Ground-Level Ozone in Four Chinese Cities: Precursors, Regional Transport

Home , Lanzhou

Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | , 5 , and 2 , D. R. Blake 2 , Q. Z. Zhang 8 , X. H. Zhou 4 , H. C. Zuo 7 20768 20767 , A. J. Ding 3 , S. J. Fan 6 , J. Gao 1,2,3 , S. M. Saunders , T. Wang 2,3 2 1,2 This discussion paper is/has beenand under Physics review (ACP). for Please the refer journal to Atmospheric the Chemistry corresponding final paper in ACP if available. Department of Civil and Environmental Engineering, Hong Kong Polytechnic University,Environment Hong Research Institute, Shandong University, Ji’nan,Chinese Shandong, Research China Academy of EnvironmentalInstitute Sciences, for Beijing, Climate China and Global Change Research and SchoolDepartment of of Atmospheric Chemistry, Sciences, University ofSchool California of at Chemistry Irvine, Irvine, and Biochemistry, CA,College University USA of of Environmental Western Science Australia, and WA, Engineering, Australia Sun Yat-Sen University, Guangzhou, College of Atmospheric Sciences, Lanzhou University, Lanzhou, Gansu, China Received: 13 July 2014 – Accepted: 1Correspondence August to: 2014 T. – Wang Published: ([email protected]) 12 and August L. 2014 Published K. by Xue Copernicus ([email protected]) Publications on behalf of the European Geosciences Union. Atmos. Chem. Phys. Discuss., 14, 20767–20803,www.atmos-chem-phys-discuss.net/14/20767/2014/ 2014 doi:10.5194/acpd-14-20767-2014 © Author(s) 2014. CC Attribution 3.0 License. X. F. Wang W. X. Wang 1 Kong, China 2 3 4 Nanjing University, Nanjing,5 Jiangsu, China 6 7 Guangdong, China 8 Ground-level ozone in four Chineseprecursors, cities: regional transport and heterogeneous processes L. K. Xue Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | 3 3 pro- levels 3 3 , CO and x erent VOC ff cult issue is formation pro- ffi 3 pollution primarily lie ered from serious O 3 and VOCs in the near ff x concentrations exceeding 3 erent areas of China depending , and suggest the urgent need to ff x pollution observed at suburban sites ) on particles and surface reactions of 3 2 ective control strategies based on scien- ff ) and its precursors made at rural/suburban 3 20770 20769 erent atmospheric conditions (e.g., with di ff erent precursor distributions. The model-calculated in situ O ff ) and volatile organic compounds (VOCs). The ozone problem is 2 erence in methodologies. All four cities su ff NO + NO -controlled regime in Lanzhou. The key VOC precursors are aromatics and ), which is a product of atmospheric photochemistry involving nitrogen ox- = erent scales (Jacob, 1999). Challenges in regulating O ), uptake of hydro peroxy radical (HO x 3 x 5 ff production was in a VOCs-limited regime in both Shanghai and Guangzhou, trends in several highly urbanized regions, i.e., the North China Plain (NCP; O 3 2 3 forming nitrous acid (HONO), were assessed. The analyses indicate the varying 2 Atmospheric models are the common tools used to understand the O China has become home to several megacities and many large cities owing to its some developed regions). The Master Chemical Mechanism (MCM) is a nearly-explicit tifically sound knowledge must beskies. in place in order to return to the clearercesses. and The cleaner chemical mechanismsresentations underlying of the the complex models atmospheric arereactivities chemistry, with usually and the simplified structures organic rep- speciesThis grouped of chemical into similar lumping one givesuncertainties model reduced when computational species applied runtimes, to (Stockwell di but etemissions; may the al., produce lumped extra 2012). mechanisms are usually optimized with emission estimates in 1995–2005, Ding et al.,(YRD; 1991–2006, 2008; Xu 2005–2011, et Zhanget al., et 2008) al., and al., 2009). Pearl Furthermore, 2014),view River Yangtze a of delta River the worsening (PRD; delta 1994–2007, projected prospectfuture T. continuing of Wang (Ohara increase the et in problem al., emissions 2007). is of Consequently, even e NO foreseen in fast-paced urban-industrialization processes. It isbeen experiencing not air surprising quality that deteriorationenergy these in use light cities and of have motor their vehicles fastthe in expansion national the in past ambient economics, decades. air High qualitywind O standards have of been large observed frequently citieset in (e.g., al., and T. 2008; down- Wang Ran et et al.,ing al., 2009; O 2006, Chou et 2010; al., J. 2011). Recent Zhang studies et also al., indicated increas- 2007; Y. Zhang ides (NO a complex coupling of primaryport emissions, chemical at transformation, di and dynamicin trans- understanding its non-linear chemistryVOCs) with and respect contributions to from precursors both (i.e., local NO and regional sources. ozone (O (Molina and Molina,photochemical 2004; smog characterized Parrish by and unhealthily high Zhu, concentrations 2009). of ground-level A typical and di NO and considerable impacts ofon the these atmospheric processes abundances inbetter of understand di aerosol these and processes NO and represent them in photochemical models. 1 Introduction Air quality in the metropolitan areas has drawn increasing attention in recent years The O and a NO alkenes in Shanghai, andduction aromatics of in several Guangzhou. heterogeneous The processes,ide potential namely, (N impacts hydrolysis on of O dinitrogen pentox- and observation-based model werethe used results to due to minimizepollution di uncertainties but in showed comparison di production of rates were comparedcontributions with of the on-site observed photochemistryport change and rates of transport. to the At infer well-processed(up the the urban to rural relative an plumes site hourly contributed of valueof to of Beijing, Shanghai, the 286 ex- Guangzhou ppbv), extremely while and high the Lanzhou O O was dominated by intense in-situ production. We analyzed measurements of ozonesites (O downwind ofLanzhou, four to elucidate large theirtion, Chinese pollution characteristics, and cities regional impacts transport, – of in Beijing, heterogeneous situ produc- processes. Shanghai, The Guangzhou same and measurement techniques Abstract 5 5 25 20 10 15 25 20 10 15 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | E, 0 18 ◦ formation 3 N, 116 0 21 ◦ uptake in O 2 problem is to dissect the local 3 concentrations at the upwind site precursors, and varying impacts of 3 3 ) on particles, and surface reactions of erent regions of China (see Fig. 1) and 2 ff 20772 20771 precursors were conducted from 2004 to 2006 in subur- 3 erent distributions in O ff and O 3 pollution, di 3 erent geographies, climates, industries and emission patterns. The same mea- ff ), uptake of hydro peroxy