On the use of HF as a reference for the comparison of stratospheric observations and models

M. Burton, W. Bell, C. Paton Walsh, T. Blumenstock, M. T. Coffey, J. W. Hanningan, W. G. Mankin, B. Galle, J. Mellqvist, E. Mahieu, R. Zander, J. Notholt, B. Sen, and G. C. Toon