By Benjamin Lange | Arctic sea ice thickness and extent have undergone significant changes over the past ~30 years. The observed changes are actually much greater than predicted by even the best global climate models for the Arctic Ocean. In addition, sea ice thickness and volume are key indicators of climate change in comparison to the long term record of sea ice extent, because thickness and volume are indicators of changes in the energy budget of the Arctic Ocean.
Not only is sea ice an important climatological element but it also serves as an important habitat for many polar organisms such as: copepods, amphipods, polar cod, polar bears and seals. Sea ice habitat properties such as thickness, roughness (e.g., density of ridges) and light transmission have been linked to the distribution of and community structure of ice associated animals. This means that as the sea ice environment continues to change so will the habitat of many key polar organisms with unknown consequences for the future Arctic ecosystem.
Thus, during PS106/2 one objective was to quantify physical-ecological properties of the sea ice environment at multiple spatial scales. This has been accomplished using a helicopter-borne electromagnetic (HEM) sea ice thickness instrument (the EM-bird) and an under-ice profiling platform, the surface and under-ice trawl (SUIT), with a mounted bio-environmental sensor array. In addition, we have conducted high-resolution, smaller-scale (floe-scale) surveys of the under-ice environment using the remotely operated vehicle (ROV).
During PS106/2 we conducted 5 HEM surveys, each with an average survey length of ~200 km and good overall coverage of the entire study area. Modal sea ice thicknesses, which are a good indicator of the most dominant, level-ice type in the region, ranged between 1.0 and 1.5 m.
If we compare the 20170627 (red in Fig. 1) HEM survey to the 20170715 (purples) survey conducted in the same region 18 days later, we can infer that there was approximately 0.25 m of sea ice melt during this period based on the change in modal sea ice thickness from 1.25 to 1.0 m (Fig.1). This estimate does not account for possible sea ice drift trajectories and thus will need to be confirmed with further analysis. Furthermore, we conducted 5 ice stations with ROV net deployments and high resolution surveys of the under-ice environmental. Last but not least, we conducted 21 SUIT hauls with profile lengths ranging from 500 m to 3 km. A typical SUIT profile is shown in the following Figure with several different parameters measured using the mounted bio-environmental sensor array (excluding light transmittance and sea ice algal biomass which can be derived from the spectral properties of light).
The SUIT was originally designed to catch under-ice organisms but now with its advanced sensor array we can link the physical sea ice habitat properties to the under-ice community composition and distributions. Combining the information derived from SUIT hauls with the ROV net and sensor array observations we can quantify the physical-ecological relationships of different sea ice habitats at multiple spatial scales (from 1 m to 3 km). These relationships can then be combined with larger scale HEM and satellite sea ice thickness observations to classify and model regional and pan-Arctic sea ice habitats and ecosystems.