Impacts of strong El Niño on summertime near-surface ozone over China
Mengyun Li, Yang Yang, Pinya Wang, Dongsheng Ji, Hong Liao
Abstract
The influences of strong El Niño events (1997/98 and 2015/16) on summertime near-surface ozone (O3) concentrations over China are investigated using the GEOS-Chem model. The results show that near-surface O3 concentrations increased by a maximum of 6 ppb (parts per billion) during the summer of the developing phase of the 1997/98 El Niño in northeastern China, mainly due to the increased chemical production related to the hot and dry conditions. Besides, the O3 concentration increased by 3 ppb during the developing summer of both the 1997/98 and 2015/16 El Niño in southern China. It was linked to the weakened prevailing monsoon winds, which led to the accumulation of O3 in southern China. In contrast, in the summer of the decaying phase of the two El Niño events, O3 concentrations decreased over many regions of China when the El Niño reversed to the cooling phase. This highlights that El Niño plays an important role in modulating near-surface O3 concentrations over China. 摘要 利用全球大气化学三维模式 (GEOS-Chem) 模拟研究两次强厄尔尼诺事件 (1997/98和2015/16) 对中国夏季近地面臭氧 (O3) 浓度的影响. 结果表明1997/98年厄尔尼诺事件发展期夏季中国东北区域O3浓度升高, 最大值超过6ppb, 这主要归因于高温晴朗低湿等气象因素导致O3化学生成升高. 此外, 两次厄尔尼诺事件发展期夏季O3浓度在中国南部均增加了3ppb, 这与盛行季风减弱导致中国南方O3局地积累有关. 相反, 在两次强厄尔尼诺衰减期夏季, 中国大部分地区O3浓度下降伴随着海温模态转变为拉尼娜事件. 这表明厄尔尼诺在调节中国近地面O3浓度中发挥着重要作用.