Precipitation anomalies in the Pan‐Asian monsoon region during El Niño decaying summer 2016

Abstract

The El Niño‐Southern Oscillation (ENSO) has an intimate relationship with Asian summer monsoon precipitation. Previous study pointed out that the most recent 2015–2016 El Niño event is tied with the 1997–1998 and 1982–1983 El Niño events as the strongest event since 1950, which may result in catastrophe in Asian monsoon region. Therefore, in this article, we mainly focus on the anomalous precipitation pattern in the Pan‐Asian monsoon region during MJJ 2016 and its impact factors. Results show that the summer precipitation anomalies display a meridional tripole pattern from north to south in the Pan‐Asian monsoon region during 2016. This pattern indicates that the anomalous increased rainfall is located over the middle–lower reaches of the Yangtze River valley–East China Sea (ECS) and the tropical eastern Indian Ocean–western Maritime Continent, while the anomalous decreased rainfall is located over the South China Sea (SCS)–Philippine Sea. Results suggest that the preceding winter and spring ENSO and the simultaneous summer Maritime Continent sea surface temperature (SST) are the primary impact factors of the pattern of tripole precipitation anomalies in the Pan‐Asian monsoon region during MJJ 2016. The preceding ENSO can intensify the western North Pacific subtropical high (WPSH), which results in the anomalous decrease in precipitation over the Indo‐China Peninsula–Philippine Sea. Meanwhile, more moisture is transported from the northwestern flank of WPSH to the Yangtze River valley–ESC to increase rainfall. In the ENSO decaying summer, the Maritime Continent SST anomalous warming induces an anomalous convergence in situ, which increases the local precipitation. Later, this warming can intensify the WPSH through the local meridional circulation. The north Indian Ocean SST, including Arabian Sea and Bay of Bengal, also has a high relationship with tripole precipitation pattern, but it cannot induce this tripole rainfall pattern, which establishes the linkage through the extending WPSH.

Shift of the principal mode of Pan-Asian monsoon summer precipitation in terms of spatial pattern

“…and less rainfall, so that the northern Indian Ocean warming cannot force anomalous rainfall in the Pan-Asian monsoon region, which is coherent with the result of Wu, Zhou, and Li (2009). Similar to P1, the anomalous warming over the northern Indian Ocean (Arabian Sea and Bay of Bengal) in P2 also corresponds to the local anomalous descending motion (Figure 9 in Gao and Wang 2016), which cannot modulate the Pan-Asian monsoon summer precipitation.…”

“…According to the study of Gao and Wang (2016), during the period 1979-2016, the spatial pattern of the first empirical can be affected by ENSO (Lu and Dong 2001;Wu, Zhou, and Li 2009;Xie et al 2009;Paek et al 2016).…”

“…In P1, the summer precipitation is mainly associated with a combination of the developing phase (central-eastern Pacific type) and decaying phase (eastern Pacific type) of ENSO; while in P2, it is primarily associated with the decaying phase of central-eastern-Pacific-type ENSO, which is modulated by the ENSO signal in the preceding winter and spring, and the Maritime Continent SST in the simultaneous summertime (Gao and Wang 2016). In comparison with P1, the relationship between summer precipitation anomalies and ENSO in P2 is more significant (Gao and Wang 2016). In future work, more research into the dynamic and physical mechanisms underlying the strengthened relationship between Pan-Asian monsoon summer precipitation and ENSO are needed.…”

“…In P2 (Figure 4(b) and (d)), owing to the stronger relationship between the summer precipitation and WPSH, the tropical Indian Ocean SST can thus increase via the WPSH to weaken the westerlies over the northern Indian Ocean. Hence, through the air-sea interaction, the tropical Indian Ocean SST can build a linkage with the Pan-Asian monsoon summer precipitation (Gao and Wang 2016). In addition, in both periods, the anomalous anticyclonic circulation over the Indochina Peninsula-tropical western Pacific region induces subsidence there, which makes less 1979-1992 and 1993-2016, respectively.…”

Different Influences of Southeastern Indian Ocean and Western Indian Ocean SST Anomalies on Eastern China Rainfall during the Decaying Summer of the 2015/16 Extreme El Niño

“…Abnormal increases of summer rainfall can result in severe floods in the region (e.g., 1983, 1991, 1998, 2016) and cause huge social and economic damage. Intensive efforts have been made to better understand and predict the summer rainfall variability over eastern China (e.g., Lau and Weng 2001;Li et al 2017;Yuan et al 2017;Gao et al 2018). El Niño-Southern Oscillation (ENSO) is one of the most important factors for modulating the interannual variability of eastern China summer rainfall (e.g., Huang and Wu 1989;Zhang et al 1999;Lau and Weng 2001;Wu et al 2003;Wang et al 2009;Wu et al 2009;Han et al 2017;Zhang et al 2017).…”