- 著者
- Haruka Ishizaki Hiroshi Matsuyama
- 出版者
- Meteorological Society of Japan
- 雑誌
- SOLA (ISSN:13496476)
- 巻号頁・発行日
- vol.14, pp.192-196, 2018 (Released:2018-12-14)
- 参考文献数
- 23
- 被引用文献数
- 10
Radar/Raingauge-Analyzed Precipitation (RA) represents 1 km-grid precipitation after 2006 created by combining radar precipitation and ground precipitation, i.e., Automated Meteorological Data Acquisition System (AMeDAS) of Japan Meteorological Agency along with ground data observed by other organizations. Although RA is slightly greater than ground precipitation, no earlier studies investigated the spatial distribution of this accuracy across Japan using 1 km grid data, as clarified in this study. We selected hourly data of RA and AMeDAS located closest each other, for which miss rates were less than 10% in 2006-2010. We then investigated the distribution of the annual precipitation ratio (RA/AMeDAS). The ratio diverged in the smaller annual precipitation, but converged to ca. 1.2 for larger annual precipitation. By setting the observational area of 46 radars across Japan using Thiessen method, we investigated the relation between the annual precipitation ratio and the distance from the radar to AMeDAS station. We found only negative relation was statistically significant. As a possible reason for this relation, we considered that RA far from the radar is affected by the attenuating and shadowing effect of heavy rainfall near the radar.
- 著者
- Hiromitsu Kanno Hiroshi Matsuyama
- 出版者
- Meteorological Society of Japan
- 雑誌
- SOLA (ISSN:13496476)
- 巻号頁・発行日
- vol.17, pp.170-176, 2021 (Released:2021-10-05)
- 参考文献数
- 34
In the Western North Pacific, there is little meteorological data available for the 19th century. We found historical documents at Chichi-jima in the Ogasawara (Bonin) Islands that report routine meteorological observations and weather conditions before 1906. In 1906, Japan Meteorological Agency began observations at Ohmura in the northwestern part of the island. The Home Ministry in Japan conducted the observations until 1906 at Ohgiura, the central part of Chichi-jima, which is 3 km away from Ohmura. We analyzed precipitation data at Ohgiura and Ohmura from 1975 to 2020 and found that the former is systematically greater than the latter. Therefore, we corrected pre-1906 precipitation at Ohgiura to ensure correlation with post-1906 precipitation at Ohmura. No discontinuous changes in the data were found around 1906. A previous study reported that annual precipitation at Ohmura for 1907-1944 was higher than that after World War II. We found that in some years from 1882 to 1906, the precipitation was less than that for 1907-1944, which agrees with the reported higher atmospheric pressure around Chichi-jima before 1906. Our study suggests that the trend of decreasing precipitation at Chichi-jima in the 20th century is not monotonous but a part of longer-scale temporal variations.
- 著者
- Hiromitsu Kanno Hiroshi Matsuyama
- 出版者
- Meteorological Society of Japan
- 雑誌
- SOLA (ISSN:13496476)
- 巻号頁・発行日
- pp.2021-030, (Released:2021-09-01)
In the Western North Pacific, there is little meteorological data available for the 19th century. We found historical documents at Chichi-jima in the Ogasawara (Bonin) Islands that report routine meteorological observations and weather conditions before 1906. In 1906, Japan Meteorological Agency began observations at Ohmura in the northwestern part of the island. The Home Ministry in Japan conducted the observations until 1906 at Ohgiura, the central part of Chichi-jima, which is 3 km away from Ohmura. We analyzed precipitation data at Ohgiura and Ohmura from 1975 to 2020 and found that the former is systematically greater than the latter. Therefore, we corrected pre-1906 precipitation at Ohgiura to ensure correlation with post-1906 precipitation at Ohmura. No discontinuous changes in the data were found around 1906. A previous study reported that annual precipitation at Ohmura for 1907-1944 was higher than that after World War II. We found that in some years from 1882 to 1906, the precipitation was less than that for 1907-1944, which agrees with the reported higher atmospheric pressure around Chichi-jima before 1906. Our study suggests that the trend of decreasing precipitation at Chichi-jima in the 20th century is not monotonous but a part of longer-scale temporal variations.
- 著者
- Yusei HISATOMI Daichi NAKAYAMA Hiroshi MATSUYAMA
- 出版者
- THE JAPAN SOCIETY OF HYDROLOGY AND WATER RESOURCES
- 雑誌
- JOURNAL OF JAPAN SOCIETY OF HYDROLOGY AND WATER RESOURCES (ISSN:09151389)
- 巻号頁・発行日
- vol.28, no.3, pp.109-123, 2015-05-05 (Released:2015-08-12)
- 参考文献数
- 38
- 被引用文献数
- 4
本研究の目的は,武蔵野台地における長期的な地下水流動を,数値モデルを利用して再現すること,及び長期的な地下水流動の変化と土地利用との関係を定量的に明らかにすることである.モデルはUSGS(アメリカ地質調査所)が開発したMODFLOW(有限差分法を用いた3次元地下水流動解析モデル)を利用した.シミュレーションは土地利用データのある1976年~2012年を対象とし,MODFLOWを用いて1日ごとの地下水位を算出した.また,4種類のGCMデータを用いて2013年~2050年における地下水流動の予測シミュレーションも行った. 計算された地下水位のデータを用いて,1977年~2012年の地下水位の低下量と観測井戸における涵養域の減少量を算出したところ,両者の間に正の相関関係があることが分かった.この要因として,1977年~2012年に,水田や農地,森林などの透水面の面積が減少し,建物用地などの不透水面の面積が増加していることが示された.2013年~2050年の地下水流動の将来予測では,土地利用が変化しないと考えると,将来的に適度な強度の降水量が増加することで地下水位が上昇することが示唆された.