On the morning of the 6th, when the lowest temperature in the morning in Seoul fell to -12 degrees Celsius, icicles are open on the trees along the riverside of Ttukseom Hangang Park in Gwangjin-gu, Seoul. The cold, brought about by the Arctic chill, is expected to continue until mid-next week. yunhap news
– It is literally an umdongseolhan (嚴冬雪寒).
Reversal phenomenon in 10-year trend
Due to the weakening of the jet stream
South to cold air mid-latitude regions
Warm winter without arctic influence
– On the morning of the 7th, the temperature in Seoul was -16.5 degrees Celsius, and in Busan-7.7 degrees Celsius.
Mount Seorak recorded -29.4 degrees Celsius below zero, and the temperature in the mountainous regions of Gangwon-do fell below -20 degrees Celsius.
The snow that fell on the 6th night froze in the strong cold, causing great inconvenience to citizens all over the country.
On the morning of the 8th, the temperature fell further, and the temperature in Seoul reached -18.6 degrees Celsius, and the temperature of the sensed temperature dropped to -25 degrees Celsius as the wind blows, causing citizens to freeze on their way to work.
South Seogwipo Island fell 3.4 degrees below zero this morning, and the whole country fell below zero.
The Meteorological Agency predicted that the cold would ease around the 13th, next Wednesday, but the cold winter weather is expected to continue for the time being.
When the temperature drops suddenly like this, citizens may wonder, “Why is the winter getting colder?”
Is it true that winter has become cold, and if so, why?
It has gotten colder in the last 10 winters.
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On the morning of the 7th, citizens wearing thick clothes are coming to work near Gwanghwamun Station in Jongno-gu, Seoul. yunhap news
– January is the coldest month of the year, the coldest month (最寒月).
By looking at the temperature distribution during this period, you can see how severe the cold is.
Meteorological Agency data show that the last 10 years (2011-2020) have become colder than the past when looking at the change in the average temperature in January in Seoul.
The average temperature in January in Seoul from 2011 to 2020 was 2.3 degrees below zero.
It was lower than -2.2 degrees in 1971-1980, -1.7 degrees in 1991-2000, and 1.8 degrees below -zero in 2001-2010.
– – The average of the lowest temperature in January in Seoul was also -6 degrees from 2011 to 2020, lower than -5.7 degrees from 1971 to 1980, 5.3 degrees from 1991 to 2000, and 5.2 degrees from 2001 to 2010.
From 1981 to 1990, the average or minimum temperature in January temporarily dropped, but overall, the temperature in January in Seoul has continued to rise since the 1970s, and the temperature has dropped again in the last 10 years.
But in January of last year, a completely different situation took place.
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On the afternoon of January 10 last year, after the warm winter weather, wild flowers are bursting on the roadside in Gangneung City, Gangwon-do. yunhap news
– The average temperature in Seoul was 1.6 degrees Celsius, and the lowest temperature average was -1.7 degrees Celsius, which was the warmest January since weather observations started in Seoul.
What else might this be?
When the jet stream weakens, the arctic cold comes down
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On the morning of the 7th, when the Arctic cold wave of -20 degrees Celsius hits, a snow removal vehicle is servicing a frozen road in Euljiro, Seoul. This strong cold, which was caused by the cold air near Siberia, is expected to continue until mid-next week. News 1
– Experts explain that the winter on the Korean Peninsula is getting colder amid warming because of the’warming paradox’.
“As global warming continues, the temperature of the Arctic rises, and the jet stream that blocks the cold air is weakening, and the cold air of the Arctic is pouring down to the south to the mid-latitude region in winter,” said Kim Ki-han of the Meteorological Administration.
Jet streams are called polar vortex, which traps the cold air in the polar regions.
When the jet stream flows at a high speed, it serves to trap the coolness of the Arctic, which slows down the jet stream and leads to a serpentine meandering.
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Arctic warming and the meandering of jet streams
– In Europe, East Asia, and North America, cold weather alternately occurs depending on where the jet stream is in the south in the northern hemisphere.
Conversely, if you enter an area where the jet stream does not droop, a warm winter like the Korean peninsula can appear like last January.
Meteorological Office Yoon Informer explained, “This cold is because the jet stream droops to the south of the Korean Peninsula, and cold air of -50 degrees Celsius descends to the north of the Korean Peninsula.”
The slowing down of the jet stream is due to Arctic Oscillation.
Arctic vibration is a phenomenon in which the air pressure difference between the North Pole and the mid-latitude increases and decreases periodically.
