Lecture 18 - Tracers in the Ocean Flashcards
(15 cards)
What is an ocean tracer?
A “label” used to track ocean transport, mixing, and circulation.
What are the three types of ocean tracers?
Conventional, transient, and deliberate tracers.
What are conventional tracers?
Natural properties like temperature, salinity, oxygen, and nutrients; can be conservative or non-conservative.
What makes a good transient tracer?
Stable, known surface concentration, no natural sources/sinks, low background, and measurable with high precision.
What are transient tracers?
Tracers with time-varying distributions, usually human-derived (e.g., tritium, CFCs).
What are deliberate tracers?
Tracers like dyes or gases intentionally released to track a body of water.
What is tritium (³H) used for in oceanography?
racing upper ocean circulation and calculating tracer age based on radioactive decay.
What are CFCs and why are they useful as tracers?
Synthetic gases that are stable, unreactive, and track water mass ventilation age due to their known atmospheric history.
How is tracer age determined with CFCs?
From the ratio of two CFCs, compared to atmospheric input functions.
What are some applications of tracer age?
Determining ocean circulation, validating models, and estimating carbon transfer.
What is SF₆ used for?
deliberate tracer for tracking water mass mixing, vertical diffusion, and gas exchange.
It’s inert, non-toxic, cheap, and detectable in tiny amounts.
What was SOIREE?
The Southern Ocean Iron Release Experiment – added iron and SF₆ to stimulate and track phytoplankton growth.
What is the dual tracer approach for gas exchange?
Using SF₆ with another tracer (e.g., Rhodamine) to estimate transfer velocity (k) at the ocean surface.
What types of tracer forms are used in oceanography?
Gases, liquids, radionuclides, and even floating plastic debris.
What determines a water parcel’s tracer age?
The time since it was last exposed to the atmosphere.
