How Do El Niño and La Niña Affect Typhoons? Decoding the Patterns of Typhoon Seasons
During El Niño years, typhoons form further east, are more intense, and Fujiwhara effects are more common; during La Niña years, formation shifts westward, leading to more landfalls in China. An analysis of the relationship between ENSO and the typhoon season.
What is ENSO?
ENSO (El Niño-Southern Oscillation) is a periodic oscillation of sea surface temperatures in the central and eastern equatorial Pacific Ocean: anomalously warm conditions constitute El Niño, while anomalously cold conditions constitute La Niña, with a typical cycle of 2–7 years. It is the most significant climatic background influencing the "character" of a typhoon year.
Typhoon Characteristics During El Niño Years
- Formation locations shift east and south: Warm water moves eastward, causing more typhoons to "be born" in the open ocean east of Guam.
- Longer over-water tracks → Greater intensity: Formation in the open ocean allows for a longer energy-gathering journey, resulting in a significantly higher proportion of super typhoons.
- Fewer total landfalls in China: With formation occurring further east, typhoons are more likely to recurve toward Japan and South Korea.
- Increased probability of the Fujiwhara effect (binary typhoons): The coexistence of multiple typhoons in the open ocean becomes more common.
Typhoon Characteristics During La Niña Years
- Formation locations shift west: There is an increased proportion of "local typhoons" forming in the South China Sea and nearshore areas east of the Philippines.
- Short development time and narrow warning window: Proximity to land means it may take only two or three days from formation to landfall.
- Higher proportion of landfalls in China: A stronger and westward-extending subtropical high guides typhoons on westward tracks toward South China.
- High risk of autumn typhoons interacting with cold air, leading to more severe rainstorm disasters.
Classic Case Studies
| Year | Background | Typhoon Season Characteristics |
|---|---|---|
| 1997 | Super El Niño | 10 super typhoons occurred throughout the year, with formation points significantly shifted eastward |
| 2018 | Developing El Niño | Frequent occurrence of open-ocean super typhoons such as Mangkhut |
| 2020 | La Niña | Rare "typhoon vacuum" in the Western Pacific in July, followed by a cluster of typhoons making landfall in China in August |
| 2021 | La Niña | Typhoons such as In-Fa moved westward to make landfall in East China, causing extreme rainstorms |
How to Prepare for the Typhoon Season Using ENSO Insights?
ENSO provides only a probabilistic background, not a definitive verdict: strong typhoons can still make landfall in China during El Niño years, and open-ocean "typhoon kings" can emerge during La Niña years. The correct approach is—during El Niño years, pay close attention to the impact of recurring paths of open-ocean super typhoons on shipping and island tourism; during La Niña years, stay alert for rapid nearshore formation and consecutive typhoon landfalls.