A further study of the mechanisms of cell regeneration, propagation, and development within two-dimensional multicell storms

The mechanisms of cell regeneration, development, and propagation within a two-dimensional multicell storm proposed by Lin, Deal, and Kulie (hereafter LDK) were further investigated by conducting a series of sensitivity tests . LDK's advection mechanism was reexamined by performing simulations utiliz ing a plateau with five additional wind profiles having a wider range of sh ear. All five cases gave results that show that the cell regeneration perio d decreases with the storm-relative midlevel inflow, similar to that propos ed by LDK. It was also found that a rigid lid is not an appropriate upper b oundary condition for multicell storm simulations. In order to test whether the advection mechanism is responsible for cell re generation with a different sounding, an idealized sounding was used. A mul ticell storm was produced along with a strong density current and gust fron t updraft. Investigation of this storm supports the advection mechanism wit hin the growing mode and a gravity wave mechanism in the propagation mode, as proposed by LDK. From further investigation, the relaxation mechanism pr oposed by Fovell and Tan was shown to exist within these simulations yet fo und to be dependent on the advection mechanism to cause cell regeneration. To avoid some problems that occurred when using a plateau, a prescribed hea t sink was used to produce a more realistic density current. This experimen t demonstrates that the advection mechanism is responsible for cell regener ation and the gravity wave mechanism is responsible for cell propagation wi thin the storm. It was found that without precipitation loading, an individual cell is stil l able to split. In this case, the compensating downdraft produced by verti cal differential advection is responsible for cell splitting and merging.