Bender, M. A., R. E. Tuleya, and Y. Kurihara, 1987: A numerical study
of the effect of island terrain on tropical cyclones. Monthly Weather
Review, 115(1), 130-155.
Abstract: A triply-nested. movable mesh model was used to study
the behavior of tropical cyclones encountering island mountain ranges.
The integration domain consisted of a 37° wide and 45° long
channel, with an innermost mesh resolution of 1/6°. The storms used
for this study were embedded in easterly flows of ~ 5 and ~ 10 m s-1
initially. Realistic distributions of island topography at 1/6°
resolution were inserted into the model domain for the region of the Caribbean,
including the islands of Cuba, Hispaniola, and Puerto Rico; the island
of Taiwan; and the region of Luzon in the northern Philippines.
It was found that the islands affected the basic flow as well as the wind
field directly associated with the storm system. The combination of these
effects caused changes in the track and translational speed of the storm.
In particular, in the case of the 5 m s-1
easterly flow, the storm accelerated and veered to the north well before
reaching Taiwan. For the other island distributions, the northward deflection
of the track and the increase of translational speed occurred near and
over the islands. After landfall, the surface pressure underwent rapid
filling. As the tropical cyclone passed over Hispaniola, the surface low
continued to move along with the upper level vortex as it transversed the
mountain range, while over Luzon it became obscure before reforming on
the lee side slope of the mountain. In case of Taiwan and the 10 m s-1
easterly zonal flow, secondary surface lows developed behind the mountain
range. The upper level vortex in this case became detached from the original
surface low and eventually coupled with a secondary one.
The intensity changes of the storm near and over the islands were strongly
related to the latent energy supply and the vertical coherence of the storm
system. Advection of dry air from near or above the mountain tops into
the storm area caused significant weakening of all the storm moving with
the weaker easterly flow. Storms leaving Hispaniola and moving over open
sea quickly reintensified as their vertical structure remained coherent.
On the other hand, storms leaving Luzon were disorganized and did not reintensify
until several hours later when the vertical coherence of the systems was
reestablished.
Although these experiments were performed for an idealized experimental
design and basic flow, many observed storms have exhibited similar behavior
in track deviation and decay. This implies that the effect of detailed
topography should be considered if an accurate forecast of the storm direction
and behavior is to be made.