Comparison of Arctic sea ice thickness and snow depth estimates from CFSR with in situ observations

Abstract

Sea ice growth is modulated by snow cover, and understanding this relationship requires an accurate determination of snow depth. However, a lack of in situ measurements complicates understanding of the interaction of snow depth with sea ice growth. We evaluated the accuracy of Climate Forecast System Reanalysis (CFSR) data for snow depth and sea ice thickness to study the change of snow depth on Arctic sea ice. We compared CFSR and snow depth data from 35 drifting buoys in 2002–2013. The mean annual cycle of CFSR snow depth corresponded well with the buoy data. However, the CFSR data had a positive bias during winter (10–20 cm) and spring (5–25 cm), and a negative bias during summer (−25–0 cm) and autumn (−5–10 cm). The CFSR data showed increases in snow depth from 1979 to 2013 over the Beaufort and northern Chukchi Seas during November. Significant positive trends in precipitation contributed to increased snow depth in this region when sea ice began to form. The results of model experiments using a 1-D thermodynamic sea ice model in the CFSR demonstrated a recommended value of snow thermal conductivity (0.16 W m−1 K−1), and suggested that the sea ice growth was effectively restricted by the recent increase in snow depth on thin ice during winter.