- 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.
- 著者
- ISHIOKA Keiichi
- 出版者
- 公益社団法人 日本気象学会
- 雑誌
- 気象集誌. 第2輯 (ISSN:00261165)
- 巻号頁・発行日
- pp.2023-008, (Released:2022-11-17)
- 被引用文献数
- 1
Inspired by the detection of the Pekeris mode of atmospheric free oscillations by a recent study, high-accuracy numerical calculations of the problem of determining the equivalent depth of atmospheric free oscillations are performed. Here, the computational method is largely based on a previous study, but with modifications to improve the accuracy of the calculation. Two equivalent depths are found, with values of 9.9 km and 6.6 km. The former corresponds to the Lamb mode and the latter corresponds to the Pekeris mode. These values deviate from those obtained in the previous study, especially for the Pekeris mode. The causes of this discrepancy is discussed, as well as the correspondence between the equivalent depths obtained in this study and that of the Pekeris mode detected in the recent study.