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The underwater noise emission from glacier calving is investigated by integrating acoustic and photographic observations made in a glacial bay and model pool. Similarities in the impact noise in these two settings are identified. Distinct fluid-dynamics processes are involved in sound generation: iceberg detachment, water entry, entrainment and collective oscillation of a bubble cloud, secondary impacts due to splashes, and calving-induced wave action. The lag between initial impact and bubble plume pinch-off from the subsurface cavity depends on ice block dimensions and drop height and may be useful in reducing errors in estimates of calving fluxes made using underwater sound. 

Abstract. Accurate estimates of calving fluxes are essential inunderstanding small-scale glacier dynamics and quantifying the contribution ofmarine-terminating glaciers to both eustatic sea-level rise (SLR) and thefreshwater budget of polar regions. Here we investigate the application ofacoustical oceanography to measure calving flux using the underwater soundsof iceberg–water impact. A combination of time-lapse photography and passiveacoustics is used to determine the relationship between the mass and impactnoise of 169 icebergs generated by subaerial calving events from Hansbreen,Svalbard. The analysis includes three major factors affecting the observednoise: (1) time dependency of the thermohaline structure, (2) variability inthe ocean depth along the waveguide and (3) reflection of impact noise fromthe glacier terminus. A correlation of 0.76 is found between the(log-transformed) kinetic energy of the falling iceberg and thecorresponding measured acoustic energy corrected for these three factors. Anerror-in-variables linear regression is applied to estimate the coefficientsof this relationship. Energy conversion coefficients for non-transformedvariables are 8×10-7 and 0.92, respectively, for themultiplication factor and exponent of the power law. This simple model canbe used to measure solid ice discharge from Hansbreen. Uncertainty in theestimate is a function of the number of calving events observed; 50 %uncertainty is expected for eight blocks dropping to 20 % and 10 %,respectively, for 40 and 135 calving events. It may be possible to lowerthese errors if the influence of different calving styles on the receivednoise spectra can be determined.