine in Sturm et al. 1995 ), 9% prairie, and 1% maritime snow classes. These snow classes take into account the wind, precipitation, and temperature regimes these snow
-s (~1 km) resolution version (G. E. Liston and M. Sturm 2011, unpublished manuscript) of Sturm et al.’s (1995) global snow classification, regridded to the pan-Arctic SnowModel simulation grid ( Fig. 2 ), shows the land area of this domain contains 10% ice (i.e., glaciers and ice sheets), 39% tundra, 34% taiga, 7% warm forests (alpine in Sturm et al. 1995 ), 9% prairie, and 1% maritime snow classes. These snow classes take into account the wind, precipitation, and temperature regimes these snow
1. Introduction With climate warming, shrubs are expanding on the Arctic tundra ( Tape et al. 2006 ; Myers-Smith et al. 2011 ; Ropars and Boudreau 2012 ), changing its winter surface from undisturbed snow to a mixed surface of snow and protruding branches. This mixed surface has a lower albedo in the visible (380–750 nm) than undisturbed snow ( Sturm et al. 2005 ; Loranty et al. 2011 ) positively feeding back on regional and global climate warming ( Sturm et al. 2001 ; Loranty and Goetz
1. Introduction With climate warming, shrubs are expanding on the Arctic tundra ( Tape et al. 2006 ; Myers-Smith et al. 2011 ; Ropars and Boudreau 2012 ), changing its winter surface from undisturbed snow to a mixed surface of snow and protruding branches. This mixed surface has a lower albedo in the visible (380–750 nm) than undisturbed snow ( Sturm et al. 2005 ; Loranty et al. 2011 ) positively feeding back on regional and global climate warming ( Sturm et al. 2001 ; Loranty and Goetz
anomalies . Arctic Sea Ice Decline: Observations, Projections, Mechanisms, and Implications, Geophys. Monogr., Vol. 180, Amer. Geophys. Union, 91–110 . Bhatt , U. S. , and Coauthors , 2010 : Circumpolar Arctic tundra vegetation change is linked to sea-ice decline . Earth Interactions , 14 . [Available online at http://EarthInteractions.org .] Bitz , C. M. , and G. H. Roe , 2004 : A mechanism for the high rate of sea-ice thinning in the Arctic Ocean . J. Climate , 17 , 3622 – 3631
anomalies . Arctic Sea Ice Decline: Observations, Projections, Mechanisms, and Implications, Geophys. Monogr., Vol. 180, Amer. Geophys. Union, 91–110 . Bhatt , U. S. , and Coauthors , 2010 : Circumpolar Arctic tundra vegetation change is linked to sea-ice decline . Earth Interactions , 14 . [Available online at http://EarthInteractions.org .] Bitz , C. M. , and G. H. Roe , 2004 : A mechanism for the high rate of sea-ice thinning in the Arctic Ocean . J. Climate , 17 , 3622 – 3631
-33 , Meteorological Services of Canada, 452 pp. Mosby , H. , 1932 : Sunshine and Radiation . Vol. 1, The Norwegian North Polar Expedition with the “Maud” 1918-1925: Scientific Results , Geofysisk Institutt, 110 pp. Ohmura , A. , 1981 : Climate and energy balance on Arctic tundra. Axel Heiberg Island, Canadian Arctic Archipelago, spring and summer 1969, 1970 and 1972. Doctoral thesis, Geographisches Institut, Eidgenössische Technische Hochschule Zürich, Zürcher Geographische Schriften 3, 448 pp . Ohmura
-33 , Meteorological Services of Canada, 452 pp. Mosby , H. , 1932 : Sunshine and Radiation . Vol. 1, The Norwegian North Polar Expedition with the “Maud” 1918-1925: Scientific Results , Geofysisk Institutt, 110 pp. Ohmura , A. , 1981 : Climate and energy balance on Arctic tundra. Axel Heiberg Island, Canadian Arctic Archipelago, spring and summer 1969, 1970 and 1972. Doctoral thesis, Geographisches Institut, Eidgenössische Technische Hochschule Zürich, Zürcher Geographische Schriften 3, 448 pp . Ohmura
boundary layer clouds over the tundra through several mechanisms. Consider an arctic cloud layer, possibly decoupled from the surface, being advected from ocean to tundra. During the summer, the albedo of the tundra is much lower than the ice pack. This, combined with a lower heat capacity for the soil and vegetation than for the nearby ocean, leads to an appreciably warmer surface over the tundra. This warmer surface in turn generates convective turbulence that warms the boundary layer and couples the
boundary layer clouds over the tundra through several mechanisms. Consider an arctic cloud layer, possibly decoupled from the surface, being advected from ocean to tundra. During the summer, the albedo of the tundra is much lower than the ice pack. This, combined with a lower heat capacity for the soil and vegetation than for the nearby ocean, leads to an appreciably warmer surface over the tundra. This warmer surface in turn generates convective turbulence that warms the boundary layer and couples the
seasons as opposed to summer only. The airmass framework has been revisited sporadically for North America ( Barry 1967 ; Willis and Grice 1977 ; Schwartz and Skeeter 1994 ; Ladd and Gajewski 2010 ). Some studies have suggested that heating differences between the tundra and boreal forest may influence or determine the location of the Arctic front ( Hare 1968 ; Krebs and Barry 1970 ; Hare and Ritchie 1972 ; Pielke and Vidale 1995 ). However, Beringer et al. (2001) found that the surface heat
seasons as opposed to summer only. The airmass framework has been revisited sporadically for North America ( Barry 1967 ; Willis and Grice 1977 ; Schwartz and Skeeter 1994 ; Ladd and Gajewski 2010 ). Some studies have suggested that heating differences between the tundra and boreal forest may influence or determine the location of the Arctic front ( Hare 1968 ; Krebs and Barry 1970 ; Hare and Ritchie 1972 ; Pielke and Vidale 1995 ). However, Beringer et al. (2001) found that the surface heat
frontal position might be important in determining the distribution of forest versus tundra, but other investigators ( Hare 1968 ; Hare and Ritchie 1972 ) instead argued that the tundra–forest boundary actually helps to control the position of the frontal zone in summer because of contrasts in albedo, evaporation, and aerodynamic roughness. However, it has now been clearly established that a primary control on the summer Arctic frontal zone is differential heating between the land and ocean ( Serreze
frontal position might be important in determining the distribution of forest versus tundra, but other investigators ( Hare 1968 ; Hare and Ritchie 1972 ) instead argued that the tundra–forest boundary actually helps to control the position of the frontal zone in summer because of contrasts in albedo, evaporation, and aerodynamic roughness. However, it has now been clearly established that a primary control on the summer Arctic frontal zone is differential heating between the land and ocean ( Serreze
