3. 1 Episode Analysis
3. 1. 1 Episode 1 (2 Nov. 2019)
Episode 1 is classified as a Stable Episode. This episode was mainly caused by the air congestion caused by low wind speeds from 10:00 am on November 2 to 12:00 pm on November 3. The color coding for all the following tables is according to the PM2.5 Korean CAI (Comprehensive air-quality index): Blue/Good (0-15), Green/Normal (16-35), Yellow/Bad (36-75), Red/Very bad (76-).
Table 1.
Hourly concentration and meteorological factors of Episode 1.
|
|
PM2.5
(μg/m3) |
Wind speed
(m/s) |
Wind
direction |
2 Nov. 2019
(39.7 μg/m3) |
4:00 |
24.9 |
1.4 |
NNE |
8:00 |
29.1 |
1.3 |
NE |
10:00 |
36.2 |
1.4 |
ENE |
15:00 |
44.8 |
1.3 |
WSW |
20:00 |
53.2 |
0.8 |
WSW |
23:00 |
54.9 |
1.5 |
WNW |
3 Nov. 2019
(32.1 μg/m3) |
3:00 |
50.2 |
0.6 |
N |
8:00 |
52.2 |
0.7 |
NW |
12:00 |
49.7 |
1.7 |
NE |
14:00 |
27.2 |
3.1 |
ENE |
18:00 |
8.2 |
4.7 |
ENE |
19:00 |
7.2 |
3.3 |
ENE |
Fig. 2.
Wind information and air pollution data near Seoul between 2-3 Nov.
According to the KMA’s regional detailed observation data (collected by the Automatic Weather System (AWS)), the pollution level increased around the eastern part of the metropolitan area during this period, so it was not affected by inflows from abroad. In addition, wind speeds were generally found to be stagnant, less than 2 m/s. A strong east wind blew after 2:00 pm on Nov. 3, ending the episode.
3. 1. 2 Episode 2 (10-11 Dec. 2019)
Episode 2 is classified as an Interference Episode. With the concentration of PM2.5 generated in Korea rising because of the stable atmosphere, an alarm-level concentration situation occurred when the inflow began.
Fig. 3.
Wind Rose during Episode 2.
There was continuous atmospheric congestion and associated high PM2.5 concentrations from December 7 to December 11 until about 1:00 pm. There were short periods of ‘normal’ concentrations but PM2.5 from abroad was introduced on Dec. 10, as can be seen by the wind direction (south-west wind). It is believed that PM2.5, which was introduced after 1:00 pm on Dec. 10, accumulated in Korea due to repeated atmospheric congestion (Fig. 4). This can also be seen from the shaded wind speed data of Table 2. The atmospheric congestion was maintained until 6:00 pm on December 11, and the episodes were resolved because there were no additional inflows from abroad.
Fig. 4.
Air Quality Prediction Model Results between 10-11 Dec.
Table 2.
Hourly concentration and meteorological factors of Episode 2.
|
|
PM2.5
(μg/m3) |
Wind speed
(m/s) |
Wind
direction |
7 Dec. 2019
(31.6 μg/m3) |
11:00 |
27.7 |
2.3 |
NE |
16:00 |
36.6 |
0.2 |
N |
19:00 |
43.4 |
1.1 |
NE |
22:00 |
47.8 |
1.5 |
NNW |
24:00 |
40.5 |
1.1 |
ENE |
8 Dec. 2019
(40.5 μg/m3) |
3:00 |
41.2 |
0.5 |
NW |
7:00 |
43.4 |
1.7 |
NNE |
12:00 |
54.9 |
1.3 |
ENE |
17:00 |
30.5 |
1 |
WNW |
21:00 |
33.2 |
1.4 |
NE |
24:00 |
37.9 |
2.1 |
ENE |
9 Dec. 2019
(45.7 μg/m3) |
3:00 |
41.3 |
2 |
ENE |
8:00 |
49.8 |
3.1 |
ENE |
14:00 |
46.0 |
3.2 |
ENE |
18:00 |
44.4 |
2.1 |
NE |
23:00 |
42.4 |
2.9 |
SSW |
10 Dec. 2019
(72.3 μg/m3) |
2:00 |
35.8 |
1.7 |
SSE |
6:00 |
36.9 |
0.5 |
NE |
10:00 |
53.3 |
1.4 |
WNW |
13:00 |
98.0 |
0.6 |
WNW |
16:00 |
108.3 |
1.2 |
SW |
21:00 |
95.0 |
1.1 |
NE |
23:00 |
90.6 |
1.6 |
NE |
11 Dec. 2019
(49.0 μg/m3) |
2:00 |
70.4 |
1 |
NNE |
5:00 |
49.3 |
3.1 |
SW |
10:00 |
118.4 |
4.3 |
W |
13:00 |
63.8 |
5.6 |
W |
16:00 |
31.0 |
4 |
WSW |
19:00 |
25.2 |
5.1 |
WNW |
3. 1. 3 Episode 3 (22-25 Dec. 2019)
Episode 3 is classified a Compound Factor Episode, as it features transitions from stable atmosphere - inflow - stable atmosphere.
