TITLE:
Active-Layer Soil Moisture Content Regional Variations in Alaska and Russia by Ground-Based and Satellite-Based Methods, 2002 through 2014
AUTHORS:
Reginald R. Muskett, Vladimir E. Romanovsky, William L. Cable, Alexander L. Kholodov
KEYWORDS:
Soil Moisture, Active Layer, Radio, Microwave, Remote Sensing, AMSR-E, AMSR2, NASA, JAXA, Alaska, Russia
JOURNAL NAME:
International Journal of Geosciences,
Vol.6 No.1,
January
19,
2015
ABSTRACT: Soil moisture is a vital
physical parameter of the active-layer in permafrost environments, and
associated biological and geophysical processes operative at the microscopic to
hemispheric spatial scales and at hourly to multi-decadal time scales. Whilein-situmeasurements can give the highest
quality of information on a site-specific basis, the vast permafrost terrains
of North America and Eurasia require space-based techniques for assessments of
cause and effect and long-term changes and impacts from the changes of
permafrost and the active-layer. Satellite-based 6.925 and 10.65 GHz sensor
algorithmic retrievals of soil moisture by Advanced Microwave Scanning Radiometer-Earth
Observation System (AMSR-E) onboard NASA-Aqua and follow-on AMSR2 onboard
JAXA-Global Change Observation Mission—Water-1 are ongoing since July 2002.
Accurate land-surface temperature and vegetation parameters are critical to the
success of passive microwave algorithmic retrieval schemes. Strategically
located soil moisture measurements are needed for spatial and temporal
co-location evaluation and validation of the space-based algorithmic estimates.
We compare on a daily basis ground-based (subsurface-probe) 50- and 70-MHz
radio-frequency soil moisture measurements with NASA- and JAXA-algorithmic
retrieval passive microwave retrievals. We find improvements in performance of
the JAXA-algorithm (AMSR-E reprocessed and AMSR2 ongoing) relative to the
earlier NASA-algorithm version. In the boreal forest regions, accurate
land-surface temperatures and vegetation parameters are still needed for
algorithmic retrieval success. Over the period of AMSR-E retrievals, we find
evidence of at the high northern latitudes of growing terrestrial
radio-frequency interference in the 10.65 GHz channel soil moisture content.
This is an important error source for satellite-based active and passive
microwave remote sensing soil moisture retrievals in Arctic regions that must
be addressed.