The stratospheric ozone rich cold intrusion during El‐Niño over the Indian region: Implication during the Indian summer monsoon
The stratospheric ozone rich cold intrusion during El‐Niño over the Indian region: Implication during the Indian summer monsoon
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DOI：
10.1002/joc.6680
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发表时间：
2020-05
期刊：
影响因子：
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通讯作者：
Chaitri Roy;S. Fadnavis;T. P. Sabin
中科院分区：
文献类型：
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作者：
Chaitri Roy;S. Fadnavis;T. P. Sabin
对流层上层的臭氧是主要的辐射成分。在这项研究中，我们利用 ECHAM5-HAMMOZ、全球化学-气候模型模拟和 ERA-中期再分析数据，研究了印度上空对流层上层平流层入侵造成的臭氧变化以及与厄尔尼诺现象同时发生的季风中断期间的相关辐射影响。我们的分析表明，厄尔尼诺期间，北印度-青藏高原（NI-TP）地区和季风反气旋东缘发生深层平流层入侵。这些入侵导致印度上空对流层上层臭氧含量大幅增加（~100 ppb）。这些入侵经常深入对流层，使表面臭氧水平提高约 10-20 ppb，并使大气顶部的辐射强迫增加约 0.33 W m−2。平流层侵入与对流层上层向东移动的波列（由气旋和反气旋环流组成）有关，该波列从异常温暖的东太平洋发出，向NI-TP区域移动。该波列输送温带冷空气团，在 NI-TP 上空对流层上层产生约 1.6-2 K 的异常冷却。对流层上层的异常冷却似乎是对抗臭氧增强导致的加热的主要因素。波列同样增强了罗斯贝波破碎，促进平流层侵入，增强了 NI-TP 区域的异常沉降。我们的分析表明，厄尔尼诺现象的突破日证实了 (a) RWB、(b) 通过 WT-1 输送冷气团和 (c) 厄尔尼诺环流造成的沉降同时发生。这些因素导致降雨不足加剧。
Ozone in the upper troposphere is a dominant radiative constituent. In this study, we investigate ozone variability due to stratospheric intrusions in the upper troposphere over India and associated radiative impacts during monsoon breaks co‐occurring with El Niño using the ECHAM5‐HAMMOZ, Global‐Chemistry‐climate model simulations, and ERA‐Interim reanalysis data. Our analysis shows that during El Niño, deep stratospheric intrusions occur at the North India‐Tibetan Plateau (NI‐TP) region and the eastern edge of the monsoon anticyclone. These intrusions lead to an enormous increase in ozone amounts (~100 ppb) in the upper troposphere over India. The intrusions frequently penetrate deep into the troposphere which enhances the surface ozone levels by ~10–20 ppb and augments radiative forcing by ~0.33 W m−2 at the top of the atmosphere. The stratospheric intrusions are associated with the eastward‐moving wave train (composed of cyclonic and anticyclonic circulations) in the upper troposphere emanating from the anomalously warm east Pacific, traversing towards NI‐TP locale. This wave train transport extra‐tropical cold air mass, producing an anomalous cooling of ~1.6–2 K in the upper troposphere over NI‐TP. The upper tropospheric anomalous cooling seems to act as a dominating factor opposing the heating due to enhanced ozone. The wave train likewise intensifies Rossby wave breaking, facilitating stratospheric intrusions, enhancing the anomalous subsidence over the NI‐TP region. Our analysis shows that break days with El Niño substantiate with simultaneous occurrence of (a) RWB, (b) transport of cold air mass via WT‐1 and (c) subsidence by El Niño circulation. These factors lead to exacerbation of deficit rainfall.