SOLA, 2019, Vol. 15, 257−261, doi:10.2151/sola.2019-046 257 Transport of Mineral Dust from Africa and Middle East to East Asia Observed with the Lidar Network (AD-Net) Nobuo Sugimoto1, Yoshitaka Jin1, Atsushi Shimizu1, Tomoaki Nishizawa1, and Keiya Yumimoto2 1National Institute for Environmental Studies, Tsukuba, Japan 2Research Institute for Applied Mechanics, Kyushu University, Fukuoka, Japan et al. 2005). We observed lifted dust layers in Korea and Japan, Abstract which were not reproduced by a regional dust transport model. We compared with global aerosol transport models and found the dust Mineral dust transported from Africa and Middle East was was transported from Africa. observed with the Asian Dust and aerosol lidar observation Net- In 2015−2016, Leibniz Institute for Tropospheric Research work (AD-Net). In March 2018, the dense Sahara dust, reported (TROPOS) conducted continuous observation with a multi-wave- by mass media as that snow in Sochi, Russia stained into orange, length Raman lidar in Dushanbe, Tajikistan (Hofer et al. 2017), was transported to Sapporo in 4 days from Sochi and observed by and they recently restarted continuous observation. That motivated the lidar. In April 2015, dust from Middle East was transported to us to study long-range-transported dust cases using recent AD-Net Nagasaki passing across the Taklamakan desert. Dust source areas data. It would be useful if we could observe the same air mass and transport paths were studied with the global aerosol transport along the transport path to study the change in characteristics of model MASINGAR mk-2 separately calculated for different dust dust. Also, recent studies of bioaerosols (microbes transported sources regions. The results showed that dust from Sahara and with dust) suggest such long-range transport might be important Middle East was transported to East Asia and sometimes mixed even if the transported amount is small (Maki et al. 2019). with dust from the Gobi desert and the Taklamakan desert. The This paper describes the analysis of two long-range trans- analysis of recent AD-Net data after 2015 showed such long- ported dust cases. One is the big Sahara dust event in March 2018 range transport cases were observed every year in March or April. where mass media (e.g. BBC, CNN) reported that Sahara dust The transport path often led over the Caspian Sea, Kazakhstan, stained snow at a skiing ground in Sochi, Russia into orange on 22 and Russia. Sahara dust transported north and reached around March 2018. Recently, Kaskaoutis et al. (2019) reported the anal- the Black Sea was transported long range by strong westerly in ysis of radiative effect of the Sahara dust events in March 2018 springtime. including this event using satellite observations. We observed the (Citation: Sugimoto, N., Y. Jin, A. Shimizu, T. Nishizawa, plume of the Sahara dust passed near Sochi on 22 March by the and K. Yumimoto, 2019: Transport of mineral dust from Africa AD-Net lidar in Sapporo on 26 March (Sugimoto et al. 2019). In and Middle East to East Asia observed with the lidar network (AD- the same period, there were dust emissions also in the Taklamakan Net). SOLA, 15, 257−261, doi:10.2151/sola.2019-046.) desert and the Gobi desert as reported by Yoon et al. (2019), and the distribution of dust was complicated. We analyzed the source areas of the observed dust plumes using the global aerosol trans- 1. Introduction port model MASINGAR mk-2 (the Model of Aerosol Species in the Global Atmosphere, mark 2) (Yukimoto et al. 2012) calculated Mineral dust is a major aerosol component determining atmo- separately for different dust source areas. spheric radiative characteristics (IPCC 2013). In the East Asian The other case is the Middle East dust case in April 2015. region, dust source areas locate close to industrial and urban areas, A lifted dust layer was reported in Dushanbe, Tajikistan (Hofer and dust is often mixed with anthropogenic aerosols. Dust con- et al. 2017). The dust was transported across the high mountain in sequently plays important role in air pollution chemistry (Wang the west of Taklamakan, and it was mixed with dust from Takla- et al. 2017). It is also shown in recent studies that microbes are makan and Gobi and transported to Japan. We observed a plume transported with mineral dust (Maki et al. 2019). To study Asian from the same dust event with the AD-Net lidar in Nagasaki. In dust and regional air pollution, we started network observations this paper, we also present a summary of long-range transported using ground-based lidars in 2001. The network is named the dust cases confirmed with the recent AD-Net data after 2015. Asian Dust and aerosol lidar observation Network (AD-Net). Cur- rently, lidars are continuously operated at 20 locations in East Asia (Japan, Korea, China, Mongolia and Thailand) (Shimizu et al. 2. Method 2017). It is understood