積雲対流の周囲に励起される重力波

Abstract

The gravity wave response of a quiescent atmosphere to a growing convective cell is investigated, using a non-hydrostatic compressible model. A series of experiments are carried out, categorized as: (i) MOIST experiments that employ a parameterization of Kessler warm cloud microphysics, and (ii) DRY experiments performed with a prescribed heating function. The heating function used in the DRY experiments is based on the latent heat released and absorbed in the convective cell of the MOIST experiment. A shallow mode disturbance having a strong updraft at low levels develops near the convective cell when the cell has reached the later growing stage. This disturbance is interpreted as the gravity wave response to higher vertical-mode forcings that increase during the earlier growing stage of the convective cell, and decrease in the later growing stage. For this shallow mode disturbance, not only the increase in the height of heating, but also the narrowness of the width of heating are important. It is found that this shallow mode disturbance is a particular response to a growing convective cell. The updraft in the low levels of the shallow mode disturbance provides a net vertical displacement. This results from a top-heavy heating profile which forms at the maximum stage of the convective cell. The newly developed cell near the original cell is probably triggered by this net vertical displacement.