Ice mass-balance buoys: a tool for measuring and attributing changes in the thickness of the Arctic sea-ice cover

Abstract

Recent observational and modeling studies indicate that the Arctic sea-ice cover is undergoing significant climate-induced changes, affecting both its extent and thickness. The thickness or, more precisely, the mass balance of the ice cover is a key climate-change indicator since it is an integrator of both the surface heat budget and the ocean heat flux. Accordingly, efforts are underway to develop and deploy in situ observing systems which, when combined with satellite remote-sensing information and numerical models, can effectively monitor and attribute changes in the mass balance of the Arctic sea-ice cover. As part of this effort, we have developed an autonomous ice mass-balance buoy (IMB), which is equipped with sensors to measure snow accumulation and ablation, ice growth and melt, and internal ice temperature, plus a satellite transmitter. The IMB is unique in its ability to determine whether changes in the thickness of the ice cover occur at the top or bottom of the ice cover, and hence provide insight into the driving forces behind the change. Since 2000, IMBs have been deployed each spring from the North Pole Environmental Observatory and in several other areas, including a few in the Beaufort Sea and Central Basin. At this point, the collective time series is too short to draw significant and specific conclusions regarding interannual and regional variability in ice mass balance. Comparisons of available data indicate that ice surface ablation is greater in the Beaufort region (67-80 cm), relative to the North Pole (0-30 cm), consistent with a longer period of melt in the more southerly location. Ablation at the bottom of the ice (22 cm), maximum ice thickness (235 cm) and maximum snow depth (28 cm) were comparable in the two regions.

A modern concept for autonomous and continuous measurements of spectral albedo and transmittance of sea ice

“…Such an autonomously drifting station would not need to be revisited for data and instrument retrieval, but would mean losing the equipment, which is rather costly with the current instrumentation. Spectral radiation measurements on buoys would be most efficient when deployed together with other buoy systems, especially with an Ice Mass-balance Buoy (IMB, Richter-Menge et al, 2006). This would allow gathering most comprehensive data sets to study sea-ice mass and energy balance from remote sites.…”

Taking into Account Atmospheric Uncertainty Improves Sequential Assimilation of SMOS Sea Ice Thickness Data in an Ice–Ocean Model

“…Drafts are converted to thickness by multiplying by a factor of 1.1 (Nguyen et al 2011). The accuracy of the IMB sounders is 5 mm (Richter-Menge et al 2006). The reader is referred to Fig.…”

Processes controlling surface, bottom and lateral melt of Arctic sea ice in a state of the art sea ice model

“…In addition, in situ measurements that provide a decomposition of sea ice melt processes (top, bottom and lateral melt) are sparse [14,15]. Recently, Perovich et al [16] quantified the relative importance of surface ice/snow melt and bottom ice melt using autonomous ice mass balance buoys deployed over more than 10 years (2000-2013) that drifted from the North Pole towards the Fram Strait.…”