The dynamics of modulational interaction between short wavelength drif
t waves and long wavelength trapped ion convective cells are investiga
ted,. It is shown that modulational instability growth rates can excee
d linear trapped ion mode growth rates. A simple set of envelope equat
ions for this system has been derived and solved. A quasi-universal fi
nal state of dipolar anisotropic convective cells with trapped drift w
aves is indicated. Drift waves with k(perpendicular-to)rho(s) greater-
than-or-equal-to 1 are trapped and undergo strong modulation.