SOLA, 2011, Vol. 7A, 017−020, doi:10.2151/sola.7A-005 17

Meteorological Features and Particulate Matter Monitoring of the Asian Dust (Hwangsa) Event Observed in Korea on 1 April 2007

Youngsin Chun and Sumin Kim Asian Dust Research Division, National Institute of Meteorological Research, , Korea

Japan. Abstract Photographs were taken in Seoul on 1 and 2 April 2007 show that the dust resulted in poor visibility. Mt. Gwanak and the The purpose of this study was to describe the meteorological 63 buildings in Yeouido are completely obscured by the dust in features and PM10 concentration of the dust event observed in one pair of photographs taken when the PM10 concentration was from 31 March to 2 April 2007. This typical dust 1,349 µg m−3 (5-minute average) from the Korea Meteorological event for Korea exhibited baroclinic instability at the 850 hPa Administration (KMA) headquarters in Shindaebang-dong, Seoul. level over . The conditions propelled a large amount However, the buildings and mountain can be discerned faintly in of dust into the air, where it was subsequently transported to the another pair of photographs, taken when the PM10 concentration Korean peninsula. The Asian dust event studied was the sixth of was 37 µg m−3. the 13 events that occurred in Korea in 2007; its maximum PM10 concentration of 2,019 µg m−3 (hourly average) was recorded in Daegu in Korea. Naked-eye observation of the event started in Baengnyeongdo on 07UTC 31 March and ended in Jejudo on 01UTC 2 April 2007. The duration of this event in Korea was 46 hours and 15 minutes.

1. Introduction

Asian dust events are most frequently observed during the springtime (March to May) with the maximum peak occurring in April (Chun et al. 2008). During the period from 31 March to 2 April 2007, a very severe dust event was observed on the Korean peninsula, prompting a ‘Hwangsa Advisory/Warning’ by the Korea Meteorological Administration. In South Korea, a ‘Hwangsa Advisory’ is issued when the hourly average dust (PM10) con- centration is expected to exceed 400 µg m−3 for over two hours. A ‘Hwangsa Warning’ is issued when the hourly average dust (PM10) concentration is expected to exceed 800 µg m−3 for over two hours. These thresholds were revised from 500 and 1,000 µg m−3, which have been in use since April 2002. The dust event was extremely severe and continued for Fig. 1. Asian dust observations from 29 March to 2 April 2007. 46 hours, recording a maximum PM10 concentration of over 2,000 µg m−3 at some sites. The extent of the event was due to the large amount of dust emission in Mongolia. Severe dust storms occurred in Mongolia during the period of 29−31 March 2007. Wind speeds of 10−40 m s−1 were recorded and visibility was reduced to less than 20 m. Furthermore, the was the strongest observed in Mongolia in spring 2007 (Jugder and Batorj 2009). The purpose of this study was to describe the meteorological features and PM10 concentration of the dust event observed and measured in South Korea from 31 March to 2 April 2007.

2. Meteorological features of dust and sandstorms

2.1 An overview of the event Present weather reports of synoptical data (SYNOP) based on naked-eye observations at meteorological observatories are used to estimate the routes of dust outbreaks (Fig. 1). The dust storm being described in the present study originated in Mongolia on 29 March 2007 (Sugimoto et al. 2010) and moved to the inner Mongolian Plateau on 30 March 2007. The dust transported to Manchuria and on 31 March 2007. Dust flows even- tually converged in South Korea on 1 April 2007 and approached

Corresponding author: Youngsin Chun, NIMR, 61 Yeouidaebang-ro, 16-gil, Donjack-gu, Seoul, 156-720, Republic of Korea. E-mail: hwangsa Fig. 2. Floating dust as captured from the roof of the KMA head- @korea.kr. ©2011, the Meteorological Society of . quarters located in Seoul, Korea. 18 Chun and Kim, Meteorological Features and Particulate Matter Monitoring of the Asian Dust

2.2 Synoptic features northwesterlies were relatively weak over the Korean peninsula. An area with strong winds located behind a low pressure The next day, i.e., 2 April, the low pressure system had moved system in Eastern Mongolia on 30 March resulted in a widespread eastward, with northerlies observed over the Korean peninsula and dust storm that spanned the Gobi, Inner Mongolia and Tengel westerlies over Japan. deserts. This low pressure system moved eastward and was in Northwesterlies from the source region to the Korean penin- Manchuria by 31 March, resulting in widespread floating dust sula were dominant on 30 March 2007 at the 300 hPa level (not over the Korean peninsula. The transport took about 36 hours shown here). The northwesterlies were replaced by westerlies on from the source region to the Korean peninsula. On 1 April, the 31 March that persisted until 2 April 2007 (not shown here). dust was transported to Japan and was observed across most of Japan, unlike for the Korean peninsula where the northerlies had 2.3 Satellite images been without dust (Fig. 3). Dust was clearly visible on 31 March as shown on the MODIS Baroclinicity with solenoid crossing the isobaric line and images in Fig. 4. However, the MTSAT images show abundant isothermal line on 00UTC 30 March 2007 was pronounced in the cloud cover over the Korean peninsula. Because of the intervening southeast of Gobi, Mongolia. At the same time, the steep pressure clouds, the horizontal distribution and intensity of the dust event gradient resulted in high wind speed. Furthermore, cold dense air could not be determined based on satellite imagery. dispersed large amounts of dust to the upper atmosphere. This cold low pressure system moved eastward and the strong pressure gradient area passed over Inner Mongolia and Manchuria; caus- ing further dust emission. Because the low pressure system was positioned over the northern part of Japan on 1 April 2007, the