When the air pressure difference between the North Pole and the mid-latitude region decreases, the Arctic vibration index is displayed as negative (-), and when the air pressure difference increases, the Arctic vibration index is displayed as positive (+).
– – As the arctic temperature rises, the arctic high pressure decreases, and the difference in air pressure between the arctic and mid-latitude regions decreases.
As the temperature or pressure difference decreases, the jet stream orbiting the North Pole weakens.
High correlation between the Arctic vibration index and the cold in January
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On the morning of the 7th, when the Arctic cold wave of -20 degrees Celsius hits, heating steam is rising from the downtown building viewed from Inwangsan Mountain, Jongno-gu, Seoul. This strong cold, which was caused by the cold air near Siberia, is expected to continue until mid-next week. News 1
– It is shown that the average value of the minimum temperature in January in Seoul by year is highly related to the Arctic Vibration Index.
As a result of comparing the average value of the Arctic Vibration Index for each year since 1960 provided by the National Oceanic and Atmospheric Administration (NOAA) in January and the average of the lowest temperature in Seoul in January by the Meteorological Administration, when the Arctic Vibration Index in January is negative (-), The minimum temperature in January was lowered, and when the index was positive (+), the minimum temperature tended to rise.
– – Even this winter, since last month, the Arctic vibration index has been showing a strong negative number.
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The trend of changes in the Arctic Vibration Index (AO Index) since last fall. Since December of last year, the Arctic Vibration Index has been negative, especially since the end of last year. Source: US Oceanic and Atmospheric Administration
– Professor Baek-min Kim of the Department of Environmental and Atmospheric Science at Pukyong National University said, “In the summer season, the effect of global warming is clear, such as intensifying heatwaves, but in winter, the warming signal has a complex pattern.” The minimum temperature does not rise and shows a tendency to stagnate.”
As temperatures in the Arctic rose due to warming, the’walls’ that blocked the cold air of the Arctic collapsed, and this made winter in the mid-latitude region colder.
Professor Kim pointed out that “from 2040 to 50, when the ice in the Arctic Ocean in summer is expected to disappear completely, during the next 20 to 30 years, the temperature fluctuations in the mid-latitude regions in winter will increase, and very cold winters and warm winters may alternate.”
In fact, warm winters like last January and severe colds like this one can appear irregularly.
On the other hand, sea ice covering the Arctic Ocean last summer decreased significantly compared to previous years, recording the second smallest area ever.
According to the National Ice and Snow Data Center of the United States, as of September 15, the area of Arctic sea ice has decreased to 3.7 million km2.
This is the second smallest size since 2012 when sea ice observation began with satellites in 1979. In 2012, when the Arctic sea ice was at its smallest, the area was about 3.4 million km2.
As Arctic temperatures rise, the ice that reflects sunlight melts, and as the sea ice melts, the area of the sea exposed to sunlight increases, and as the sea absorbs more sunlight, the seawater temperature rises, and the vicious circle of sea ice melting again begins. have.
Still, winter is getting warmer
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On the morning of January 7, last year, when the daytime minimum temperature was 18.5 degrees Celsius and the warm weather reminiscent of spring, azaleas bloom on the Jeju National University campus. yunhap news
– In the long term, winter is getting warmer.
In the 30 years between 1908 and 1930, the average of the lowest temperature in January in Seoul was -9.4 degrees, and between 1931 and 1960, the average temperature was -9.3 degrees.
However, it rose to -7.1 degrees from 1961 to 1990 and -5.5 degrees from 1991 to 2020.
The average temperature in January in Seoul was -4.5 degrees from 1908 to 1930 and -4.7 degrees from 1931 to 1960, but increased to -3.1 degrees from 1961 to 1990 and -1.97 degrees from 1991 to 2020.
The biggest feature is that even in Seoul in the first half of the 20th century, there were not a few cases where temperatures were below -20 degrees Celsius, but the temperature has never dropped below -20 degrees in Seoul since it reached -20.2 degrees on January 5, 1970.
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A graph showing the minimum temperature in Seoul every year since 1908. Overall, the year-round minimum temperature is on the rise, and after 1980, the case of the year-round minimum temperature dropping below -20 degrees has completely disappeared.
– This is because global warming and urban heat island phenomenon overlapped.
The urban heat island phenomenon refers to a phenomenon in which the temperature in the center of the city becomes higher than the outside due to the heat generated by the use of energy in factories, buildings, and automobiles.
The lowest temperature measured in Seoul was 23.1 degrees below zero on December 31, 1927.
Reporter Kang Chansu [email protected]
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