We thought spring and autumn were transitional periods, a process of change between periods of great season change. Because air masses that greatly affect the Korean Peninsula change during the transition period, especially in the case of late spring or early autumn, the temperature difference between Seonbong and Seogwipo regions will be huge due to the movement of the Siberian air mass. Especially in autumn, as winter approaches, We thought the temperature would fall from Seonbong, which is relatively north due to the expansion of the Siberian air mass. Therefore, we thought that the temperature difference between the two regions would be huge as the temperature drops faster than Seogwipo where the Siberian air mass does not affect. However, high pressure, which affects spring and fall on the entire Korean Peninsula, was not the Siberian and North Pacific air masses, which we know of. The survey found that the shorter periodic effects of migratory anticyclone that had modified or separated from these large masses were greater. the survey was conducted on spring and fall mobility high pressure, which has a common effect on the total Korean Peninsula(North, Seonbong and South, Seogwipo).
Migratory [travelling] anticyclone
: High pressure that moves continuously without the central position being stagnant
Most of the high pressure is stationary anticyclone with little movement of the center. But, the high pressure developed as a thermal cause is often separated from the center when heated at the edge. Because the center moves rapidly, this case is called Migratory [travelling] anticyclone.
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It is small because it is separated from the stationary anticyclone formed by thermal causes.
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It usually moves about 40 to 50km/h from west to east.
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Wind speed is less than 5 to 6m/s.
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It is oval, and its long axis is 1,000 to 3,000 km.
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An important influence on the climate of spring and autumn in Korea.
Unlike the North Pacific air mass that is structurally developed by atmospheric circulation, the Siberian air mass develops as the air in the Siberian region cools and becomes relatively heavy due to winter surface cooling. As the Siberian air mass is a base formed by the cooling of the air, it expands and contracts according to season and weather. The cold, dry air in Siberia continues to expand its power to lower latitudes, extending it to areas no longer cold and dry. When such cold, dry air reaches a relatively warm area, the properties of air change, which we call the degeneration of the Siberian air mass, or migratory anticyclone.
Siberia is heated to a certain extent when the degenerated Siberian air mass, migratory anticyclone, affects Korea in spring and autumn. Therefore, the power is weak compared to the midwinter and the temperature varies depending on the wind direction. When the north wind blows, relatively winterlike weather and southern wind blows, summerlike weather appears.
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In spring and autumn, extratropical cyclone goes east often together, there is a low pressure between the preceding and subsequent high pressure, and they move in response to the east wind of the western wave, so if they pass, there will be three to four days of periodic change in weather.
Spring
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Migratory anticyclone is located east to west near Korea. (East-West high pressure belt)
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It is affected by migratory anticyclone developed in the Yangtze-river air mass.
(Today the Yangtze-river air mass is considered unsuitable as the origin of the air mass. It is because the Yangtze River basin is located in the mid-latitude area, so that the air flows quickly and does not have homogeneous surface characteristics.)
*Air mass: this refers to a homogeneous air parcel of a certain size, and a certain amount of air that generally appears in the synoptic scale(typically at least 1,000km in horizontal direction and 3~10km in a vertical direction). In order for the air mass to form, the characteristics of the origin are homogeneous, the air at the origin must be stable and above a certain size.
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Length: 1000~1500km
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Migratory anticyclone, which appears in spring, is the high pressure belt that is sometimes seen in autumn.
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Trough of low pressure passes south and north of the Korean Peninsula, and the movement speed of high pressure is slow. Therefore, it has the characteristic of the relatively continuous long-term clear weather.
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If the amplitude of the upper air flow is greatly developed north and south, the Siberian air mass will be directly extended to the Korean Peninsula. As the atmospheric pressure is deployed like winter, the cold weather suddenly continues, which is called the "the last cold snap".
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Siberian air mass is weakened, the low pressure developed on Chinese Huanan and the East China sea affects the Korean Peninsula. Also, there are frequent warm front type fogs that are highly sustainable with weak rainfall.
Daily temperature during Mar~May in Seonbong
Daily temperature during Mar-May in Seonbong
Daily temperature during Mar-May in Seogwipo
We identified the change trend by drawing a deviation graph of the average value of the set period for each year. This allowed both regions to see the form of temperature changes with longer cycles in the spring than in the autumn. In general, similar temperature is maintained over a period of time is a part of this year. Deviation values than in the autumn shows not much of a wave of change.
Daily temperature during Mar-May in Seogwipo
20040426 12UTC
Seogwipo : the front of upper trough
It is located close to the center of the low pressure system(extratropical cyclone), which is tilted from the upper trough, and a migratory anticyclone is approaching behind the low pressure. The current weather in Seogwipo is raining under the influence of the cold front of extratropical cyclone, but as high pressure approaches, the weather will gradually clear up. The west wind is blowing by the cyclone.
Seonbong : the front of upper trough
(estimate) The center of the high pressure presumed to be the migratory anticyclone is located behind the Seonbong. Since it has yet to pass Seonbong, cloudy weather is estimated in Seonbong, located in front of trough.
