  Recent analyses of the WMAP data have suggested that the low-order multipoles
of the CMB anisotropy distribution show cosmologically interesting and
unexpected morphologies and amplitudes. In this paper, we apply a power
equalization (PE) filter to the high-latitude WMAP data in order to reconstruct
these low-l multipoles free from the largest Galactic foreground modelling
uncertainties in the Galactic plane. The characteristic spatial distributions
of the modes of order l=2,3,4,5 have been determined as a function of
frequency, sky coverage and two methods for foreground correction: using the
template fitting results of Bennett et al. (2003) and by a simple linear
projection scheme assuming the spectral dependence of the foreground
components. Our analyses suggest that the K and Ka frequency bands remain
significantly contaminated by residual foreground emission for the WMAP Kp2
mask. However, the l=3,4,5 multipole maps for the Q, V and W channels indicate
that, after foreground cleaning, these multipoles are dominated by the CMB
anisotropy component. We confirm the Tegmark et al. (2003) result that the
octopole does indeed show structure in which its hot and cold spots are centred
on a single plane in the sky, and show further that this is very stable with
respect to the applied mask and foreground correction. The estimated quadrupole
is much less stable showing non-negligible dependence on the Galactic
foreground correction. Including these uncertainties is likely to weaken the
statistical significance of the claimed alignment between the quadrupole and
octopole. Nevertheless, these anisotropy patterns are also present for in
COBE-DMR data, and are unlikely to be associated with instrumental systematic
artifacts.
