A Gridded Reconstruction of Warm Season Precipitation for Asia Spanning the Past Half Millennium

Abstract

The authors reconstructed May-September precipitation over the Asian continent (58-558N, 608-1358E) back to AD 1470 on the basis of tree-ring data, historical documentary records, ice core records, and the few long-term instrumental data series available in the region. They employed the method of Regularized Expectation Maximization (RegEM) and applied it to 44 subregions within the continent. Verification exercises demonstrate that the reconstruction is skillful over most of the study domain, with eastern China, India, and other regions of humid climate displaying the greatest skill. Lower reconstruction skill is observed in semiarid and arid regions, which was attributable at least in part to the scarcity of observations available for calibration/ validation. The precipitation reconstructions agree well with previous reconstructions, where they are available. The explanatory value of the reconstruction is illustrated using five historically documented severe droughts in north-central China during the past half millennium. The reconstructions both validate and provide a larger-scale context for understanding these past climate events and their relationship with the Asian summer monsoons.

Multi-proxy reconstructions of May–September precipitation field in China over the past 500 years

“…Figure 6 shows the spatial patterns of the May-September precipitation field relative to the 1961-1990 climatological mean during five severe droughts in China. The selection of five drought periods follows Feng et al (2013) but the spatial patterns in our reconstruction display some clear differences from their results. A "north drought with south flooding" dipole pattern in eastern China is seen in Fig.…”

“…This offers an excellent and timely opportunity to integrate the data from tree-ring records from western China and historical records in eastern China to reconstruct the precipitation field for the whole of China. Feng et al (2013) reconstructed the precipitation field in East Asia using multi-proxy records that reflect the variability in precipitation (e.g. Liu et al, 2016).…”

Atmospheric circulation processes contributing to a multidecadal variation in reconstructed and modeled Indian monsoon precipitation

“…While considerable improvements have been made to correct it over the years, it remains an issue under investigation. Meanwhile, the reconstructed data suffer a bias of underestimating the precipitation because of saturation of biological processes to precipitation information [Feng et al, 2013]. While the difference between the simulated and reconstructed precipitation is from both the mean values and fluctuations of these data series, the fluctuations around their means are similar [Feng et al, 2013].…”

“…Meanwhile, the reconstructed data suffer a bias of underestimating the precipitation because of saturation of biological processes to precipitation information [Feng et al, 2013]. While the difference between the simulated and reconstructed precipitation is from both the mean values and fluctuations of these data series, the fluctuations around their means are similar [Feng et al, 2013]. In other words, while the simulated and reconstructed precipitations may have slightly different mean values, their variations are comparable.…”

“…As an effort to address these questions, we examine multidecadal variations in the Indian summer monsoon precipitation over the past half millennium from A.D. 1470 to 1999, using a recently reconstructed gridded data set of May-September total precipitation [Feng et al, 2013]. Meanwhile, we evaluate the data set from simulations of paleo-climate circulation and precipitation by a paleo-general circulation model (GCM).…”