Halide Out Experiment, a Antarctic CRC experiment to study the Antarctic pack ice during winter. The project aims include: (1) providing a quantitative assessment of the mass budget and Antarctic winter sea ice and to relate this to the rate of water mass modification; (2) providing a quantitative estimate of the surface energy exchanges in the winter Antarctic sea ice zone and, in conjunction with FORMEX, to relate surface vertical energy exchange to the ocean heat budget and advection; and (3) describing the processes by which new ice deforms and thickens and the atmospheric and ocean forcing which determine these processes.