From 9:00 am on December 22 to 6:00 am on December 23, air congestion continued at low wind speeds, resulting in PM2.5 accumulation (Fig. 5). From 9:00 am on the 23rd, the concentration of PM2.5 reduced slightly because of strong wind speed, but the inflow of high-concentration PM occurred owing to the flow of northwest winds. This is also confirmed by the wind speed data shaded in Table 3. After that, atmospheric congestion occurred again by the 25th, and domestic PM2.5 began to accumulate. The re-formed atmospheric congestion lasted until December 25th, with a high concentration of PM2.5 being maintained (Fig. 7). The cause of high PM2.5 concentration within the period changed twice within a continuing episode, so the episode was defined as a compound factor type.
Fig. 5.
Air Quality Prediction Model Results during 22-23 Dec.
Fig. 6.
Air Quality Prediction Model Results during 23 Dec.
Table 3.
Hourly concentration and meteorological factors of Episode 3.
|
|
PM2.5
(μg/m3) |
Wind speed
(m/s) |
Wind
direction |
22 Dec. 2019
(44.1 μg/m3) |
4:00 |
35.6 |
1.9 |
ENE |
9:00 |
41.3 |
1.8 |
NE |
14:00 |
43.8 |
2.2 |
ENE |
19:00 |
51.2 |
1.9 |
SSE |
23:00 |
49.6 |
0 |
- |
23 Dec. 2019
(40.1 μg/m3) |
4:00 |
36.8 |
1.1 |
NE |
9:00 |
41.0 |
3.4 |
NNW |
12:00 |
44.2 |
3.5 |
WNW |
16:00 |
36.7 |
2.4 |
N |
20:00 |
37.4 |
1.7 |
NW |
24:00 |
50.6 |
1.6 |
NW |
24 Dec. 2019
(52.1 μg/m3) |
3:00 |
53.2 |
0.9 |
NE |
8:00 |
54.5 |
1.9 |
NNE |
11:00 |
62.1 |
1.3 |
ENE |
16:00 |
49.4 |
0.6 |
NNE |
22:00 |
47.5 |
1.6 |
NE |
25 Dec. 2019
(37.3 μg/m3) |
2:00 |
45.4 |
1.3 |
E |
6:00 |
43.2 |
0 |
- |
11:00 |
48.6 |
1.5 |
ESE |
14:00 |
40.2 |
1.5 |
SSW |
15:00 |
34.0 |
1.6 |
SW |
20:00 |
23.9 |
1.3 |
WNW |
Fig. 7.
Wind Rose during the latter half of Episode 3.
3. 1. 4 Episode 4-1 (2-4 Jan. 2020)
Episode 4-1 is classified as an Accumulation Episode.
Episode 4-1 seems to have started at 11:00 am on the same day after the concentration slowly rose from 3:00 am on January 2. Furthermore, from 1:00 pm on January 2, the east wind began to change to the west wind, and the trend continued until 7:00 pm on the 2nd. However, from 8 pm, the wind speed weakened to 0.7 m/s, resulting in atmospheric stagnation, which continued until 3:00 am on January 3. Also, as can be seen from the shaded portion of Table 4, the main wind direction is northward. After that, the trend continued to rise and fall, but as the wind speed rose sharply to 4 m/s at 14:00 on the 4th (Fig. 8), the accumulated concentration was resolved, and Episode 4-1 ended.
