Comment on « Diffusion of HNO3 in ice »

Sommerfeld et al. (1998) (hereafter: SKL) attempted to measure HNO3 diffusion in ice. Although they used HNO3 partial pressures much higher than atmospheric, they encountered contamination problems, and conclude that they could not obtain meaningful values of the diffusion coefficient of HNO3 in ice. In earlier measurements, we used a method having some similarities with theirs (Dominé and Thibert, 1995). SKL suggest that our data may have been affected by contamination. Here we examine their methods, find many differences with ours, and demonstrate that our data was not affected by contamination. We point out questionable choices in their experimental procedure, and in the earlier work of Diehl et al. (1995) and discuss the difference between their solubility data and ours. We propose changes to the procedure of SKL, so that an independent set of reliable data can be obtained on the diffusion and solubility of HNO3 in ice.