文献一覧: Yamamoto Naoto (著者)

3 0 0 0 OA A Formulation of a Three-Dimensional Spectral Model for the Primitive Equations

著者: ISHIOKA Keiichi YAMAMOTO Naoto FUJITA Masato
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.2022-022, (Released:2021-12-28)
被引用文献数: 1

In the discretization of the primitive equations for numerical calculations, a formulation of a three-dimensional spectral model is proposed that uses the spectral method not only in the horizontal direction but also in the vertical direction. In this formulation, the Legendre polynomial expansion is used for the vertical discretization. It is shown that semi-implicit time integration can be efficiently done under this formulation. Then, a numerical model based on this formulation is developed and several benchmark numerical calculations proposed in previous studies are performed to show that this implementation of the primitive equations can give accurate numerical solutions with a relatively small degrees of freedom in the vertical discretization. It is also shown that, by performing several calculations with different vertical degrees of freedom, a characteristic property of the spectral method is observed in which the error of the numerical solution decreases rapidly when the number of vertical degrees of freedom is increased. It is also noted that an alternative to the sponge layer can be devised to suppress the reflected waves under this formulation, and that a “toy” model can be derived as an application of this formulation, in which the vertical degrees of freedom are reduced to the minimum.

2022-12-14 07:07:01
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3 0 0 0 OA 縄文時代晩期における気候変動と土器型式の変化

著者: 山本直人 YAMAMOTO Naoto
出版者: 名古屋大学文学部
雑誌: 名古屋大学文学部研究論集. 史学 (ISSN:04694716)
巻号頁・発行日: vol.56, pp.59-67, 2010-03-31

Compared chronologically between the cooling periods and the calibrated dates of earthenware typesfrom the late phase of the late Jomon period to the early Yayoi period in the Hokuriku District, it can befound that: (i) the boundary dates (1350 cal BC) between both the cooling period of 1400 to 1350 cal BCand the Inoguchi II /Yokaichi-shimbo types closely correlate to each other; (ii) the boundary date (900cal BC) between the cooling period of 900 cal BC and the Nakaya/Shimono type are also correlated;and, (iii) the boundary dates (800 cal BC) between the cooling period of 850 to 700 cal BC and theShimono/Nagatake type also show a similar correlation. Cooling resulting from decreases in solaroutput seriously affected the livelihood of the Jomon people. I have hypothesized that in the criticalsituation described above, the Jomon people changed the patterns earthenware, patterning tools, andthe positions onto which print/patterns were inscribed as part of their prayers for regeneration; and,consequently that the types of earthenware changed chronologically. However, there are three boundary dates in which no evidence of the occurrence of a cooling periodwas found, despite changes in earthenware types; one is the boundary date (1300 cal BC) between theYokaichi-shimbo type and the Okyoduka type, another is the boundary date (1100 cal BC) between theOkyoduka type and the Nakaya type, and the other is that (600 cal BC) between the Nagatake typeand the Shibayama-demura type. Changes in these earthenware types conceivably resulted from othercauses which are yet to be determined.