Impact of East Asian summer monsoon on the air quality over China: View from space

Zhao, Chun; Wang, Yuhang; Yang, Qing; Fu, Rong; Cunnold, D. M.; Choi, Yunsoo

doi:10.1029/2009jd012745

Cited by 107 publications

(106 citation statements)

References 70 publications

(95 reference statements)

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“…Moreover, Zhang et al (2010) used a numerical model to simulate the impact of weak/strong monsoon circulations on interannual variations of aerosols over eastern China under the conditions of the same anthropogenic emissions and suggested that the decadal-scale weakening of the East Asian summer monsoon is responsible for the increase in aerosol concentrations over eastern China. Using satellite products, Zhao et al (2010) showed consistent disappearance of CO and ozone (O 3 ) enhancements over southeastern China at the onset of East Asian summer monsoon and the reemergence after the monsoon wanes, which confirmed the strong modulation of monsoon system on regional air quality. Liu et al (2013) further demonstrated a potential influence from the variation of large-scale circulation, El Niño-Southern Oscillation, upon the interannual fluctuation of summertime aerosol optical depth (AOD).…”

Section: Y Zheng Et Al: Impact Of Atmospheric Circulations On Aementioning

confidence: 67%

Impact of atmospheric circulations on aerosol distributions in autumn over eastern China: observational evidence

Zheng

Yang

et al. 2015

Atmos. Chem. Phys.

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Abstract. Regional heavy pollution events in eastern China (110-122 • E, 28-40 • N) are causing serious environmental problems. In this study, the relationship between the degree of regional pollution and the patterns of large-scale atmospheric circulation over eastern China in October is investigated using 10-year (2001-2010) Terra/MODIS aerosol optical depth and NCEP reanalysis data by both case study and composite analysis. Eighteen polluted and 10 clean episodes are selected and categorised into six polluted types and three clean types respectively. Generally speaking, weather patterns such as a uniform surface pressure field in eastern China or a steady straight westerly in the middle troposphere, particularly when being at the rear of the anticyclone at 850 hPa, are typically responsible for heavy pollution events. Meanwhile, clean episodes occur when strong southeastward cold air advection prevails below the middle troposphere or air masses are transported from sea to land. Uniform descending motion prevails over the study region, trapping pollutants in the lower atmosphere. Therefore, the value of vertical velocity averaged from 1000 to 100 hPa and divergence of wind field in the lower troposphere are used in this study to quantify the diffusion conditions in each circulation type. The results reveal that it is often a clean episode when both the mean downward motion (larger than 2.56 × 10 −2 Pa s −1 ) and the divergence of lowlevel winds (larger than 1.79 × 10 −2 s −1 ) are strong. Otherwise, it is more likely to be a polluted episode.

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Section: Y Zheng Et Al: Impact Of Atmospheric Circulations On Aementioning

confidence: 67%

Impact of atmospheric circulations on aerosol distributions in autumn over eastern China: observational evidence

Zheng

Yang

et al. 2015

Atmos. Chem. Phys.

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“…2 A and B). We simulate the Octobers of 2008-2010 by using the Regional chEmical trAnsport Model (REAM) (24,25) to examine the key parameters driving the surface ozone difference among the three years. Fig.…”

Section: Resultsmentioning

confidence: 99%

“…We used the 3D REAM to explore the missing mechanisms in the biosphere-chemistry-climate interactions. The REAM has been applied over North America, East Asia, and the Polar Regions (24,25,(44)(45)(46)(47)(48)(49). The model has a horizontal resolution of 36 km and 30 vertical layers in the troposphere.…”

Section: Methodsmentioning

confidence: 99%

Climate-driven ground-level ozone extreme in the fall over the Southeast United States

Zhang

Wang

2016

Proc. Natl. Acad. Sci. U.S.A.

