Tuleya, R. E., 1991: Sensitivity studies of tropical storm genesis
using a numerical model. Monthly Weather Review, 119(3),
721-733.
Abstract: This study investigates two cases of the FGGE III-B tropical
cyclone genesis study of Tuleya (1988) in more detail. These two cases
occurred within a week of one another in the tropical North Atlantic in
August 1979. One disturbance developed into Hurricane David, the other
did not develop past the depression stage. At one point in their evolution
the disturbances had quite similar values of low-level vorticity. In the
developing case of Hurricane David, the disturbance propagated along in
a low-level wave trough with an accompanying high wind maximum. In the
nondeveloping case the initial disturbance was also embedded in a wave
trough with an associated wind maximum. This low-level wave propagated
westward leaving the depression in its wake. The different environmental
flow was responsible for the different behavior. Synoptic and budget analyses
revealed significant differences in disturbance structure and vorticity
and equivalent potential temperature tendencies at the time of approximate
equal strength of the two disturbances. The evolution of these two disturbances
was quite robust even to reasonable increases to the initial relative humidity.
Supplementary experiments of the developing case were performed by altering
the sea surface temperature and surface evaporation. It was found that
the difference in storm evolution was minor in a case when climatological
mean values of sea surface temperatures were specified.
The climatological mean values were ~0.5 K lower than the August 1979 mean
used in the control simulation. In addition, an experiment without evaporation
led to a propagating easterly wave with little development. Furthermore,
when the evaporation was specified to a climatological constant value,
there was intensification into a weak tropical storm with a rather peculiar
structure. Apparently, at least in this case, processes other than evaporation-wind
feedback led to moderate storm intensification.