Observations and Modelling of Fronts and Frontogenesis

OBSERVATIONS AND MODELLING OF FRONTS AND FRONTOGENESIS
IN THE UPPER OCEAN
I. INTRODUCTION
This thesis comprises two separate projects. The common
theme is fronts and frontogenesis in the upper ocean.
Fronts, regions of unusually large horizontal gradients
in fluid properties, are an important form of physical
oceanographic variability. Though they have received
considerable attention from oceanographers (the recent
monograph The Physical Nature and Structure of Oceanic Fronts
(Fedorov, 1986) contains 279 references), a full
understanding of their role in the ocean still awaits us.
In Chapter II, we present an analysis of upper ocean
temperature data collected near the North Pacific Subtropical
Frontal Zone. In this region of the North Pacific, the
large-scale meridional gradients of temperature, salinity,
and density are intensified in a Frontal Zone. Wind-driven
convergence is the probable primary cause of this
intensification (Roden, 1975). Many small scale fronts are
evident in the data. Baroclinic instability is likely
important in the development of these smaller scale features.
In Chapter III, we present a model for wind-driven
therniocline upwelling at a coastal boundary. In this case,
the action of the wind on the ocean is again frontogenetic.