Table 4.
Hourly concentration and meteorological factors of Episode 4.
|
|
PM2.5
(μg/m3) |
Wind speed
(m/s) |
Wind
direction |
2 Jan. 2020
(40.8 μg/m3) |
6:00 |
30.8 |
1.7 |
NE |
11:00 |
38.8 |
2 |
NE |
13:00 |
44.9 |
1.8 |
SSW |
19:00 |
47.4 |
2 |
WNW |
20:00 |
47.2 |
0.7 |
NW |
3 Jan. 2020
(45.1 μg/m3) |
3:00 |
54.0 |
1.5 |
WNW |
5:00 |
53.2 |
1.5 |
WNW |
9:00 |
53.7 |
2.2 |
WNW |
12:00 |
49.2 |
2.4 |
NW |
23:00 |
39.6 |
0.6 |
NW |
4 Jan. 2020
(37.8 μg/m3) |
4:00 |
38.4 |
1.5 |
NE |
8:00 |
40.8 |
1.1 |
ENE |
12:00 |
53.4 |
2.8 |
NNW |
14:00 |
37.7 |
4 |
NNW |
16:00 |
26.2 |
3.4 |
NNW |
Fig. 8.
Weather map on 3 Jan.
3. 1. 5 Episode 4-2 (5 Jan. 2020)
Episode 4-2 is classified as a Stable Episode.
At the time of Episode 4-2’s occurrence, the wind speed was definitely slower than before and after the episode, which can be seen through the wind speed distribution chart below. In particular, most parts of Seoul showed stronger wind speed at the end of Episode 4-2 (Fig. 10). Therefore, Episode 4-2 can be judged to have been caused by atmospheric congestion and was resolved as the wind speed increased.
Fig. 9.
Wind rose in Episode 4-2.
Fig. 10.
Wind information and air pollution data near Seoul at 6:00 am on 5 Jan.
Table 5.
Hourly concentration and meteorological factors of Episode 4-2.
|
|
PM2.5
(μg/m3) |
Wind speed
(m/s) |
Wind
direction |
5 Jan. 2020
(35.9 μg/m3) |
2:00 |
33.8 |
0.8 |
NW |
6:00 |
36.2 |
0 |
N |
9:00 |
38.3 |
0.7 |
NE |
12:00 |
45.6 |
1.1 |
ENE |
14:00 |
33.3 |
1.8 |
SW |
21:00 |
35.5 |
1.8 |
NE |
3. 1. 6 Episode 5 (9-11 Jan. 2020)
Episode 5 is classified as a Compound Factor Episode with a inflow - stable atmosphere - inflow sequence.
Episode 5 began when high concentrations of PM2.5 from China flowed in owing to the west-northwest wind. According to observations in Jung-gu, Seoul, air congestion in areas near Seoul began from 9:00 pm on Jan. 9 to 12:00 pm on Jan. 10, with the average hourly wind speed not exceeding 1.5 m/s. The low wind speeds are shaded in Table 6. From 1:00 pm on January 10th, the inflow of high concentrations from abroad began again with the west-northwest winds and continued until 7:00 pm on January 11. Since then, the wind direction did not change, but the episode ended owing to rapid wind speed enhancement (7:00 pm average: 1.4 m/s → 8:00 pm average: 4.6 m/s).
Fig. 11.
Air Quality Prediction Model Results on 8 Jan.
Fig. 12.
Wind rose for Episode 5.
Fig. 13.
Weather map on 11 Jan.
Table 6.
