[In Search of LAB] Research Team Identifies the Impact of El Nino on the Korean Peninsula Climate

Research Team Led by Distinguished Professor Changhoe Heo
Department of Climate and Energy Systems Engineering, Ewha Womans University

Ewha Womans University announced on November 7 that the research team led by Distinguished Professor Changhoe Heo of the Department of Climate and Energy Systems Engineering has found that El Nino has only a minimal impact on seasonal climate changes such as temperature, typhoons, and precipitation.

(From right) Jinwon Kim, Research Professor at Ewha Womans University; Jieun Kim, Undergraduate Student; Changhoe Heo, Distinguished Professor; Seungwoo Yoo, Graduate Student at Seoul National University. Ewha Womans University

This study is the first in Korea to comprehensively analyze the actual effects of El Nino on the Korean climate based on more than 100 years of long-term climate data. It is expected to contribute to future climate forecasting and the development of strategies to respond to extreme weather events in Korea.

The research team examined the correlation between the average winter temperature anomaly in Korea and the El Nino index over a period of more than 100 years, from 1920 to 2023. They found a correlation coefficient of 0.28, which is statistically significant but limited in its ability to explain winter temperature changes. In addition, only 34% of the years in which El Nino or La Nina occurred had higher or lower temperatures than the average, indicating that it is difficult to determine Korea's winter temperatures based solely on the El Nino phenomenon.

In contrast, other climate factors such as the upper-level jet stream (-0.80), the Siberian High (-0.70), Northwest Pacific sea surface temperature (0.65), and Arctic Oscillation (0.42) showed a much stronger correlation with winter temperatures. Multiple linear regression analysis also revealed that these factors have a much greater impact than El Nino, with the Northwest Pacific sea surface temperature being the most significant factor explaining temperature changes in Korea.

Similar results were found in the analysis of summer typhoons. There was no statistically significant difference in the number of typhoons making landfall in Korea, the frequency of typhoons, or their tracks during El Nino and La Nina years. Seasonal average precipitation was also found to be more strongly influenced by the position and intensity of the upper-level jet stream and the North Pacific High than by El Nino.

Professor Heo emphasized, "There has been a tendency in the media and elsewhere to definitively identify El Nino and La Nina as the main causes of abnormal temperatures, precipitation, and typhoons in Korea, but this lacks scientific evidence. Such oversimplified explanations can reduce the accuracy of climate forecasts." He added, "The tropical Pacific is more than 10,000 km away from Korea, and its influence is only indirect. Korea is a small country where tropical and mid-latitude meteorological phenomena are intricately intertwined, making it difficult to determine the climate based on a single factor such as El Nino."

The study was conducted by Research Professor Jinwon Kim, undergraduate student Jieun Kim, and graduate student Seungwoo Yoo at Seoul National University. The results were recently published in the meteorology and atmospheric science journal, Asia-Pacific Journal of Atmospheric Sciences.