Fig. 3. Hwangsa weather charts at surface (left) and 850 hPa (right) levels from 30 March to 2 April 2007. SOLA, 2011, Vol. 7A, 017−020, doi:10.2151/sola.7A-005 19

Fig. 5. PM10 monitoring sites in , Korea and Japan. Fig. 4. MODIS1) and MTSAT-1R IDDI2) images from 31 March to 1 April 2007. 1) Moderated-Resolution Imaging Spectroradiaometer 2) Multi-functional Transport Satellite-1Replacement Infrared Difference Dust Index (a)

) Baotou -3 Chifeng m Hohhot Yan’an Datong Dalian 3. PM10 mass concentration measured in China, Jinan Jinzhou Korea and Japan Shenyang Concentration (µg Qingdao The locations of PM10 monitoring sites in China (CNEMC, 10 sites), Korea (NIMR and NIER, 36 sites) and Japan (ADORC, (b) NIMR, KOREA Sokcho 10 sites) are shown in Fig. 5. 2000 Gwangdeoksan Daegwallyeong

PM10 concentration data from China, Korea and Japan show ) Chuncheon -3 Baengnyeongdo the temporal evolution of dust as shown in Fig. 6. m 1500 Ulleungdo Kwanaksan Along the flow of dust outbreak, the maximum PM10 concen- Yeongwol KGAWO Andong tration in China peaked on 31 March 2007, on 1 April in Korea, 1000 Gunsan Daegu and on 2 April in Japan. Gwangju −3 Gudeoksan

The PM10 dust concentration was 1,104 µg m (daily aver- Concentration (µg 500 Heuksando Gosan age) in Dalian, China. In Korea, the hourly averages in Daegu Jinju −3 −3 Ganghwa and Ulsan were 2,019 µg m and 1,873 µg m , respectively. Gyegryelbi-do −3 0 Yeongdeok The maximum PM10 concentration recorded 932 µg m in Ijira, 3/26 3/27 3/28 3/29 3/30 3/31 4/1 4/2 4/3 4/4 4/5 Japan. The daily averaged concentrations in China, Korea and Japan (c) NIER, KOREA Donghae were compared, and were found to be similar with concentra- 2000 Suwon −3 Gimhae ) Gimcheon tions of 1,104, 1,084, 1,043 µg m in Dalian, Ulsan and Daegu, -3 Gwangju m 1500 Daegu respectively (Fig. 7). The daily maximum concentration was Daejeon −3 Busan recorded at 488 µg m in Ijira, Japan. Seoul 1000 Ulsan Incheon Mokpo Jeonju Jeju

4. Conclusion Concentration (µg 500 Seosan Cheongju The dust event from 31 March to 2 April 2007 was occured 0 3/26 3/27 3/28 3/29 3/30 3/31 4/1 4/2 4/3 4/4 4/5 and transported from Mongolia to China, Korea and Japan. Infor- mation on the dust storm, its meteorological features and PM10 (d) concentration were shared for this study, which concluded the JAPAN Rishiri 2000 Tappi following: Sado-seki ) Happo -3

m Ijira 1500 Oki First, Banryu Yusuhara (a) The dust event studied was the sixth of 13 events that occurred Hedo 1000 Ogasawara in Korea in 2007. The maximum PM10 concentration was recorded as 2,019 µg m−3 (hourly average) in Daegu.

Concentration (µg 500 (b) The daily averaged PM10 concentrations in China, Korea and Japan traced the temporal evolution of the dust and were 0 1,104 µg m−3 in Dalian, China, 1,084 µg m−3 (Daegu) and 1,043 µg m−3 (Ulsan) in Korea, and 488 µg m−3 in Ijira, Japan Fig. 6. Dust monitoring data: (a) diurnally averaged PM10 from (maximum). China; (b) hourly averaged PM10 from KMA, Korea; (c) hourly (c) The first revised ‘Hwangsa Warning’ was issued, as the hourly averaged PM10 from NIER, Korea; (d) hourly averaged PM10 averaged dust (PM10) concentration was expected to exceed from Japan. 20 Chun and Kim, Meteorological Features and Particulate Matter Monitoring of the Asian Dust

events. For data sharing, it is important to have a standard calibra- tion for the PM10 measurement instruments in each country. The building up of a PM10 international network will be useful for the research in to and monitoring of dust events in East Asia.

Acknowledgements

This research paper contributes to the Joint Research on Dust and Sandstorm under TEMM-WG-I. We would like to thank the Joint Research on Dust and Sandstorms among Mongolia, China, Korea and Japan. This paper was based on the Shenyang work- shop of the Working Group(I) held in June 2009 in China. Some of the research in this paper was supported by the “Development and Application of Asian Dust Monitoring and Prediction techniques” in NIMR, KOREA. Special thanks to the Ministry of , the National Institute of Envi- ronmental Research of Korea, and the Ministry of Environment of Japan for sharing their PM10 concentration observations for this Fig. 7. Daily averaged maximum PM10 concentrations in China, study. Korea (NIMR, NIER) and Japan in 2007. References

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