A meridional dipole in premonsoon Bay of Bengal tropical cyclone activity induced by ENSO

TitleA meridional dipole in premonsoon Bay of Bengal tropical cyclone activity induced by ENSO
Publication TypeJournal Article
Year of Publication2016
JournalJournal of Geophysical Research: Atmospheres
Volume121
Pages6954-6968
Date Published06/2016
Abstract / Summary

Analysis of Bay of Bengal tropical cyclone (TC) track data for the months of May–June during 1979–2014 reveals a meridional dipole in TC intensification: TC intensification rates increased significantly in the northern region and decreased in the southern region. The dipole is consistent with changes in the large-scale TC environment estimated using the Genesis Potential Index (GPI) for the same period. While an increase in lower troposphere cyclonic vorticity and midtroposphere humidity in the northern Bay of Bengal made the environment more favorable for TC intensification, enhanced vertical wind shear in the southern Bay of Bengal tended to reduce TC development. These environmental changes were associated with a strengthening of the monsoon circulation for the months of May–June, driven by a La Niña-like shift in tropical Pacific SSTs and associated tropical wave dynamics. Finally, analysis of a suite of climate models from the Coupled Model Intercomparison Project Phase 5 archive shows that most models correctly reproduce the link between ENSO and premonsoon Bay of Bengal TC activity at interannual timescales, demonstrating the robustness of our main conclusions.

URLhttp://onlinelibrary.wiley.com/doi/10.1002/2016JD024936/full
DOI10.1002/2016JD024936
Journal: Journal of Geophysical Research: Atmospheres
Year of Publication: 2016
Volume: 121
Pages: 6954-6968
Date Published: 06/2016

Analysis of Bay of Bengal tropical cyclone (TC) track data for the months of May–June during 1979–2014 reveals a meridional dipole in TC intensification: TC intensification rates increased significantly in the northern region and decreased in the southern region. The dipole is consistent with changes in the large-scale TC environment estimated using the Genesis Potential Index (GPI) for the same period. While an increase in lower troposphere cyclonic vorticity and midtroposphere humidity in the northern Bay of Bengal made the environment more favorable for TC intensification, enhanced vertical wind shear in the southern Bay of Bengal tended to reduce TC development. These environmental changes were associated with a strengthening of the monsoon circulation for the months of May–June, driven by a La Niña-like shift in tropical Pacific SSTs and associated tropical wave dynamics. Finally, analysis of a suite of climate models from the Coupled Model Intercomparison Project Phase 5 archive shows that most models correctly reproduce the link between ENSO and premonsoon Bay of Bengal TC activity at interannual timescales, demonstrating the robustness of our main conclusions.

DOI: 10.1002/2016JD024936
Citation:
Balaguru, K, L Leung, and GR Foltz.  2016.  "A meridional dipole in premonsoon Bay of Bengal tropical cyclone activity induced by ENSO."  Journal of Geophysical Research: Atmospheres 121: 6954-6968.  https://doi.org/10.1002/2016JD024936.