How does El Nino-Southern Oscillation affect tropical cyclone activity around the globe ?
El Nino/Southern Oscillation (ENSO) – During El Nino events (ENSO warm phase), tropospheric vertical shear is increased inhibiting tropical cyclone genesis and intensification, primarily by causing the 200 mb (12 km or 8 mi) westerly winds to be stronger (Gray 1984). La Nina events (ENSO cold phase) enhances activity. Recently, Tang and Neelin (2004) also identified that changes to the moist static stability can also contribute toward hurricane changes due to ENSO, with a drier, more stable environment present during El Nino events. Reference: Tang, B. H., and J. D. Neelin, 2004: ENSO Influence on Atlantic hurricanes via tropospheric warming. Geophys. Res. Lett.: Vol 31, L24204. ” The Australian/Southwest Pacific shows a pronounced shift back and forth of tropical cyclone activity with fewer tropical cyclones between 145° and 165°E and more from 165°E eastward across the South Pacific during El Nino (warm ENSO) events. There is also a smaller tendency to have the tropical cyclones orig
The effect of El Nino-Southern Oscillation (ENSO) on Atlantic tropical cyclones is described in subject F2). The Australian/Southwest Pacific shows a pronounced shift back and forth of tropical cyclone activity with fewer tropical cyclones between 145 and 165E and more from 165E eastward across the South Pacific during El Nino (warm ENSO) events. There is also a smaller tendency to have the tropical cyclones originate a bit closer to the equator. The opposite would be true in La Nina (cold ENSO) events. See papers by Nicholls (1979), Revell and Goulter (1986), Dong (1988), and Nicholls (1992). The western portion of the Northeast Pacific basin (140W to the dateline) has been suggested to experience more tropical cyclone genesis during the El Nino year and more tropical cyclones tracking into the sub-region in the year following an El Nino (Schroeder and Yu 1995), but this has not been completely documented yet. The Northwest Pacific basin, similar to the Australian/Southwest Pacific ba