20040427 12UTC
Seogwipo : the back of upper trough
The extratropical cyclone, which is caused by tilting from the upper trough, is passing, and the migratory anticyclone is approaching. The weather is getting better and better as the rain stops, and we can see that clouds are shrinking to 6/8. The north wind is blowing, so the temperature is relatively low (temperature is lower than in the high latitudes of the Korean Peninsula and continental China).
Seonbong : the front of upper trough
(estimate) Although the center of high pressure, which was assumed to be migratory anticyclone, does not exist in the weather map, it is assumed that the cloud conditions in Sinuiju, located at the back of Seonbong, were full of 8/8, but now there are no clouds 24 hours later, and that the migratory anticyclone may have passed through Sinuiju. However, Vladivostok, located in front of Seonbong, is still full of clouds after 24 hours. Therefore, since migratory anticyclone is estimated to be near Seonbong, it will have clearer weather than it was 24 hours ago.
20040428 00UTC
Seogwipo : the back of upper trough
The center of the migratory anticyclone is located close to Seogwipo. We can see the clear sky without clouds. The northern wind is blowing, and the temperature is relatively lower than that in the surrounding area(lower than temperature in the continental China where latitude is high).
Seonbong : the back of upper trough
(estimate) Since air pressure is higher than before, it is expected to have relatively more clear weather.
Autumn
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Cold high pressure(mainly the Siberian air mass) developed in the Continent of high-altitude areas slowly moves southward. The cold, dry air that originally had heated up and changed into a mild, rather dry air mass and moved to the Korean Peninsula.
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The weather is nice, but the wind dis weak and the humidity is higher than the Siberian high pressure. So it is easy to become unstable and the visibility is somewhat worse.
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The movement of the air pressure system is generally smooth as the upper air flow is still weak despite the development of the Siberian air mass. Also, the temperature rises significantly by the time a high pressure separated from the Siberian air mass passes near the Korean Peninsula.
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As the center of the migratory anticyclone moves eastward in Korea and the pressure trough follows it, the weather worsens relatively quickly.
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Therefore, the weather changes periodically when Korea is under the influence of migratory anticyclone.
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The Siberian air mass is extended to Chinese Huanan, and the modified air mass in Huanan is associated with the ridge that follows the upper air pressure trough. Therefore, when moving to the Korean Peninsula, it forms East-West high pressure belt, bringing about continuous clear weather. This is called the season of “high sky and plump horses”.
Daily temperature during Sep~Nov in Seonbong
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Daily temperature during Sep~Nov in Seonbong
Daily temperature during Sep~Nov in Seogwipo
Daily temperature during Sep~Nov in Seogwipo
We identified the change trend by drawing a deviation graph of the average value of the set period for each year. This allowed both regions to see the form of temperature changes in autumn, with a period of three to seven days, even if it is longer. Due to the rapid movement of migratory anticyclone, the wave appears repeatedly accordingly, showing a tendency to gradually cool down in November. This allowed us to see the weather in autumn, which is affected by the migratory anticyclone.
Although we wanted to analyze the weather map for September, the early autumn, there is a rain zone near Seogwipo, which is relatively located in the south, presumed to be a rainy season from September to early October. On the website of the Korea Meteorological Administration, the section drawn with green lines was recorded separately in the weather chart because it is assumed to be a rainy season. If this is a rainy season, high pressure in the Seogwipo area was not considered migratory cyclone because it is the North Pacific high pressure. So we chose the data in November without assuming rainy season mark.
20041105 00UTC
Seogwipo : the front of upper trough
It is located between the cold front and the warm front of low-pressure(extratropical cyclone) which is a little tilted from upper trough. Southern wind is blowing, Therefore, the weather is clear with few clouds, and the temperature is relatively high.
Seonbong : the front of upper trough
(estimate) It is located just outside the isobar of center of the low pressure, so we can say Seonbong is relatively located in the low pressure zone. When referring to the Weather symbol in the surrounding area, there will be cloudy weather covered with clouds.
20041105 12UTC
Seogwipo : the front of upper trough
The upper trough and the center of surface extratropical cyclone is judged to be tilted a lot. Despite its location on the back of the trough, Seogwipo is still located in front of the cold front of the extratropical cyclone. However, since it is located closer to the cold front than 12 hours ago, it has relatively cloudy weather.
Seonbong : the back of upper trough
(estimate) Located at the center of the ground surface extratropical cyclone. Therefore, there is a high probability of rain in the sky completely covered with clouds. The wind will blow in the direction of blowing into the center of the low pressure.
20041106 00UTC
Seogwipo : the back of upper trough
Although Seogwipo is away from the extratropical cyclone, the weather is not clear yet, not long after the extratropical has passed. The sky is overcast with clouds. The wind is blowing in the north-west wind
Seonbong : the back of upper trough
(estimate) Located on the back of the cold front at the surface extratropical cyclone. It's been a while since the center of the low pressure passed Seonbong area. Therefore, it is assumed that it will not be located in the precipitation zone. It is possible to assume that the sky is full of clouds through the weather symbols of the surrounding area.