Monsoon Intra-Seasonal Variability in Boreal Summer

Abstract

The model output of version two of the spectral and grid-point Flexible Global Ocean–Atmosphere–Land System Models, FGOALS-s2 and FGOALS-g2, respectively, are evaluated from four aspects including spatial distribution of variance, propagation characteristics, eastward component of 30–80 day intra-seasonal oscillation (ISO) mode, and westward component of 12–24 day ISO mode. Both models are essentially able to capture horizontal patterns of intra-seasonal variance, although FGOALS-g2 reproduces a larger magnitude of variability. Compared to the poor simulation of the intra-seasonal variability (ISV) eastward propagation, these models can effectively simulate the northward propagation of low-frequency (30–80 day) ISV. Deviations of eastward and westward variance centers in the two models may be attributed to the model bias of precipitation over the Maritime Continent and the western North Pacific (WNP). Moreover, the magnitude of eastward and westward variance simulated by the two models is smaller than the observed values.