Mean sea surface temperature changes influence ENSO-related precipitation changes in the mid-latitudes

Area of Science:

• Climate Science
• Atmospheric Science
• Oceanography

Background:

• El Niño events significantly alter precipitation patterns globally, particularly in densely populated areas.
• Predicting future El Niño-driven precipitation changes under global warming remains challenging due to a lack of scientific consensus.

Purpose of the Study:

• To investigate how different types of El Niño events influence precipitation in mid-latitude regions under future global warming scenarios.
• To clarify the role of tropical Pacific mean sea surface temperature (SST) changes in modulating El Niño's remote impacts on precipitation.

Main Methods:

• Analysis of Coupled Model Intercomparison Project (CMIP) simulations.
• Examination of the relationship between El Niño types, mean SST changes, and precipitation responses.

Main Results:

• Future precipitation changes are strongly correlated with how El Niño types respond to tropical Pacific mean SST shifts.
• A La Niña-like mean SST change amplifies basin-wide El Niño, increasing East Asian and North American precipitation by ~20% through enhanced moisture transport.
• An El Niño-like mean SST change favors more frequent eastern Pacific El Niño events, boosting precipitation in North America.

Conclusions:

• The projection of mean SST is critical for determining the specific type of El Niño event and its subsequent impact on remote precipitation.
• This study underscores the nuanced influence of El Niño on precipitation, emphasizing the need to consider SST dynamics for accurate climate change impact assessments.