West Antarctic Ice Core West Antarctic Ice Core Chemistry and Self-Organizing Chemistry and Self-Organizing

Maps: A First LookMaps: A First Look

David B. Reusch and Richard B. AlleyDavid B. Reusch and Richard B. AlleyDepartment of GeosciencesDepartment of Geosciences

and EMS Environment Instituteand EMS Environment Institute

Penn State UniversityPenn State University

Funded by the Office of Polar ProgramsFunded by the Office of Polar Programsand the Division of Atmospheric Sciences, and the Division of Atmospheric Sciences,

National Science FoundationNational Science Foundation

Paul A. MayewskiPaul A. MayewskiDepartment of Earth SciencesDepartment of Earth Sciencesand Climate Change Instituteand Climate Change Institute

University of MaineUniversity of Maine

Self-organizing Maps (SOMs)Self-organizing Maps (SOMs)

A projection (mapping) A projection (mapping) from the multidimensional from the multidimensional input space to the 2-D input space to the 2-D pattern spacepattern spacePatterns arranged in a Patterns arranged in a grid by similarity (closer = grid by similarity (closer = more)more)

A tool for extracting generalized A tool for extracting generalized patterns of variability from patterns of variability from

multivariate datamultivariate data

Flexible grid size based on Flexible grid size based on problem being studiedproblem being studied

Self-organizing Maps (SOMs)Self-organizing Maps (SOMs)

Each input record Each input record matches one pattern matches one pattern most closelymost closelyRecords matching the same Records matching the same pattern have it in commonpattern have it in common

Also used for classifying multivariate Also used for classifying multivariate data and studying its temporal data and studying its temporal

behaviorbehavior

Basis for frequency, Basis for frequency, transition and trajectory transition and trajectory mapsmaps

Holocene West AntarcticaHolocene West Antarctica Environmental Context Environmental Context

Retreating ice sheetRetreating ice sheet Elevation changes at Siple DomeElevation changes at Siple Dome Changing distance to sea ice/open Changing distance to sea ice/open

waterwater Other circulation changes?Other circulation changes?

A Brief Look AtA Brief Look AtTaylor DomeTaylor Dome

Future WorkFuture Work

Further SOM-based analysis of ice Further SOM-based analysis of ice core chemistry data to assess the core chemistry data to assess the value of this technique for these datavalue of this technique for these data Continue with Siple Dome/Taylor DomeContinue with Siple Dome/Taylor Dome Add other useful sites/coresAdd other useful sites/cores Add non-seasalt chemistryAdd non-seasalt chemistry

Comparisons with other data sources Comparisons with other data sources on the climate history of this regionon the climate history of this region