A wavelet analysis of a three-dimensional 7-day explicit simulation of the
tropical cloud systems in the Global Atmosphere Research Programme (GARP) A
tlantic Tropical Experiment Phase III is performed. Three physically distin
ct regimes (squall line, nonsquall cloud cluster, and scattered convection)
in a doubly periodic domain are analyzed using discrete Meyer wavelets. Th
ese wavelets are complete and facilitate the inversion of the decomposed mo
des.
The full wavelet spectra well characterize the spatial localization of each
physical variable, in particular, the vertical velocity and the condensate
fields. The probability distribution of the wavelet coefficients is non-Ga
ussian despite the horizontal winds, the temperature, and humidity being cl
osely Gaussian in physical space. This demonstrates the effectiveness of th
e wavelet basis for analyzing cloud system organization. The full wavelet s
pectrum also selects a preferred spatial orientation of the convective orga
nization in physical space.
A pseudospectrum is defined by taking the maximum absolute value of the wav
elet coefficients for a given horizontal wavenumber vector as the spectrum
coefficient. Unlike the conventional spectrum, this pseudospectrum objectiv
ely selects the observed convective-scale and mesoscale structure character
istic of observed mesoscale convective systems.
The results demonstrate the broad utility of discrete Meyer wavelet analysi
s for objectively characterizing the structure and organization of multisca
le convective cloud systems in an objective way.