In the 21st century, the Arctic has become more accessible to resource extraction and transportation than ever before due to sea ice decline. Being able to accurately predict future seasonal Arctic sea ice extent is more important than ever before. Data from Bering Strait moorings have established a clear negative correlation between heat flux and sea ice where, as heat flux increases, sea ice extent decreases. This study evaluates the heat flux measurements in the Simple Ocean Data reAnalysis (SODA 3.3.1) and the Ocean ReAnalysis System 4 (ORAS4), comparing them to in situ mooring data and assessing their ability to predict sea ice retreat in the Chukchi Sea.

The SODA relies on the Modular Ocean Model v5 ocean with MERRA-2 atmospheric forcing. ORAS4 relies on the NEMO V3.0 ocean model with ERA atmospheric forcing. First retreat day (FRD) for sea ice in the Chukchi Sea (i.e., the first day that sea ice concentration in the Chukchi Sea dropped below 30%) was sourced from combined passive microwave records. While SODA did significantly correlate to mooring data for most months, the correlation between ORAS4 and the mooring data was more consistently significant. This result is especially remarkable because ORAS4 does not assimilate any submerged mooring data in the Arctic region.

SODA 3.3.1 and ORAS4 produced the data that correlated strongest to the sea ice retreat data. When comparing SOD 3.3.1 and ORAS4 heat flux model residuals year-by-year, there are some years when one model would have performed better than the other but generally speaking, ocean reanalysis data outputs are accurate enough that we no longer need to rely solely on observational data from submerged Arctic Moorings to model seasonal Arctic sea ice retreat.


Crawford, Alex




Atmospheric Sciences | Climate | Oceanography


arctic, sea ice, ocean reanalysis, climate variability, chukchi sea, heat flux, bering strait

Publication Date


Degree Granted

Bachelor of Arts

Document Type

Senior Independent Study Thesis



© Copyright 2019 Ben Sershen