The Influence of the Madden-Julian Oscillation on Tropical Cyclone Activity in the Fiji Region
Savin S Chand, Kevin JE Walsh
JOURNAL OF CLIMATE | AMER METEOROLOGICAL SOC | Published : 2010
This study examines the modulation of tropical cyclone (TC) activity by the Madden-Julian oscillation (MJO) in the Fiji, Samoa, and Tonga regions (FST region), using Joint Typhoon Warning Center best-track cyclone data and the MJO index developed by Wheeler and Hendon. Results suggest strong MJO-TC relationships in the FST region. The TC genesis patterns are significantly altered over the FST region with approximately 5 times more cyclones forming in the active phase than in the inactive phase of the MJO. This modulation is further strengthened during El Niño periods. The large-scale environmental conditions (i.e., low-level relative vorticity, upper-level divergence, and vertical wind shear..View full abstract
The best-track tropical cyclone data were obtained from the Joint Typhoon Warning Center Web site at http://www.usno.navy.mil/NOOC/nmfc-ph/RSS/jtwc/best_tracks/. The NCEP-NCAR reanalysis products were also obtained online from the NOAA Web site (http://www.cdc.noaa.gov). The authors are thankful to Dr. Matthew Wheeler for providing the MJO indices for the period extending back to 1969 (obtained online from the Web site at http:// www.bom.gov.au/bmrc/clfor/cfstaff/matw/maproom/RMM/RMMestimates.69toRealtime.txt). We also thank Professor David Karoly for his advice. We appreciate constructive comments by Professor Neville Nicholls and the other two anonymous reviewers. Finally, I acknowledge the Australian government-sponsored Endeavour Postgraduate Award under which I am doing my doctorate degree at the University of Melbourne.