PROJECT TITLE :

Snow Water Equivalent of Dry Snow Measured by Differential Interferometry

ABSTRACT:

Massive scale mapping of snow water equivalent (SWE) could be a long-lasting request in many scientific and economical fields. Active and passive microwave remote sensing ways are explored, as local methods can not be generalized because of the spatial inhomogeneity of the snow pack. Microwaves interact with snow by absorption, scattering, and refraction. For dry snow of a few meters depth and frequencies below twenty GHz, absorption and scattering within the snow volume are negligible compared with the backscattered energy from the underlying ground. The signal delay caused by refraction will be measured with differential radar interferometry, but phase wrapping errors and temporal decorrelation should be thought-about. We demonstrate that large ΔSWE will be accurately determined from dense time series of differential interferograms at Xand Ku-band by temporal integration. Lost part cycles are reconstructed with a 2-frequency approach. Temporal decorrelation is minimized by a temporal resolution of four h. A linear function between ΔSWE and phase difference springs, that deviates only some p.c from the exact solution and which depends negligibly on snow density and stratigraphy. ΔSWE retrieved from observations of the SnowScat instrument (SSI) were validated against observed SWE from totally different reference instruments, put in at a take a look at website near the town of Sodankylä, Finland. An accuracy below ±six mm SWE was achieved at frequencies of ten and 16 GHz for up to 200 mm of ΔSWE. An exceptionally high temporal coherence was observed for up to thirty days for dry snow, whereas for wet snow it decayed among hours.