Hadley circulations and large scale motions of moist convection in the two dimensional numerical model

As a tool for understanding the meridional circulation of the atmosphere, a two-dimensional ( latitude -- height ) numerical model is used to clarify the relationship between the Hadley circulation and large-scale motions associated with moist convection. The model is based on the primitive equations including the moist process, and two kinds of coordinates are used: the spherical coordinate and the Cartesian coordinate with a uniform rotation. The surface temperature is externally fixed and the troposphere is cooled by the radiation; unstable stratification generates large-scale convective motions. Dependencies on the surface temperature difference from north to south Delta T_s are investigated. The numerical results show that a systematic multi-cell structure exists in every experiment. If the surface temperature is constant (Delta T_s = 0 ), convective motions are organized in the scale of the Rossby deformation radius and their precipitation patterns have a periodicity of the advective time tau_D. As Delta T_s becomes larger, the organized convective system tends to propagate toward warmer regions. The convective cells calculated in the Cartesian coordinate model is very similar to those of the mid-latitudes in the spherical coordinate model. In particular, the Hadley cell can be regarded as the limit of the convective cells in the equatorial latitudes.Comment: Submitted to J. Meteor. Soc. Japan. 36 pages for text and 16 pages for figures. Only LaTeX source files for the text are included in a tar-gzipped file. Full paper including postscript figures is requested from the author (2.3 MB). Japanese version is also available from the autho

Triple linking numbers and triple point numbers of certain T2T^2-links

The triple linking number of an oriented surface link was defined as an analogical notion of the linking number of a classical link. We consider a certain $m$-component $T^2$-link ($m \geq 3$) determined from two commutative pure $m$-braids $a$ and $b$. We present the triple linking number of such a $T^2$-link, by using the linking numbers of the closures of $a$ and $b$. This gives a lower bound of the triple point number. In some cases, we can determine the triple point numbers, each of which is a multiple of four.Comment: 15 pages, 4 figures, minor modification