radical (HO 5 forming nitrous acid (HONO) (Brown et al., 2006; Thornton et al., 2008; Su et al., O 2 2 Beijing is the capital city of China and among the largest cities in the world. It is lo- Shanghai is the largest city of China and located in the Yangtze River Delta. It has To evaluate the atmospheric impacts of emerging Chinese megacities, intensive Another challenge in understanding ground-level O over 23 million population, 2 million vehicles, China’s largest petrochemical complex, cated on the northwesternaccommodates periphery more of than the 19 densely-populated millionfactories North inhabitants, and China 5 power million Plain, plants. and automobiles, The and2005 observations dozens were in of carried a out from280 rural m 21 a.s.l.), June about mountainous to 50 km area 31 northsite July in (generally was downwind Chang in in summer) Ping10 of a km the district away fruit downtown. (Wang The (CP; et farm al., 40 with 2006). sparse population and anthropogenic emissions about city in Western China (Lanzhou; seedownwind Fig. of 1). The city sampling sites centersscale were during selected pollution carefully and the processes. studyet These periods al. sites to (2006); have been Gao allowhere described et investigation we separately al. of only by (2009); give regional- a Wang Q. brief Zhang outline. et al. (2009) and Pathak et al. (2009), and heterogeneous chemistry in major cities of China. 2 Methodology 2.1 Study areas and sites The field experiments were conducted inNorthern rural/suburban (Beijing), areas Eastern near three (Shanghai) megacities and in Southern (Guangzhou) China, and a large for assessing the atmospheric impactanalysis, of an on-going rapid observation-based urbanization MCM in modeltributions China. (OBM) of For was data in deployed situ toimpacts photochemistry quantify of the and con- several regional heterogeneous transportserious processes. and Overall, O to this assess study the reveals potential the similarly quality data in the mid-2000s in major urban areas of China, which will be invaluable from experiments in comparison of the results. These studies generated much high- can be regarded asthere the are regional very background limited forregional studies the transport that based receptor estimated on site. the the To observations contributions our at a of knowledge, single local locale production (e.g.,observations Frost and of et al., O 1998). ban/rural areas near four Chineseand major cities, Lanzhou. namely These Beijing, Shanghai, citieshave Guangzhou, di are located insurement di techniques were utilized in all campaigns to minimize uncertainties arising is the chemical transport modelbut that may is ideal be to subject quantifyet local to al., and uncertainties regional 2010; from contributions Tiecomprises the et concurrent emission al., measurements inventory 2013). from estimates2010; The at (X. Berlin other least Wang et approach a al., pair is 2013). of observation-based It stations and assumes (T. usually Wang that et the al., O NO 2008). These processes areaerosol believed to loadings. be However, more they relevantnisms in are (such as China usually MCM), given and ignored its totheir very by date potential only impacts high most very and limited suggested of studies(e.g., the the have Kanaya important attempted et role current to al., of evaluate mecha- 2009; HO Liu et al., 2012). and regional contributions. Two types of methods have been widely used for this. One Saunders et al., 2003),tochemistry and for hence a is variety theneous of best chemical environments. choice processes Another to which source investigatepreviously have atmospheric of thought. recently pho- uncertainty been Several is found cases(N heteroge- to in be point more are complex the than hydrolysis of dinitrogen pentoxide mechanism that has the minimum amount of chemical lumping (Jenkin et al., 2003; 5 5 20 25 15 10 25 20 10 15 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | ). pro- 3 ) cou- to NO. , VOCs, y y Advanced TEI Model 43c , NO, NO 2 ) in Beijing, Shang- TEI Model 42cy , CO, SO 3 pollution in late spring, and can 3 Thermo Environmental Instruments E), a suburban mountainous area with events. In total, 47, 68, 76, and 24 VOC 0 3 41 ◦ E, 20 m a.g.l.), which is approximately 45 km 0 ) with internal zeroing automatically done ev- 20774 20773 MSP, WPS model 1000XP 06 ◦ N, 103 0 8 ◦ N, 121 0 27 ◦ non-methane hydrocarbons (NMHCs) were measured by col- 10 –C 2 E, 17 m a.g.l.), a suburban area about 50 km southeast of downtown 0 ). CO was measured by a non-dispersive infrared analyzer ( 33 pollution in summer (Zhang et al., 2000). The sampling site was located were detected by a chemiluminescence analyzer ( ◦ was observed with a pulsed UV fluorescence analyzer ( 3 y 2 N, 113 0 42 was monitored by a UV photometric instrument ( ◦ Methane and C Lanzhou is a large city of over 3 million people and an industrial center in the inte- Guangzhou is a megacity of over 12 million people in southern China. It is in the 3 oxidation of 143 primary VOCs(Jenkin together et with al., 2003; the Saunders latest et IUPAC inorganic al., 2003). nomenclature Besides, heterogeneous processes includ- at facilitating both a thorough evaluationprehensive of modeling VOC pollution analysis for for the campaigns thesamples and high were a collected O com- in Beijing, Shanghai, Guangzhou, and Lanzhou,2.3 respectively. Observation-based model An observation-based chemical boxduction. model The was model utilized is largely tobuilt similar quantify on to the the the Master one in-situ Chemical outlined Mechanism O in (v3.2), a Xue nearly-explicit et mechanism al. describing (2013). Briefly, it is and mass spectrometry (the analysisIrvine) was (Xue et undertaken al., in 2013). the Generally,the one University field sample of was campaigns California collected (note at at thatIn noon the each addition, day sampling during multiple was not samplesone made sample were consecutively every taken at two Lanzhou). on hours selected from ozone 07:00 to episode 19:00 days, LT. Such normally a sampling strategy aimed a Wide-range Particle Spectrometerhai ( and Lanzhou. Temperature,speed, pressure, and relative solar humidity radiationabove (RH), were measurement continuously wind techniques measured and direction by qualitydescribed and assurance/control elsewhere a (Gao procedures weather et have station. al., been All 2009; Xue the et al.,lecting 2011). whole air samples inysis evacuated by stainless-steel gas canisters chromatography with with flame subsequent ionization anal- detection, electron capture detection, Pollution Instrumentation, Model 300EU ery 2 h. SO NO and NO pled with anAerosol external number molybdenum and oxide size distribution