Hourly concentration and meteorological factors of Episode 5.
|
|
PM2.5
(μg/m3) |
Pressure
(hPa) |
Wind
speed
(m/s) |
Wind
direction |
8 Jan. 2020
(20.6 μg/m3) |
9:00 |
3.1 |
1001.3 |
1.8 |
WNW |
15:00 |
31.6 |
1005.8 |
1.9 |
W |
19:00 |
42.7 |
1009 |
4 |
W |
21:00 |
46.3 |
1011.2 |
4.9 |
W |
9 Jan. 2020
(39.3 μg/m3) |
3:00 |
40.4 |
1012.5 |
2.2 |
W |
7:00 |
44.0 |
1013.3 |
1.2 |
NW |
12:00 |
39.2 |
1013.5 |
3.3 |
NW |
17:00 |
36.4 |
1012.9 |
3.1 |
WNW |
21:00 |
36.6 |
1014.5 |
0.5 |
NW |
23:00 |
41.7 |
1014.8 |
0.6 |
NW |
10 Jan. 2020
(48.3 μg/m3) |
3:00 |
49.2 |
1015 |
0.6 |
NNE |
7:00 |
56.7 |
1014.3 |
0 |
N |
12:00 |
60.5 |
1013.2 |
0.8 |
SSW |
15:00 |
57.3 |
1011.7 |
2.9 |
W |
17:00 |
36.1 |
1011.9 |
2.8 |
WNW |
23:00 |
36.3 |
1011.8 |
1.4 |
W |
11 Jan. 2020
(39.6 μg/m3) |
1:00 |
38.3 |
1011.3 |
0.6 |
W |
5:00 |
40.8 |
1010.5 |
0.4 |
N |
10:00 |
45.7 |
1011.7 |
0.1 |
N |
20:00 |
30.7 |
1008.2 |
4.6 |
NNW |
23:00 |
39.5 |
1008.2 |
1.9 |
WNW |
12 Jan. 2020
(32.2 μg/m3) |
4:00 |
47.0 |
1006.9 |
2.1 |
WNW |
7:00 |
40.8 |
1007.1 |
1.5 |
WNW |
11:00 |
46.0 |
1008.2 |
2.3 |
NW |
14:00 |
29.2 |
1006.2 |
3.9 |
WNW |
18:00 |
20.1 |
1006.9 |
3.4 |
W |
3. 1. 7 Episode 6-1 (17-18 Jan. 2020)
Episode 6-1 is classified as a Stable Episode under the influence of high pressure system over the Korean Peninsula.
The weather map was checked from the 16th, the day before the 17th high concentration period, to check the weather pattern. The transient high pressure produced from the Siberian high pressure and the deterioration of nearby systems was evident from the 16th. Usually, during the winter, the transient high pressure from China moves toward the Korean Peninsula carrying with it China’s PM2.5, and when the transient high pressure settles down, there is very little wind which prevents the dilution of PM2.5 (Fig. 14). In this episode, the transient high pressure was located near the west coast and above the Korean Peninsula without moving into the Korean Peninsula, making it difficult to determine the presence of significant inflow from just this data. However, the gap between the isometric lines on the 17th shows that the wind is weak overall, so this should result in atmospheric congestion.
Fig. 14.
Weather map on 16/17 Jan.
Table 7.
Hourly concentration and meteorological factor of Episode 6-1.
|
|
PM2.5
(μg/m3) |
Pressure
(hPa) |
Wind
speed
(m/s) |
Wind
direction |
17 Jan. 2020
(36.5 μg/m3) |
2:00 |
31.1 |
1014.5 |
0.5 |
WNW |
5:00 |
33.8 |
1013.9 |
1.1 |
NNE |
9:00 |
39.0 |
1013.8 |
1 |
NE |
12:00 |
42.3 |
1013.3 |
0.9 |
WSW |
17:00 |
39.1 |
1011.1 |
1.8 |
WNW |
23:00 |
37.7 |
1011.5 |
0.6 |
NNE |
18 Jan. 2020
(39.8 μg/m3) |
2:00 |
38.6 |
1011.5 |
1.4 |
W |
5:00 |
47.3 |
1010.7 |
1.3 |
NE |
8:00 |
49.2 |
1011.5 |
1 |
WNW |
12:00 |
64.2 |
1011.6 |
1.5 |
WNW |
16:00 |
33.2 |
1009.6 |
3.2 |
W |
20:00 |
21.7 |
1010.5 |
2.7 |
WNW |
3. 1. 8 Episode 6-2 (19 Jan. 2020)
Episode 6-2 is classified as a Transboundary Inflow Episode due to the prevailing west wind.
