Assessment of PMIP3 model simulations of megadroughts over the eastern China during the last millennium

The simulated spatiotemporal characteristics and variability of decadal megadroughts over the eastern China during the last millennium of 7 model simulations from the Paleoclimate Modelling Intercomparison Project Phase 3 (PMIP3) archive were assessed, and the corresponding mechanisms of the megadroughts were also investigated. The simulated megadrought features of frequencies, durations, magnitudes and spatial distributions were compared with reconstructed data. Comparison showed that climate models can reasonably reproduce the major features of megadroughts, however, the simulated megadroughts are not temporal synchronous with the reconstructed megadroughts, indicating that the internal variability rather than external forcing initiates the observed megadroughts. The simulated spatial distributions of wind and sea level pressure (SLP) anomalies during megadrought years showed that megadroughts over the eastern China corresponded to weakening of the East Asia Summer Monsoon (EASM) and strengthening of the East Asia Winter Monsoon (EAWM). A pattern of sea surface temperature anomalies (SSTA) with significant negative SSTA over the western central North Pacific and significant positive SSTA over eastern North Pacific and equatorial Pacific, resembling a positive PDO-like pattern, was found to suppress precipitation in eastern China. Therefore, it could be concluded that that internal climate variability is the main trigger of the megadroughts over the eastern China, while the North Pacific decadal variability is considered the key driving factor influencing the EASM and EAWM.