Observations and Modelling of Fronts and Frontogenesis

advection of a tongue of cold water in a frontal meander, but
cooling by entrainment may also have contributed. Large
(1986) present evidence for large entrainment events in
the North Pacific during the fall season. These appear to be
shear mixing events driven by the near-inertial response to
storms.
A 0.7 °C temperature inversion, roughly 5 kin wide,
occurred at 100 kin, near the well-compensated front
encountered during Tow 1. Isotherm cross-sections of this
feature are displayed in Figure II,5c. The presence of an
inversion implies an anomalous local T-S relation, according
to which the warmer, more saline water is denser. The warm,
dense water most likely originated from the warm side of the
front, with which it may be contiguous. The wind record
(Table 11.2) suggests an Ekman flow to the southeast, nearly
normal to the tow track, so that the cooler surface water may
have been advected over the warmer water from the northwest.
II.4.a Statistics
11.4 Analysis
To characterize the temperature variability
statistically, we have calculated probability densities of
temperature gradient and temperature deviation from
climatology. Table 11.3 lists climatological surface
14