Episode 6-2 was initially analyzed by checking the 1/19 wind speed distribution chart and forecast data. The wind speed data showed stronger winds from 1:00 pm on the 19th compared to the two previous days, and it was mostly westerly winds. By checking the situation of PM2.5 coming from abroad through the forecast data (Fig. 15), it was quite easy to see that Episode 6-2 was caused by a influx of high concentration PM2.5 from abroad owing to strong westerly winds.
Fig. 15.
Air Quality Prediction Model Results on 13 Jan.
Fig. 16.
Wind information and air pollution data near Seoul between 19-20 Jan.
Table 8.
Hourly concentration and meteorological factors of Episode 6-2.
|
|
PM2.5
(μg/m3) |
Pressure
(hPa) |
Wind
speed
(m/s) |
Wind
direction |
19 Jan. 2020
(46.8 μg/m3) |
5:00 |
28.7 |
1008.4 |
0.9 |
W |
11:00 |
42.2 |
1007.8 |
1.4 |
SSW |
13:00 |
70.6 |
1006.7 |
3.7 |
WNW |
14:00 |
78.5 |
1006.3 |
3.6 |
W |
15:00 |
69.2 |
1006.1 |
6 |
NW |
19:00 |
59.7 |
1008.1 |
2.7 |
W |
23:00 |
63.7 |
1009.3 |
1.7 |
WNW |
20 Jan. 2020
(29.1 μg/m3) |
1:00 |
67.5 |
1009.7 |
0.9 |
NNW |
4:00 |
38.5 |
1009.6 |
1.3 |
W |
7:00 |
33.6 |
1010.3 |
2.5 |
W |
12:00 |
21.0 |
1011.9 |
3.7 |
WSW |
3. 1. 9 Episode 7 (23-25 Jan. 2020)
Episode 7 is classified as a Compound Factor Episode with a stable atmosphere - inflow - stable atmosphere sequence.
In Episode 7, PM2.5 was accumulated in Korea because of atmospheric congestion since the morning of January 23. Afterwards, inflows from abroad were observed on the afternoon of the 23rd. Based on air quality measurements, PM2.5 concentrations in the Seoul metropolitan area and Chungcheong Bay were found to increase first (Fig. 17). On January 25, PM2.5 introduced the previous day from China accumulated in Korea, and there were high concentrations of PM2.5 in the western half of the country.
Fig. 17.
Air Quality Prediction Model Results on 24 Jan.
Fig. 18.
Wind information on 23 Jan and 25 Jan, 2020.
Table 9.
Hourly concentration and meteorological factors of Episode 7.
|
|
PM2.5
(μg/m3) |
Pressure
(hPa) |
Wind
speed
(m/s) |
Wind
direction |
23 Jan. 2020
(40.9 μg/m3) |
3:00 |
28.0 |
1012 |
1.3 |
NNE |
6:00 |
37.5 |
1012.1 |
0.9 |
NNW |
9:00 |
43.3 |
1013.6 |
0.6 |
NW |
11:00 |
47.5 |
1013.5 |
0.8 |
WSW |
18:00 |
44.0 |
1013.6 |
3.3 |
WNW |
20:00 |
37.9 |
1015.1 |
4 |
NW |
24 Jan. 2020
(50.7 μg/m3) |
0:00 |
45.8 |
1016.4 |
3.2 |
WNW |
4:00 |
45.8 |
1017.9 |
2.1 |
WNW |
14:00 |
50.8 |
1019.1 |
2.7 |
WNW |
18:00 |
55.5 |
1019.3 |
2.4 |
NW |
23:00 |
53.9 |
1020 |
0.8 |
NNW |
25 Jan. 2020
(36.5 μg/m3) |
2:00 |
53.1 |
1020 |
1.3 |
NNE |
8:00 |
46.1 |
1019.8 |
1.3 |
NNE |
11:00 |
39.5 |
1019.4 |
1.8 |
ENE |
18:00 |
24.0 |
1017.8 |
2.4 |
WNW |
19:00 |
22.4 |
1017.6 |
3.1 |
NW |
21:00 |
26.7 |
1018.2 |
1.6 |
WNW |
3. 1. 10 Episode 8 (1-2 Feb. 2020)
Episode 8 is classified as an Accumulation Episode.
