We use a set of mixed-layer drifting buoy trajectories from the Califo
rnia Current (20 degrees N-40 degrees N) during 1985-1990 to obtain st
atistically reliable estimates of the mean currents, the mean variance
field, and the geographically varying. diffusivity, integral timescal
es, and integral space scales. Typical values for the diffusivity are
1.1-8.7 x 10(7) cm(2) s(-1), while the timescales and space scales are
2.1-7.1 days and 16-59 km, respectively. The variance field displays
a strong westward gradient out to 125 degrees W, and diffusivity shows
a tendency to decrease toward the southwest part of the domain. Signi
ficant anisotropy is found in the variance field near the coastal boun
dary and at 30 degrees N, 130 degrees W, which is the region where the
subarctic and northern subtropical fronts approach the California Cur
rent. The antisymmetric component of the diffusivity tensor indicates
that cyclonic eddies dominate the mesoscale signature of drifters in t
his region. We seek simple parameterizations to relate the scales of m
otion of the random velocity field to the diffusivity by testing least
squares fits to kappa(infinity) proportional to u(0)(2)T and kappa(in
finity) proportional to u(0)L, where u(0)(2) is the velocity variance.
We found no cases for which these two hypotheses could be distinguish
ed. For the meridional component the linear regressions are not succes
sful, which suggests that the meridional departure velocities result f
rom a flow regime that is significantly organized by, for example, wav
es or coherent structures. A subset of the drifters measured temperatu
re along their tracks, and we use the resultant data to produce the fi
rst direct estimates of the horizontal eddy heat nux divergence based
on Lagrangian estimates. In addition, we separately compute the ''eddy
diffusivity'' parameterization of the eddy heat flux divergence, del
. [u'theta'] = del(kappa del Theta), using our diffusivity estimates a
nd a sea surface temperature climatology. The two independent terms ag
ree well, which provides a measure of reassurance about the diffusivit
y estimates. The eddy heat flux divergence in the California Current i
s very small (<5 W m(-2)) and does not appear to be significant in the
long-term heat budget of the upper ocean in this region.