Model-observation comparison of sea ice floe size distribution in the Arctic

Abstract:

The floe size distribution (FSD) in the marginal ice zone (MIZ) is controlled by ice advection, thermodynamics (lateral melting) and dynamics (winds, currents and ocean surface waves). These controlling factors have different effects on FSD in different areas of the Arctic Ocean. The MIZ in the Pacific sector is likely to be influenced by a warm ocean due to enhanced sea-ice albedo feedback, whilst the MIZ in the Atlantic sector is more likely to be influenced by ocean surface waves. As a result, FSD has different regional characteristics in these two sectors.

To understand the regional differences in FSD and the dominant physical factors controlling FSD, we compared FSD observations with the outputs from Waves-in-Ice module and Power law Floe Size Distribution (WIPoFSD) model and two types of prognostic floe size-thickness distribution models. Observational FSD data were derived from 1-m resolution MEDEA images at three different locations in the Arctic. The results from the observation show that FSD in the Chukchi Sea site (70° N, 170° W) is the most dynamic as it contains a larger percentage of smaller floes and undergoes a greater interannual variability in the FSD compared to the East Siberian Sea (82° N, 150° E) and Fram Strait sites (84.9° N, 0.5° E). Our initial comparison between model and observation also shows similar patterns. A more detailed comparison analysis is still underway and will be presented at the meeting.

This research will contribute to improving MIZ model parameterisations and a more accurate projection of the future Arctic sea ice and climate.