Publication Date:
2017-10-10
Description:
A reflectometry station has been setup in 2013 near Ny-Ålesund, Svalbard at 78.9082 ∘ N, 11.9031 ∘ E. The main goal of the setup is to resolve the spatial and temporal variations in snow and ice cover, based on reflection power observations at grazing elevations. In this study, we develop a method to map the recorded signal power to the main reflection contributions while also discussing the spatial characteristics of the observations. A spectral analysis resolving differential Doppler between direct and reflected signals is presented to identify reflections contributions for a complete year (2014). Strong water reflections are identified with power ratios higher than 70 dB/Hz and constant Doppler shifts of 0.5 − 0.6 Hz for all elevations. Contributions with ratios higher than 40 dB/Hz can be related to specular land or glacier reflections, for which Doppler shift usually increases with the elevation angle and the distance between reflection point and receiver. Reflections nearby, around 3 − 5 km, show differential Doppler of 0.4 − 0.5 Hz while for reflections further than 16 km away, Doppler shift is usually larger than 0.8 Hz. Azimuth variations cause cross-track drift of up to 4 ∘ during the observation year. Topography-induced shadowing of very low-lying satellites limits the extent of the monitoring area. However, the amount of satellites tracked daily, up to 30, allows the GNSS-R station to constantly record reflections over areas with thick snow cover and glaciers. This offers the possibility to compare the derived reflected power with local meteorological data to resolve snow and ice variations on the area.
Print ISSN:
0048-6604
Electronic ISSN:
1944-799X
Topics:
Geosciences
,
Physics
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