Chemistry Reference
In-Depth Information
wind direction in comparison to a clean interface (see figure 9). A strong
surface film inhibits direct renewal of the water surface and modifies the
length scale and orientation of near surface turbulence (Schimpf et al.
2004).
Fig. 9.
Examples of the formation of stationary temperature streaks at the water
surface which oriented parallel to the wind direction
Infrared observations of the effects of surface films on heat and gas
transfer have been made
in situ
(Frew et al. 2004). Figure 10 (upper)
shows the instrumented air-sea interaction catamaran LADAS operating
within a banded surface slick during the CoOP97 study. Simultaneous in-
frared imaging and measurements of wave slope and surfactants outside
and inside of the slick determined that, when the slick was entered, the sur-
face temperature distribution shifted toward lower temperatures and the
spatial scales of the temperature fluctuations at the sea surface increased
(Fig. 10, lower), characteristic of reduced surface renewal and an attenua-
tion of mixing in the aqueous boundary layer. The estimated temperature
gradient increased from 0.13 Kelvin to 0.24 Kelvin and the net heat flux
dropped from 77.2 Watt m
-2
to 36.5 Watt m
-2
. The 80% increase in ǻT and
a 50% decrease in the heat flux lead to a decrease in the estimated heat
transfer velocity from 49.7 cm h
-1
to 13.1 cm h
-1
.