catalytic (10 nm converter – to 10 µm) reduce were NO measured in real-time by (TEI), Model 49i particle number and size distribution,O and meteorological parameters at the four cities. in Renshoushan Park (RSP;some 36 peach trees and other(Xigu vegetation petrochemical (J. M. district) Zhangcenter is et is al., located 2009). about about The 15 km19 industrial 5 km June to zone to to the 16 southeast. the July The 2006. southwest, intensive and campaign2.2 the was conducted urban from Measurement techniques The same set of techniques were deployed to measure O rior western China. Ita is mean situated altitude in of acal 1520 narrow m industry valley a.s.l. basin as This in unique well“basin” mountainous topography, as together of regions vehicle O with with emissions its (0.2 petrochemi- million cars in 2006), makes it a typical center of theof Pearl River consumer Delta, products.22 which The has been measurementsGuangzhou. a were The “world made data factory” atin collected for this between a Wan paper. 20 wide Qing Thus Aprilbe range the Sha and compared present 26 (WQS; study with targets(J. May and Zhang the 2004 supplement et O al., were previous 2007; analyzed Y. investigations Zhang that et al., focused 2008). on autumn Meteorological Station (31 northwest of Shanghai. Althoughfected Taicang by belongs urban to plumes Jiangsusummer-monsoon of Province, season. Shanghai it The under is observationsanalyzed the often taken in af- prevailing from the southeasterly present 4 study. winds May to in 1 the June 2005 were steel manufacturer, seaport and other industries. The study site was in the Taicang 5 5 25 20 10 15 25 20 10 15 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | ) 3 3 % (R1) (R3) (R4) (R5) (R6) (R7) (R8) < (R2a) (R2b) from the tradi- ] x O, temperature, 3 2 on ground/particle with our model. In production and de- ][O 2 x 2 3 alone (by considering erence between P(O 3 ff [HO 6 photolysis (R2) and reac- k 3 NMHCs, H + ] 3 10 instead of O –C ] (2) 3 episode days with 00:00 LT as the 2 3 3 ) other than O [OH][O ,C 2 5 4 ])[O i k (R6), atoms of O (R7) and Cl (R8), and net rates with those of O ) (1) 2 3 + NO 2 ] 3 + [VOC 3 i 20776 20775 9 or O ][O O 2 k , NO, CH 2 ( 2 = Criegee biradical (R9) x X on aerosols and reactions of NO [NO + 4 2 + k ] 3 + ] by peroxy radicals; Kanaya et al., 2009; Xue et al., 2013). 3 , CO, SO denotes N 3 2 (R4), OH (R5), HO and HO M [Cl][O 2 8 3 carbonyls k destruction is mainly facilitated by O 2 2 2 production is eventually achieved by the combination of O atom ]( [NO][O 2 2 3 + M 3 O → O 3 ] , NO 2O O O 2 M k 3 + + 5 + 2 2 O + + + production rate can be determined from the di 3 + 3 O ] O 2 2 O 3 2 + O D) 3 ][O][ 1 + 2 + OH NO production and destruction rates can be calculated as: [O][O [O 2 NO HO → 7 3 3 O( O [O ClO k O → → 1 O production rates). M ). We also compared our-derived O → → k J 3 2 + → → (R1), and O 3 3 → 3 → + O 2 = = unsat. VOCs O ) ) O hv hv NO NO O Cl + 3 3 + 2 + + + + + + + + ecting dry deposition rates was assumed to vary from 300 m at night to 1500 m in The model read the inputs every hour to calculate the in situ O The observed data of O 2 3 3 3 3 3 3 3 (O (O ff L tional method, and foundin both the methods Supplement). showed overall good agreement (see Fig. S2 Thus the O P Then the net O and L(O HO O O O O O O O O OH Here we determined directlythe the troposphere, reaction rates O ofwith O O tions with NO (R3),unsaturated NO VOCs (R9). the oxidation of NO to NO to the production of total oxidant (O for isoprene) and temperature (for isoprene),available. for Photolysis which continuous frequencies measurements were were(Saunders computed et al., as 2003), a andmodel function were calculations further of were scaled made solar by forinitial zenith the the time. measured angle identified solar Before O radiation. eachof The simulation, the the campaign-average model dataunmeasured pre-ran species. so for that nine the days model with approached constraints astruction steady rates. The state ozone for production rates the calculated by the OBM usually correspond see Fig. S1) in thetions same were season not (May in 2012). real-time, the Forestimated time-dependent hydrocarbons as concentrations for at follows. which hourly During the resolution the observa- were were daytime taken, (i.e., 07:00–19:00 the LT) when datations multiple gaps were samples were estimated based filled on by the time regressions with interpolation. CO The (for most nighttime hydrocarbons concentra- except and 2000 m) showed thatin its net impact O on the modeling results was negligible (i.e., pressure, and aerosol surface and radiusolution were averaged of or 1 interpolated h with and aculated time used res- from as the the aerosol model numberwhere inputs. and such The size measurements aerosol distribution surface were measurements.tained and For not from Guangzhou radius available, a were we similar cal- used suburban the site in average Hong diurnal Kong data (Tung Chung, ob- close to the WQS site; surfaces producing HONO aresitions also of incorporated inorganic (see gases, details peroxides,in in PANs, the carbonyls Sect. model and 3.4). from organic Dry thea acids depo- recent are compilation adopted (Zhang etthe al., afternoon. 2003). The Sensitivity mixing-layer model height runs with other maximum mixing heights (i.e., 1000 ing uptake of N 5 5 20 25 15 10 25 20 10 15 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | - α/β precursors 3 ) and Guangzhou 1 − 4 carbons (C4HC), and low- ≥ species were categorized into precursors observed in the four + 3 and CO as shown in Fig. 2. The low- y of 127 ppbv observed. The pollution in levels (Ding et al., 2013). At the down- 3 concentration was recorded at 178 ppbv. x 3 mixing ratio was 286 ppbv, which is by far and CO are shown in Fig. 2. At the rural 3 y 20778 20777 levels highlight the serious problem in the Beijing pollution conditions observed in the four cities. At episode days (here defined as days when the peak 3 3 3 precursors 3 of 143 ppbv. Our observations highlight the serious ozone pollution in the PRD is serious not only in autumn but also in 3 ect of its high NO ff 3 formation regimes in the four cities (see next section). and O ) was measured at the Beijing site, which should be ascribed to 1 3 3 − in total), followed by those in Shanghai (5.85 s erent hydrocarbon distributions among the four cities were also illus- ff 1 − erent O ff levels measured in Shanghai (24–39 ppbv) and Guangzhou (24–52 ppbv) exceeded 100 ppbv; 44 % of the total) were observed during the 6 week mea- -pinenes) and biogenic hydrocarbons (BHC; comprising isoprene and ). This is opposite to the patterns for NO 3 y 1 − α/β Furthermore, di Figure 3 documents the average