Robustness of simulating aerosol climatic impacts using regional model (WRF-Chem v3.6): the sensitivity to domain size

Abstract. Domain size can have significant impacts on regional modeling results, but few studies examining the sensitivities of regional modeling results of aerosol impacts to domain size. This study investigates the regional modeling sensitivities of aerosol impacts on East Asian summer monsoon (EASM) to domain size. The simulations with two different domain sizes demonstrate consistently that aerosols induce the cooling of lower troposphere that leads to the anti-cyclone circulation anomalies and thus the weakening of EASM moisture transport. The aerosol-induced adjustment of monsoonal circulation results in a spatial pattern of “+-+-+” for precipitation change over the continent of China. Domain size has a great influence on the simulated meteorological fields. For example, the simulation with increasing domain size produces weaker EASM circulation, which also affect aerosol distributions significantly. This leads to the difference of simulated strength and area extent of aerosol-induced changes of lower-tropospheric temperature and pressure, which further results in different locations of circulation and precipitation anomalies over the continent of China. For example, over Southeast China, aerosols induce the increase (decrease) of precipitation from the smaller-domain (larger-domain) simulation. Different domain sizes simulate consistently aerosol-induced increase of precipitation around 30° N over East China. This study highlights the important impacts of domain size on regional modeling results of aerosol impacts on circulation and precipitation, which may not be limited to East Asia. More generally, this study also implies that proper modeling of meteorological fields with appropriate domain size is one of the keys to simulate robust aerosol climatic impacts.