MODELLING ANALYSES ON THE MONSOON PRECIPITATION CHANGE OVER CHINA DURING THE LAST INTERGLACIAL
Monsoon precipitation is an important component of the global water cycle.Previous studies have mainly focused on contemporary and future monsoon precipitation,with relatively limited work on monsoon precipitation changes during past warm periods,especially at the regional scale from a modelling perspective.Using all available simulation data from fifteen global coupled climate models participating in the latest phase 4 of the Paleoclimate Modelling Intercomparison Project(PMIP4),the present study centrally investigates changes in monsoon precipitation and its intensity over China during the Last Interglacial(LIG:approximately 127 ka before present)relative to the preindustrial period,and analyses the related dynamic mechanisms.Results show that all models can reasonably reproduce the large-scale characteristics of the observed annual,winter,and summer precipitation climatology over China.Compared to the preindustrial period,with an overall northwestward expansion of the monsoon region,the multimodel ensemble mean shows an increase of 37％in the monsoon precipitation and a strengthening of 6％in the monsoon precipitation intensity over China during the LIG,with a qualitative agreement among individual models.In response to the LIG orbital forcing,the summer surface warming is stronger over middle latitudes than that over lower latitudes of China,leading to a decrease in the meridional temperature gradient and thus the weakening and poleward shift of the East Asian westerly jet.The weakened westerlies suppress the water vapor transport from the upstream and reduce the monsoon precipitation in the upper reaches of the Yellow River,while the northward movement of the westerly jet increases the monsoon precipitation in North China but suppresses the precipitation in the lower reaches of the Yangtze River.On the other hand,the LIG summer surface warming is overall stronger in the East Asian continent than that in the adjacent oceans of the western North Pacific and the South China Sea,which causes increases in both zonal and meridional land-sea thermal contrasts and thus sea level pressure gradients,enhancing the East Asian summer monsoon circulation and associated water vapor transport from the adjacent oceans to the inland of China.Collectively,the monsoon region expands,the monsoon precipitation increases,and the monsoon precipitation intensity strengthens as a whole over China during that interglacial period.In general,the LIG monsoon precipitation change over China simulated by the multimodel mean is qualitatively consistent with most precipitation reconstruction records over the monsoon region,although uncertainties still exist in simulations and reconstructions.This study helps to gain a deeper understanding for the mechanism of regional monsoon precipitation changes under the warming background,thus providing reference for scientific projection of its future changes.
Last InterglacialChinamonsoon precipitationmodellingPMIP4 simulations
万方数据
维普