reactivities towards OH of major hydrocarbons We then examined the distributions of major O (35 and 43 %)nant and AHC R-AROM class (34 with and ana average 39 predominant %). contribution role of In and 46 composed Guangzhou, %.the on And R-AROM propene average in 70 and was % Lanzhou, ethene of the alkenes levels thethe domi- played were AHC AHC extremely reactivity. In reactivity. high, These particular, both resultsand of imply suggest which di contributed distinct 53 emission % patterns of of O the fact that our site isemissions. located It in also a implies rural that mountainousical the area processing urban with during few plumes local transport had anthropogenic and undergone were extensive photochem- less reactive whentrated. reaching the In Beijing Beijing site. and Shanghai, the AHC reactivities were dominated by both alkenes and pinenes), with AHCaromatics further except grouped for into benzene),reactivity reactive alkenes, hydrocarbons alkanes aromatics (LRHC; with (R-AROM; includingbenzene; including methane, see all ethane, in propane,Lanzhou Table (9.33 acetylene s S1). and The(5.23 s highest hydrocarbon reactivityest was reactivity determined (2.77 s in lower afternoon concentrations in Lanzhou. in the four citiesterpretation (see of Supplement the foranthropogenic hydrocarbon hydrocarbons the speciation, (AHC; OH encompassing the reactivity most calculation). 50 species To except facilitate for in- isoprene 27 ppbv), while the CO levels were comparable in the four cities despite the relatively were significantly higher than those in Beijing (rural site; 11–16 ppbv) and Lanzhou (7– cities. The meansite diurnal of profiles Beijing oflate with NO afternoon little till the local evening,the emissions, corresponding suburban to both sites regional precursors downwind transportthey of showed of exhibited Shanghai, urban high a plumes. Guangzhou levels At morning andcaused in maximum Lanzhou, by and/or the in another the comparison, eveningThe shallow peak, NO boundary which were layer mainly and enhanced emissions in the rush hours. wind site of Guangzhou,measurement seven days. episodes The (19 maximum %) hourly wereThis O encountered indicates that throughout the the O 37 late spring. In Lanzhou, eightwith episodes a (29 maximum %) hourly tookpollution O place in during the the large 4 week cities campaign of China. hourly O surement period. The maximumthe hourly highest O value reportedquency in of China episodes in and open extremearea. O literatures At the (Wang suburban et site al.,4 near week 2006). Shanghai, campaign six Such with episode fre- the daysShanghai (21 maximum %) (YRD) hourly occurred seemed O during relatively the be lighter due than those to in the other titration three e cities, which may 3.1 Overview of O Table 1 summarizes the overallthe rural O site of Beijing, eighteen O 3 Results and discussion 5 5 25 20 10 15 25 20 10 15 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | 3 3 3 3 − ect trans ff cient R chem ). The . Thus ffi x R peak at − 3 meas 100 ppbv to R to downwind ect the vege- meas ∼ pollution. This ff 3 R 3 = ect corresponding ff trans 100 ppbv at 12:00 LT). R ) were computed every ∼ time series ( accumulation throughout concentrations (Cardelino 3 3 3 pollution, by calculating the deps R 3 pollution in the four cities, we erence ( ff 3 levels were observed and the most 3 increase in the early morning. This should 3 mixing ratios is a combined result of in situ episodes at the four cities (the results were and contributions of in situ production, depo- 3 3 20780 20779 3 -rich air aloft when the nocturnal boundary layer is mixing ratios increased sharply from 3 3 ) and deposition rates ( 40 ppbv at 08:00 LT) to noon ( levels observed at the rural site downwind of Beijing. As ects were also noticed for the Guangzhou and Lanzhou ∼ chem ff 3 episodes (3 per city; Beijing: 9, 26, 30 July 2005; Shanghai: formation was determined during these episodes (e.g., up R at Shanghai, Guangzhou and Lanzhou). Regional transport 3 3 1 − concentrations from the observed O ect of a given emission reduction on O 3 ff rise was attributed to the transport of urban plumes from Beijing that and related parameters during these episodes are shown in Figs. S3– 3 3 production ( production rate to decrease in precursor concentrations, and can be used . This is a very typical case at CP in summer, and highlights the e 3 3 3 increase and even had potential to export the produced O 3 ) can be considered as the contribution from regional transport (note that the e decrease. Similar wind e We then examined the ozone formation regimes in Shanghai, Guangzhou and In comparison, the in situ production dominated the O We are particularly interested in the relative roles of in-situ photochemistry and trans- Figure 4 displays the time series of O 220 ppbv within less than two hours (14:00–15:00 LT), during which the in-situ O 3 deps crease in O as a metric for the e to 50, 90 and 40generally ppbv h made a negative contributionindicates (i.e., that export) to the the airserved observed masses O O at theseregions. sites were reactive enough to sustain theLanzhou, ob- where in siturelative photochemistry incremental dominated the reactivity O (RIR) with the OBM. RIR is defined as the ratio of de- export of Beijing urban pollutiontation in and the crops afternoon, in which downwind can areas. adversely a the daytime at suburbanFig. sites 4b–d). downwind Very of strong Shanghai, O Guangzhou and Lanzhou (see shown in Fig. 4a,accumulation both from in morning situ ( productionIn and the regional afternoon, transport however, contributed the∼ to O the O production had been weakened due tosuch the a relatively sharp low O levels ofhad VOCs and undergone NO extensive photochemicalproduced processing O and contained high amounts of O cases. These results suggestprocesses that and hence our is method capable can of quantifying capture the the contributions variations ofport regional in in transport. the physical extremely high O 14:00–15:00 LT; but after that the wind direction shifted to northerly, leading to a sharp southeasterly winds brought urban plume to the study site, resulting in an O sition and regional transport forsimilar typical for O other casesare for illustrated. each One city and isincrease during are the the not intrusion early shown). morning ofpresented Two period. an interesting residual At important phenomena all boundary-layer contributor four to air cities, thebe O in contributing attributed particular to to Lanzhou, mixing O broken with down. the The O otherto is the the variation sudden changes in of surface the winds. transport During e the Beijing case (Fig. 4a), for example, the rate of change inin O situ net O hour by the OBM as describedR in Sect. 2.3. Then theof di atmospheric mixing was also included in this term). comprehensive measurements (i.e.,time multiple series daily of O VOCS6.) samples) At were a given made. location,photochemistry, (The the regional change transport of (both O contributions horizontal of and chemistry vertical)import) and and or transport deposition. negative The can (i.e.,the be destruction contributions either and of positive in-situ export).pollution (i.e., photochemistry In by production and the using regional and present observations transport study, coupled to we with the examined OBM observed O analysis. We first determined the To understand the processesanalyzed in contributing detail twelve to O high7, O 8, 22 May 2005;These Guangzhou: cases 18, were 23, chosen 24 because May elevated 2004; O Lanzhou: 5, 11, 12 July 2006). 