Chemistry Reference
In-Depth Information
Total standard deviation (K), 3rd June 1996
0.1
0.095
0.09
0.085
0.08
20.75
21
21.25
21.5
21.75
22
22.25
22.5
22.75
Time (UTC, hours)
Small scale vs large scale variability
wind
0.02
0.015
0.01
0.005
0
0
0.005
0.01
0.015
0.02
0.025
0.03
Large scale variability (K)
Fig. 10.
Upper left
: Standard deviation of temperature in the de-trended images
plotted against time for a two hour subset of the data. Lower left: the variability at
a larger scale (~1- 3 m) against the variability at a smaller scale (~0.1 - 1 m) in a
150 second period of the large excursion at ~2200 UTC.
Righ
t: A low-pass proc-
essed image at ~ 2200 UTC near the peak in variability. The image covers a 6.4m
x 6.4 m area of sea surface. The approximate wind direction and temperature
anomaly scale are shown below. Features preferentially aligned with the wind and
spaced ~ 1 metre apart are apparent
In general patterns appear to be the result of a complicated pattern of
embedded vortices, preferentially aligned approximately in the direction of
the wind, with the addition of a few relatively extreme fluctuations in
patches. It seems most likely that vortices in the upper ocean imprint tem-
perature fluctuations on the surface by partial renewal. Reorganisation of
surfactants on the surface, and resulting variability in emissivity, by vor-
tices may also play a role in their imaging. During the excursion at ~2200
UTC, there is a trend in the skewness of temperature within images, with
extreme hot values predominating over extreme cold values early in the
excursion. There appears to be highly variable mixing phenomena at play,
but a full interpretation is beyond us.
4 Laboratory observations
The interpretation of field data on surface images is often made more diffi-
cult by limitations in the absolute measurement of both surface and bulk
