Factors influencing the spatial distribution of soil moisture derived from airborne SAR in watersheds near Nome and in Utguiavik, Alaska
Abstract
Researchers in the DOE Office of Science Next-Generation Ecosystem Experiments, NGEE-Arctic, and NASA Arctic Boreal Vulnerability Experiment (ABoVE) projects are collaborating on the development of regional soil moisture data products to improve and assess Earth System Models. Here we present our analysis of in-situ measurements of soil moisture, soil physical properties,and thaw depth collected during the summer of 2017 coincident with NASA ABoVE airborne overflights of L and P-band SAR instruments. New analyses show that the spatial distribution of soil moisture and active layer depth derived from Airborne SAR- using a two-layer dielectric structure (Chen et al. 2019)- differ based on local geomorphology, topography, climate and vegetation properties across a range of field sites and settings near Utqiaġvik , AK and Nome, AK. In Utqiaġvik , in-situ data were collected at high-center, flat-center, and low-center polygons during the June SAR P-band and September L-band overflights. At all sites on the Seward Peninsula, in-situ data were collected in May and August, coincident with P-band overflights. At each field site the same measurement techniques were used including the establishment of multiple 100m by 100m plots designated for SAR ground-truthing. Within each "SAR plot" two 60 meter transects were established along which both soil moisture and thaw depth measurements were taken. This configuration is consistent with the ABoVE protocols which enables proper averaging of multiple pixels for airborne or spaceborne SAR data. In-situ volumetric soil water content (VWC) data were collected during SAR overflights using Hydrosense-II soil-water sensors and data loggers (VWC). The in-situ Hydrosense VWC values corresponded well with laboratory analyses of soil samples collected at the sites. Soil moisture and thaw depth are key factors controlling subsurface biogeochemistry and surface ecosystem type and function. These observations and analyses provide a unique benchmark dataset with which to test predictions of spatial variation and temporal evolution of soil moisture in local and regional permafrost models.
LA-UR-19-27411- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.B12D..04D
- Keywords:
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- 0426 Biosphere/atmosphere interactions;
- BIOGEOSCIENCES;
- 0428 Carbon cycling;
- BIOGEOSCIENCES;
- 0439 Ecosystems;
- structure and dynamics;
- BIOGEOSCIENCES;
- 0475 Permafrost;
- cryosphere;
- and high-latitude processes;
- BIOGEOSCIENCES