교과서 밖으로 나온 장마, 기상학의 새로운 패러다임을 맞이하다 > K-wave Trends

The biggest change in this redefinition is that the 'Okhotsk Sea high pressure', which was the core mechanism of the existing rainy season, was completely deleted from the concept. The meteorological community concluded that the very existence of the Sea of ​​Okhotsk high pressure is scientifically unclear and is no longer valid in modern meteorological analysis to explain the cause of the rainy season. In the past, textbooks taught that the cold and humid Sea of ​​Okhotsk air mass collided with the hot and humid North Pacific air mass to form a stagnation front, but the actual atmospheric flow is much more complex and dynamic than this. This academic decision can be interpreted as a determination to reflect the latest meteorological data and observation technology rather than resting on past knowledge. Now, in our educational field, it is expected that the old explanations that relied on unrealistic high pressure will gradually disappear, and more scientific and empirical meteorology education will be provided.

The definition of the rainy season has now been expanded beyond the narrow framework of 'stagnant front' to the comprehensive period concept of 'rainy season'. The newly defined rainy season refers to the entire period in which favorable conditions for precipitation are formed between the warm and humid air mass in the south and the cold air mass in the north as the North Pacific high pressure moves north. This means that even if there are days with no rain or little precipitation during the rainy season, if the atmospheric environment meets the conditions for the rainy season, it is included in the category of the rainy season. While the existing concept of the rainy season focused on 'continuous precipitation phenomenon', it now aims to increase the accuracy of weather forecasts and the efficiency of social communication by focusing on 'atmospheric conditions in which precipitation can occur'.

The causes of precipitation are also much more diverse and not limited to stagnant fronts. Modern summer precipitation is caused by various meteorological mechanisms, such as mid-latitude cyclones and convective precipitation as well as stagnant fronts, and this definition embraces all of these complex aspects. However, precipitation caused by typhoons was clearly excluded from the category of the rainy season, making the meteorological difference between the rainy season and typhoons clear. Regarding the opinion raised by some to 'replace the rainy season with the rainy season', the Korean Meteorological Society drew a line by stating that it was premature due to academic and social confusion. This can be read as a cautious strategy by the Korean meteorological community to maintain the unique value of the term ‘rainy season’ while filling it with substance in line with modern climate change.

Meanwhile, looking at the real-time weather situation, the cold air at the upper level of the Korean Peninsula effectively blocks the expansion of hot high pressure in early June, and the heat takes a breather for a while. As of the 7th, the cold pressure trough of -22 degrees Celsius at 5.6km in the sky blocked the northward movement of the subtropical high pressure near Japan, resulting in slightly cooler weather than usual. However, as the weekend passes, temperatures will gradually rise, and the typical heat of early summer is expected to return, with daytime temperatures rising to around 30 degrees, especially in the southern region. In such a changeable weather environment, there is a high risk of swell waves occurring on the coast, so the Korea Meteorological Administration strongly urges people to refrain from approaching the seashore rocks or breakwaters.

This redefinition of rainy season terminology goes beyond simply replacing academic words, and shows the meteorological authorities' efforts to communicate more accurately with citizens in the era of climate crisis. This is because it contains the will to scientifically resolve the 'dry rainy season' controversy that recurs every rainy season and the public's doubts about the cause of precipitation. Experts believe that this change will greatly contribute to improving public awareness of the rainy season and increasing the utilization of weather information. Meteorology must constantly evolve in a changing climate environment, and this change in definition is the first step in that evolution. The summer we will face in the future will be much more complex and dynamic than past textbook knowledge, so understanding the new definition is essential.