Simulation of the Last Glacial Maximum climate over East Asia with a regional climate model nested in a general circulation model

Abstract The East Asian climate at the Last Glacial Maximum (LGM, 21,000 years B.P.) has been simulated using a regional climate model (RegCM2) nested in an atmospheric general circulation model of the Institute of Atmospheric Physics (IAP-AGCM). Boundary conditions for the LGM simulations are consistent with the Paleoclimate Modelling Intercomparison Project (PMIP). The results show that the nested regional model reproduces well the colder LGM climates over East Asia. The simulated annual mean surface temperature is 2 °C–4 °C colder than the present over the East Asian continent, with the coldest anomaly of about 8 °C in the vicinity of current coastal areas, where land is exposed due to lowering sea level at the LGM. The precipitation changes are complex, with general features of drier conditions over eastern China and its neighborhood and wetter conditions over western China than the present. Compared with the driving IAP-AGCM, the RegCM2 results display better agreement with geological reconstructions over East Asia. Especially in the mideastern and southern China, the simulated warming changes by the IAP-AGCM disagree with cooling in paleodata, whereas the RegCM2 reproduces realistic cooler LGM climate. Thus the current work proves that the high-resolution RegCM2 can capture additional regional details in the LGM simulation, produced by improved representation of topography and physics.