During Episode 8, high concentrations occurred owing to the accumulation of PM2.5 inflow from overseas as well as domestic PM2.5. Based on the air quality concentration forecast on the 31st, high concentrations of PM2.5 were moving towards the metropolitan area and Chungcheong Province because of the northwest wind. On January 31, when external inflows were expected, PM2.5 concentrations in the metropolitan and Chungcheong provinces were generally higher than in other regions. On the morning of February 2, air congestion also occurred, causing accumulation of both PM2.5 inflows and domestically generated PM2.5.
Fig. 19.
Air Quality Prediction Model Results on 1 Feb.
Fig. 20.
Weather map on 2 Feb. 09:00.
Table 10.
Hourly concentration and meteorological factors of Episode 8.
|
|
PM2.5
(μg/m3) |
Pressure
(hPa) |
Wind
speed
(m/s) |
Wind
direction |
31 Jan. 2020
(20.0 μg/m3) |
12:00 |
13.0 |
1008.8 |
2.3 |
WNW |
14:00 |
33.2 |
1008.2 |
3.4 |
W |
19:00 |
32.4 |
1010.1 |
3.3 |
W |
22:00 |
34.7 |
1011.5 |
2.1 |
W |
1 Feb. 2020
(52.5 μg/m3) |
2:00 |
36.2 |
1011.6 |
0.7 |
WSW |
8:00 |
36.4 |
1013.6 |
0.6 |
NNE |
13:00 |
57.2 |
1013.4 |
1.7 |
SW |
20:00 |
73.4 |
1014.2 |
1.8 |
NW |
23:00 |
66.0 |
1014.4 |
0.8 |
NW |
2 Feb. 2020
(53.9 μg/m3) |
4:00 |
60.4 |
1015 |
0.3 |
N |
6:00 |
63.5 |
1015.1 |
0.6 |
N |
11:00 |
77.0 |
1016.2 |
1.2 |
NW |
15:00 |
54.3 |
1013.8 |
3.4 |
WNW |
18:00 |
38.8 |
1013.7 |
3.8 |
NW |
23:00 |
33.4 |
1013.9 |
3.3 |
W |
3. 1. 11 Episode 9-1 (11 Feb. 2020)
Episode 9-1 is classified as an Accumulation Episode.
In Episode 9, from the afternoon of the 11th, high concentrations of PM2.5 came down from the north. Thereafter, high concentrations remained until the morning of the 12th owing to atmospheric congestion. On the 12th, precipitation occurred in the Seoul area, and the concentration of PM2.5 decreased as the low-pressure base passed through the Korean Peninsula.
Fig. 21.
Air Quality Prediction Model Results on 11 Feb.
Fig. 22.
Weather map on 11 Feb. 21:00.
Table 11.
Hourly concentration and meteorological factors of Episode 9-1.
|
|
PM2.5
(μg/m3) |
Pressure
(hPa) |
Wind
speed
(m/s) |
Wind
direction |
11 Feb. 2020
(35.1 μg/m3) |
9:00 |
34.2 |
1017.8 |
3.2 |
ENE |
12:00 |
41.5 |
1018.3 |
1.8 |
E |
14:00 |
38.4 |
1016 |
1.2 |
E |
17:00 |
30.5 |
1014.9 |
2.6 |
W |
23:00 |
40.5 |
1014.8 |
0.3 |
N |
12 Feb. 2020
(33.2 μg/m3) |
3:00 |
41.3 |
1012.4 |
1.3 |
NE |
7:00 |
41.0 |
1009.6 |
1.7 |
ENE |
10:00 |
41.1 |
1008.1 |
4 |
ENE |
12:00 |
38.5 |
1006.7 |
4.9 |
ENE |
16:00 |
24.6 |
1002.7 |
2.6 |
ENE |
3. 1. 12 Episode 9-2 (13-15 Feb. 2020)
Episode 9-2 is classified as a Stable Episode.
