HR: 1330h
AN: H32A-0514    [PDF]
TI: Comparisons of Bulk Dielectric Measurements of Tundra Moss Using 7 Different Technologies
AU: * Overduin, P P
EM: fsppo@uaf.edu
AF: Institute for Northern Engineering, University of Alaska Fairbanks, Fairbanks, AK 99775 United States
AU: Yoshikawa, K
EM: ffky@uaf.edu
AF: Institute for Northern Engineering, University of Alaska Fairbanks, Fairbanks, AK 99775 United States
AU: Nolan, M
EM: fnman@uaf.edu
AF: Institute for Northern Engineering, University of Alaska Fairbanks, Fairbanks, AK 99775 United States
AU: Kane, D L
EM: ffdlk@uaf.edu
AF: Institute for Northern Engineering, University of Alaska Fairbanks, Fairbanks, AK 99775 United States
AB: We seek correlations between measurements made by a variety of soil bulk-dielectric measurement devices in the two dominant moss types of Alaska's North Slope. In permafrost regions, the soil moisture content of the shallow subsurface exerts a critical control over the thermal properties regime of the deeper subsurface. The dynamics of land cover change are directly related to shifts in water balance and thus in moisture regimes in the shallow subsurface of the active layer. On Alaska's North Slope, soil moisture content data is being collected by a variety of research projects using numerous technologies, few of which are calibrated for soils high in organic content. We have carried out tests and calibrations for seven different soil moisture probes that measure moisture content using electromagnetic properties of the soil for Sphagnum and feather moss species. Two types of tundra cover the North Slope, Moist Acidic Tundra (MAT) and Moist Non-acidic Tundra (MNT), which differ in pH and in dominant bryophytic species. The dominant moss genus in the MAT and MNT are Sphagnum and feather moss species. All of the probes tested required a unique calibration equation for calculating water content from probe output, usually the bulk soil dielectric. The spatially weighted sensitivity of the sensor to the soil dielectric is one of the most important parameters influencing moisture measurement. We present calibration equations for each probe in the two moss types. The relationship between penetration depth and soil moisture levels is also considered with respect to optimum probe placement for ground-truthing of remotely sensed data. Ground-based and remotely sensed estimates of bulk dielectric are well-matched for comparison, as SAR remote-sensing also relies on the dielectric properties of the soil. The penetration depth of SAR microwaves has been found to be nonlinearly dependent on soil moisture, and small errors in field measurements can interfere with ground-truthing efforts. Thus one outcome of our research is to improve our ability to validate remote-sensing data, such that point measurements can more reliably interpolated to watershed-scales.
DE: 1823 Frozen ground
DE: 1866 Soil moisture
DE: 1875 Unsaturated zone
DE: 1894 Instruments and techniques
DE: 9315 Arctic region
SC: Hydrology [H]
MN: 2003 Fall Meeting