WEKO3
アイテム
茨城県中部沿岸海域における底層流速の変動特性
https://fra.repo.nii.ac.jp/records/2007781
https://fra.repo.nii.ac.jp/records/20077810df635aa-f9ce-4ebc-91e3-2be72b4f53b4
| Item type | 紀要論文 / Departmental Bulletin Paper(1) | |||||
|---|---|---|---|---|---|---|
| 公開日 | 2024-06-18 | |||||
| タイトル | ||||||
| タイトル | 茨城県中部沿岸海域における底層流速の変動特性 | |||||
| 言語 | ja | |||||
| タイトル | ||||||
| タイトル | On the Characteristics of Bottom Layer Flow off Ibaraki Prefecture in Japan | |||||
| 言語 | en | |||||
| 言語 | ||||||
| 言語 | jpn | |||||
| 資源タイプ | ||||||
| 資源タイプ識別子 | http://purl.org/coar/resource_type/c_6501 | |||||
| 資源タイプ | departmental bulletin paper | |||||
| アクセス権 | ||||||
| アクセス権 | metadata only access | |||||
| アクセス権URI | http://purl.org/coar/access_right/c_14cb | |||||
| 著者 |
武内, 智行
× 武内, 智行 |
|||||
| 抄録 | ||||||
| 内容記述タイプ | Abstract | |||||
| 内容記述 | There are a number of unclarified points regarding the characteristics of sub-surface flow in coastal areas. However, design velocity, namely estimated maximum velocity, must be given when designing sub-surface structures such as artificial reefs at the bottom and floating fish aggregators moored in the middle layer. Therefore the author carried out long-term observations on the bottom layer flow since 1981 and tried to make clear its characteristics. Field data were obtained for a period of four years and a half off Kuji and two years and a half off Kawajiri in Ibaraki prefecture in Japan. The depth of those were 40 m and 130 m. Current meter was placed 2 m above the bottom with sub-surface buoy system. The sampling interval was five minutes, and the instrument was recovered and newly set up every month. With the data of those long-term observations, the characteristics of the bottom layer flow in the coastal areas are discussed and a semi-empirical method proposed by Nakamura estimating the design velocity for submarine structures is examined. The results are as follows : (1) The data aquisition ratio was as good as 80~90%. (2) The main flow direction was south or north along a contour line, and the south direction was most prominent. In Kawajiri data, the flow direction is almost steady in each season, but Kuji data shows more irregular variations. Off Kawajiri, strong offshore current, so called "Dashishio", occurrs frequently in summer and autumn, but it does not occur so often off Kuji. (3) In hourly averaged data, the maximum velocity was 46 cm/s off Kuji and 53 cm/s off Kawajiri. The average was 7.4 cm/s and 8.0 cm/s, respectively. It flows ceaselessly off Kuji. On the other hand slack flow is often seen off Kawajiri. But occurrence frequency of strong flow off Kawajiri was greater than that of Kuji. (4) Most significant peak in power spectrum is at the period of a day caused by tidal current. Period of a few days caused by drift current or others and a half day caused by tidal flow are noted as well. In almost all cases, energy density was decreased with the gradient of -5/3. (5) Off Kuji strong flow was observed when the typhoon or depression was passing. Off Kawajiri, however, it was observed when "Dashishio" occurred, that may be caused by internal tidal waves disturbed by typhoon or depression. (6) Estimated maximum velocity based on Nakamura's method was greater than the observed velocity except a few cases. About these exceptional cases, there are unique phenomena such as "Dashishio". Considering those phenomena, we can get the estimated values that is greater than that of the observed ones. Therefore, it is suggested that his method is reasonable. | |||||
| 言語 | en | |||||
| 書誌情報 |
ja : 水産工学研究所研究報告 en : Bulletin of National Research Institute of Fisheries Engineering 巻 8, p. 59-80, ページ数 22, 発行日 1987-03 |
|||||
| 出版者 | ||||||
| 出版者 | 水産工学研究所 | |||||
| 言語 | ja | |||||
| 出版者 | ||||||
| 出版者 | National Research Institute of Fisheries Engineering | |||||
| 言語 | en | |||||
| ISSN | ||||||
| 収録物識別子タイプ | PISSN | |||||
| 収録物識別子 | 0388-9718 | |||||
| 書誌レコードID | ||||||
| 収録物識別子タイプ | NCID | |||||
| 収録物識別子 | AN00332937 | |||||
| 情報源 | ||||||
| 識別子タイプ | Local | |||||
| 関連識別子 | nrife_k_8_59 | |||||
| 関連サイト | ||||||
| 識別子タイプ | URI | |||||
| 関連識別子 | https://agriknowledge.affrc.go.jp/RN/2010370933 | |||||
| 言語 | ja | |||||
| 関連名称 | 日本農学文献記事索引(agriknowledge) | |||||
