GEOMAR Helmholtz Centre for Ocean Research Kiel
Wischhofstr. 1-3
D-24148 Kiel
Germany
Phone: +49-431 600-0
Fax: +49-431 600-2805
E-mail: info(at)geomar.de
December 20, 2021: Ocean Circulation and Climate Dynamics Colloquium
Dr. Nora Loose, University of Colorado, Boulder, USA: Oceanic teleconnections in the North Atlantic: "From dynamical proxy potential to observing system design"
When? Monday, 20. December 2021 at 4pm
Where? ZOOM meeting room: https://geomar-de.zoom.us/j/84863047351?pwd=NDc1bkR0Q3lldUhnRHphK1VWUnYyQT09
Meeting-ID: 848 6304 7351
Kenncode: 707547
We would like to inform you that this seminar will be exceptionally recorded. We will only record the presentation without the Q&A part.
Abstract:
Oceanic quantities of interest (QoIs), for example, ocean heat content or transports, are often inaccessible to direct observation, due to the high cost of instrument deployment and logistical challenges. Therefore, oceanographers seek proxies for undersampled or unobserved QoIs. Conventionally, proxy potential is assessed via statistical correlations, which measure covariability without establishing causality. In this talk, we introduce an alternative method: quantifying dynamical proxy potential. Using an adjoint model, this method unambiguously identifies the physical origins of covariability. A North Atlantic case study illustrates our method within the ECCO (Estimating the Circulation and Climate of the Ocean) state estimation framework.
We find that wind forcing along the eastern and northern boundaries of the Atlantic drives a basin-wide response in North Atlantic circulation and temperature. Due to these large-scale teleconnections, localized temperature observations can inform transport QoIs at great distances.
Finally, we establish a link between the notion of dynamical proxy potential and Hessian-based uncertainty quantification (UQ) in ocean state estimation. Within the UQ framework, dynamical proxy potential can be interpreted to measure uncertainty reduction in the QoI, given the new information provided by the observations. With its two interpretations, dynamical proxy potential is simultaneously rooted in (i) ocean dynamics and (ii) uncertainty quantification and optimal observing system design, the latter being an emerging branch in computational science. The new method may therefore foster dynamics-based, quantitative ocean observing system design in the coming years.
