著者

Kenji Kai Kei Kawai Atsuya Ito Yuki Aizawa Yuki Minamoto Erdenebadrakh Munkhjargal Enkhbaatar Davaanyam

出版者

Meteorological Society of Japan

雑誌

SOLA (ISSN:13496476)

巻号頁・発行日

vol.17, pp.130-133, 2021 (Released:2021-07-30)

参考文献数

24

被引用文献数

5

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The Gobi Desert is a dominant source of dust on the Asian continent. In this study, we analysed the characteristics of a typical Mongolian dust storm and identified a prominent dust hotspot in the Gobi Desert. During a field survey from Ulaanbaatar (the capital of Mongolia) to Dalanzadgad in the Gobi Desert, we encountered a typical dust storm on 28 April 2019, exhibiting a distinct dust wall. The head of the dust storm crossed the road several kilometres ahead of our vehicle. The head of the storm had a height of 600 m, and its structure suggested that the dust storm was induced by a gravity current. We entered the front of the dust storm and measured a maximum wind speed of 18.2 m/s and a visibility of less than 10 m. The normalized dust number concentration at 7 μm was 59 cm−3. Moreover, Himawari-8 Dust RGB imagery showed that the dust storm occurred in an orographic convergence zone. This zone connects two valleys that are sandwiched between three mountains in the Gobi Desert: the Khangai, Altai, and Gurvan Saikhan Mountains. Our results suggest that this zone is a remarkable dust hotspot in the Gobi Desert.

著者

Kenji Kai Kei Kawai Kazuma Ohara Yuki Minamoto Yoshitaka Jin Teruya Maki Jun Noda Tatsuo Shiina Enkhbaatar Davaanyam

出版者

公益社団法人 日本気象学会

雑誌

SOLA (ISSN:13496476)

巻号頁・発行日

vol.19, pp.269-273, 2023 (Released:2023-11-03)

参考文献数

17

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The mass concentration of Asian dust in the atmosphere is an essential parameter of the atmospheric environment in East Asia. In April 2016, we conducted simultaneous observations using an optical particle counter (OPC) installed on a tethered balloon and a ceilometer in the Gobi Desert. We estimated the mass-extinction conversion factor MECF (gm−2) from the relationship between the dust extinction coefficient and dust mass concentration obtained by simultaneous observations. The MECF at Dalanzadgad in the Gobi Desert is 2.16 gm−2 at 910 nm and 1.91 gm−2 at 532 nm. A previous study on Asian dust showed that the values of the MECF were 1.78 gm−2 in Beijing, 1.40 gm−2 in Seoul, 1.18 gm−2 in Tsukuba (Japan), and 1.04 gm−2 at averaged AD-Net lidar stations in Japan. The MECF values decreased from the Asian dust source to the lee-side areas. This result suggests that the MECF depends on the size distribution of the dust.

著者

Kei Kawai Hitoshi Matsui Reiji Kimura Masato Shinoda

出版者

Meteorological Society of Japan

雑誌

SOLA (ISSN:13496476)

巻号頁・発行日

vol.17, pp.239-245, 2021 (Released:2021-12-18)

参考文献数

41

被引用文献数

4

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The emission of Asian dust in arid regions of East Asia is controlled by many land surface parameters such as snow cover, soil moisture, and vegetation. In climate models, these factors are represented by the threshold friction velocity u*t, but its treatment has large uncertainties. Here we show that the treatment of u*t is important for estimating the emissions, transport, and climate impacts of Asian dust. Our global aerosol model simulates dust event frequencies that better agree with observations in East Asia when u*t over a smooth surface is changed from the default value of 0.23 m s−1 to an observation-based value of 0.40 m s−1. Also, seasonal Asian dust emissions become more variable, increasing by 31% in spring and decreasing by 46% in summer and fall, and the annual amounts of Asian dust transported and deposited over the North Pacific (Arctic) increase by 43% and 49% (130% and 73%), respectively. Our results demonstrate that better representation of u*t in climate models is necessary to improve estimates of the emissions and transport of Asian dust and better understand its roles in the Earth system, such as its interactions with radiation, clouds, snow/ice albedo, and land and ocean biogeochemistry.

著者

Kei Kawai Hitoshi Matsui Reiji Kimura Masato Shinoda

出版者

Meteorological Society of Japan

雑誌

SOLA (ISSN:13496476)

巻号頁・発行日

pp.2021-042, (Released:2021-11-02)

被引用文献数

4

---

The emission of Asian dust in arid regions of East Asia is controlled by many land surface parameters such as snow cover, soil moisture, and vegetation. In climate models, these factors are represented by the threshold friction velocity u*t, but its treatment has large uncertainties. Here we show that the treatment of u*t is important for estimating the emissions, transport, and climate impacts of Asian dust. Our global aerosol model simulates dust event frequencies that better agree with observations in East Asia when u*t over a smooth surface is changed from the default value of 0.23 m s−1 to an observation-based value of 0.40 m s−1. Also, seasonal Asian dust emissions become more variable, increasing by 31% in spring and decreasing by 46% in summer and fall, and the annual amounts of Asian dust transported and deposited over the North Pacific (Arctic) increase by 43% and 49% (130% and 73%), respectively. Our results demonstrate that better representation of u*t in climate models is necessary to improve estimates of the emissions and transport of Asian dust and better understand its roles in the Earth system, such as its interactions with radiation, clouds, snow/ice albedo, and land and ocean biogeochemistry.

