The compressibility of ice to 2.0 kbar

To understand in situ properties of ice under pressure, we need an accurate model for ice compressibility. Many studies have estimated ice compressibility, but there still remains considerable controversy with respect to the magnitude and temperature dependence of ice compressibility. The specific objectives of this study were to (1) present a new model for estimating the compressibility of ice based on chemical thermodynamic principles, and (2) compare these model results with previous work. A thermodynamic equation that relates equilibrium constants to molal volumes and compressibilities of water and ice was the basic model used to estimate ice compressibilities. All terms in this equation (equilibrium constants, temperature, pressure, molal volumes of ice and water at 1 atm, and water compressibilities) are definable along the pressure ice/water melting curve except for ice compressibility, which we estimated from the equation. Our estimate of ice compressibility demonstrated a significant temperature dependence. In contrast, most other studies, especially those that rely on elastic parameters, only demonstrate a weak temperature dependence. All recent studies show a significantly lower ice compressibility than the classic Bridgman studies. The results of this work are in agreement with most other databases and models and indicate a general consensus on the compressibilities of water and ice up to 1200 bar of pressure. Between 1200 and 2000 bar, there are discrepancies that are unlikely to be resolved without further experimental work that directly estimate the compressibility of ice over a range of temperatures. A comparison of calculated ice core densities from Antarctica, with and without corrections for pressure, demonstrate the utility of this model for understanding in situ ice properties under pressure. (C) 2004 Elsevier B.V All rights reserved.