In Episode 9-2, there was a slight inflow of PM2.5 during the morning of the 13th, but long-term atmospheric stagnation led to high concentrations for three days. From the 16th, the wind speed increased and the PM2.5 decreased rapidly because of rain.
Fig. 23.
Wind information and air pollution data near Seoul during Episode 9-2.
Table 12.
Hourly concentration and meteorological factors of Episode 9-2.
|
|
PM2.5
(μg/m3) |
Pressure
(hPa) |
Wind
speed
(m/s) |
Wind
direction |
13 Feb. 2020
(54.3 μg/m3) |
1:00 |
28.3 |
1004.6 |
1.7 |
W |
7:00 |
47.8 |
1007.4 |
0 |
N |
9:00 |
56.8 |
1008.8 |
0 |
N |
10:00 |
64.8 |
1009.2 |
0.8 |
WNW |
18:00 |
58.7 |
1009.2 |
1.5 |
W |
21:00 |
56.1 |
1010.4 |
0.4 |
N |
14 Feb. 2020
(54.3 μg/m3) |
5:00 |
53.5 |
1010.3 |
1 |
WNW |
9:00 |
52.9 |
1010.7 |
0.2 |
N |
13:00 |
63.2 |
1009.6 |
0.7 |
NNW |
18:00 |
70.1 |
1009.3 |
0.8 |
SW |
23:00 |
75.0 |
1012 |
0.3 |
N |
15 Feb. 2020
(48.6 μg/m3) |
6:00 |
52.2 |
1010.4 |
1.9 |
E |
12:00 |
38.6 |
1009.2 |
2.6 |
E |
17:00 |
37.4 |
1004.7 |
1.8 |
WNW |
22:00 |
52.7 |
1004.5 |
1.4 |
WNW |
16 Feb. 2020
(18.5 μg/m3) |
0:00 |
38.8 |
1001.7 |
1 |
ESE |
1:00 |
35.8 |
1001.9 |
4.8 |
W |
3:00 |
3.1 |
1001 |
4.9 |
W |
8:00 |
18.7 |
1002.1 |
4.8 |
WNW |
3. 1. 13 Episode 10-1 (20-21 Feb. 2020)
Episode 10-1 is classified as a Stable Episode.
Since the afternoon of the 19th, the entire Korean Peninsula was affected by a high-pressure zone, causing the wind speed to drop sharply. This stagnant phenomenon continued until the afternoon of the 21st, resulting in a high-concentration episode. The congestion was resolved because of strong winds in the afternoon of the 21st.
Fig. 24.
Weather map on 21 Feb.
Table 13.
Hourly concentration and meteorological factors of Episode 10-1.
|
|
PM2.5
(μg/m3) |
Pressure
(hPa) |
Wind
speed
(m/s) |
Wind
direction |
19 Feb. 2020
(24.2 μg/m3) |
10:00 |
22.6 |
1020.2 |
1.6 |
NE |
15:00 |
25.0 |
1018.6 |
2.8 |
W |
20:00 |
28.2 |
1018.9 |
0.2 |
N |
20 Feb. 2020
(44.5 μg/m3) |
1:00 |
37.2 |
1020 |
1.1 |
NE |
4:00 |
38.3 |
1020.5 |
1 |
NE |
10:00 |
50.0 |
1023.4 |
0.9 |
ESE |
16:00 |
50.4 |
1022 |
2.4 |
WNW |
21:00 |
35.4 |
1023.9 |
1.2 |
WSW |
21 Feb. 2020
(45.4 μg/m3) |
0:00 |
38.6 |
1023.9 |
0.6 |
N |
3:00 |
46.5 |
1023.4 |
0.7 |
NW |
12:00 |
78.3 |
1021.1 |
1.5 |
ENE |
15:00 |
43.7 |
1017.4 |
4 |
SW |
17:00 |
28.0 |
1016.2 |
3 |
SW |
21:00 |
30.2 |
1014.3 |
3.1 |
SW |
3. 1. 14 Episode 10-2 (22 Feb. 2020)
Episode 10-2 is classified as Transboundary Inflow Episode.
