Gridded pan-Arctic total neutral atmospheric 10-m drag coefficient estimates derived from ICESat-2 ATL07 sea ice height data (Version 2)

This data-set contains average drag coefficient estimates for the whole of the Arctic (resampled onto a 25 km polar stereographic grid) for each month from 11.2018 to 06.2022. The total drag coefficients are referenced to a height of 10 meters and a neutrally stratified atmosphere is assumed. The total drag is the sum of open water drag scaled with (1-A) where A is sea ice concentration (Spreen et al., 2008), drag due to floe edges incorporated via a constant derived from parameterization (Lüpkes et al., 2012) and scaled with A(1-A), sea ice skin drag scaled with A, and sea ice form drag due to obstacles (e.g. ridges) computed from sea ice feature averages (Garbrecht et al., 2002) derived from ICESat-2 ATL07 sea ice heights (for all 25 km grid cells filled by ICESat-2 ATL07 data) (Kwok et al., 2021). Each individual component is also given as a separate variable in the data-set. In addition, the sea ice feature averages (10-km average obstacle height and obstacle spacing) used to derive form drag due to obstacles is also gridded and included in the data files. Obstacles below a threshold value of 20 cm and those that do not fulfill the Rayleigh Criterion (wherein if the trough between two peaks is smaller than the higher of two crests, only the higher one is considered) are omitted. Lastly, we scale up the ICESat-2 ATL07-derived form drag coefficients via a regression derived from comparing them to drag coefficients derived from topographic data collected during the 04.2019 NASA airborne Operation IceBridge ICESat-2 under-flights (Studinger, 2013). This is to deal with the sampling issues associated with resolution differences. The current updated version corrects for unrealistic negative ICESat-2 ATL07-derived obstacle form drag coefficients by fixing the y-intercept of the regression used to scale up the values to zero.