著者

Kei Kawai Yuta Nishio Kenji Kai Jun Noda Erdenebadrakh Munkhjargal Masato Shinoda Nobuo Sugimoto Atsushi Shimizu Enkhbaatar Davaanyam Dashdondog Batdorj

出版者

Meteorological Society of Japan

雑誌

SOLA (ISSN:13496476)

巻号頁・発行日

vol.15, pp.52-56, 2019 (Released:2019-03-07)

参考文献数

21

被引用文献数

4

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Asian dust is transported over a long range via the mid-latitude westerlies when dust is lifted to the free troposphere over the source regions, whereas dust remaining in the atmospheric boundary layer is not transported far. In the Gobi Desert, a major source region of Asian dust, a ceilometer (compact lidar) monitors the vertical distribution of dust at Dalanzadgad, Mongolia. On 29-30 April 2015, the ceilometer observed a developed dust storm over the ground, followed by a dust layer within a height of 1.2-1.8 km. The dust storm had already developed in the upwind region before reaching Dalanzadgad. This feature was also shown in the ceilometer observation data. The dust layer remained at almost the same height for 12 h, because the dust became trapped within an inversion layer at a height of 1.2-1.5 km over cold air. This result suggests that the inversion layer prevented the dust from reaching the free troposphere, thereby restraining the long-range transport of the dust via the westerlies. This is the first paper that reports this type of vertical distribution of dust in the source region based on observation data.

著者

Yuki Minamoto Kotaro Nakamura Minrui Wang Kei Kawai Kazuma Ohara Jun Noda Enkhbaatar Davaanyam Nobuo Sugimoto Kenji Kai

出版者

Meteorological Society of Japan

雑誌

SOLA (ISSN:13496476)

巻号頁・発行日

vol.14, pp.33-38, 2018 (Released:2018-03-01)

参考文献数

17

被引用文献数

16

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A large-scale dust event occurred in East Asia during early May 2017, and transported dust was measured all over Japan. We performed an analysis of the entire dust event using multiple sources: a local ceilometer measurement, measurements from an optical particle counter in the Gobi Desert (Dalanzadgad, Mongolia), a study of Dust RGB imagery obtained from Himawari-8, lidar measurements from Japan, and meteorological data. Our results show that three extratropical low pressure systems occurred consecutively in Mongolia and generated dust storms in the Gobi Desert. The dust generated by the third low pressure system was transported to Japan by a cold front and two pressure troughs, which were associated with the low pressure system. Remarkably, the Dust RGB imagery shows both the occurrence and the transportation of the dust, and was able to detect two dust outbreaks in the Horqin Sandy Land of Northern China and their transportation to eastern Japan; this shows that the Horqin Sandy Land was one of the source regions of this dust event.

著者

Kenji Kai Kei Kawai Atsuya Ito Yuki Aizawa Yuki Minamoto Erdenebadrakh Munkhjargal Enkhbaatar Davaanyam

出版者

Meteorological Society of Japan

雑誌

SOLA (ISSN:13496476)

巻号頁・発行日

pp.2021-023, (Released:2021-06-18)

被引用文献数

5

---

The Gobi Desert is a dominant source of dust on the Asian continent. In this study, we analysed the characteristics of a typical Mongolian dust storm and identified a prominent dust hotspot in the Gobi Desert. During a field survey from Ulaanbaatar (the capital of Mongolia) to Dalanzadgad in the Gobi Desert, we encountered a typical dust storm on 28 April 2019, exhibiting a distinct dust wall. The head of the dust storm crossed the road several kilometres ahead of our vehicle. The head of the storm had a height of 600 m, and its structure suggested that the dust storm was induced by a gravity current. We entered the front of the dust storm and measured a maximum wind speed of 18.2 m/s and a visibility of less than 20 m. The normalized dust number concentration at 7 μm was 59 cm−3. Moreover, Himawari-8 Dust RGB imagery showed that the dust storm occurred in an orographic convergence zone. This zone connects two valleys that are sandwiched between three mountains in the Gobi Desert: the Khangai, Altai, and Gurvan Saikhan Mountains. Our results suggest that this zone is a remarkable dust hotspot in the Gobi Desert.

著者

Masashi Yamamoto Yuta Natori Kei Kawai

出版者

The Japanese Society for Horticultural Science

雑誌

The Horticulture Journal (ISSN:21890102)

巻号頁・発行日

pp.OKD-162, (Released:2018-03-13)

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An investigation of local citrus genetic resources grown on the Chuuk Islands of the Federated States of Micronesia was conducted in August 2013. A total of 21 accessions were examined. According to the morphological traits, ten, four, four, two, and one accession resembled lime (local name “Nayimis”), sour orange (“Kurukur”), calamondin (“Tangerin” and “Gunkan”), sweet orange (“Kurukur” and “American Kurukur”), and pummelo (“Kurukur”), respectively. Next, cleaved amplified polymorphic sequence (CAPS) analysis was conducted. Then, precise accession identification was made based on the results of CAPS analysis in conjunction with morphological traits. “Nayimis” accessions were classified into at least two types. Genotypes of “Nayimis” type 1 were identical to those of Mexican lime. A genetic influence from mandarin was detected in “Nayimis” type 2. Although the morphological traits of all “Kurukur” sour orange types were similar, their diversity was revealed by CAPS analysis. The genotype of one “Kurukur” accession was identical to that of sour orange. Genotypes of the sweet orange-type “Kurukur” and “American Kurukur” were different. The types of “American Kurukur” and sweet orange were the same. Pummelo-type “Kurukur” was considered to be true pummelo based on the results of morphological and molecular markers. Morphologically, the calamondin-like accessions “Tangerin” and “Gunkan” showed the same genotype combinations on CAPS analysis. These genotypes were identical to those of calamondin used as a control. The combined results of morphological and molecular markers offer valuable information for the identification of citrus genetic resources on the Chuuk Islands.