The Effects Of Snow Ventilation on Chemical Concentrations

Abstract

Ice cores contain a suite of chemical tracers which, when correctly interpreted, can reveal properties of the paleo-atmosphere and the climate system. These chemical constituents have been subjected to a series of physical and chemical processes at each step on their journey from the remote paleo-atmosphere into the ice (see Neftel, this volume; Waddington, this volume). Current research in polar snow chemistry focuses on the transfer functions, i.e. the chemical and physical processes that control the concentrations and fluxes of these atmospheric components at each step. Understanding the transfer functions is essential to the ice core - paleoclimate Inverse Problem, i.e. the derivation of the paleo-climate from the ice core data (Waddington, this volume). In this paper we focus mainly on one step in the Forward Problem; this is the transfer of dry-deposited chemical tracers from the local atmosphere into the snow by air flow through the snow (windpumping). Nearly two decades ago in a seminal paper entitled The filtering effect of snow, Gjessing (1977) summarized this topic as follows: