Global cyclone and anticyclone tracks, 1948-2022

Abstract

This dataset includes all global surface anticyclones as well as both surface and 500hPa cyclones tracked using the University of Melbourne cyclone tracking scheme over all available years until 2022. The dataset is an update of that available at https://doi.org/10.6084/m9.figshare.c.4944135.v1, but with some changes to parameters:The intensity of surface cyclones is based on the Laplacian averaged within 2 degrees of the centre rather than 5 degrees, to better detect the most intense part of the low500hPa lows are also included. In contrast to previous datasets for ERA5 (e.g. https://doi.org/10.6084/m9.figshare.19669518.v1) these are tracked using 6-hourly instantaneous 500hPa geopotential height, rather than daily mean fields.These anticyclones and 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/, with additional example processing scripts available at https://github.com/apepler/cyclonetracking. The included ".incycloc" and ".intrack" files give the parameters used for tracking. Tracks are provided for ERA5 during 1959-2022, JRA55 for 1958-2022, and NCEP1 for 1948-2022. Cyclone tracks are provided based on the weakest intensity threshold, noting that the associated paper reports results for only lows exceeding additional minimum intensity thresholds. Both open and closed circulations are included, although only closed circulations are used in the paper. Each zipfile contains all results for a single synoptic type and reanalysis. 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.Column headings:ID Track IDFix Instance within trackDate Date* (UTC)Time Time (UTC)Open/closed Is there closed circulation (0) or an "open" ridge. Lon LongitudeLat LatitudeMSLP Central pressure (hPa) or central height (Z500, m)Laplacian Laplacian of MSLP (hPa. Deg.lat^2) or (m. Deg.lat^2), which represents the curvature of the MSLP. This is a better indicator of the strength of a system, and represents the curvature of the field. Depth Depth of system relative to the background region (hPa)Radius Radius of system (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) These need to be corrected when using multiple files, noting that the true year of the Jan-Dec data is given in the filename.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 (2023) Emerging trends in extratropical lows and their rainfall over Australia (submitted to ERCL)</ul