Different controls of tropical cyclone activity in the Eastern Pacific for two types of El Nino
Journal
Geophysical Research Letters
Journal Volume
43
Journal Issue
4
Pages
1679--1686
Date Issued
2016
Author(s)
Abstract
The El Niño-Southern Oscillation (ENSO) is known to have different modes of expression, characterized by different dynamics and spatial anomalies patterns: the Eastern Pacific (EP) and Central Pacific (CP) El Niño. The main region of influence of the former is located in the Eastern Pacific, while CP events have a stronger signature of ocean/climate anomalies in the Central West Pacific. This leads to distinctive oceanic and atmospheric signatures that likely have different influences on tropical cyclone (TC) activity in the Eastern Pacific, the second most active region in the world. In this study we investigate the respective role of oceanic and atmospheric conditions on TC formation and intensification in the Eastern Pacific associated with these two flavors of ENSO. We find that the oceanic control, through meridional redistribution of subsurface heat, is the main driver of TC activity during the hurricane season following EP events. In contrast, atmospheric conditions tend to be destructive to TC intensification after those events. The altered atmospheric circulation, in particular the reduction of vertical wind shear and the increase in relative humidity, tends to be more influential in controlling TC activity post CP events. However, unlike for subsurface heat, these changes in atmospheric conditions are not statistically distinct between these two ENSO flavors - although they are consistent across all atmospheric data sets tested. Overall, unlike after EP El Niño events, the hurricane season activity following a CP event is not significantly different from neutral or even La Niña years. ©2016. American Geophysical Union. All Rights Reserved.
Subjects
Eastern Pacific; El Niño types; ENSO; ocean heat content; tropical cyclone
Other Subjects
Atmospheric pressure; Climatology; Humidity control; Hurricanes; Nickel compounds; Storms; Tropics; Atmospheric circulation; Atmospheric conditions; Eastern pacific; ENSO; Ocean heat content; Region of influences; Tropical cyclone; Tropical cyclone activity; Atmospheric humidity; atmospheric circulation; climate change; El Nino-Southern Oscillation; heat budget; hurricane event; oceanic circulation; relative humidity; spatial analysis; tropical cyclone; wind shear; Pacific Ocean
Type
journal article