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110

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Ground-level ozone is adverse to human and vegetation health. High ground-level ozone concentrations usually occur over the United States in the summer, often referred to as the ozone season. However, observed monthly mean ozone concentrations in the southeastern United States were higher in October than July in 2010. The October ozone average in 2010 reached that of July in the past three decades . Our analysis shows that this extreme October ozone in 2010 over the Southeast is due in part to a dry and warm weather condition, which enhances photochemical production, air stagnation, and fire emissions. Observational evidence and modeling analysis also indicate that another significant contributor is enhanced emissions of biogenic isoprene, a major ozone precursor, from water-stressed plants under a dry and warm condition. The latter finding is corroborated by recent laboratory and field studies. This climate-induced biogenic control also explains the puzzling fact that the two extremes of high October ozone both occurred in the 2000s when anthropogenic emissions were lower than the 1980s and 1990s, in contrast to the observed decreasing trend of July ozone in the region. The occurrences of a drying and warming fall, projected by climate models, will likely lead to more active photochemistry, enhanced biogenic isoprene and fire emissions, an extension of the ozone season from summer to fall, and an increase of secondary organic aerosols in the Southeast, posing challenges to regional air quality management.ground-level ozone | ozone season | regional climate change | isoprene | air quality G round-level ozone is a pollutant harmful to human and vegetation health (1, 2). High ground-level ozone events are typically found in the summer when the formation of ozone is active through photochemical reactions involving nitrogen oxides (NO x = NO + NO 2 ) and volatile organic compounds (VOCs). However, ozone concentrations are sensitive to weather and climate (3-8), and the high-ozone season could extend beyond summer in the future (9-13). Previous climate-chemistry model studies have estimated the change of ground-level ozone (ΔO 3 ) in the United States resulting only from meteorological changes. Their results show large variation in the sign and magnitude of ΔO 3 in the fall, especially over forested regions such as the southeastern United States (SE) (10, 13). The lack of consensus reflects the uncertainties in modeling regional climate change and the consequent response of ground-level ozone.In this study, we focus on analyzing the historical ozone records. Fig. 1A Fig. S1). The number increases to 324 exceedances at 112 stations if the new US ambient ozone standard threshold value, 70 ppbv, is used (SI Appendix, Fig. S1). The regional average reached 65 ppbv during October 8-10, 2010 ( Fig. 2A). ppbv, considerably lower than that in the summer ozone season (∼50 ppbv in July). However, in the two extreme years, 2000 and 2010, regional monthly mean [O 3 ] MDA8 are 52 and 49 ppbv, respectively, two interannual standa...

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“…He et al (2008) analyzed the seasonal variations of O 3 concentrations measured over the period [2004][2005][2006] and found that O 3 concentrations peak in spring and autumn with a summer trough in central eastern China and the western Pacific, the areas that are influenced by clean air from the southern oceans during the summer monsoon. Studies by , Lin et al (2009), and Zhao et al (2010) reported that the increasing clouds associated with the EASM rainfall suppress photochemical production of O 3 by altering solar radiation, which also contributes to the minimum O 3 concentrations in summer.…”

Section: H Liao Et Al: Interannual Variations Of Summertime Surfacementioning

confidence: 99%

Impacts of the East Asian summer monsoon on interannual variations of summertime surface-layer ozone concentrations over China

2014

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Abstract. We apply a global three-dimensional Goddard Earth Observing System (GEOS) chemical transport model (GEOS-Chem) driven by the NASA/GEOS-4 assimilated meteorological fields to quantify the impacts of the East Asian summer monsoon (EASM) on interannual variations of June-July-August (JJA) surface-layer O 3 concentrations over China. With anthropogenic emissions fixed at year 2005 levels, the model simulation for years shows that the changes in meteorological parameters alone lead to interannual variations in JJA surface-layer O 3 concentrations by 2-5 % over central eastern China, 1-3 % in northwestern China, and 5-10 % over the Tibetan Plateau as well as the border and coastal areas of southern China, as the interannual variations are relative to the average O 3 concentrations over the 21 yr period. Over the years 1986-2006, the O 3 concentration averaged over all of China is found to correlate positively with the EASM index with a large correlation coefficient of +0.75, indicating that JJA O 3 concentrations are lower (or higher) in weaker (or stronger) EASM years. Relative to JJA surface-layer O 3 concentrations in the strongest EASM years (1990, 1994, 1997, 2002, and 2006), O 3 levels in the weakest EASM years (1988, 1989, 1996, 1998, and 2003) are lower over almost all of China with a national mean lower O 3 concentration by 2.0 ppbv (parts per billion by volume; or 4 %). Regionally, the largest percentage differences in O 3 concentration between the weakest and strongest EASM years are found to exceed 6 % in northeastern China, southwestern China, and over the Tibetan Plateau. Sensitivity studies show that the difference in transboundary transport of O 3 is the most dominant factor that leads to lower-O 3 concentrations in the weakest EASM years than in the strongest EASM years, which, together with the enhanced vertical convections in the weakest EASM years, explain about 80 % of the differences in surface-layer O 3 concentrations between the weakest and strongest EASM years. We also find that the impacts the EASM strength on JJA surface-layer O 3 can be particularly strong (comparable in magnitude to the impacts on O 3 by changes in anthropogenic emissions over years for certain years. The largest increases in O 3 by anthropogenic emissions are simulated over southeastern China, whereas the largest impacts of the EASM on O 3 are found over central and western China.

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Impact of East Asian summer monsoon on the air quality over China: View from space

Cited by 107 publications

References 70 publications

Impact of atmospheric circulations on aerosol distributions in autumn over eastern China: observational evidence

Impact of atmospheric circulations on aerosol distributions in autumn over eastern China: observational evidence

Climate-driven ground-level ozone extreme in the fall over the Southeast United States

Impacts of the East Asian summer monsoon on interannual variations of summertime surface-layer ozone concentrations over China

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