Short-Term Variability in Alaska Ice-Marginal Lake Area: Implications for Long-Term Studies

Lakes in direct contact with glaciers (ice-marginal lakes) are found across alpine and polar landscapes. Many studies characterize ice-marginal lake behavior over multi-decadal timescales using either episodic ~annual images or multi-year mosaics. However, lakes dynamic features that experience short-term (i.e., day to year) variations area volume superimposed on longer-term trends. Through aliasing, this variability could result erroneous long-term estimates of change. We develop implement an automated workflow Google Earth Engine quantify monthly between 2013 2019 south-central Alaska Landsat 8 imagery. employ a supervised Mahalanobis minimum-distance land cover classifier incorporating three datasets maximize performance: shortwave infrared imagery, the normalized difference vegetation index (NDVI), spatially filtered panchromatic reflectance. observe physically-meaningful variance sub-annual timescales, median fluctuation be 10.8% its average area. The signal (slow growth) noise (physically-meaningful variability) ratio is 1.5:1, indicating responsible for ~33% observed change lake. magnitude similar nonglacial lakes, suggesting cause not glacial origin. These data provide new context interpreting behaviors encourage attention even studies.