It feels like summer is getting hot these days. The rainy season began in Jeju Island from yesterday (10th) afternoon. Every chapter started ten days earlier than normal. Although it was not directly affected by the rainy season front line on the southern coast of Jeju Island, the Meteorological Agency said it was the beginning of the rainy season because of the continuous rain since yesterday. It rained last night in the whole country except Jeju Island, but it is not the beginning of the rainy season because the rain will not continue in the future. At the beginning of the rainy season, a major phenomenon in the summer, the Korea Meteorological Administration began to recommend the use of other terms instead of the terms used in the past. It is recommended that the expression of'congestion front' and'jangmatbi' should be expressed as'rain rain by stagnant front' instead of'rainy front'. Of course, it is not a wrong expression, but it is not a familiar expression. Why is the Korea Meteorological Administration trying to change the expressions of rainy season and rainy season that have dominated one of the summer phenomena for a long time?
● What is the rainy season?
The rainy season basically refers to the phenomenon of heavy rain for a long period of time. In the word rainy season,'jang' is the long-term Chinese word for long, and'ma' is the old Korean word for water. During the rainy season, various types of precipitation appear, such as precipitation by air pressure bones, showers, and precipitation by common rainy season fronts. Of these, the rainy season front line refers to the boundary line (congestion front line) created by the meeting of a warm and humid tropical air mass located in the south of Korea and a cold and wet large air mass in the north in summer. Riding the southwest wind on this rainy front, along the edge of the high pressure of the North Pacific, a large amount of warm, moist air flows around the front, so it rains for a long time. This is why the rainy season front cannot be left out when talking about the rainy season. (See picture below)
The Korea Meteorological Administration observes the rainy season in the central, southern, and Jejudo regions. Looking at the last 30 years, the rainy season in the central region is divided into June 25 to July 25, the southern region from June 23 to July 24, and Jeju Island from June 20 to July 20. During this period, the number of precipitation days averaged 17 days in both central, southern, and Jeju Island, and it rained a little over 50% of the rainy season. Precipitation was slightly over 400mm in the central part, and in the southern part, there was a difference between Daegu and Gwangju, but it fell about 300mm. Jeju Island recorded 305.3mm.
● The rainy season that has become a relay?
On July 28, 1998, the Korea Meteorological Administration announced the end of the long and long rainy season. However, just two days later, on July 31, a heavy rain began around the area of Jirisan and there were about 100 casualties. Not only this, the cloudy and rainy weather continued throughout the country. Looking at the one-month weather diary in Seoul in August 1998, it is more difficult to find days when it is not raining. (See the calendar below)
At the time, the Korea Meteorological Administration declared that the rainy season had ended because the rainy season was over, and that the concept of the rainy season was different from the general public. This year, the Meteorological Administration announced the start of the rainy season in Jeju on the date of yesterday, which is affected by the low pressure of China, not by the rainy season. The rainy season refers to the entire period of rain, but not the period of rain under the influence of the rainy season. In the end, it was a long time ago, but the explanation of the Meteorological Agency at that time was not fully understood. Even if it doesn't have to go far, Seoul continued to rain and stop until mid-August after the Korea Meteorological Administration announced the end of the rainy season in late July. In the opposite case, the beginning of the rainy season was declared, but in some cases it was not raining. The word made at this time is'dry rainy season'. The intuition itself is strange because it is a word that was created by the fact that there was no rain during the rainy season. If there is no rain after the rainy season or a lot of rain falls after the rainy season, the Korea Meteorological Administration has always met the people. It is impossible to accurately and quantitatively predict the start and end of the rainy season with the characteristics of climate rather than the characteristics of weather. However, the rainy season, which is an important phenomenon in the summer, is a necessary phenomenon for forecasting, so it would be a good idea to inform the Meteorological Administration of the start and end of the rainy season.
In 2009, the Korea Meteorological Administration announced that it would no longer make rainy weather forecasts in summer forecasts. The forecast will end with the start and end of the rainy season, period and precipitation, which were announced during the summer forecast in late May. At the time, the Korea Meteorological Administration said that it was difficult to predict accurately because the climate was changing. This year, 11 years later, the term “congestion front” is recommended rather than the rainy season front, and the term rainy season rather than the beginning and end of the rainy season is recommended. From the perspective of the Korea Meteorological Administration, the responsibility for the rainy season and the announcement of the rainy season are becoming less and less responsible. It is true that the climate has changed and predictions have become difficult. However, it seems difficult to completely avoid the view that such a change in the Korea Meteorological Administration is a change to avoid national criticism when the forecast is wrong.
● Why is the rainy season important?
During the 2006 rainy season (June 21-July 29), rain struck 1,068.4mm in Seoul and 949.6mm and 587.1mm in Chuncheon and Daegu, respectively. Jeju Island rained 900.4mm for 25 days during the rainy season in 1985. The average annual precipitation is about 1,200~1,400mm, so you can see how much rain fell during the rainy season. According to the Korea Electrical Safety Corporation, the rate of electric shock accidents is the highest during this period (rainy season), and according to the Insurance Association, traffic accidents are reported to be 2,900 on average a day and 4,500 casualties. In addition, during the rainy season, many casualties and property damage, such as flood damage, were counted due to heavy rain. It is natural that forecasts and rainy seasons are important.
Many factors influence the summer rainy season. China's thermal cyclones, Okhotsk high pressure, and typhoons are typical examples. When the Okhotsk Sea has a high-pressure force, cold air masses can penetrate the rainy season, causing instability and strong thunderstorms and heavy rains. Typhoons can transmit a great deal of water vapor and latent heat, create heavy rain, and even revitalize the dying rainy season. Since the rainy season itself is a system of complex elements, it is not easy to predict precipitation, duration, start and end. Weather forecasts made by the Japan Meteorological Administration are wrong because of scientific limitations. If the weather forecast of the Korea Meteorological Administration has been well suited to the current short-term forecast, the Korea Meteorological Administration has no reason not to give up on the 2009 rainy season forecast. Rather, it may be increased by more mid- and long-term forecasts. But reality is not. In addition to scientific limits, the public's jealousy is making the Meteorological Agency's work defensive, which has to include uncertainty. It seems to be part of using the more comprehensive scientific terminology, the stagnant wire, instead of the rainy season wire that has been used so far. We need to see if changes in terms such as traffic jams and the rainy season will help the forecast and people's lives in the future.
As I said, the rainy season is a climatic factor, not a weather forecast. There may be criticism, but unconditional criticism can make the Meteorological Agency crumble as it is now. We need healthy criticism that acknowledges scientific limitations rather than unconditional criticism of the Meteorological Administration. The Korea Meteorological Administration seems to need to be boldly criticized for forecasting, while explaining the scientific limitations. In the end, for good forecasting, we need to make healthy criticisms based on the more daring frontal breakthroughs of the agencies in charge of business and the understanding of the people's forecasting system.