Fusion of proxy and model data to resolve Southern Hemisphere atmospheric circulation patterns during the common era

S. A. Browning, I. D. Goodwin, S. J. Phipps

Research output: Contribution to conferenceAbstract

Abstract

Recently available global climate model (GCM) experimental data such as the CMIP5/PMIP3 last millennium simulations combined with expanding archives of proxy records provide an unprecedented opportunity to understand the climatic history of the Southern Hemisphere. The challenge for paleoclimate researchers is to produce quantitative climatic reconstructions that make the best use of all available data and are coherent across multiple lines of evidence. As part of the AUS2K regional contribution to the PAGES (Past Global Changes) 2K network we present decadal resolution sea level pressure field reconstructions for the Southern Hemisphere mid-latitudes during Little Ice Age (1350-1850CE). The spatial reconstructions have been produced using evidence from a multivariate suite of proxy records to derive climate state analogues from two complementary surrogate datasets, a 10,000yr MK3L simulation at seasonal resolution and the modern NCEP/NCAR re-analysis at daily resolution. The reconstruction methodology is highly flexible in terms of input data, synthesising a range of proxy information including temperature, hydrological and wind field records. Best matching climate state analogues are identified from each of the surrogate datasets by calculating the minimum Euclidean distance between a vector of standardised multivariate proxy records and an array of corresponding pseudo-proxy timeseries. By selecting analogues using only information derived from the geographic location of the proxy records the methodology makes no assumptions about the stationarity of teleconnection patterns identified during the calibration period. Common Era paleoclimate records from the Southern Hemisphere display evidence of persistent anomalies such as multi-decadal droughts that lie outside the range of variability seen in the modern record. The presented reconstructions resolve changes in persistent atmospheric anomalies that are consistent with proxy evidence and can be interpreted in terms of changes in the leading modes of modern mid-latitude climate variability such as the Southern Annular Mode, The Pacific South America Modes and zonal wavenumber 3 circulation.
Original languageEnglish
Number of pages1
Publication statusPublished - 2012
EventAmerican Geophysical Union Fall Meeting (45th : 2012) - San Francisco, CA
Duration: 3 Dec 20127 Dec 2012

Conference

ConferenceAmerican Geophysical Union Fall Meeting (45th : 2012)
CitySan Francisco, CA
Period3/12/127/12/12

Keywords

  • Data processing
  • Atmospheric circulation
  • Models

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