3.2 Process analysis: regional transport vs. in situ formation 5 5 25 20 10 15 25 20 10 15 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | x 5 (3) O and 2 pro- 2 (R10) 2 formation, precursors 3 3 cient of N ffi hydrolysis on the 5 O 2 and production yield of and to a lesser extent to 5 x ), which is usually accumu- O 2 2 emissions may aggravate the formation regimes were consis- x 3 is the first order rate constant and and can be calculated from the gas formation by releasing both NO 10 5 derived on real atmospheric particles 0) in the base model, and conducted k 3 5 O cient of N pollution in Lanzhou is to cut the NO 2 O = formation from N ffi 2 3 N concentrations (Chang et al., 2011). This is the reactive uptake coe 2 ϕ ( γ , and 5 5 2 2 O O 2 20782 20781 production with a moderate yield of 60 %. 2 N 2 γ erent among cities. In Shanghai and Guangzhou, ff 10 k 2 were negative. Within the AHC dominated were reactive is the aerosol surface area concentration and is calculated x ClNO aero may produce nitryl chloride (ClNO ∅ · S formation was most sensitive to NO aero · 5 + S 5 3 O − 3 O 2 2 N cient way to alleviate the O NO γ formation in both cities, yet cutting NO formation. · · ffi ) production was highly VOC-sensitive, specifically AHC-controlled (see 5 3 3 hydrolysis O 3 is the mean molecular speed of N 2 5 − ∅ 5 N is the production yield of ClNO ν O O · 2 2 (2 problems. 0.03 with no production of ClNO ϕ N 1 4 3 ν , which are highly variable and dependent on the aerosol composition, humidity = → 2 = 5 5 production. In particular, light olefins such as propene and ethene were the most production during the selected episodes in the four cities. Overall, the ClNO O O 2 Figure 6 illustrates the impacts of ClNO In Lanzhou, the O 3 3 2 N 10 k O duced/accumulated at night may enhance considerably the next-day’s O process has not been consideredis by most here of parameterized the in current our mechanisms MCM-based (e.g., model MCM), as and follows. N Where, estimated by where kinetic theory (Aldener eton al., aerosol 2006); surfaces; based on the measuredthis particle process number size primarily distributions.ClNO lies The in current uncertainty the of and uptake temperature coe (Chang et al.,from 2011). The limited available field2011, and observations references were therein). inγ In the the present range study, ofsensitivity we analyses 0–0.04 adopted by a (Chang including ClNO moderate et value al., of The hydrolysis of N lated at night and canchlorine enhance atom the (it next-day’s O can oxidizeis hydrocarbons considered like OH) to via be photolysis. first The order hydrolysis rate of the N 3.3.1 N emissions (from petrochemical andemissions power of plants olefins as (from welldecrease the as in petrochemical O vehicles), plants) while could reducing also result in3.3 considerable Impact of heterogeneous processes In this section, wegeneous assess processes the on potential the impactsthem ozone in of production the several in OBM poorly-understood the and four hetero- conducting target sensitivity cities, analyses. by incorporating structure of Lanzhou, which isChina a National well-known Petroleum petrochemical Corporation citysmall – in Lanzhou petrochemical West Petrochemical China plants Company with located andnents the in of many its the petrochemical Xigu plant district.that emissions Light (Ryerson the et olefins most al., are e 2003). major The results compo- suggest suggests that reducing emissions ofweaken aromatics the (and O also alkeneslocal for O Shanghai) would AHC. Within the AHC, alkenes wereO the most important compounds responsibleabundant for reactive the species, both ofactivity which (figure presented not approximately shown). half Such of high the AHC levels of re- olefins are attributable to the industrial during the episodes are shown intent Fig. among 5. cases Overall, the for each O citythe but di in-situ O Fig. 5a). The RIRsaromatics for and NO alkenes in Shanghai and aromatics in Guangzhou (see Fig. 5b). This and Chameides, 1995). The daytime-average RIRs for major groups of O 5 5 10 20 25 15 25 20 10 15 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | - x 3 is ffi (4) ) is and 2 con- con- is the x in the (R11) 10 %) aero 2 2 HO 2 S < γ 11 k HO production γ is a consid- 3 usion coe is the uptake ; and 5 ff cient ( 2 2 on average (or -limited regime O ffi x reduction would 1 2 HO cient radical sink − γ 2 ffi and/or aerosol surface. peak of 1.3 ppbv at the 3 ppb h x concentrations. 2 ∼ 2 formation regimes (i.e., the which can be adopted in air 3 2 ). Such HO loss on the modeled HO 3 formation at NO − 2 photochemistry in the high-NO levels by about 50 % due to its 3 is the gas phase di ClNO 3 and particle surface, which in turn production should be attributed to 2 cm g ϕ x 3 10 %). At the Beijing site, however, 2 D < production (Kanaya et al., 2009). This and 3 5 hydrolysis, the uptake coe O 0.02 in the base model, and changed it to 2 5 15 % in the daytime-average O N = 1600 µm (Mozurkewich et al., 1987); O on the real particles. ∼ γ production rates by 2 2 20784 20783 1 ∼ 2 3 − loss is dominated by its reactions with NO HO s HO 2 γ is the mean molecular speed of HO 2 γ 2 on aerosol surface can act as an e HO aero ν 2 S or lower loadings of aerosols, adopting a higher uptake production rates ( 1 x − ects of heterogeneous HO 3 production regime at our rural site). This indicates that the ff ! 3 2 erent types of non-metal aerosols at room temperatures, with ff by aerosols 0.2) measured on the Cu-doped aqueous surfaces (Mao et al., HO 2 ν > · erent cities are clearly illustrated. These impacts mainly depend on 4 production rates during episodes in the four cities. Varying impacts 2 11 ff 0.4) would only lead to little to moderate reductions in the HO on particles; are urgently required to better understand this process and to pro- 3 k conditions, the HO 2 HO = 2 x presents another large source of uncertainty in current studies of O γ 2 21 %) and O -sensitive O 2 + x HO < g γ reduction would lead to less reduction in O r D 2 is the surface-weighted particle radius; products

