"If the Arctic Cools Further, Pacific Winds Blow Stronger," New Study Reveals Atmospheric and Oceanic Cooling Effects

UNIST Lecturer Professor Lee and University of Hawaii, US, Identify Impact of Polar Climate Change on Tropical Regions
'Polar Cooling Strengthens Tropical Pacific Trade Winds' ... Science Advances November 20 Issue

A research illustration showing the impact of polar cooling on tropical oceans.

[Asia Economy Yeongnam Reporting Headquarters Reporter Kim Yong-woo] How do temperatures in the Antarctic and Arctic affect the winds of the Pacific Ocean?

A study has found that making the cold polar regions even colder strengthens the wind intensity in the distant tropical Pacific.

A joint research team from Korea and the U.S. revealed this fact by applying climate simulations that induce cooling effects in the polar regions.

The research team led by Assistant Professor Kang Sa-ra from the Department of Urban Environmental Engineering at Ulsan National Institute of Science and Technology (UNIST, President Lee Yong-hoon) confirmed through climate model simulations that reducing solar radiation in the Antarctic and Arctic causes a cooling effect that strengthens the tropical Pacific trade winds, which blow near the equator in the Pacific Ocean.

This study is gaining attention as a new hypothesis explaining the recent trend of strengthening tropical Pacific trade winds.

Previous climate models predicted a weakening of the tropical Pacific trade winds. These trade winds blow due to the temperature difference between the cold eastern Pacific, such as the waters off South America, and the warm western Pacific.

Climate models are a type of simulation that formulates complex elements such as the atmosphere, continents, oceans, and glaciers into mathematical equations and calculates them using supercomputers.

Professor Kang’s team conducted a simulation experiment using climate models to reduce the amount of sunlight in the Antarctic and Arctic.

UNIST Lecturer Professor Ra (center) and research team.

This was to reflect the effect of resolving the overestimation of Antarctic solar radiation, identified as a source of climate model errors, and the effect of decreased Arctic solar radiation caused by fine dust reflecting sunlight in the industrialized Northern Hemisphere.

As a result, the cooling effects generated in the Antarctic and Arctic were transmitted to the tropical Pacific via seawater and air, strengthening the trade winds.

The research team also found that ocean circulation plays a greater role than atmospheric circulation in strengthening the tropical Pacific trade winds.

To do this, they used a “hierarchical model experiment technique,” which involves adding or removing components such as the atmosphere or ocean in the climate model to assess the importance of each element.

Professor Malte Stuecker of the University of Hawaii in the U.S. explained, “Using the hierarchical model experiment technique devised in this study, we can not only understand the relative influence of the atmosphere and ocean on tropical climate but also comprehend the differences in the pathways through which cooling phenomena originating in the Antarctic and Arctic are transmitted to tropical regions.”

Researcher Shin Ye-cheol from UNIST’s Department of Urban Environmental Science, who participated in the study, said, “The propagation of Arctic cooling effects through the atmosphere is blocked by the Intertropical Convergence Zone (tropical rain belt) located just north of the equator in the Northern Hemisphere. We found that the presence of cold seawater rising in the eastern Pacific is necessary for the Arctic cooling effect to influence tropical climate.”

Professor Kang Sa-ra pointed out, “This study is an important outcome showing that improving simulation errors in high-latitude regions can reduce errors in tropical regions, where prediction errors are frequent.”

Professor in the Department of Urban Environmental Engineering, UNIST instructor.

Professor Kang said, “The hierarchical model experiment technique devised in this research can be used for additional analysis of ‘bidirectional remote correlations’ between tropical and high-latitude regions in future climate predictions or interpretations of ancient climates.”

The influence of polar climate change on the tropics began to be recognized from the early 2000s when ancient climates were reconstructed, unlike the influence of tropical climates on the polar regions.

This study was published online on November 20 in the international academic journal Science Advances. The research was supported by the Korea Research Foundation’s Women Scientists and Research Exchange Support Program.

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