The neutral form drag coefficient is an important parameter when estimating surface turbulent fluxes over Arctic sea ice. The form drag caused by surface features (๐ช๐
๐,๐๐) dominates the total drag in the winter, but long-term pan-Arctic records of ๐ช๐
๐,๐๐ are still lacking for Arctic sea ice. In this study, we first developed an improved surface feature detection algorithm and characterized the surface features (including height and spacing) over Arctic sea ice during the late winter of 2009-2019 using the full-scan laser altimeter data obtained in the Operation IceBridge mission. ๐ช๐
๐,๐๐ was then estimated using an existing parameterization scheme. This was followed by applying a satellite-derived backscatter coefficient (๐๐๐๐ ) to ๐ช๐
๐,๐๐ regression model to extrapolate, for the first time, ๐ช๐
๐,๐๐ to the pan-Arctic scale for the entire winter season over two decades (from 1999 to 2021). We found that the surface features have a larger height and smaller spacing over multi-year ice (1.15 ยฑ 0.21 m and 142 ยฑ 49 m) than over first-year ice (0.90 ยฑ 0.16 m and 241 ยฑ 129 m). The monthly mean ๐ช๐
๐,๐๐ increases through the winter, from 0.2 ร 10 โ3 in November to 0.4-0.5 ร 10 โ3 in April. The central Arctic has the largest ๐ช๐
๐,๐๐ (up to 2 ร 10 โ3), but experienced a drop of ~50% in the period from 2001/2002 to 2008/2009. The interannual fluctuations in ๐ช๐
๐,๐๐ are strongly linked to the variability of sea ice thickness and deformation, and the latter has become increasingly important for ๐ช๐
๐,๐๐ since 2009.