Abstract
Between 2012 and 2018 we mapped near-peak seasonal snow depths across
two swaths covering 126 km in Northern Alaska using aerial
structure-from-motion photogrammetry and lidar surveys. The surveys were
validated by over a hundred thousand ground-based depth measurements.
Using a quantitative method for identifying drift areas, we conducted a
snowdrift census that showed on average 18% of the study area is
covered by snowdrifts each winter, with 40% of the
snow-water-equivalent contained in the drifts. Within the census we
identified six types of drifts, some of which fill each winter, others
which do not. The seasonal drift evolution was distinctly different in
the two swaths, a result largely explained by physiographic differences.
Using four metrics from the field of image quality analysis, we tested
the year-to-year fidelity of these drift patterns, finding overall high
year-to-year similarity (>70%), but with higher similarity
values for filling drifts, and higher similarity in one swath vs. the
other, again a function of the physiography. These high drift fidelity
values are best explained by climatically convergent cumulative
wind-blown snow fluxes interacting with drift traps to produce the same
drifts year after year despite considerable differences in winter
weather. However, due to the existence of filling vs. non-filling
drifts, and a predicted increasing frequency of rain-on-snow events in
the Arctic, future snowdrift patterns and drift evolution in the Arctic
are likely to diverge from those of today.