r formation would result in an average nighttime ClNO and ClNO − 2 values for ambient aerosols at Mt. Tai (0.13–0.34) and Mt. Mang (0.09–0.40) in cient ( cient of HO → 5 2 = ffi ffi 2 O Figure 7 elucidates the e 2 HO 11 photochemistry in the high-aerosolstudies environments are like required Beijing, to and quantify more the observational coe centrations ( a faster uptake wouldvery reduce high loadings significantly of thein aerosol turn HO surface result ( inrates an (note average decrease that of athe relatively more smaller NO reduction inuptake O of HO (i.e., at high-NO its heterogeneous loss is lesssame important) HO as well asthan the at O the VOCs-limited regime). Atrelatively the higher Shanghai, levels Guangzhou of and Lanzhou NO sites with 2010, and references therein).γ Taketani et al. (2012) recentlyChina. reported Here relatively we large adoptedan a upper value limit of (0.4) for sensitivity model runs. centrations and O of this process in di the abundances of aerosol surface, and are also related to the levels of nitrogen oxides the aerosol surface density. Similara to parameter N with large uncertaintyture and and is RH related (Thornton to etrange the al., of aerosol 2008). 0.01–0.2 composition, The for tempera- laboratory di studiesmuch determined higher the values ( coe our model by adding the following reaction. HO The reaction rates were assumedreaction to constant be that first can order in be the calculated HO by k 3.3.2 Uptake of HO The heterogeneous loss of HO at high aerosol loadings andprocess thus is attenuate also O usually ignored by the current mechanisms, and here was included in at the other three sites dueThese to results their suggest relatively lower that levels of theerable NO uncertainty nighttime heterogeneous in process the ofand current N understanding high-aerosol of environments O suchN as Shanghai. Clearly,vide in-situ more realistic measurements parameterizations of of quality models. sity (more interface) and nitrogenClNO oxides (more reactants). ForShanghai instance, site including with the high concentrationswould of enhance both the NO daytime-average O 14 % in percentage). In comparison, this process seems to be less significant ( and this impact is highly dependent on the abundances of both aerosol surface den- Where cient and is assumed to be 0.247 cm 5 5 25 20 10 15 20 10 15 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | , g on (5) (6) γ ect ff 1 (neg- − (R12) (R13) cients during 2 ffi the het- 6 − ff during the 10 5 − × 3.2 ppb h 10 ∼ × and ect), and the net e 1 ff − are the uptake coe a ective surface density of the ff γ 6.8 ppb h NO reaction (e.g., Su et al., 2008 and ∼ . With more intense solar radiation, + g 2 production by consuming NO γ − ; 3 400) was used (Li et al., 2010). As to V is the e 2 / / 1 %). This corresponds well to the distri- concentrations (Aumont et al., 2003), and per geometric ground surface was used to < ect O 2 2 ff a 20786 20785 2 at nighttime, and increased it to 5 6 − forming HONO were used during the daytime than at night. For at nighttime, and increased it to 2 2 10 a 6 (solar radiation production rates by γ − × 3 × 1 10 5 = − and × a g 1 10 γ γ = × g g 16 %) in Shanghai and Guangzhou respectively, but lead to little a k γ k may play an important role in atmospheric photochemistry in the ∼ is the aerosol surface area concentration. Considering the photo- V S aero 2 S · · V (Vogel et al., 2003). , and some additional sources have been proposed (e.g., Su et al., / g a aero 2 ective surface area of 1.7 m γ γ S ff · · value of 2 is the mean molecular speed of NO 25 and 2 2 HONO HONO g 2 environments such as Shanghai and Guangzhou, and need to be included are the first order rate constants for the ground and aerosol surface reactions, ∼ γ NO NO x a ν ν NO on the ground and aerosol surfaces were also taken into account in the base ect) and releasing OH via HONO photolysis (positive e on various surfaces should be an important source of HONO (Su et al., 2008; on the ground and aerosol surfaces; S → k · · → ν ff 2 2 2 2 2 8 1 4 1 = = and NO , we chose a value of In-situ measurements of HONO, which were not available in China until recent The heterogeneous reactions of NO NO a a g g ever, identification of additional HONO source(s) is beyond scope of the present study. processes of NO high-NO in the air quality models. years, have shown surprisingly elevatedthroughout concentrations the of HONO daytime (up in todaytime the the HONO PRD ppb cannot region level) be (e.g.,actions Su explained of et by NO al., only2011). 2008). including It Such the is high above not levels heterogeneous known of if re- this phenomenon was also the case at our study sites, how- change for the Beijingbutions and of Lanzhou nitrogen sites oxides ( observedloading at seems the not four a sitesneous (see key HONO Fig. factor formation 2). here, on And the whichat aerosol ground is the surface generally in ground dominates line than level those with (Su on the et the fact al., aerosol that 2008). the These heteroge- results suggest that the heterogeneous calculate the S ative e depends on their balance. Weerogeneous conducted HONO sensitivity sources, model runs whichThe by is results turning are the o shown case inhance of Fig. the most 8. daytime-average We O current can atmosphericaverage see ( models. that including these processes would en- we used a value of daytime with solar radiation smaller thana 400 higher W m γ the day. An e and 2011). It hasof been NO suggested that theLi photo-enhanced et al., heterogeneous 2010). reactions Inmodel. the In present addition study, HONO to was the notof homogeneous measured source, NO but heterogeneous simulated sources within from the model reactions by adopting thewere parameterizations assumed used to by be Lithe first et processes order were al. of simplified (2010). as the The follows. NO reaction rates HONO is a keyin reservoir atmospheric of chemistry. the Recenting” hydroxyl studies source(s) radical have for indicated (OH) daytime possible and HONO,considering which existence hence the cannot of plays homogeneous be “miss- source a reproduced from by crucial the current role OH models only 3.3.3 Surface reactions of NO of NO ground, and enhanced production of HONO from the2010), surface reactions higher (George, values 2005; of Monge et al., k where k and can be estimated as k 5 5 25 20 10 15 10 20 25 15 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | photo- at least loss on in a pol- 3 2 2 5 O 2 levels (up to . These find- erent