著者

FUJITA Mikiko SATO Tomonori YAMADA Tomohito J. KAWAZOE Sho NAKANO Masuo ITO Kosuke

出版者

Meteorological Society of Japan

雑誌

気象集誌. 第2輯 (ISSN:00261165)

巻号頁・発行日

pp.2019-022, (Released:2018-12-17)

被引用文献数

4

---

We investigated extremely heavy precipitation that occurred around the Kinugawa River, Japan, in September 2015, and the probability of extreme precipitation occurrence, using data from a large ensemble forecast more than 1,000 members that were dynamically downscaled to 1.6 km horizontal grid spacing. The observed event was statistically rare among simulated cases and 3-day accumulated precipitation around the target area was equivalent to the 95th percentile among all simulated ensemble members. Our results show that this extreme precipitation event occurred under specific conditions: two coexisting typhoons at close proximity that produces a high atmospheric instability, and water vapor transport from the Pacific Ocean. We also assessed the probability of extreme precipitation in mountainous areas other than the Kinugawa River case. Heavy precipitation also occurred southwest of the Kinugawa River region due to two typhoons, similar to the Kinugawa River case. The tracks of these typhoons shifted marginally; however, there was a difference in the water vapor supplied to the area, causing heavy precipitation. The large-ensemble downscaled data used in this study hence enable us to evaluate the occurrence probability of a torrential rainfall event that was rarely observed, which may contribute to updating a disaster mitigating plan for possible similar disasters in future.

著者

飯島 慈裕 会田 健太郎 浅沼 順 石川 守 岩崎 博之 太田 岳史 小谷 亜由美 佐藤 友徳 篠田 雅人 杉浦 幸之助 朴 昊澤 檜山 哲哉 平沢 尚彦 金子 有紀 堀 雅裕 GOMBOLUUDEV Purevjav OYUNBAATAR Dambaravjaa IIJIMA Yoshihiro AIDA Kentaro ASANUMA Jun ISHIKAWA Mamoru IWASAKI Hiroyuki OHTA Takeshi KOTANI Ayumi SATO Tomonori SHINODA Masato SUGIURA Konosuke PARK Hotaek HIYAMA Tetsuya HIRASAWA Naohiko KANEKO Yuki HORI Masahiro

出版者

三重大学大学院生物資源学研究科

雑誌

三重大学大学院生物資源学研究科紀要

巻号頁・発行日

no.43, pp.15-25, 2017-09

---

宇宙航空研究開発機構によって2014年2月に打ち上げられた全球降水観測計画(GPM: Global Precipitation Measurement)の主衛星は高緯度地域の降水量が新規に得られる。このデータの検証は,今後の寒冷圏陸域の水循環・水資源研究等への利用促進に向けた観測精度の向上を図るうえで必要不可欠である。本研究プロジェクトでは,観測研究を実施してきた国内外の機関が協働して,北東ユーラシア(主としてモンゴル・東シベリア)で既設の観測システムを改良し,他の衛星データ解析と合わせて,夏季降水(降雨),冬季降水(降積雪)およびそれらの空間分布に関する地上検証を行う。また,今後の応用研究に向けて,陸面モデル・分布型河川流出モデル,メソ気象モデルを利用した,地域規模のGPM観測データの利用可能性を検討する。

著者

TAMURA Kenta SATO Tomonori

出版者

Meteorological Society of Japan

雑誌

気象集誌. 第2輯 (ISSN:00261165)

巻号頁・発行日

pp.2020-065, (Released:2020-08-28)

被引用文献数

2

---

Polar mesocyclones (PMCs) occur frequently over the northern Sea of Japan. In this study, topographic effects on PMC genesis in this region were examined using long-term numerical simulations extending over 36 winter seasons. Sensitivity experiments showed that PMC genesis decreases in the part of the northern Sea of Japan when the mountain region at the eastern end of the Eurasian continent is removed. For example, the generation of PMCs over offshore west of Hokkaido decreases significantly when the mountain range is removed, whereas the generation of PMCs over the Strait of Tartary remains unchanged. According to composite analysis, this result can be attributed to the different responses of subregional oceanic surface wind to the removal of the mountains. In the experiment without mountains, cold air outbreaks from the continent blow directly over the Sea of Japan causing strong westerly winds over the offshore west of Hokkaido. Consequently, PMCs tend to make landfall earlier and before reaching maturity. The uniformly distributed westerly wind also has negative impact on PMC genesis because of weakened horizontal wind shear and meridional temperature gradient. In contrast, the low-level wind over the Strait of Tartary prior to PMC genesis is unaffected by the mountains and thus topographic effects are not required for PMC genesis in this region. These results indicate that the responses of PMCs to topographic forcing has a regional variability.

著者

Sato Tomonori Tsujimura Maki Yamanaka Tsutomu Iwasaki Hiroyuki Sugimoto Atsuko Sugita Michiaki Kimura Fujio Davaa Gombo Oyunbaatar Dambaravjaa

出版者

American Geophysical Union

雑誌

Journal of geophysical research: Atmospheres (ISSN:2169897X)

巻号頁・発行日

vol.112, no.D17, pp.D17112, 2007-09

被引用文献数

48

---

Origin of water vapor, which falls as precipitation over arid/semiarid area in northeast Asia, is investigated by modeling and observational approaches. The regional climate model evaluates the spatiotemporal variations of precipitation and water vapor budget, which are used to drive the single-layer isotope circulation model. Intraseasonal variations of δ 18O in precipitation are well simulated during June-July-August of 2003. The δ 18O in water vapor experiences rapid decreases according to the passage of synoptic-scale disturbances. The rapid decreases of δ 18O are attributed to two processes. (1) The δ 18O in air mass locally decreases over the western mountains associated with the mountain precipitation; the light vapor is advected to eastern Mongolia by the prevailing westerly wind. (2) Convective systems pass by in the vicinity of the observation site, which persistently keep the lower δ 18O in the air mass. Origin of the water vapor during June-July-August in 2003 is evaluated by the colored moisture analysis in which the tracers are assigned depending on the region where the water vapor finally evaporated. Seasonal mean result indicates that the regions contributing to precipitation in Mongolia are not low-latitude regions but central Asia and western Siberia located to the northwest of Mongolia. Observed multilevel isotopic composition supports the model estimation. The moisture transport along the southwesterly wind of the Asian summer monsoon has difficulty reaching Mongolia as a monthly/seasonal mean perspective. However, eastern Mongolia and northeast China are situated on the border area between westerly wind moisture transport (by midlatitude synoptic cyclones) and southerly wind moisture transport (by Asian summer monsoon).