Episode 10-2 is a simple inflow type. There was a high concentration of external inflow due to the strong west wind. It was also quickly resolved by the fast wind speed (Fig. 25).
Fig. 25.
Weather map on 22 Feb. at 21:00 pm.
Table 14.
Hourly concentration and meteorological factors of Episode 10-2.
|
|
PM2.5
(μg/m3) |
Pressure
(hPa) |
Wind
speed
(m/s) |
Wind
direction |
22 Feb. 2020
(39.0 μg/m3) |
2:00 |
9.9 |
1011 |
5.8 |
W |
5:00 |
31.7 |
1011.3 |
3.7 |
W |
6:00 |
43.8 |
1011.8 |
3.6 |
W |
8:00 |
73.0 |
1013 |
3.2 |
W |
10:00 |
87.3 |
1013.4 |
4.2 |
W |
11:00 |
83.9 |
1013.4 |
3.1 |
WSW |
13:00 |
64.2 |
1012.5 |
5.2 |
WSW |
14:00 |
43.9 |
1012.1 |
4.3 |
WNW |
16:00 |
36.1 |
1013.3 |
4 |
W |
17:00 |
28.9 |
1013.7 |
5.8 |
W |
21:00 |
16.8 |
1017.7 |
3.8 |
W |
22:00 |
16.4 |
1018.6 |
5 |
WNW |
23:00 |
18.3 |
1018.7 |
2.5 |
W |
3. 1. 15 Episode 11 (7-9 Mar. 2020)
Episode 11 is classified as a Stable Episode.
In Episode 11, atmospheric stagnation continued because of the high-pressure effect throughout the episode, for three days. Fig. 26 shows that the Korean Peninsula is under relative high pressure. In addition, looking at the wind speed data, shaded in Table 15, the overall low wind speed of 1.5 m/s or less can be confirmed. Low pressure was generated from the afternoon of the 10th and the high concentration situation was resolved (Fig. 26).
Fig. 26.
Wind information and air pollution data near Seoul during Episode 11.
Table 15.
Hourly concentration and meteorological factors of Episode 11.
|
|
PM2.5
(μg/m3) |
Pressure
(hPa) |
Wind
speed
(m/s) |
Wind
direction |
6 Mar. 2020
(27.5 μg/m3) |
17:00 |
32.2 |
1009.2 |
1.3 |
W |
20:00 |
35.3 |
1010.1 |
2.2 |
W |
22:00 |
34.5 |
1010.1 |
1.3 |
NNE |
7 Mar. 2020
(39.4 μg/m3) |
2:00 |
36.4 |
1009.2 |
0.8 |
NNE |
7:00 |
39.0 |
1008.7 |
1.4 |
ENE |
15:00 |
28.4 |
1005.6 |
1.7 |
SW |
22:00 |
44.2 |
1007.2 |
1.5 |
WNW |
8 Mar. 2020
(45.1 μg/m3) |
2:00 |
40.5 |
1008.1 |
0.8 |
NW |
5:00 |
42.0 |
1008.7 |
0.3 |
N |
9:00 |
46.1 |
1010.1 |
1.3 |
E |
15:00 |
37.8 |
1006.8 |
1.1 |
SE |
21:00 |
46.9 |
1007.4 |
1.2 |
WNW |
9 Mar. 2020
(42.0 μg/m3) |
0:00 |
50.6 |
1007.3 |
0.6 |
NNE |
4:00 |
49.9 |
1006.6 |
0.5 |
NW |
7:00 |
49.2 |
1006.0 |
0.6 |
NNE |
23:00 |
40.1 |
1000.8 |
1.4 |
WNW |
10 Mar. 2020
(29.3 μg/m3) |
4:00 |
53.1 |
997.6 |
1.9 |
WNW |
7:00 |
51.0 |
996.6 |
1 |
NW |
10:00 |
31.8 |
996.8 |
4 |
NW |
13:00 |
9.0 |
995.5 |
3.2 |
WNW |
19:00 |
7.8 |
998.1 |
3.7 |
WNW |