precur- x 3 pollution, local ff levels. And the 3 x and N . The HO 3 x production. Undoubtedly, 3 was more important for the 2 orts are needed to determine ff . hydrolysis was more significant at the pollution and showed di 5 3 O 2 20788 20787 levels in Shanghai and Guangzhou were higher than y formation, and further e precursors were made at a rural site downwind of Beijing 3 3 ered from severe O ff production was VOCs-limited in Shanghai and Guangzhou and and O 3 erent regions of China, and suggest further necessity to better ff 3 The authors are grateful to Steven Poon, Waishing Wu and Jiamin Zhang precursor distributions, roles of transport and in situ production, and 3 -limited in Lanzhou. The key VOC species were aromatics and alkenes in production at the Lanzhou site seemed to be less sensitive to all of these production were assessed. The N x 3 3 in major urban areas ofbe China. particularly The valuable high-quality for datation/industrialization assessing taken process the in in atmospheric China. the impact mid-2000 s of will rapid urbaniza- The HONO formation fromGuangzhou surface reactions and of Shanghai NO sitesO mainly owing toprocesses their due to high its NO relatively lowings concentrations indicate of the aerosol and varying NO chemistry impacts in of heterogeneous di processesunderstand on these the processes. O In summary, the results of thischemistry study vs. have provided outside insights impact, into O and potential impacts of heterogeneous chemistry The four citiessor su distributions. The NO that in Lanzhou, whiledominant an opposite anthropogenic pattern hydrocarbons wasGuangzhou, found were and for alkenes both the alkenes VOC in and reactivity. aromatics The Lanzhou, in aromatics BeijingTransport of and in Shanghai. “aged” urban plumes286 ppbv) resulted at in the the rural extremely high site O downwind of Beijing, while intense in situ photochem- Shanghai and aromatics in Guangzhou. The potential impacts of severalO poorly-understood heterogeneous processes on Shanghai site due toaerosols its was more high relevant levels for of Beijing both because of aerosol its and very NO high aerosol loadings. ical production dominatedLanzhou. at The the O suburbanNO sites of Shanghai, Guangzhou and Bates, T., and Fehsenfeld, F.: Reactivity and loss mechanisms of NO 4. 1. 2. 3. 4 Summary Measurements of O and suburban sites of Shanghai,elucidate Guangzhou and the Lanzhou. O The dataimpacts were of analyzed heterogeneous to processes. The major findings are summarized as follows. present an importantin HONO situ source measurements and ofphotochemistry can HONO including enhance are O O criticalthe for “missing” better source(s). understanding the atmospheric The analyses presented here clearly indicate that the surface reactions of NO Aldener, M., Brown, S., Stark, H., Williams, E., Lerner, B., Kuster, W., Goldan, P., Quinn, P., References sity of Leeds forsearch providing Grants the Council mechanism. ofsupported The Hong by field Kong the measurements (HKRGC; PolyU5144/04E), were(PolyU5015/12P). Hong and funded Kong the by Polytechnic data the University analysis Re- (1-BB94 were and 1-ZV9N) and the HKRGC The Supplement related to thisdoi:10.5194/acpd-14-20767-2014-supplement article is available online at for their contributions to theing field the work, study and sites. to Tijian We Wang would and like Jie to Tang for thank their the help Master in Chemical select- Mechanism group in Univer- Acknowledgements. 5 5 20 10 15 15 10 20 25 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | , ) 3 x /O x /HO x : a review, , 2010. 5 O 10.5194/acp- 2 , 2006. 10.5194/acp-3-181-2003 10.5194/acp-10-6551-2010 10.1029/2006JD007252 , 2011. formation, Atmos. Chem. Phys., 12, 7737–7752, , 2009. 20790 20789 3 , 2013. , 2008. mann, J., Stemmler, K., and Ammann, M.: Photoenhanced , 2012. ff budgets and O on solid organic compounds: a photochemical source of HONO?, x 2 10.5194/acp-9-7711-2009 10.5194/acp-11-9825-2011 , 2010. 10.5194/acp-8-1-2008 10.5194/acp-13-5813-2013 10.5194/acp-12-7737-2012 10-5823-2010 doi: Crounse, J.Jimenez, D., J. Spencer, L.,hen, Fried, K. R. A., C., Chen, Weibring, M., G., P.,Yantosca, Crawford, R. J. Walega, Beaver, H., M., J. McNaughton, Le M. C., Sager, G., Clarke, P.,in and A. Hall, R., the Carouge, D., Jaeglé, S. C.: Arctic L., Chemistry R., Wennberg, Fisher, troposphere of J. in Weinheimer, hydrogen A., P. oxide spring, A. radicals Atmos. J., O., (HO Chem. Co- Phys., Cubison, 10, 5823–5838, M. doi: J., Amoroso, A., Costabile, F., Chang, C.-C., andCAREBeijing-2007: Liu, RO S.-C.: Summertime photochemistry during 2003. Taketani, F., Okuzawa, K., Kawamura, K.,of Akimoto, photochemical H., and ozone Wang,analysis production Z. using F.: over comprehensive Rates measurements and Central of7711–7723, regimes East ozone doi: precursors, China Atmos. Chem. in Phys., June 9, 2006: aof HONO box sources model onCampaign, Atmos. the Chem. photochemistry Phys., 10, in 6551–6567, Mexico doi: City during the MCMA-2006/MILAGO uptake of gaseous NO Faraday Discuss., 130, 195–210, 2005. Jersey, 1999. the Master Chemical Mechanism,volatile organic MCM compounds, v3 Atmos. Chem. (Part Phys., B): 3, 181–193, tropospheric doi: degradation of aromatic Goldan, P. D., Herwehe, J.,S. Hubler, A., G., Kuster, Norton, W.B. R. C., Martin, A., B., R., Westberg, Parrish, McMillen, H.southeastern D. R. D., H., United T., Ridley, Montzka, and States B.(ROSE) during Williams, A., progarm, E. the J. Shetter, Geophys. 1990 J.: R. Res.-Atmos., Rural Photochemical 103, E., 22491–22508, Oxidants ozone Walega, 1998. in production J. the in G., Southern the Watkins, Environment rural size distributions in the Yangtze Riverpolluted delta conditions, in Atmos. China: Environ., formation 43, and 829–836, growth 2009. of particles under tology over Beijing: analysis of aircraft8, data 1–13, from doi: the MOZAIC program, Atmos. Chem. Phys., Petäjä, T., Kerminen, V.-M., and Kulmala,River M.: Delta: Ozone an and overview fine of particle 15830, yr in doi: data the at western the Yangtze SORPES station, Atmos. Chem. Phys., 13, 5813– atmospheric chemistry, ambient measurements,Aerosol and Sci. model Tech., 45, calculations 665–695, of 2011. N production of ozone in9825–9837, Beijing doi: during the 2008 Olympic Games, Atmos. Chem. Phys., 11, Dube, W. P.,Trainer, M., Meagher, J. F., Fehsenfeld,in F. C., nocturnal and nitrogen Ravishankara, oxide A. processing R.: and Variability 2006. its role in regional air quality, Science, 311, 67–70, cursor relationships in the urban atmosphere, J. Air Waste Manage., 45, 161–180, 1995. luted marine environment: results from inStudy situ 2002, measurements J. during Geophys. New Res., England 111, Air Quality D23S73, doi: chemistry in the polluted boundary layer, Atmos. Environ., 37,changes, 487–498, 2003. and impact ofTexas Area, regional Environ. Sci. background Techol., ozone 47, 13985–13992, transported 2013. into the greater Houston, Ding, A. J., Wang, T., Thouret, V., Cammas, J.