Millennium-length precipitation Reconstruction over South-eastern Asia: aPseudo-Proxy Approach

Abstract. Quantifying hydroclimate variability beyond the instrumental period is essential for putting current and future fluctuations into long-term perspective and to provide a test-bed for evaluating climate simulations. For South-earstern Asia such quantifications are scarce and millennium-long attempts are still missing. In this study we take a pseudo-proxy approach to evaluate the potential for generating summer precipitation reconstructions over South-eastern Asia during the past millennium. The ability of a series of novel Bayesian approaches to generate reconstructions at either annual or decadal resolutions and under diverse scenarios of pseudo-proxy records' noise is analysed and compared to the classic Analogue Method. We find that for all the algorithms and resolutions a high-density of pseudo-proxy information is a necessary but not sufficient condition for a successful reconstruction. Among the selected algorithms, the Bayesian techniques perform generally better than the Analogue Method, being the difference in abilities highest over the semi-arid areas and in the decadal-resolution framework. The superiority of the Bayesian schemes indicates that directly modelling the space and time precipitation field variability encapsulates more relevant value than just relying in similarities within a restricted pool of observational analogues, in which certain hydroclimatic regimes might be absent. Using a pseudo-proxy network with locations and noise-levels similar to the ones found in the real world, we conclude that performing a millennium-long precipitation reconstruction over South-eastern Asia is feasible as the Bayesian schemes provide skilful results over most of the target area.