Dependence on Seasonally Varying Atmospheric Boundary Conditions and the Firn Structure

• Main Authors: Der Philosophisch Naturwissenschaftlichen Fakultät, Der Universität Bern, Karin Weiler, Aus Deutschland, Prof Dr, T. F. Stocker
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Antarctic; Kohnen; Antarc*
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.219.5718; http://www.climate.unibe.ch/main/thesis/weiler08phd.pdf

Summary The dependence of the firn air composition on seasonally varying atmospheric boundary conditions and the firn structure has been studied based on firn air samples from two Antarctic sites, Halley and Kohnen. The Halley data set consists of six profiles sampled in a two month resolution in the year 2003. Settling of the firn and snow accumulation led to a shift of the depth levels of both, the firn air sampling setup and the thermistors. Prediction of this sample level shift with a 1–dimensional box model developed in the frame of this study coincides with the decrease of the analyzed diurnal temperature cycle. By forcing the temperature–diffusion model with the surface temperature history of Halley, temperature oscillations in the firn column originating from seasonal atmospheric temperature variations are reasonably well reproduced. Thus, the dependence of the thermal conductivity on firn density as derived by Schwander et al. [1997] is sufficient also on the seasonal scale. In order to simulate thermal fractionation of the different gas species, thermal