Passive Remote Sensing of Lake Ice and Snow using Wideband Autocorrelation Radiometer (WiBAR)
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Snow cover plays a vital role in providing the water supplies for domestic, industrial, and agricultural purposes. The snow cover also is important to the global climate. Therefore, understanding of the global snow cover dynamics is required for both the planet's climate and humans. Conventionally, differential scatter darkening is a common technique to detect the snow thickness. This technique is region specific and depends on the statistics of snow grains. Ice formation process and ice thickness monitoring are important parameters in analyzing the overall pressure exerted to the off-shore structures such as wind farms. Lake ice measurement is also required for the safety purposes in the lakes favorable for ice fishing or skating. The traditional way to measure the lake ice thickness is by a cumbersome drilling process through the ice, which is a labor intensive task. It also increases the risk of lake ice cracking. For future in-situ or remote planetary applications, analysis of the ice sheets formed over the planetary surface or lunar regolith is informative for space scientists. These issues demonstrate the requirement for a remote accurate measurement setup, which can estimate the thickness without disturbing or breaking the ice.
In this work, a novel technique to accurately estimate the thickness of any layered low-absorbing media including snow pack and fresh water ice using wideband autocorrelation radiometer (WiBAR) is presented. This technique relies on finding the autocorrelation response of the upwelling brightness temperature. The autocorrelation response provides enough information to estimate the microwave travel time delay of the bounced back thermal emission and consequently the thickness of the snow or ice layer. We have successfully designed, implemented, and tested our handheld ground base ice/snow thickness sensor under several scenarios including snow on top of undulated and vegetation covered terrain, ice over the lake water, air gap above water, snow cover under the forest canopy in the presence of radio frequency interference (RFI).
This approach opens up the possibility of handheld, remote, and RFI-resilient ice/snow thickness sensors and also remote airborne/spaceborne planetary ice sheet thickness detectors. The accuracy of our technique in estimating the thickness of snow/ice layer is within 1.5cm.