The files contain tracks of cyclones based on the ERA-Interim and the ASR reanalyses. A cyclone is detected from filtered vorticity at 850hPa and tracked by the tracking algorithm of Kevin Hodges. For more information see: Stoll, P., Graversen, R. G., Noer, G., & Hodges, K. (2018). An objective global climatology of polar lows based on reanalysis data. Quarterly Journal of the Royal Meteorological Society. For questions, please contact the author.