Abstract. The East Asian summer monsoon (EASM) is an important part of the
global climate system and plays a vital role in the Asian climate. Its
seasonal predictability is a long-standing issue within the monsoon scientist
community. In this study, we analyse the seasonal (the leading time is at
least 6 months) prediction skill of the EASM rainfall and its associated
general circulation in non-initialised and initialised simulations for the
years 1979–2005, which are performed by six prediction systems (i.e. the
BCC-CSM1-1, the CanCM4, the GFDL-CM2p1, the HadCM3, the MIROC5, and the
MPI-ESM-LR) from the Coupled Model Intercomparison Project phase 5 (CMIP 5).
We find that most prediction systems of simulated zonal wind over 850 and 200 hPa
are significantly improved in the initialised simulations compared to
non-initialised simulations. Based on the knowledge that zonal wind indices
can be used as potential predictors for the EASM, we select an EASM index
based upon the zonal wind over 850 hPa for further analysis. This assessment
shows that the GFDL-CM2p1 and the MIROC5 added prediction skill in simulating
the EASM index with initialisation, the BCC-CSM1-1, the CanCM4, and the
MPI-ESM-LR changed the skill insignificantly, and the HadCM3 indicates a
decreased skill score. The different responses to initialisation can be
traced back to the ability of the models to capture the ENSO (El
Niño–Southern Oscillation) and EASM coupled mode, particularly the Southern
Oscillation–EASM coupled mode. As is known from observation studies, this
mode links the oceanic circulation and the EASM rainfall. Overall, the
GFDL-CM2p1 and the MIROC5 are capable of predicting the EASM on a seasonal
timescale under the current initialisation strategy.
Pattern-based statistical downscaling of East Asian Summer Monsoon precipitation
