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Seminar: Monday, November 28, 2022

Dr. Izett sits in a field of purple flowers with the backdrop of rocky mountains. Dr. Izett smiles at the camera wearing dark sunglasses and a black pull-over.
Robert Izett
Dalhousie University and the Ocean Frontiers Institute

Please join us on Monday November 28 at 12:40 pm for the UGA Department of Marine Sciences seminar. Dr. Robert Izett, a Postdoctoral Research Fellow at Dalhousie University and the Ocean Frontiers Institute, will present his work entitled, This little piggy went to market, this little PIGI went to sea: New tools to estimating mixed layer net community production from autonomous O2 and N2 observations. If anyone would like to meet with the speaker after the talk, please email Dr. Rivero-Calle to set up a meeting (


In this seminar, I present new tools for estimating mixed layer net community production (NCP) using underway, ship-based optode and gas tension device (GTD) measurements of O2 and N2. The underway gas measurements lead to the derivation of a new NCP tracer, ΔO2/N2', which is shown to be a near-analog for the widely-used NCP tracer, ΔO2/Ar. In contrast to ΔO2/Ar measurements which require complex and expensive instrumentation to make at sea, ΔO2/N2' is derived using relatively inexpensive sensors and simple numerical calculations. In this seminar, I first provide an overview of a fully-autonomous O2/N2 measurement system, named the “Pressure of In-situ Gases Instrument” (i.e., PIGI). I then describe the derivation of ΔO2/N2' using a simple one-dimensional mixed layer model and freely available environmental data. By applying these measurements and model calculations in the Subarctic Northeast Pacific and Canadian Arctic Ocean, I finally demonstrate a strong spatial coherence between mass spectrometry-derived ΔO2/Ar and PIGI-derived ΔO2/N2' observations across a range of hydrographic regimes. Notwithstanding some limitations, I show that offsets between mixed layer NCP estimates derived from ΔO2/Ar and ΔO2/N2' are typically smaller than other errors in NCP calculations. The new approach has the capacity to significantly expand global NCP measurements from various underway platforms, including research vessels, volunteer observing ships, and/or autonomous (unattended) surface vehicles. I conclude the seminar by describing continued developments and plans for PIGI-based NCP measurements.

The Zoom link for those of you joining from your computers will be Marine Sciences Room 239 and the Skidaway Auditorium will have a live feed of the talk.


The room will be open at 12:20 pm, and the talk will begin at 12:40 pm.


Our complete schedule of talks this semester is listed on the calendar:


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