An Autonomous Network Measuring Changes in the Thickness of the Arctic Sea Ice Cover

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 autonomous systems designed to observe changes in the mass balance of the ice cover. We are in the early stages of deploying a network of autonomous ice mass balance buoys (IMB). An IMB buoy consists of sensors to measure snow accumulation and ablation, ice growth and melt, and internal ice temperature plus a satellite transmitter. In some cases a Web cam is added allowing the evolution of surface conditions to be observed. IMB buoys have been deployed each spring during the past five years from the North Pole Environmental Observatory and in several other areas including a few in the Beaufort Sea and Central Basin. Preliminary observations indicate that there is significant regional and interannual variability in the mass balance, with considerable differences in ice growth, as well as the relative amounts of surface and bottom ablation. North Pole buoys have recorded significant interannual variability in surface ablation, with values ranging from 5 to 35 cm. Results from the Beaufort Sea show year to year variations in bottom melt of 25 to 60 cm. Data from autonomous IMB buoys will be integrated with other in situ observations, satellite remote sensing information, and numerical modeling results to provide a comprehensive picture of changes to the Arctic sea ice cover.