CMIP6 global cyclone tracks
This folder contains CMIP6 cyclone tracks generated for Pepler (2024) and Pepler et al. (2025). For associated reanalysis datasets see https://doi.org/10.6084/m9.figshare.24086898.v1.
These cyclones were identified using the Murray and Simmonds (1991) and Simmonds et al. (1999) cyclone tracking scheme. The source code and documentation is available at https://cyclonetracker.earthsci.unimelb.edu.au/
Tracks are provided for 8 CMIP6 models from historical simulations for 1950-2014, and ssp3-7.0 for 2015-2099. Surface cyclones are tracked using 6-hourly MSLP, and upper cyclones are tracked using 6-hourly 500 hPa geopotential height for models where this is available. These models were selected based on availability of 6-hourly 500hPa data on the NCI node of the ESGF.
Cyclone tracks are provided based on the weakest intensity threshold, with stronger thresholds typically identified to select lows for use in the paper. For more details on the parameters used for detection and tracking see the files *incycloc and *intrack which are used as inputs for the tracking scheme.
A separate track file is provided for each year, beginning on 1 December of the previous year, to allow for the identification of cross-year tracks when relevant. Each .tar.gz file includes all tracks for one simulation, e.g. $model_$member_$ssp_$level_$details.tar.gz
Column headings:
- ID Track ID
- Fix Instance within track
- Date Date* (UTC)
- Time Time (UTC)
- Open/closed Is there closed circulation (0) or an "open" ridge.
- Lon Longitude
- Lat Latitude
- MSLP Central pressure (hPa)
- Laplacian Laplacian of MSLP (hPa. Deg.lat^2), which represents the curvature of the MSLP. This is a better indicator of the strength of a system
- Depth Depth of cyclone (hPa) between central point and outer radius
- Radius Radius of cyclone (degrees)
- Up Steering velocity (U)
- Vp Steering velocity (V)
*Dates are two digit years, and in some cases are wrong because of the way the tracking scheme works (e.g. 1999-2001).
References:
- Murray, R. J., and I. Simmonds, 1991: A numerical scheme for tracking cyclone centres from digital data. Part I: Development and operation of the scheme. Aust. Meteorol. Mag., 39, 155166.
- Simmonds, I., R. J. Murray, and R. M. Leighton, 1999: A refinement of cyclone tracking methods with data from FROST. Aust. Meteorol. Mag., (special edition), 3549.
- Pepler, Acacia (2024) Recent trends in extratropical lows and their rainfall over Australia. Journal of Southern Hemisphere Earth Systems Science 74, ES24002. https://doi.org/10.1071/ES24002
- Pepler AS, Di Virgilio G, Dowdy AD, Goyal R, Su C-H, Thatcher M, and Syktus J. (2025) Projections of Australian low pressure systems in downscaled CMIP6 models Submitted to JSHESS
