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

Kazutoshi Sato,Jun Inoue

doi:10.1007/s00382-017-3607-z

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.

Highlights

IntroductionChanges in snow properties (e.g., snow depth, snow cover, date of snowmelt, and surface albedo) influence atmospheric circulation patterns and surface heat budgets (Matsumura et al 2010)
Changes in snow properties influence atmospheric circulation patterns and surface heat budgets (Matsumura et al 2010)
Comparison of the Climate Forecast System Reanalysis (CFSR) with Ice Mass Balance (IMB) buoy data showed that simulated snow depth was in good agreement with in situ snow depth during November

Summary

Introduction

Changes in snow properties (e.g., snow depth, snow cover, date of snowmelt, and surface albedo) influence atmospheric circulation patterns and surface heat budgets (Matsumura et al 2010). Snow with a high surface albedo reflects downward solar radiation, which is important to those heat budgets. Previous studies have reported that the growth and decay of sea ice are controlled by snow loading (snow depth and density) on sea ice (Sturm et al 2002; Blazey et al 2013; Riche and Schneebeli 2013). Snow depth on sea ice is an important component of sea ice growth through the insulating effect of snow (Maykut and Untersteiner 1971). Increased snowfall on sea ice delays sea ice melt via reduced absorption of solar radiation and prevents that ice from growing during autumn and winter. The climatology of snow depth for multiyear ice (MYI) has been generated using snow depth and density data from Soviet drifting stations in the Arctic Ocean since 1937 (Warren et al 1999)

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