El Niño–Southern Oscillation–related principal interannual variability modes of early and late summer rainfall over East Asia in sea surface temperature-driven atmospheric general circulation model simulations

Abstract

[1] A large portion of interannual variability during early summer (May-June mean; hereinafter referred to as MJ) and late summer (July-August mean; hereinafter referred to as JA) rainfall over East Asia is dominated by El Niño-Southern Oscillation (ENSO) events. Four ENSO-related modes have been identified by using empirical orthogonal function (EOF) decomposition analysis on East Asian rainfall for the period 1980-1999, with EOF2 for MJ rainfall (hereinafter referred to as MJ-2; similar notations are used for other modes) corresponding to the developing phase of La Niña events, while MJ-3, JA-1, and JA-2 correspond to the decaying phase of El Niño events. The authors investigate the predictability of ENSO-related MJ and JA rainfall modes by analyzing the outputs of 12 atmospheric general circulation models (AGCMs) of the Atmospheric Model Intercomparison Project Phase II (AMIP II), which were run in an AGCM stand-alone mode and were forced by the monthly historical sea surface temperature (SST) from 1980 to 1999. The results show that although the climatological differences between MJ and JA rainfall are reasonably reproduced by most AGCMs, the four ENSO-related interannual variability modes of MJ and JA rainfall show different predictabilities. While both atmospheric circulation and precipitation anomalies associated with MJ-3 (the slow El Niño decaying mode) are reasonably reproduced by nearly all the models, the JA-1 (MJ-2) mode is only partly reproduced by about two thirds (half) of the AMIP II models. All models fail to reproduce the JA-2 mode. The relatively low skills in predicting both JA-1 and JA-2 modes are primarily due to the bias of the AMIP models in simulating both the intensity and the position of the western North Pacific anticyclone. The predictability of the JA-1 mode is slightly higher than that of JA-2, and the difference results from the stronger and longer persistence of SST anomaly (SSTA) forcing associated with the decaying ENSO events. The low skill of the MJ-2 prediction is due to the weak SSTA forcing associated with the developing phase of La Niña. The skills of the AMIP II models in predicting the leading interannual variability modes of East Asian summer rainfall do not depend on the horizontal resolutions of the models.Citation: Li, B., and T. Zhou (2011), El Niño-Southern Oscillation-related principal interannual variability modes of early and late summer rainfall over East Asia in sea surface temperature-driven atmospheric general circulation model simulations,

Can coupled models perform better in the simulation of sub‐seasonal evolution of the western North Pacific subtropical high than atmospheric models in boreal summer?

“…Although the sub‐seasonal variation of the Asian summer monsoon in multi‐models has been investigated (e.g., Lin et al ., ), whether the CMIP5 models can reasonably reproduce the sub‐seasonal evolution of the WNPSH has not been mentioned by most previous research. The WNPSH experiences sub‐seasonal eastward and northward shifts from June to August, leading to different stages of the rainy season in eastern China (early summer, late summer) (e.g., Li and Zhou, ; Ye and Lu, ; Xue et al ., ). In our earlier work, we investigated the sub‐seasonal evolution of the WNPSH simulated by CMIP5 AGCMs and argued that most models can reproduce the northward jump of the WNPSH, but have difficulties in simulating the eastward retreat of the WNPSH from July to August (Dong et al ., ).…”

Predictable patterns of the May–June rainfall anomaly over East Asia

“…Besides more and more studies that focus on the impacts of Arctic sea ice and aerosol on East Asia climate [ Lau and Kim , ; Chen et al ., ], related predictors may also be added to P‐E models to improve the prediction skill in the future work. Given that there is still uncertainty among different data sets, further efforts should strive to assess the possible influence of such uncertainty on the seasonal precipitation prediction [ North et al ., ; Beven et al ., ; Li and Zhou , ; Laloy and Vrugt , ; B. Wang et al ., 2014].…”

“…Traditional seasonal forecast of EASM deals with June‐July‐August mean rainfall anomalies, which may not be the best strategy because the EASM rainy season is typically from May to August [ Wang and LinHo , ] and pronounced differences exist between the early summer (May–June, or MJ) and peak summer (July–August, or JA): both climatological mean states and the principal modes of interannual variability exhibit distinct spatial and temporal structures [ Wang et al ., ; Li and Zhou , ; Qin et al ., ; Oh and Ha , ]. Besides, the seasonal marches from May to June and from July to August are both relatively gradual [ Wang et al ., ].…”

Connection between Two Leading Modes of Autumn Rainfall Interannual Variability in Southeast China and Two Types of ENSO-Like SSTA

“…For example, the precipitation was much more in the early spring of 1992 [10], but a drought occurred there in the late spring of 2011 year [11,12]. Due to SEC located in the summer monsoon area, summer precipitation is a great part of the whole-year precipitation there, and precipitation characteristics differ greatly between early summer (May and June) and peak summer (July and August), in relation to the north-south activities of summer monsoon [13][14][15][16]. Compared to spring and summer seasons, the autumn is a less rainfall season, but the temporal and spatial variations of autumn precipitation are more complex [17], with more frequent drought [18].…”

“…So the relationship between SEC rainfall and SST has attracted a lot of attention [22,27,28]. It has been investigated that the interannual variability of the tropical Pacific SST [13,14,29], as well as the tropical India Ocean, has important effects on the SEC rainfall [30,31]. For instance, the SSTAs over the Maritime Continent (MC) can influence the SEC summer rainfall by modifying the cross-equatorial flows [32,33].…”