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Snow accumulation and melt are dynamic features of the cryosphere indicative of a changing climate. Spring melt and refreeze timing are of particular importance due to the influence on subsequent hydrological and ecological processes, including peak runoff and green-up. To investigate the spatial and temporal variability of melt timing across a sub-arctic region (the Yukon River Basin (YRB), Alaska/Canada) dominated by snow and lacking substantial ground instrumentation, passive microwave remote sensing was utilized to provide daily brightness temperatures (T b ) regardless of clouds and darkness. Algorithms to derive the timing of melt onset and the end of melt-refreeze, a critical transition period where the snowpack...
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A multiple-proxy investigation was undertaken on two short cores (85 cm and 101 cm long) from Kepler Lake, an evaporation-insensitive, groundwater-fed marl lake in South-Central Alaska, with the goal of reconstructing climate and environmental changes in recent centuries. The proxies employed in this study include: calcite Carbon-Oxygen isotopes, organic matter (OM) Carbon-Nitrogen isotopes, and loss on ignition (LOI) analysis. An 800-year chronology for two cores was established based on four calibrated AMS 14 C dates on terrestrial macrofossils, 210 Pb analysis and core-to-core correlations using LOI results. δ18 O VPDB values of inorganic calcite range from -17.0[per thousand] to -15.7[per thousand], with the...
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Northern peatlands in boreal and subarctic regions store about 500 Gt of carbon (C). Understanding the fate of this large C pool under a warmer climate is important, as temperatures in northern latitudes have increased quicker than the global averages over the past 100 years. Both regional climate (e.g., temperature and precipitation) and local factors (e.g., topography) influence peatland response to climate changes. To better understand peatland response to climate changes, paleoecological techniques were used to study the C accumulation and paleohydrololgy of peatlands in different Alaskan climate regions. In addition, local-scale factors were studied through comparison of two nearby peatlands in different surficial...
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A multiple-proxy investigation was undertaken on two short cores (85 cm and 101 cm long) from Kepler Lake, an evaporation-insensitive, groundwater-fed marl lake in South-Central Alaska, with the goal of reconstructing climate and environmental changes in recent centuries. The proxies employed in this study include: calcite Carbon-Oxygen isotopes, organic matter (OM) Carbon-Nitrogen isotopes, and loss on ignition (LOI) analysis. An 800-year chronology for two cores was established based on four calibrated AMS 14 C dates on terrestrial macrofossils, 210 Pb analysis and core-to-core correlations using LOI results. δ18 O VPDB values of inorganic calcite range from -17.0[per thousand] to -15.7[per thousand], with the...
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A multiple-proxy investigation was undertaken on two short cores (85 cm and 101 cm long) from Kepler Lake, an evaporation-insensitive, groundwater-fed marl lake in South-Central Alaska, with the goal of reconstructing climate and environmental changes in recent centuries. The proxies employed in this study include: calcite Carbon-Oxygen isotopes, organic matter (OM) Carbon-Nitrogen isotopes, and loss on ignition (LOI) analysis. An 800-year chronology for two cores was established based on four calibrated AMS 14 C dates on terrestrial macrofossils, 210 Pb analysis and core-to-core correlations using LOI results. δ18 O VPDB values of inorganic calcite range from -17.0[per thousand] to -15.7[per thousand], with the...
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