A Global Climatology of Baroclinically Influenced Tropical Cyclogenesis*

McTaggart-Cowan, Ron; Galarneau, Thomas J.; Bosart, Lance F.; Moore, Richard W.; Martius, Olivia (2013). A Global Climatology of Baroclinically Influenced Tropical Cyclogenesis*. Monthly Weather Review, 141(6), pp. 1963-1989. American Meteorological Society 10.1175/MWR-D-12-00186.1

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Tropical cyclogenesis is generally considered to occur in regions devoid of baroclinic structures; however, an appreciable number of tropical cyclones (TCs) form in baroclinic environments each year. A global climatology of these baroclinically influenced TC developments is presented in this study. An objective classification strategy is developed that focuses on the characteristics of the environmental state rather than on properties of the vortex, thus allowing for a pointwise “development pathway” classification of reanalysis data. The resulting climatology shows that variability within basins arises primarily as a result of local surface thermal contrasts and the positions of time-mean features on the subtropical tropopause. The pathway analyses are sampled to generate a global climatology of 1948–2010 TC developments classified by baroclinic influence: nonbaroclinic (70%), low-level baroclinic (9%), trough induced (5%), weak tropical transition (11%), and strong tropical transition (5%). All basins other than the North Atlantic are dominated by nonbaroclinic events; however, there is extensive interbasin variability in secondary development pathways. Within each basin, subregions and time periods are identified in which the relative importance of the development pathways also differs. The efficiency of tropical cyclogenesis is found to be highly dependent on development pathway. The peak efficiency defined in the classification subspace straddles the nonbaroclinic/trough-induced boundary, suggesting that the optimal environment for TC development includes a baroclinic contribution from an upper-level disturbance. By assessing the global distribution of baroclinically influenced TC formations, this study identifies regions and pathways whose further study could yield improvements in our understanding of this important subset of TC developments.

Item Type:

Journal Article (Original Article)

Division/Institute:

08 Faculty of Science > Institute of Geography > Physical Geography > Unit Impact
10 Strategic Research Centers > Oeschger Centre for Climate Change Research (OCCR)
08 Faculty of Science > Institute of Geography

UniBE Contributor:

Romppainen-Martius, Olivia

Subjects:

500 Science > 550 Earth sciences & geology
900 History > 910 Geography & travel

ISSN:

0027-0644

Publisher:

American Meteorological Society

Language:

English

Submitter:

Monika Wälti-Stampfli

Date Deposited:

13 Dec 2013 15:28

Last Modified:

14 Apr 2016 10:48

Publisher DOI:

10.1175/MWR-D-12-00186.1

Uncontrolled Keywords:

Cyclogenesis/cyclolysis, Subtropical cyclones, Tropical cyclones, Upper troposphere, Climatology, Classification

BORIS DOI:

10.7892/boris.39479

URI:

https://boris.unibe.ch/id/eprint/39479

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