On the importance of reviewing historical tropical cyclone intensities

Historical tropical cyclone datasets (“best tracks”) have been extensively used in the past to establish broad climatologies, identify relative changes in frequency and occurrence between basins and to estimate intensity on a regional basis. Increasingly, however, in line with the proposed potential effects of anthropogenic climate change, global best track datasets are being used to infer possible trends in intensification. The paper therefore plans to examine the likely variation in quality, consistency and accuracy of historical tropical cyclone intensity values and to identify a number of potential pitfalls for inferring intensity trends on the basis of such data. Firstly, the technical development of intensity estimation over the past 35 years will be summarised and, importantly, placed within the context of personnel training, experience and access to facilitating technologies, such as automating procedures and the availability of verifying data. Secondly, an example of a rigorous re-analysis of historical best track intensities from the Australian North West Shelf region will be presented that will demonstrate the benefits of reanalysis in a specific basin. Thirdly, the paper will consider the implications of these results for other regions, using other selected examples of storms whose intensities are deemed, prima facie, in need of review.