Transit-time distributions: A tool to diagnose<br/><br/>rates and pathways of tracer transport in<br/><br/>advective/diffusive flow

Monday, April 12, 2010 - 9:00am - 9:45am
EE/CS 3-180
Thomas Haine (Johns Hopkins University)
Keywords: Transit-time distribution (TTD);
tracer transport rates and pathways

Abstract: I will explain the concept of transit-time distributions (TTDs) to
diagnose passive tracer transport in geophysical fluids, like the
Earth's ocean and atmosphere. The TTD is directly related to the Green's
function to the advection/diffusion equation for the concentration of a
dynamically-passive trace substance. Diagnosing and interpreting the
TTD, rather than the passive tracer field itself, focuses attention on
the advective/diffusive transport properties of the underlying flow, and
removes the influence of the tracer sources and sinks. The TTD therefore
quantifies fundamental transport rate and pathway information about the
flow. Various basic mathematical constraints on the TTD function exist,
which may illuminate traditional diagnostics of tracer stirring and
mixing. Applications of the TTD approach are presented in ocean
circulation models, and using ocean tracer measurements.
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