Reconstruction of Dynamical Fields of the Common Era

Abstract:

Data assimilation (DA)-based reconstructions provide a means of optimally combining proxy data with the statistical-dynamical constraints of a climate model. Through these reconstruction techniques one may explicitly reconstruct any climate variable of interest, from surface temperature to atmospheric or oceanic circulation. Yet standard DA approaches must be modified to meet the challenges of the available paleoclimatic data, including dating uncertainty and multiple time scales. We present the first DA-based reconstruction technique that can address dating uncertainty and arbitrary proxy time scales. We examine this technique with pseudoproxy tests incorporating proxy dating uncertainty, varying proxy time scales, varying proxy network and noise characterizations and generating pseudoproxies through proxy system models. We also apply this DA technique to the PAGES2k proxy database over the Common Era. Through both the pseudo and real proxy tests we identify dynamical fields of the coupled atmosphere-ocean system that can be most robustly reconstructed.