Seasonal Changes in Hydrology, Energy Balance and Chemistry in
the Active Layers of Arctic Tundra Soils in Taymyr Peninsula,
Russia
J. Boike! and P.P. Overduin 2
(1) Alfred- Wegener-Institut jur Polar- und Meeresforschung, Forschungsstelle Potsdam, Telefirafenberg A43,
D 14473 Potsdam, Germany
(2) Department of Geography, York University, 4700 Keele St., North York, Ontario, M31 1 P3. Canada
Revised 9 July 1997 and accepted in revised form 10 October 1997.
Abstract - This study seeks to address gaps in our understanding of the complex coupled
energy and water balance of the active layer, the boundary between atmosphere and
permafrost. Measurement profiles installed in a variety of landscapes provided
microclimatological, hydrological, chemical and physical data, including radiative energy,
soil water contents, soil water chemistry and soil temperatures. It was found that the active
layer freezes in one of two modes: either from the surface downward or in low water content
nodes within the soil profile. The mode of freezing appears to depend on both soil
heterogeneity and soil volumetric water content. Even at temperatures of less than -1 OC a
significant volume of water remains unfrozen, an important consideration because the
freezing process is the dominant heat source for the active layer in the fall. Solute exclusion
has little effect on the soil water concentration profile, and thus little effect on the progress
of freezing.
Introduction and objectives
The active layer, the upper ground layer which freezes and thaws annually in permafrost areas,
is of hydrological, biological, geomorphological and climatological importance. Conditions for
groundwater and surface water flow, gas fluxes, plant growth and soil formation are all limited
and to some extent determined by this zone. The moisture and heat transfer characteristics of
this layer also determine the boundary layer interactions of the underlying permafrost and the
atmosphere and are therefore important input parameters for geothermal or climate modeling. In
addition, potential global climate change is expected to have a more severe effect at higher
latitudes than in temperate regions (Smith, 1986). Changes in the characteristics of the
permafrost (thickness, temperature, moisture content) can indicate climate change, provided the
system permafrost-active layer-atmosphere is sufficiently well understood: the polar regions can
thus be used as an indicator for global change.
Hydrological processes in the active layer are the synthesis of a complex interplay between
hydrological inputs (snow and ground ice melt, rain) and microclimatological factors (e.g. net
radiation, evaporation, vegetation and snow cover). Measurements of these variables become
especially important during periods of phase change since the thermal and moisture regimes of
the active layer are strongly coupled through phase transitions.
During the winter, the active layer is covered with dry snow characterized by a high albedo
and low sublimation rate (Ohmura, 1982). With increasing net radiation in spring, the albedo
and sublimation rate of the snow increase and snowmelt is initiated. Evaporation rates are
highest shortly after the initiation of snowmelt due to water saturation of the soil surface and the
occurrence of overland flow (Ohmura, 1982). Soil temperatures increase steadily in the frozen
ground and thaw of the active layer is initiated. During phase change, the ground temperatures
are stabilized around o=c through the consumption of latent heat (,zero curtain effect';
Washburn, 1973). With progress of the summer, the thaw depth of the active layer deepens as
In: Kassens. H., H.A. Bauch, I. Dmitrenko, H. Eicken, H.-W. Hubberten, M. Melles, J. Thiede and L. Timokhov (eds.)
Land-Ocean Systems in the Siberian Arctic: Dynamics and History. Springer-Verlag, Berlin, 1999,299-306.
the Active Layers of Arctic Tundra Soils in Taymyr Peninsula,
Russia
J. Boike! and P.P. Overduin 2
(1) Alfred- Wegener-Institut jur Polar- und Meeresforschung, Forschungsstelle Potsdam, Telefirafenberg A43,
D 14473 Potsdam, Germany
(2) Department of Geography, York University, 4700 Keele St., North York, Ontario, M31 1 P3. Canada
Revised 9 July 1997 and accepted in revised form 10 October 1997.
Abstract - This study seeks to address gaps in our understanding of the complex coupled
energy and water balance of the active layer, the boundary between atmosphere and
permafrost. Measurement profiles installed in a variety of landscapes provided
microclimatological, hydrological, chemical and physical data, including radiative energy,
soil water contents, soil water chemistry and soil temperatures. It was found that the active
layer freezes in one of two modes: either from the surface downward or in low water content
nodes within the soil profile. The mode of freezing appears to depend on both soil
heterogeneity and soil volumetric water content. Even at temperatures of less than -1 OC a
significant volume of water remains unfrozen, an important consideration because the
freezing process is the dominant heat source for the active layer in the fall. Solute exclusion
has little effect on the soil water concentration profile, and thus little effect on the progress
of freezing.
Introduction and objectives
The active layer, the upper ground layer which freezes and thaws annually in permafrost areas,
is of hydrological, biological, geomorphological and climatological importance. Conditions for
groundwater and surface water flow, gas fluxes, plant growth and soil formation are all limited
and to some extent determined by this zone. The moisture and heat transfer characteristics of
this layer also determine the boundary layer interactions of the underlying permafrost and the
atmosphere and are therefore important input parameters for geothermal or climate modeling. In
addition, potential global climate change is expected to have a more severe effect at higher
latitudes than in temperate regions (Smith, 1986). Changes in the characteristics of the
permafrost (thickness, temperature, moisture content) can indicate climate change, provided the
system permafrost-active layer-atmosphere is sufficiently well understood: the polar regions can
thus be used as an indicator for global change.
Hydrological processes in the active layer are the synthesis of a complex interplay between
hydrological inputs (snow and ground ice melt, rain) and microclimatological factors (e.g. net
radiation, evaporation, vegetation and snow cover). Measurements of these variables become
especially important during periods of phase change since the thermal and moisture regimes of
the active layer are strongly coupled through phase transitions.
During the winter, the active layer is covered with dry snow characterized by a high albedo
and low sublimation rate (Ohmura, 1982). With increasing net radiation in spring, the albedo
and sublimation rate of the snow increase and snowmelt is initiated. Evaporation rates are
highest shortly after the initiation of snowmelt due to water saturation of the soil surface and the
occurrence of overland flow (Ohmura, 1982). Soil temperatures increase steadily in the frozen
ground and thaw of the active layer is initiated. During phase change, the ground temperatures
are stabilized around o=c through the consumption of latent heat (,zero curtain effect';
Washburn, 1973). With progress of the summer, the thaw depth of the active layer deepens as
In: Kassens. H., H.A. Bauch, I. Dmitrenko, H. Eicken, H.-W. Hubberten, M. Melles, J. Thiede and L. Timokhov (eds.)
Land-Ocean Systems in the Siberian Arctic: Dynamics and History. Springer-Verlag, Berlin, 1999,299-306.