CORDEX-CMIP6 Australian cyclone tracks

This archives cyclone tracks for the historical and ssp370 scenarios generated from 40 regional climate models which downscaled CMIP6 data using the CORDEX-Australasia framework. The models are described in more detail in Pepler et al. (2015), and are the produce of four different Australian state and federal agencies:The Bureau of Meteorology (BOM) BARPA-R, which downscaled 7 GCMs and is available at https://dx.doi.org/10.25914/gjzx-kr91The CSIRO CCAM simulations, which downscaled 7 GCMs and is available at https://dx.doi.org/10.25914/rd73-4m38The Queensland Government (UQ-DES) simulations from QldFCP-2, which has 16 simulations using a range of GCMs and CCAM settings, available at https://dx.doi.org/10.25914/2c0z-8t40The NSW Government simulations from NARCliM2.0, which downscaled 5 GCMs using two different WRF setups and is available at https://dx.doi.org/10.25914/3r9s-pb86For all RCMs, cyclones were tracked in 6-hourly MSLP and 500hPa geopotential height data 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/. Similar datasets are also available for a small selection of CMIP6 GCMs (https://doi.org/10.6084/m9.figshare.28887851.v1) and reanalyses (https://doi.org/10.6084/m9.figshare.28887851.v1).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. The regions used for tracking differ slightly between the three modelling methods (BARPA, CCAM and NARCliM), and are apparent through the relevant incycloc file.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_$agency_$rcm_$ssp_$level_$details.tar.gzColumn 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)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 systemDepth Depth of cyclone (hPa) between central point and outer radiusRadius 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). To correct these, check the number of unique years in the file - if there is only one year, then that is the same as given in the filename; if there are 2 years, the first month will be the December of the previous year. 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 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<br>

本数据集归档了历史情景与SSP370情景下的气旋轨迹，相关轨迹由40个区域气候模式（Regional Climate Model, RCM）生成，这些模式通过CORDEX-Australasia框架对耦合模式比较计划第六阶段（CMIP6）数据进行降尺度处理。相关模式的详细信息可见Pepler等人（2015）的研究，其数据由四家澳大利亚州级及联邦级机构产出：
1. 澳大利亚气象局（Bureau of Meteorology, BOM）的BARPA-R模式，对7个全球气候模式（Global Climate Model, GCM）进行降尺度，数据可通过https://dx.doi.org/10.25914/gjzx-kr91获取；
2. 澳大利亚联邦科学与工业研究组织（Commonwealth Scientific and Industrial Research Organisation, CSIRO）的CCAM模拟结果，对7个GCM进行降尺度，数据可通过https://dx.doi.org/10.25914/rd73-4m38获取；
3. 昆士兰州政府（UQ-DES）基于QldFCP-2开展的模拟结果，包含16组采用不同GCM与CCAM参数设置的模拟，数据可通过https://dx.doi.org/10.25914/2c0z-8t40获取；
4. 新南威尔士州政府的NARCliM2.0模拟结果，采用两种WRF配置对5个GCM进行降尺度，数据可通过https://dx.doi.org/10.25914/3r9s-pb86获取。

针对所有区域气候模式，研究采用Murray与Simmonds（1991）及Simmonds等人（1999）提出的气旋追踪方案，基于每6小时一次的海平面气压（MSLP）与500hPa位势高度数据追踪气旋。该追踪方案的源代码与文档可通过https://cyclonetracker.earthsci.unimelb.edu.au/获取。此外，针对少量CMIP6 GCM（https://doi.org/10.6084/m9.figshare.28887851.v1）与再分析数据（https://doi.org/10.6084/m9.figshare.28887851.v1）也提供了类似数据集。

本数据集提供的气旋轨迹基于最弱强度阈值生成，更强的强度阈值通常用于筛选本文研究所用的低压系统。如需了解追踪与检测所用参数的更多细节，请查阅作为追踪方案输入文件的*incycloc与*intrack文件。三种建模方法（BARPA、CCAM与NARCliM）所用的追踪区域存在细微差异，相关差异可通过对应的incycloc文件体现。

每个年份对应单独的轨迹文件，文件起始时间为前一年的12月1日，以便识别跨年度的气旋轨迹。每个.tar.gz压缩包包含单组模拟的全部轨迹文件，命名格式示例为：$model_$member_$agency_$rcm_$ssp_$level_$details.tar.gz。

数据集文件的列标题说明如下：
- ID：轨迹编号
- Track ID：轨迹唯一标识
- Fix Instance within track：轨迹内的固定实例序号
- Date：日期（UTC）*
- Time：时间（UTC）
- Open/closed：是否存在闭合环流（0代表无闭合环流，即“开放”脊）
- Lon：经度
- Lat：纬度
- MSLP：中心气压（单位：百帕，hPa）
- Laplacian：海平面气压的拉普拉斯值（单位：hPa·(°纬度)^-2），用于表征海平面气压的曲率，是衡量系统强度的更优指标
- Depth：气旋中心与外围半径间的气压差（单位：hPa）
- Radius：气旋半径（单位：度）
- Up：引导气流U分量速度
- Vp：引导气流V分量速度

*注：日期采用两位年份格式，部分情况下因追踪方案的运行逻辑会出现日期错误（例如1999-2001）。修正方法如下：若文件中仅存在1个唯一年份，则该年份与文件名中给出的年份一致；若存在2个唯一年份，则第一个月为前一年的12月。

参考文献：
1. Murray R J, Simmonds I. 1991: 基于数字数据追踪气旋中心的数值方案 第一部分：方案的开发与运行. 澳大利亚气象杂志, 39, 155–166.
2. Simmonds I, Murray R J, Leighton R M. 1999: 基于FROST数据改进气旋追踪方法. 澳大利亚气象杂志(特刊), 35–49.
3. Pepler AS, Di Virgilio G, Dowdy AD, Goyal R, Su C-H, Thatcher M, Syktus J. 2025: 降尺度CMIP6模式中澳大利亚低压系统的投影研究（已提交至JSHESS）