final_program_abstracts[1]

11 IMSC Session Program
Mechanistic modeling of proxy data for Bayesian climate
reconstructions
Monday - Parallel Session 3
Susan E. Tolwinski-Ward, Michael N. Evans, Malcolm K. Hughes and Kevin J.
Anchukaitis
Paleoclimate reconstructions may benefit from the inclusion of information on the
mechanisms that form climate proxy data{ signatures of past climate variability
imprinted on natural archives through biological, physical or chemical processes. We
present a simple forward model of tree ring width formation, called VS-Lite, which is
efficient enough to be integrated into Bayesian climate reconstructions. VS-Lite runs
on monthly temperature and precipitation inputs, and accounts for the nonlinear
inuences of temperature and moisture availability on annual growth through the
principle that the more limiting factor will control the proxy response. The model
simulates two networks of North American ring width chronologies with comparable
or better skill than regression of the proxy series on the principal components of
monthly climate data. VS-Lite also performs more consistently with its calibrationinterval
skill in verification exercises.
In an analogue of classical pseudoproxy climate field reconstructions, we also
evaluate the results of a Bayesian hierarchical modeling experiment that conditions
past climate on synthetic tree-ring series. The target variables are the known
temperature and precipitation fields generated by a General Circulation Model. VS-
Lite generates the \observed" ring width data from the target fields, and also relates
past climates to these proxy series at the data level of the Bayesian hierarchy. We
compare our results to those from a more standard approach based on extrapolation of
statistical- empirical climate-ring width relationships.
Abstracts 74