Observationally constrained modeling of atmospheric oxidation capacity and photochemical reactivity in Shanghai, China
Observationally constrained modeling of atmospheric oxidation capacity and photochemical reactivity in Shanghai, China
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DOI：
10.5194/acp-20-1217-2020
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发表时间：
2020-02
影响因子：
6.3
通讯作者：
Jian Zhu;Shanshan Wang;Hongli Wang;Sheng’ao Jing;S. Lou;A. Saiz‐Lopez;Bin Zhou
中科院分区：
文献类型：
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作者：
Jian Zhu;Shanshan Wang;Hongli Wang;Sheng’ao Jing;S. Lou;A. Saiz‐Lopez;Bin Zhou
抽象的。一个与主化学机理相耦合的基于观测的模型(V3.3.1)
并受到一整套观察的限制，开发了一套研究
大气氧化能力(AOC)、羟基反应性、羟基链长和
三种不同臭氧(臭氧)的HOX(=OH+HO2)预算
中国在上海的浓度水平。2018年5月1日至9月30日连续5个月的观测显示，空气质量水平为轻度
污染或更差(环境空气质量指数，AQI，>； 100)
12 d，其中臭氧是10 d的主要污染物，表明
年，臭氧污染是上海空气质量的主要挑战
2018年夏天。臭氧及其前体的水平以及
气象参数，揭示了两者之间的显著差异
不同的臭氧水平，表明高水平的前体是
臭氧污染的前提条件，以及强辐射是必不可少的
驱动力。通过将输入JNO2值增加40 %，
模拟臭氧水平相应增加了30 %-40 %
同样水平的前驱物质。模拟结果表明，AOC主要由
在白天涉及OH自由基的反应，有一个积极的
与臭氧水平的相关性。与非甲烷挥发物的反应
有机化合物(NMVOCs；30 %-36 %)、一氧化碳(CO；26 %-31 %)和二氧化氮(NO2；21 %-29 %)占主导地位
上海地区不同臭氧水平下的OH反应性。在这些人中
NMVOCs、烯烃和含氧VOCs(OVOCs)在OH中起着关键作用
反应性，定义为OH寿命的倒数。更长的OH链
在清洁的条件下发现的长度主要是由于在
大气层。高水平的自由基前体物(例如，臭氧、HONO和
OVOCs)促进HOX的生产和循环，以及白天
HOX的主要来源从早上的HONO光解转移到
臭氧在下午光解。对于自由基汇来说，反应
由于NO2在早上高峰时间主导了激进的终止，
而自由基的反应也是导致下沉的原因之一
下午的霍克斯。此外，贡献最大的四个物种
臭氧形成势(OFP)为甲醛、甲苯、乙烯和
间/对二甲苯。这四种药物的浓度比(∼23 %)
物种对总NMVOCs的贡献与其贡献不成比例
(∼55 %)到OFP，这意味着控制关键挥发性有机化合物物种
排放比限制大气中VOC的总浓度更有效
防治臭氧污染。
Abstract. An observation-based model coupled to the Master Chemical Mechanism (V3.3.1)
and constrained by a full suite of observations was developed to study
atmospheric oxidation capacity (AOC), OH reactivity, OH chain length and
HOx (=OH+HO2) budget for three different ozone (O3)
concentration levels in Shanghai, China. Five months of observations from 1 May to 30 September 2018 showed that the air quality level is lightly
polluted or worse (Ambient Air Quality Index, AQI, of > 100) for
12 d, of which ozone is the primary pollutant for 10 d, indicating
ozone pollution was the main air quality challenge in Shanghai during
summer of 2018. The levels of ozone and its precursors, as well as
meteorological parameters, revealed the significant differences among
different ozone levels, indicating that the high level of precursors is the
precondition of ozone pollution, and strong radiation is an essential
driving force. By increasing the input JNO2 value by 40 %, the
simulated O3 level increased by 30 %–40 % correspondingly under the
same level of precursors. The simulation results show that AOC, dominated by
reactions involving OH radicals during the daytime, has a positive
correlation with ozone levels. The reactions with non-methane volatile
organic compounds (NMVOCs; 30 %–36 %), carbon monoxide (CO; 26 %–31 %) and nitrogen dioxide (NO2; 21 %–29 %) dominated
the OH reactivity under different ozone levels in Shanghai. Among the
NMVOCs, alkenes and oxygenated VOCs (OVOCs) played a key role in OH
reactivity, defined as the inverse of the OH lifetime. A longer OH chain
length was found in clean conditions primarily due to low NO2 in the
atmosphere. The high level of radical precursors (e.g., O3, HONO and
OVOCs) promotes the production and cycling of HOx, and the daytime
HOx primary source shifted from HONO photolysis in the morning to
O3 photolysis in the afternoon. For the sinks of radicals, the reaction
with NO2 dominated radical termination during the morning rush hour,
while the reactions of radical–radical also contributed to the sinks of
HOx in the afternoon. Furthermore, the top four species contributing to
ozone formation potential (OFP) were HCHO, toluene, ethylene and
m/p-xylene. The concentration ratio (∼23 %) of these four
species to total NMVOCs is not proportional to their contribution
(∼55 %) to OFP, implying that controlling key VOC species
emission is more effective than limiting the total concentration of VOC in
preventing and controlling ozone pollution.