Impact of horizontal spatial resolution on the derivation of the source–receptor relationship—an extra-tropical cyclone case

A numerical study has been made to evaluate the impact of horizontal resolution on the estimation of the source—receptor (S—R) relationship. Numerical experiments with four different horizontal grid sizes have been performed for an extra-tropical cyclonic episode in East Asia. CSU RAMS and YU-SADM (Yonsei University’s sulfuric acid depositionmodel) have been used to simulate meteorological and pollutant fields, respectively.

In this study, enhanced spatial resolution has improved the simulation of an extra-tropical cyclone, cold front and associated precipitation systems. As spatial resolution increases, the circulation associated with the cyclone and cold front becomes stronger, and the amount of frontal rainfall increases. This study has shown that enhancement of spatial resolution tends to increase self-contributions but decrease foreign contributions to the wet deposition associated with an extra-tropical cyclone. It has been found that increased precipitation for enhanced spatial resolution reduces the amount of transported pollutant but increases the wet deposition of locally emitted pollutants. The larger self-contribution for higher resolutions may also be partially due to the increased strength of resolved convection. The impact of enhancing spatial resolution on dry deposition is felt mostly over downstream regions where the centres of the lows and fronts pass. Contributions from upstream sources increase as cyclonic circulation becomes stronger with increasing spatial resolution. On the other hand, enhancing spatial resolution does not significantly affect the S—R relationship for eitherdry or wet deposition in the other regions where the extra-tropical cyclone does not pass. This study indicates that improved simulation of a cold front does not significantly affect the S—R relationship for wet deposition over the area of passage of the cold front. An additional discussion infers a S—R relationship for the wet deposition associated with a typical extra-tropical cyclone.