THEORETICAL AND SYNOPTIC STUDIES OF LOW-LEVEL TROPICAL PERTURBATIONS.
TRAVELERS RESEARCH CENTER INC HARTFORD CONN
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This study deals theoretically with a the effect of a variable Coriolis parameter on the propagation and growth of small perturbations in a uniformly moving, statically unstable atmosphere and b the stability properties of small perturbations in a statically unstable baroclinic zonal flow. A variable Coriolis parameter results in a speeds of propagation that, depending on static stability and latitude, may be either westward or eastward relative to the basic flow and b an increase in scale of marginally unstable perturbations. Perturbations that develop in a statically unstable baroclinic flow are much larger than those that develop in a uniformly moving atmosphere and range from a few hundreds to a few thousands of kilometers. Short waves, unstable in a resting atmosphere, appear unable to feed on the potential energy of basic flow. The incomplete synoptic part deals with a modestly intense low-level perturbation. Tentative results show it to be embedded in a conditionally unstable, slightly baroclinic easterly flow, to have a wavelength of about 1600 km, and to be moving faster than the flow in which it is embedded. The ratio of its greatest horizonal wind divergence to its greatest relative vorticity is about 0.5. Author