Change in Tropical Cyclone Efficiency Under Different ENSO Conditions in the Western North Pacific Ocean
Journal
Geophysical Research Letters
Journal Volume
53
Journal Issue
2
ISSN
0094-8276
1944-8007
Date Issued
2026-01-14
Author(s)
Abstract
Tropical cyclones (TCs) can be considered as Carnot heat engines, where thermodynamic efficiency depends on the sea surface temperature (SST) and TC outflow temperature (To) in the upper atmosphere. This study investigates how TC efficiency in the western North Pacific (WNP) Ocean varies under different El Niño-Southern Oscillation (ENSO) conditions: the Eastern Pacific (EP), the Central Pacific (CP), and the Mixed El Niño types, as well as La Niña. We also explore how these changes affect a TC's theoretical upper bound (potential intensity (PI)). Using a reanalysis data set from 1979 to 2024, we find that TC efficiency decreases during La Niña, due to warmer To, and increases during CP El Niño, where upper-level cooling dominates. EP and Mixed El Niño show more heterogeneous responses. These efficiency changes contribute to PI variability from −38 to +27%, depending on ENSO type and region.
Subjects
Pacific Ocean
Pacific Ocean (Central)
Pacific Ocean (North)
Atmospheric pressure
Atmospheric temperature
Atmospheric thermodynamics
Climatology
Heat engines
Hurricanes
Oceanography
Surface waters
Tropical cyclone
Tropical engineering
Tropics
Upper atmosphere
Carnot heat engines
Condition
Eastern pacific
EL Nino
El Nino southern oscillation
La nina
North Pacific Ocean
Thermodynamic efficiency
Western North Pacific
cooling
data set
El Nino
El Nino-Southern Oscillation
La Nina
outflow
sea surface temperature
tropical cyclone
Efficiency
Publisher
American Geophysical Union (AGU)
Type
journal article