The Korea Institute of Ocean Science and Technology (KIOST) has identified, for the first time in the world, the mechanism by which super typhoons occur throughout the year in the Northwest Pacific Ocean, the region with the most typhoon activity. It published its findings in the world-renowned journal Nature Communications.^*

* KIOST’s Sok Kuh Kang, Sung Hun Kim, Jiyun Shin, Eun Jin Kim, Kyeong Ok Kim, Hyoun Woo Kang , et al., The North Equatorial Current and Rapid Intensification of Super Typhoons, Nature Communications, March 2024.

The Northwest Pacific Ocean is a region where typhoons are typically generated, and powerful typhoons occur there every year, having a significant impact on East Asia, including Korea. In particular, ocean climate change in this region plays an important role in understanding and predicting the nature of global climate change.

The research team analyzed the occurrence trends and marine environment characteristics of super typhoons in the Northwest Pacific Ocean, including Super Typhoon Mangkhut, which occurred in 2018 and persisted as a Category 5 typhoon for 3.5 days, the longest period in history.

According to the research results, the high ocean heat content^* of the North Equatorial Current,^** which flows between 8 and 17 degrees north latitude, and large density difference caused by the low-salinity water from the Intertropical Convergence Zone^*** are the main drivers of super typhoons.

* Ocean heat content (OHC) represents the thermal energy of a unit-width (cm2) column of water in the ocean. The height of the column represents the height from the surface of the water to a depth of 26 degrees isotherm.

** The North Equatorial Current, the dominant current in the Northwest Pacific Ocean, is 1,000 kilometers wide north-to-south and flows eastward from the west coast of the Americas toward the east coast of the Philippines, carrying warm water from the tropics to the west.

*** The Intertropical Convergence Zone is a region of clouds located in an east-west band near the equator. It is a region where hot, humid southeasterly and northeasterly trade winds meet and rise near the equator, resulting in active rain cloud formation and heavy rainfall.

When a typhoon passes over ocean waters with a temperature above 26 degrees Celsius, it can receive a lot of energy from the ocean and grow into a super typhoon if it passes over waters with high ocean heat content.

The prevailing view so far has been that the high ocean heat content of the Northwest Pacific’s warm eddies, which lie between 17 and 25 degrees north latitude, triggers the intensification of typhoons, leading to super typhoons. This study, however, identifies a new analysis and mechanism that suggest the North Equatorial Current plays an important role in super typhoon development throughout the year.

The research team also suggests that the ocean heat content of the North Equatorial Current has been increasing continuously over the past 40 years due to climate change, along with an intensification of typhoons.

In particular, last year’s Super Typhoon Mawar, which occurred in May, persisted as a Category 5 for the longest period of time in history, and the researchers used the underwater elevator robot ^(*) deployed in this research project to confirm that the typhoon’s cooling effect on the sea surface was suppressed to within 1.0℃, which is what allowed Mawar to maintain its super typhoon strength. This was used as data to verify the super typhoon intensification mechanism proposed in the paper.

* The underwater elevator robot ascends and descends between depths of 200 and 1,000 meters every three hours to 10 days to measure water temperature and salinity, among others.

This research result is significant as it shows that Korea’s ocean and typhoon research capabilities have reached a world-class level. The results of the paper and ocean observation data will be used as a basis for long-term forecasting of ocean climate change patterns and are expected to contribute to preventing damages caused by and preparing countermeasures against future marine climate disasters.

The research project, funded by the Marine and Fisheries Research and Development Project (implementing agency: Ministry of Oceans and Fisheries, specialized agency: Korea Institute of Marine Science and Technology Promotion), is the result of an international collaboration between KIOST and researchers from the National Oceanic and Atmospheric Administration (NOAA), Sorbonne University (France), National Taiwan University, University of Rhode Island (United States), University of Galway (Ireland), and European Centre for Medium-Range Weather Forecasts (ECMWF).