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ecosystems north of 65°N are a net source of CO 2 of 1–1.2 Gt. The CO 2 concentration that was measured beneath the snow in winter in Siberia was similar to that measured in arctic tundra in Alaska ( Kelley et al. 1968 ; Coyne and Kelley 1974 ) and temperate alpine ( Sommerfeld et al. 1993 ), suggesting also that the northern ecosystems could exhibit large winter CO 2 effluxes. The winter CO 2 emission from the northern soils would increase the average CO 2 concentration in air over the Arctic by
ecosystems north of 65°N are a net source of CO 2 of 1–1.2 Gt. The CO 2 concentration that was measured beneath the snow in winter in Siberia was similar to that measured in arctic tundra in Alaska ( Kelley et al. 1968 ; Coyne and Kelley 1974 ) and temperate alpine ( Sommerfeld et al. 1993 ), suggesting also that the northern ecosystems could exhibit large winter CO 2 effluxes. The winter CO 2 emission from the northern soils would increase the average CO 2 concentration in air over the Arctic by
and HgOH oxidation products were also considered too unstable ( Goodsite et al. 2004 ; Calvert and Lindberg 2005 ; Hynes et al. 2009 ). BrO and Br were proposed as the oxidants driving the atmospheric Hg depletion events as well as ozone depletion in the Arctic due to their fast reaction kinetics and active bromine cycling over the snow and sea ice surfaces ( Goodsite et al. 2004 ; Dastoor et al. 2008 , 2015 ; Mao et al. 2010 ; Stephens et al. 2012 ; Toyota et al. 2014 ; Wang et al. 2019
and HgOH oxidation products were also considered too unstable ( Goodsite et al. 2004 ; Calvert and Lindberg 2005 ; Hynes et al. 2009 ). BrO and Br were proposed as the oxidants driving the atmospheric Hg depletion events as well as ozone depletion in the Arctic due to their fast reaction kinetics and active bromine cycling over the snow and sea ice surfaces ( Goodsite et al. 2004 ; Dastoor et al. 2008 , 2015 ; Mao et al. 2010 ; Stephens et al. 2012 ; Toyota et al. 2014 ; Wang et al. 2019
not at theequator, where the Ekman boundary layer itself isundefined. This agrees with observations--from Kuettner's, off the arctic tundra to Plank's over the Floridapeninsula--and the absence of any observations indicating rolls at the equator. The abrupt appearance of the cloud streets in directconformity with the incidence of the geostrophic windupon the coast in Fig. la may be explained by the behavior of secondary flow magnitude vs roughness. Theincidence of land would imply an increase
not at theequator, where the Ekman boundary layer itself isundefined. This agrees with observations--from Kuettner's, off the arctic tundra to Plank's over the Floridapeninsula--and the absence of any observations indicating rolls at the equator. The abrupt appearance of the cloud streets in directconformity with the incidence of the geostrophic windupon the coast in Fig. la may be explained by the behavior of secondary flow magnitude vs roughness. Theincidence of land would imply an increase
Grass- Semi Arctic Tundra Forest land desert Desert/9* 0 0--0.33 0.33-1 1-2 2-3 >3D 0 0-0.33 0.33-1 1-1.4 1.4-1.7. >1.7 Wm. 2 ,0 20 40 60 80 100,.120VOL. 41, NO. 18 140 160 ' f ~ i i ~ ; i i ~'_ /. 120 i60
Grass- Semi Arctic Tundra Forest land desert Desert/9* 0 0--0.33 0.33-1 1-2 2-3 >3D 0 0-0.33 0.33-1 1-1.4 1.4-1.7. >1.7 Wm. 2 ,0 20 40 60 80 100,.120VOL. 41, NO. 18 140 160 ' f ~ i i ~ ; i i ~'_ /. 120 i60
(albedo 0.70-0.90); partial snow or ice cover(0.40-0.69); patchy snow in high latitudes or desert,steppe or grasslands in middle and low latitudes (0.200.39); tundra in high latitudes or scattered forests inmiddle and low latitudes (0.16-0.19); and dense forests(0.07-0.15). The albedo over the oceans is a functionof latitude only and corresponds to the average seasonalzenith angle of the sun. These geographical distributionsof seasonal surface albedo replace the single valuesused previously for all
(albedo 0.70-0.90); partial snow or ice cover(0.40-0.69); patchy snow in high latitudes or desert,steppe or grasslands in middle and low latitudes (0.200.39); tundra in high latitudes or scattered forests inmiddle and low latitudes (0.16-0.19); and dense forests(0.07-0.15). The albedo over the oceans is a functionof latitude only and corresponds to the average seasonalzenith angle of the sun. These geographical distributionsof seasonal surface albedo replace the single valuesused previously for all
desert, steppe and grassland (albedo 0.20-0.39)may be seen at 18 000 YBP over northern Africaand central Asia relative to today's distribution, andequatorward displacements of the regions of scatteredforests and tundra (albedo 0.16-0.19) also occurredduring the ice age over the continents of both hemispheres. The maximum albedos assigned at 18000YBP (Fig. 5a) are 0.90 for the Antarctic ice sheetand 0.80 for the other ice sheets, with 0.80 and 0.70assigned to the Antarctic and Arctic sea ice
desert, steppe and grassland (albedo 0.20-0.39)may be seen at 18 000 YBP over northern Africaand central Asia relative to today's distribution, andequatorward displacements of the regions of scatteredforests and tundra (albedo 0.16-0.19) also occurredduring the ice age over the continents of both hemispheres. The maximum albedos assigned at 18000YBP (Fig. 5a) are 0.90 for the Antarctic ice sheetand 0.80 for the other ice sheets, with 0.80 and 0.70assigned to the Antarctic and Arctic sea ice
