Journal of the Meteorological Society of Japan. Ser. II
Online ISSN : 2186-9057
Print ISSN : 0026-1165
ISSN-L : 0026-1165
Large-Scale Cloud Disturbances Associated with Equatorial Waves
Part I: Spectral Features of the Cloud Disturbances
Yukari N. Takayabu
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1994 Volume 72 Issue 3 Pages 433-449


Spectral features of large-scale cumulus convective systems over the tropical oceanic area are studied and classified in terms of the atmospheric equatorial waves. Three-hourly GMS infrared data for the period of 1981-1989 are utilized. Some significant features of cloud-atmosphere systems are deduced.
As an average feature for the total analysis period, robust signals are identified with Kelvin waves, westward-propagating mixed Rossby-gravity waves (MRGW), n=1 Rossby waves and n=1 westward-propagating inertio-gravity waves (WIGW). Some indications of eastward-propagating n=0 gravity waves and n=2 WIGW are also presented.
A common equivalent depth of 15-30m among different wave modes is indicated from the frequency-wavenumber distribution of cloud disturbances. On the other hand, an equatorial radius of deformation of ∼7° is deduced independently from the latitudinal distribution of cloud spectra which shows a good agreement with the above equivalent depth.
Seasonal variation of dominant cloud disturbances is also described and discussed in relation to the mean wind profile.

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