Uncertainties of Precipitation Simulated By the CMIP5 Models and Its Sensitivity to Model Resolution

Abstract:

By investigating the inter-comparison between individual model and multi-model ensemble (MME) from the Coupled Model Intercomparison Project Phase 5 (CMIP5), model uncertainty on summer precipitation over Eastern China is analyzed. Although MME has the ability in reproducing summer precipitation over Eastern China, large model spread exists among models in both climatology and interannual variation. The model uncertainties are small in relatively weak rainfall, but large in heavy or none rainfall. Two possible reasons are proposed for the large uncertainties: different partitioning of stratiform/convective precipitation and horizontal resolutions. As a continued work, sensitivity of uncertainty to model resolutions are further investigated from the aspect of global precipitation. High-resolution MME (HMME) has much lower-frequency but stronger precipitation events than low-resolution MME (LMME) over most tropical regions. The partitions of convective and stratiform precipitation are quite different between the HMME and LMME: the former has much higher ratio of stratiform precipitation while the latter has more convective precipitation. Additionally, the large differences in precipitation between the HMME and LMME are related to differences in the SST and its accompanied large-scale circulation.