Making sense of δ18O proxies in monsoon Asia using an iCESM-driven proxy system model network
Abstract
We construct a network of speleothem, ice, and tree-ring cellulose δ18O pseudoproxies from the sites of annual resolution proxies across monsoon Asia using an 1850-2014 AMIP style isotope-enabled run of CESM. We use the output variables from iCESM along with our proxy system models (PSM) in order to answer three questions. What would be the expected strengths and signs of the correlations among members of the pseudoproxy network if (1) the pseudoproxies simply record precipitation amount, (2) the pseudoproxies record δ18Opr and (3) the pseudoproxies are modeled using proxy system models. We then compare these intra-network correlations of the pseudoproxies with those of the real proxy network. We find that the naïve assumption that the proxies simply record local precipitation cannot explain the observed relationship between the δ18O proxies. The pseudoproxy network using δ18Opr from iCESM does a much better job explaining the relationships among the proxy network. Finally, the proxy system modeled network has relationships that best match the real proxies. The discrepancies between the PSM pseudoproxies and the proxy networks can be attributed to some combination of oversimplified PSMs, problems with the GCM in capturing climate dynamics, and insufficiently short model runs. This test clearly demonstrates that isotope-enabled climate models and proxy system models are essential for interpreting δ18O paleoclimate proxies. Assumptions about proxies being controlled by a local amount effect can be right (often for the wrong reasons) or can be horribly wrong as we show in correlation maps between pseudoproxies and regional precipitation.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2016
- Bibcode:
- 2016AGUFMPP31C2299L
- Keywords:
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- 3344 Paleoclimatology;
- ATMOSPHERIC PROCESSESDE: 4912 Biogeochemical cycles;
- processes;
- and modeling;
- PALEOCEANOGRAPHYDE: 4928 Global climate models;
- PALEOCEANOGRAPHYDE: 4944 Micropaleontology;
- PALEOCEANOGRAPHY