Enhancement of the relationship between the winter Arctic oscillation and the following summer circulation anomalies over central East Asia since the early 1990s
Enhancement of the relationship between the winter Arctic oscillation and the following summer circulation anomalies over central East Asia since the early 1990s
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20世纪90年代初以来冬季北极涛动与东亚中部夏季环流异常之间关系的增强
DOI：
10.1007/s00382-017-3818-3
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发表时间：
2018
期刊：
影响因子：
4.6
通讯作者：
Feng Guolin
中科院分区：
文献类型：
--
作者：
Qiao Shaobo;Hu Po;Feng Taichen;Cheng Jianbo;Han Zixuan;Gong Zhiqiang;Zhi Rong;Feng Guolin
考虑到冬季北极涛动（AO）对随后东亚夏季气候异常的影响可能存在滞后性，且不同时期二者之间的关系可能存在差异，本研究对这些系统之间的非平稳关系及相应的联系机制进行了研究。 1988年左右，检测到冬季AO指数发生变化，1958-1987年和1988-2014年平均AO指数分别为-0.69和0.10，其差异超过了99%的置信水平。政权更迭后，特别是自 20 世纪 90 年代初以来，负（正）冬季 AO 指数与次年夏季东亚中部 (CEA) 的正（负）高度异常相对应。同时，西风急流偏北（南），东亚夏季风偏强（弱），导致华中地区暖（冷）异常，东北地区降水显着增加（减少）。 1990年代初期以后，冬季AO与随后的夏季CEA上空高度异常的联系增强，很大程度上是由于同期冬季AO与随后的印度夏季季风（ISM）降雨的联系增强。负（正）冬季 AO 有利于 ISM 地区降雨量的增加（减少），从而引发正（负）环全球遥相关（CGT），并导致 CEA 上空显着正（负）高度异常。冬季 AO 影响随后 ISM 降雨量的一种方式是，负（正）冬季 AO 记忆将由次年夏季热带大西洋正（负）海面温度（SST）异常维持，这导致了拉尼娜（厄尔尼诺）发展阶段并增加（减少）了 ISM 降雨量。
Considering the possible lag of the impact of the winter Arctic oscillation (AO) on the subsequent summer climate anomalies over East Asia and that the relationship between them may differ during different periods, the non-stationary relationship between these systems and the corresponding mechanism of connection are investigated in this study. A regime shift of the winter AO index was detected around 1988, with mean AO indices of −0.69 and 0.10 for 1958–1987 and 1988–2014, respectively, and their differences passed the 99% confidence level. After the regime shift and especially since the early 1990s, negative (positive) winter AO indices corresponds with positive (negative) height anomalies over central East Asia (CEA) during the following summer. Meanwhile, the westerly jet stream tends to be northward (southward) and the East Asian summer monsoon (EASM) is strong (weak), which contributes to the warm (cold) anomalies over central China and the significantly enhanced (reduced) rainfall over northeast China. After the early 1990s, the enhanced connection of the winter AO and the following summer height anomalies over CEA is largely due to the enhanced connection of the winter AO and the following Indian summer monsoon (ISM) rainfall during the same period. The negative (positive) winter AO favors increasing (decreasing) rainfall over the ISM region, which triggers a positive (negative) circumglobal teleconnection (CGT), and results in significantly positive (negative) height anomalies over CEA. One way the winter AO could influence the following ISM rainfall is that the negative (positive) winter AO memories will be maintained by the positive (negative) sea surface temperature (SST) anomalies over the tropical Atlantic of the following summer, which are responsible for the La Niña (El Niño) developing phase and increases (decreases) the ISM rainfall.