TITLE : Geophysical Investigation of Soil Moisture Distribution and Behavior in Permafrost Soils from Interior Alaska

PRESENTER: Mr. Taylor Sullivan, Permafrost Geophysicist, University of Wyoming

ABSTRACT: The seasonally thawed active layer above permafrost serves as a climate variable to monitor permafrost conditions. This study considers the seasonal development of soil moisture distribution within the active layer of interior Alaska to help constrain remotely-sensed active layer thickness and permafrost predictions that will inform carbon cycle response to changing global climate. To address the question of how soil moisture distribution within the soil column evolves throughout a thaw season and influences thaw depths, we utilized geophysical techniques including Ground Penetrating Radar (GPR) and nuclear magnetic resonance (NMR). GPR measurements yield information about electromagnetic wave propagation velocity which can be used to calculate the dielectric constant of a medium--indicative of soil moisture. Borehole NMR (BNMR) measurements reveal information about water content and relative pore size distributions of bound versus unbound water throughout the soil column. Lab-NMR measurements on synthesized- and field- soil samples with varying degrees of saturation and thaw serve as a basis of comparison for BNMR field data from five boreholes in the Alaskan interior. Results from this investigation constrain key parameters of soil-freezing- and remote-sensing- models of soil moisture and active layer thickness, which in turn inform the response of permafrost processes to changing global temperatures.

PRESENTATION

HOST: ERDC-CRREL, Signature Physics Branch (CEERD-RRD, 603 646 4206)