Buoys based on new technology yield valuable information on Arctic sea ice thickness

The sea ice thickness and oceanic heat flux at ice bottom were investigated using an automatic unmanned ice mass balance buoy (IMB) deployed in the Pacific Arctic Section (PAS).

Buoy was deployed during third Chinese National Arctic Research Expedition (CHINARE) program in mid-August 2008 during ice camp period. This IMB worked 10 months before stop iridium data transmission. The ice thickness changes from initial 1.95 cm down to minimum 1.46 m in mid-October and recovered to 3.12 m in June 2009 along the buoy drift trajectory.

The Finnish Meteorological Institute was the international key partner of CHINARE2008 program. We have contributed to the surface energy balance measurements during ice camp period. This study is part of EC funded DAMOCLES project. The IMB drifted a distance of 650 km from north-east Chukchi Sea eastward over the Alpha Ridge into the Makarov Basin, then across the Lomonosov Ridge into the Amundsen Basin, north of Greenland during its life time.

The ice temperature at the ice surface exhibited persistent high-frequency variations due to diurnal and synoptic-scale atmospheric forcing. These signals propagated downward with damped magnitude and temporal lag. The competition of oceanic and conductive heat flux dominated the low-frequency variations of ice growth. However, high-frequency variations in ice growth were controlled largely by the oceanic heat flux. Study suggested that the average upward oceanic heat flux was 7.1 W/m2. This was in agreement with that derived from another IMB initially deployed some 160 km north of our buoy site in 2005. Relatively high oceanic heat flux (10–15 W/m2) was observed during autumn and early winter to summer warming of the surface ocean. Upward mixing of warm deep water, as observed when our buoy drifted over the shallow region of the Lomonosov Ridge (85.4º – 85.9ºN, 52.2º – 66.4ºW), demonstrated the impact of bathymetry on the oceanic heat flux under ice cover, and consequently on the basal ice mass balance.

More information:

Senior Researcher, Bin Cheng, bin.cheng@fmi.fi

Lei, R., N. Li, P. Heil, B. Cheng, Z. Zhang, and B. Sun (2014), Multiyear sea-ice thermal regimes and oceanic heat flux derived from an ice mass balance buoy in the Arctic Ocean, J. Geophys. Res. Oceans, 119, doi:10.1002/2012JC008731.

http://onlinelibrary.wiley.com/doi/10.1002/2012JC008731/abstract