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

被引用文献数

1

---

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 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

---

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

Fumio MARUYAMA Kenji KAI Hiroshi MORIMOTO

出版者

(公社)日本気象学会

雑誌

気象集誌. 第2輯 (ISSN:00261165)

巻号頁・発行日

vol.93, no.3, pp.331-341, 2015 (Released:2015-07-10)

参考文献数

23

被引用文献数

1 4

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A climatic regime shift is characterized by an abrupt transition from one quasi-steady climatic state to another. We attempted to explain the change of multifractal behavior of climate indices when a regime shift occurred. We used the wavelet - transform method to analyze the multifractal behaviors of the El Niño/Southern Oscillation (ENSO) index (Niño3.4 index), Pacific Decadal Oscillation (PDO) index, North Pacific Index (NPI), Pacific/North American pattern (PNA) index, and West Pacific pattern (WP) index. We showed the change of multifractality of these climate indices. When the wavelet coherences between the Niño3.4 index and NPI, NPI and PDO index, and Niño3.4 and PDO indices became strong, changes from multifractal to monofractal behavior were observed at climatic regime shifts. It may be possible to explain the background of the change of fractality by regarding climate change as the consequence of mutual interactions of various climatic elements. A fluctuation increase is observed in a coupled chaotic system just before chaos synchronization, which is when fractality and states change. We expect that a similar mechanism possibly exists for a climatic regime shift. When fluctuations became large and multifractality became strong, a climatic regime shift occurred and a change from multifractal to monofractal behavior was observed. The strong interaction of climatic phenomena, such as the ENSO, PDO, and Aleutian Low, caused a climatic regime shift. The fractality change of the PDO index almost corresponded to the regime shifts. In terms of multifractal analysis, we conclude that a climatic regime shift corresponds to a change from multifractality to monofractality of the PDO index.

著者

Ryosuke Nogami Mari Nagata Risa Imada Kenji Kai Takashi Kawaguchi Shuji Tani

出版者

Pesticide Science Society of Japan

雑誌

Journal of Pesticide Science (ISSN:1348589X)

巻号頁・発行日

pp.D23-038, (Released:2023-12-26)

参考文献数

43

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From the 992 samples of culture extracts of microorganisms isolated from soil in Japan, we found that the extract of Streptomyces sp. no. 226 inhibited Orobanche minor seed germination without significantly affecting the seed germination of Trifolium pratense and the growth of Aspergillus oryzae and Escherichia coli. Using ESI-MS, 1H-NMR, and 13C-NMR, we identified the active compound as cycloheximide. Cycloheximide had half-maximum inhibitory concentrations of 2.6 ng/mL for the inhibition of seed germination of O. minor and 2.5 µg/mL for that of the conidial germination of A. oryzae. Since cycloheximide is known to inhibit translation by interacting with ribosomal protein L28 (RPL28) in yeast, we investigated whether RPL protein of O. minor plays a critical role in the inhibition of O. minor seed germination. Our data suggested that O. minor RPL27A was not sensitive to cycloheximide by comparing it to the strain expressing S. cerevisiae RPL28. These findings suggest the presence of an unidentified mechanism by which cycloheximide hinders O. minor seed germination.

著者

Kenji Kai

出版者

Pesticide Science Society of Japan

雑誌

Journal of Pesticide Science (ISSN:1348589X)

巻号頁・発行日

pp.J19-02, (Released:2019-07-26)

参考文献数

63

被引用文献数

16

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Microorganisms produce and secrete a variety of secondary metabolites including fatty acids, polyketides, terpenoids, alkaloids, and peptides. Among them, many molecules act as chemical signals that play important roles in inter-/intra-species microbial communication or the interaction with host organisms. In this review, I focus on our recent reports of the microbial signaling molecules involved in bacterium–fungus, bacterium–plant, and fungus–plant interactions. Their potential contribution to pest management is also discussed.

著者

Kenji Kai Keiji Mine Kohki Akiyama Satoshi Ohki Hideo Hayashi

出版者

Pesticide Science Society of Japan

雑誌

Journal of Pesticide Science (ISSN:1348589X)

巻号頁・発行日

vol.43, no.4, pp.283-286, 2018-11-20 (Released:2018-11-20)

参考文献数

18

被引用文献数

10

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3種のペプタイボール,trichorizin HA II (1), HA V(2)およびHA VI(3)をTrichoderma harzianum HK-61株を植菌したオカラ培養物より単離した.それらの化学構造は,機器分析と化学誘導体化により確定した.Trichorzin類は,キュウリモザイクウイルスがササゲに感染するのをμMオーダーで阻害した.