  The horizontal stirring properties of the flow in a region of the
East-Australian Current are calculated. A surface velocity field derived from
remotely sensed data, using the Maximum Cross Correlation method, is integrated
to derive the distribution of the finite-time Lyapunov exponents. For the
region studied (between latitudes 36 S and 41 S and longitudes 150 E and 156 E)
the mean Lyapunov exponent during 1997 is estimated to be 4 x 10^{-7} s^{-1}.
This is in close agreement with the few other measurements of stirring rates in
the surface ocean which are available. Recent theoretical results on the
multifractal spectra of advected reactive tracers are applied to an analysis of
a sea-surface temperature image of the study region. The spatial pattern seen
in the image compares well with the pattern seen in an advected tracer with a
first-order response to changes in surface forcing. The response timescale is
estimated to be 20 days.
