• Estimating methane ebullition from lakes that freeze using SAR remote sensing
    • Melanie Engram (Research staff , WERC)
    • March 03, 2017

Northern lakes are a significant source of atmospheric methane, a potent greenhouse gas, yet large uncertainties exist in quantifying lake-source methane by scaling up field measurements from a few study lakes to the millions of lakes in the pan-Arctic. Our recent work using satellite-based synthetic aperture radar (SAR) data showed the potential for detecting lake ebullition using SAR images of lake ice.

We showed a significant correlation between SAR backscatter from lake ice and ebullition bubbles: L-band SAR backscatter intensity increases with ebullition bubbles trapped by early winter lake ice. We have developed an empirical model based on this correlation between polarimetric L-band SAR backscatter values from lake ice and field-measurements of ebullition in lakes to quantify ebullition across surfaces of over 5,000 individual Alaskan lakes in satellite SAR scenes. This new approach to estimate lake-source methane from ebullition offers a unique opportunity to improve knowledge about methane fluxes for seasonally ice-covered lakes in the pan-Arctic and sub-Arctic.

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