Reconstructing MIS 3 ocean states from proxy records via an inverse method - a quantification of uncertainties
Abstract
Proxy records from Marine Isotope Stage 3 (MIS 3) during the last glacial cycle show several rapid climate fluctuations between cold, stadial conditions and mild, interstadial conditions, known as Dansgaard-Oeschger events. Using a full ocean general circulation and sea ice model in a deterministic inverse problem, we aim to obtain two seasonally varying equilibrium states that represent these two distinct climate states and that are consistent with both the model dynamics and the globally available proxy data. While the same four-dimensional variational method has been used for ocean model - proxy data comparison in previous attempts, e.g., applied to the Last Glacial Maximum, an error estimate on the reconstructed ocean state has not been considered in these studies. A way to quantify such uncertainties is through the inverse of the Hessian matrix of the cost function, evaluated at the minimizer of the cost function. Here we present a preliminary step, in which we work with artificial data, subsampled from two model states that are meant to mimic stadial and interstadial conditions, respectively. We use the Hessian method to explore the capability of the available MIS 3 proxy data to constrain ocean circulation, taking into account its sparsity and uncertainties. We furthermore address the question of how errors in proxy records propagate onto uncertainties in inferred model variables and quantities of interest of the climate system such as ocean heat transport.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2016
- Bibcode:
- 2016AGUFMPP31C2291L
- Keywords:
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- 3344 Paleoclimatology;
- ATMOSPHERIC PROCESSESDE: 4912 Biogeochemical cycles;
- processes;
- and modeling;
- PALEOCEANOGRAPHYDE: 4928 Global climate models;
- PALEOCEANOGRAPHYDE: 4944 Micropaleontology;
- PALEOCEANOGRAPHY