Ice profiling sonars: a comparison of error budgets

An accurate understanding of the volume of ice in the Arctic is a critical component of understanding the Earth´s heat budget. Estimation of this volume is a complex problem involving both spatial coverage issues as well as accuracy of the ice thickness measurements themselves. Much of the data from which such estimations are made has been taken from 637-class US Navy submarines. Unfortunately, there will be little or no data from this class of submarine in the future as they are all being decommissioned. New observations will be made with new sonars and the ability to accurately and robustly compare observations between the new and old measurement systems is necessary to minimize the confusion due to differences between them. This paper describes the sonar system used to collect the existing data sets from the 637-class submarines, a new sonar for making similar observations from autonomous underwater vehicles (AUVs) in the future and establishes a reference framework for evaluating error budgets in this type of sonar system. A careful intercomparison between the old and the new sonars to establish a robust basis for extending the observational time series should be done