with the studies using the network obser- vations and chemical transport models that the major dust source We used the AD-Net two-wavelength (1064 nm and 532 nm) areas in East Asia are the Taklamakan desert in China, the Gobi and polarization sensitive (532 nm) lidar data (https://www-lidar. desert in Mongolia and China, and Loess Plateau in China. Dust nies.go.jp/AD-Net/) to identify transported dust plumes (Shimizu from Gobi and Loess Plateau is usually transported near the sur- et al. 2017). In the analysis, we firstly used archived results of face and significantly affect the environment of the lower atmo- the Navy Aerosol Analysis and Prediction System (NAAPS) of sphere (Sugimoto et al. 2003; Shimizu et al. 2004). It is often the U.S. Naval Research Laboratory (https://www.nrlmry.navy. mixed with air pollution (Pan et al. 2017). Dust from Taklamakan mil/aerosol/) to find possible long-range-transported dust cases is often uplifted and transported long distance in the free tropo- from Africa or Middle East. We then searched corresponding dust sphere (Uno et al. 2009). plumes in AD-Net data. When the corresponding dust plumes Dust emitted outside of East Asia is sometimes transported are found, we performed backward trajectory analysis using the to East Asia. Cases of long-range transport of mineral dust from Hybrid Single-Particle Lagrangian Integrated Trajectory model Africa and Middle East (Tanaka et al. 2005) and soot from oil (HYSPLIT) of U.S. National Oceanic and Atmospheric Admin- field burning in Middle East (Tazaki et al. 2004) were reported. istration (Stein et al. 2015) (https://ready.arl.noaa.gov/HYSPLIT. We also reported a Sahara dust case observed in East Asia (Park php). We also confirmed the dust transport paths using the Cloud- Aerosol Lidar and Infrared Pathfinder Satellite Observations Corresponding author: Yoshitaka Jin, National Institute for Environmental (CALIPSO) data when available (Winker et al. 2009) (https:// Studies, 16-2 Onogawa, Tsukuba, Ibaraki 305-8506, Japan. E-mail: jin. www-calipso.larc.nasa.gov). To confirm the dust emission source [email protected]. ©The Author(s) 2019. This is an open access article published by the Meteorological Society of Japan under a Creative Commons Attribution 4.0 International (CC BY 4.0) license (http://creativecommons.org/license/by/4.0). 258 Sugimoto et al., Dust Transported from Africa and Middle East to East Asia Sochi Sapporo Fig. 2. HYSPLIT backward trajectory of the Sahara dust plume indicated in Fig.Fig 1.. 2. HYSPLIT backward trajectory of the Sahara dust plume indicated in Fig. 1 lated by MASINGAR mk-2. Figure 3 presents time-height indication of dust extinction Fig. 1. Time-height indications of attenuated backscatter coefficient at 532 coefficient in Sapporo from 24 to 27 March 2018 compared with nm (top), volume depolarization ratio at 532 nm (middle), and the ratio of the MASINGAR mk-2 results calculated separately for different the attenuated backscatter coefficients at 1064 nm to 532 nm (bottom), in dust source areas. The observed dust extinction coefficient was Fig. 1Sapporo. Time- heightin Marchindications 2018. of attenuated backscatter coefficient at 532 nm~0.06 km−1 at maximum on 26 March, and the optical depth of the plume estimated from the lidar profile was ~0.3. The particle (top), volume depolarization ratio at 532 nm (middle), and the ratio of thedepolarization ratio and backscattering color ratio (β1064nm/β532nm) areas, we used the results of the global aerosol transport model (not shown in the figure) were ~0.28 and ~0.4, respectively. The attenuatedMASINGARbackscatter mk-2 calculatedcoefficients separatelyat 1064 nm forto 532differentnm (bottom), dust sourcein Sapporo color ratio was low compared to that in major Gobi dust cases areas (Sahara, Middle East, Taklamakan, and Gobi). Spatial reso- (~1.0). This suggests the particle size of the long-range-transported inlutionMarch was2018 TL479. (40 km) for 2018 and TL159 (110 km) for 2015 Sahara dust was small, or the plume was mixed with other aerosols depending on the version of MASINGAR. such as sulfate and smoke. However, the mixing with other aero- We used the dust extinction coefficient to compare the lidar sols was not likely from the results of NAAPS. Although it is not observations with the model results. In the lidar data analysis, possible to estimate the mass concentration of dust without know- the total extinction coefficient profiles were derived firstly by the ing the size distribution and the optical characteristics, in a rough backward Fernald method with a constant lidar ratio (here we used estimation using an empirical conversion factor (Sugimoto et al. 3 S1 = 50 sr), and then the method using the particle depolarization 2003), it was about 50 μg/m . It was high as long-range trans- ratio was applied to estimate extinction coefficients for non-spher- ported dust.