1. A Global Tropical Cyclone Climatology: Revisiting Gray (1968, 1979)
Phil Klotzbach
Department of Atmospheric Science
Colorado State University
February 7, 2017
Co-Authors: Brian Brettschneider, Ethan Gibney, Carl Schreck, Michael Bell, William Gray (Deceased)

2. In Memory of Bill Gray (1929-2016)

3. Outline Data Occurrence of Global Tropical Cyclone (TC) Activity
Revisitation of Gray TC Genesis Parameters
ENSO’s Impacts on Global TC Activity
Summary

4. Data Sources Tropical Cyclone Data (1985-2014)
Historical best-track data from the National Hurricane Center, Central Pacific Hurricane Center, and Joint Typhoon Warning Center as archived in the International Best Track Archive for Climate Stewardship
- SST – NOAA Optimum Interpolation SST version 2
Large-scale atmosphere conditions – Climate Forecast System Reanalysis

5. Comparison between Gray (1968) and 1985-2014 Climatology

8. 15-day Running Mean Applied

9. Gray (1968)

10. Named Storm Tracks ( )

11. Hurricane Track Density (1985-2014)

15. El Niño minus La Niña Accumulated Cyclone Energy Generation (1985-2014)

16. El Niño minus La Niña

17. El Niño minus La Niña

18. El Niño minus La Niña

21. Summary
Global TC numbers have increased from pioneering genesis study of Gray (1968), primarily due to observational improvements
- No significant trend in TC number or intensity over past 30 years
Northern Hemisphere TC season much more peaked than Southern Hemisphere TC season

22. Summary (Continued)
Densest regions for hurricane activity are just east of Philippines and in eastern portion of Northeast Pacific
Gray’s original TC genesis parameters still valid
ENSO significantly impacts basinwide TC levels (El Niño increases TC activity in the Northwest Pacific, Northeast Pacific and South Pacific, while La Niña increases TC activity in the North Atlantic, North Indian Ocean and near Australia)