Publication Abstracts

Bieli et al. 2019, in press

Bieli, M., S.J. Camargo, A.H. Sobel, J.L. Evans, and T. Hall, 2019: A global climatology of extratropical transition, Part II: Statistical performance of the cyclone phase space. J. Climate, in press, doi:10.1175/JCLI-D-18-0052.1.

This study analyzes the differences between an objective, automated identification of tropical cyclones (TCs) that undergo extratropical transition (ET), and the designation of ET determined subjectively by human forecasters in best-track data in all basins globally. The objective identification of ET is based on a TC's trajectory through the cyclone phase space (CPS), calculated from the Japanese 55-year Reanalysis (JRA-55) or the ECMWF Interim Reanalysis (ERA-Interim). The resulting classification into "ET storms" and "non-ET storms" underlies the global climatology of ET presented in Part I of this two-part study. Here, the authors investigate how well the CPS classifications agree with those in the best-track records calculated from JRA-55 or from ERA-Interim data.

According to F1 scores and Matthews correlation coefficients (MCCs), the classification of ET storms in the CPS agrees best with the best-track classification in the Western North Pacific (MCC>0.7) and the North Atlantic (MCC>0.5). In other basins, the correlation between the CPS classification and the best-track classification is only slightly higher than that of a random classification.

The JRA-55 classification achieves higher performance scores than does the ERA-Interim classification, and the differences are statistically significant in all basins. The lower performance of ERA-Interim is mainly due to a higher false alarm rate, particularly in the Eastern North Pacific. Overall, the results show that while the CPS-based classifications are good enough to be useful for many purposes, there is almost certainly room for improvement — in the representation of the storms in reanalyses, in our objective metrics of ET, and in our scientific understanding of the ET process.

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BibTeX Citation

@unpublished{bi06100q,
  author={Bieli, M. and Camargo, S. J. and Sobel, A. H. and Evans, J. L. and Hall, T.},
  title={A global climatology of extratropical transition, Part II: Statistical performance of the cyclone phase space},
  year={2019},
  journal={J. Climate},
  doi={10.1175/JCLI-D-18-0052.1},
  note={Manuscript accepted for publication}
}

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RIS Citation

TY  - INPR
ID  - bi06100q
AU  - Bieli, M.
AU  - Camargo, S. J.
AU  - Sobel, A. H.
AU  - Evans, J. L.
AU  - Hall, T.
PY  - 2019
TI  - A global climatology of extratropical transition, Part II: Statistical performance of the cyclone phase space
JA  - J. Climate
DO  - 10.1175/JCLI-D-18-0052.1
ER  -

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