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GAMMA SWE. Snow Water Equivalent (SWE) over each MSA was measured using operational airborne gamma radiation measurements. Water in the snow attenuates natural terrestrial gamma radiation emitted from soil, and is the basis for reliable airborne SWE measurements.
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GAMMA SWE • Snow Water Equivalent (SWE) over each MSA was measured using operational airborne gamma radiation measurements. • Water in the snow attenuates natural terrestrial gamma radiation emitted from soil, and is the basis for reliable airborne SWE measurements. • Principal source of SWE validation data over AMSR-footprint scale area NOAA AC690 over Rabbit Ears MSA (moderate topography) NOAA AC690 over North Park MSA (flat topography)
GAMMA SWE NORTH PARK MSA • 84 GAMMA Flight Lines, measuring 30% of the land surface of the MSA • Principal AMSR CalVal Site • Flat, unforested • Shallow, dry snow • “Best” conditions for AMSR algorithms to measure SWE Illinois River ISA Potter Creek ISA Michigan River ISA Mean SWE: 2.8 cm Std Dev: 1.3 cm Preliminary GAMMA SWE Analysis – IOP1
GAMMA SWE Rabbit Ears MSA Buffalo Pass ISA Spring Creek ISA • 22 GAMMA Flight Lines • Difficult test conditions for AMSR snow algorithm • Increased topographic complexity and forest cover • Increased snow depth increases scattering, reduces Tb; more difficult to differentiate from thin wet snow Walton Creek ISA Mean SWE: 26.7 cm Std Dev: 9.5 cm Preliminary GAMMA SWE Analysis – IOP1
GAMMA SWE FRASER MSA • 23 GAMMA Flight Lines • Difficult test conditions for AMSR snow algorithm • Greatly increased topographic complexity and forest cover St. Louis Creek ISA Fool Creek ISA Alpine ISA Mean SWE: 11.8 cm Std Dev: 3.0 cm Preliminary GAMMA SWE Analysis