Abstract
In this study, a developed regional ocean–atmosphere coupled model FROALS was applied to the CORDEX East Asia domain. The performance of FROALS in the simulation of Asian summer monsoon during 1989–2010 was assessed using the metrics developed by the CLIVAR Asian–Australian Monsoon Panel Diagnostics Task Team. The results indicated that FROALS exhibited good performance in simulating Asian summer monsoon climatology. The simulated JJA mean SST biases were weaker than those of the CMIP5 multi-model ensemble mean (MMEM). The skill of FROALS approached that of CMIP5 MMEM in terms of the annual cycle of Asian summer monsoon. The simulated monsoon duration matched the observed counterpart well (with a spatial pattern correlation coefficient of 0.59). Some biases of CMIP5 MMEM were also found in FROALS, highlighting the importance of local forcing and model physics within the Asian monsoon domain. Corresponding to a strong East Asian summer monsoon, an anomalous anticyclone was found over western North Pacific in both observation and simulation. However, the simulated strength was weaker than the observed due to the responses to incorrect sea surface anomalies over the key regions. The model also accurately captured the spatial pattern of the intraseasonal variability variance and the extreme climate indices of Asian summer monsoons, although with larger amplitude. The results suggest that FROALS could be used as a dynamical downscaling tool nested within the global climate model with coarse resolution to develop high-resolution regional climate change projections over the CORDEX East Asia domain.
Highlights
Asian monsoon influences countries with more than one third of the world’s population
In prescribed sea surface temperature experiments, Zhou et al (2009a) analyzed the output of atmospheric general circulation models (AGCMs) that participated in the climate variability and predictability (CLIVAR) international climate of the twentieth century (C20C) project and found that among the Asian–Australian monsoon subsystems the East Asian summer monsoon has the lowest reproducibility and is poorly modeled during 1950–1999
The results indicated that some improvements were seen from CMIP3 multi-model ensemble mean (MMEM) to CMIP5 MMEM, but the simulated biases remained, i.e., northward shift of the western North Pacific subtropical high
Summary
Asian monsoon influences countries with more than one third of the world’s population. Song and Zhou (2014a) compared the climatology and interannual variability of East Asian summer monsoon simulated by CMIP3 (coupled model intercomparison project phase 3) and CMIP5 AGCMs. The results indicated that some improvements were seen from CMIP3 multi-model ensemble mean (MMEM) to CMIP5 MMEM, but the simulated biases remained, i.e., northward shift of the western North Pacific subtropical high. The lack of air–sea interaction has been regarded as the major factor contributing to the poor simulated rainfall over the Asian summer monsoon region in SST forced simulations (Zhou et al 2009a, b; Li et al 2010) Another possible way to improve the simulation of the Asian summer monsoon is to develop high-resolution climate models. The previously developed regional ocean atmosphere coupled model FROALS (Zou and Zhou 2013a) is applied to the CORDEX East Asia domain.
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