-P., and Nédélec, P.: Tropospheric ozone clima- Chou, C. C.-K., Tsai, C.-Y., Chang, C.-C., Lin, P.-H., Liu, S. C., and Zhu, T.: Photochemical Chang, W. L., Bhave, P. V., Brown, S. S., Riemer, N., Stutz, J., and Dabdub, D.: Heterogeneous Cardelino, C. A. and Chameides, W. L.: An Observation-based model for analyzing ozone pre- Brown, S. S., Ryerson, T. B., Wollny, A. G., Brock, C. A., Peltier, R., Sullivan, A. P., Weber, R. J., Berlin, S. R., Langford, A. O., Estes, M., Dong, M., and Parrish, D. D.: Magnitude, decadal Aumont, B., Chervier, F., and Laval, S.: Contribution of HONO sources to the NO Mao, J., Jacob, D. J., Evans, M. J., Olson, J. R., Ren, X., Brune, W. H., Clair, J. M. St., Liu, Z., Wang, Y., Gu, D., Zhao, C., Huey, L. G., Stickel, R., Liao, J., Shao, M., Zhu, T., Zeng, L., Kanaya, Y., Pochanart, P., Liu, Y., Li, J., Tanimoto, H., Kato, S., Suthawaree, J., Inomata, S., Li, G., Lei, W., Zavala, M., Volkamer, R., Dusanter, S., Stevens, P., and Molina, L. T.: Impacts Jenkin, M. E., Saunders, S. M., Wagner, V., and Pilling, M. J.: Protocol for the development of Jacob, D. J.: Introduction to Atmospheric Chemistry, Princeton University Press, Princeton, New George, C., Strekowski, R., Kle Frost, G. J., Trainer, M., Allwine, G., Buhr, M. P., Calvert, J. G., Cantrell, C. A., Fehsenfeld, F. C., Gao, J., Wang, T., Zhou, X. H., Wu, W. S., and Wang, W. X.: Measurement of aerosol number Ding, A. J., Fu, C. B., Yang, X. Q., Sun, J. N., Zheng, L. F., Xie, Y. N., Herrmann, E., Nie, W., 5 5 30 25 20 15 10 30 25 20 15 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | - ffi , 2003. ect of petro- , 2009. loss in aque- 10.5194/acp- ff 2 10.5194/acp-3- radicals by aerosol 2 , 2006. 10.1029/2002JD003070 ionic species in four major cities on tropospheric ozone formation , 2007. x cients for HO 2.5 , W. S.: A review of tropospheric at- ffi , 2013. , 2010. ff 10.5194/acp-9-6217-2009 , 2012. , 2008. 10.1029/2006GL027689 , 2009. 20791 20792 10.5194/acp-7-4419-2007 , 2009. , 2008. 10.5194/acp-13-5655-2013 10.5194/acp-10-7603-2010 10.1029/2007JD009236 mann, J., and Kurtenbach, R.: Measuredand simulated vertical profiles ff 10.5194/acp-12-11907-2012 10.5194/acp-9-1711-2009 , 2010. on aqueous particles, J. Geophys. Res., 92, 4163–4170, 1987. 2 , 2003. 10.1029/2008JD010752 10.1029/2007JD009060 1994–2007, Atmos. Chem. Phys., 9, 6217–6227, doi: Increasing surface ozone concentrations in the background atmosphere of Southern China, during the 2008 Beijing Olympics:Phys., 10, secondary 7603–7615, pollutants doi: and regional impact, Atmos. Chem. and Wiedensohler, A.: Nitrous acid (HONO) and its daytime sources at a rural site heimer, A., Chen,vations J., and and WRF-Chem Cai, modeling forPhys., C.: the 13, Megacity MIRAGE-Shanghai 5655–5669, field doi: impacts campaign, Atmos. on Chem. regional ozoneof formation: nitrous obser- acid –Environ., 37, Part 2957–2966, II. 2003. Modelsimulations and indications forBeijing, China, a Geophys. photolytic Res. Lett., source, 33, Atmos. doi: Blake, D., Wang, S. L., Ding, A. J., Chai, F. H., Zhang, Q. Z., andRussell, Wang, A. W. X.: G.: Air ProcessPearl quality analysis River and Delta, China, sensitivity during studytiscale the Air of PRIDE-PRD2004 Quality regional modeling campaign ozone system, using formation Atmos. the over Chem. Community the Phys., Mul- 10, 4423–4437, doi: 161-2003 mospheric chemistry and gas-phasesphere, chemical 3, 1–32, mechanisms 2012. for air quality modeling, Atmo- ous atmospheric aerosols: regional and globalRes.-Atmos., impacts 113, on doi: tropospheric oxidants, J. Geophys. 10-4423-2010 Frost, G. J., Goldan, P.man, D., J. Holloway, J. A., S., Nicks Hubler, Jr.,chemical G., D. industrial Jakoubek, K., emissions R. Parrish, of O., D. reactivein D., Kuster, Houston, alkenes Roberts, W. Texas, and C., J. J. NO Neu- Geophys. M., Res.-Atmos., and 108, Sueper, 4249, D. doi: T.: E of the Masteraromatic Chemical volatile Mechanism, organic compounds, MCM Atmos. v3 Chem. Phys., (Part 3, A): 161–180, doi: tropospheric degradation of non- Cheng, P., Zhang, Y.,OH and radicals, Poschl, Science, 333, U.: 1616–1618, Soil 2011. nitrite asand a Akimoto, source H.: ofparticles Measurement atmospheric sampled of HONO from overall and ambient11907–11916, uptake air doi: at coe Mts. Tai and Mang (China), Atmos. Chem. Phys., 12, of China: nitrate1711–1722, formation doi: in an ammonia-deficient atmosphere, Atmos.Xu, Chem. Phys., J. 9, China: M., analysis anddoi: based Guenther, on A.: ground Ozone level photochemical observations, production J. in Geophys. Res.-Atmos., urban 114, Shanghai, during thedoi: 2004 PRIDE-PRD experiment in China, J. Geophys. Res.-Atmos., 113, 54, 644–680, 2004. cient of HO emission inventory ofChem. anthropogenic Phys., emission 7, 4419–4444, sources doi: for the period 1980–2020, Atmos. George, C.: Light changes6605–6609, theatmospheric 2010. reactivity of soot, P. Natl. Acad. Sci. USA, 107, Wang, T., Wei, X. L., Ding, A. J., Poon, C. N., Lam, K. S.,Wang, Li, T., Nie, Y. S., W., Gao, Chan, J., L. Xue, L. Y., and K., Gao, Anson, X. M.: M., Wang, X. F., Qiu, J., Poon, C. N., Meinardi, S., Su, H., Cheng, Y. F., Shao, M., Gao, D. F., Yu, Z. Y., Zeng, L. M., Slanina, J., Zhang, Y. H., Tie, X., Geng, F., Guenther, A., Cao, J., Greenberg, J., Zhang, R., Apel, E., Li, G., Wein- Wang, T., Ding, A. J., Gao, J., and Wu, W. S.: Strong ozone production in urban plumes from Wang, X., Zhang, Y., Hu, Y., Zhou, W., Lu, K., Zhong, L., Zeng, L., Shao, M., Hu, M., and Vogel, B., Vogel, H., Kle Stockwell, W. R., Lawson, C. V., Saunders, E., and Goli Thornton, J. A., Jaegle, L., and McNeill, V. F.: Assessing known pathways for HO Saunders, S. M., Jenkin, M. E., Derwent, R. G., and Pilling, M. J.: Protocol for the development Taketani, F., Kanaya, Y., Pochanart, P., Liu, Y., Li, J., Okuzawa, K., Kawamura, K., Wang, Z., Ryerson, T. B., Trainer, M., Angevine, W. M., Brock, C. A., Dissly, R. W., Fehsenfeld, F. C., Su, H., Cheng, Y. F., Oswald, R., Behrendt, T., Trebs, I., Meixner, F. X., Andreae, M. O., Ran, L., Zhao, C. S., Geng, F. H., Tie, X. X., Tang, X., Peng, L., Zhou, G. Q., Yu, Q., Pathak, R. K., Wu, W. S., and Wang, T.: Summertime PM Parrish, D. D. and Zhu, T.: Clean air for megacities, Science, 326, 674–675, 2009. Mozurkewich, M., McMurry, P. H., Gupta, A., and Calvert,Ohara, T., J. Akimoto, H., G.: Kurokawa, Mass J., accommodation Horii, N., coe Yamaji, K., Yan, X., and Hayasaka, T.: An Asian Molina, M. J. and Molina, L. T.: Megacities and atmospheric pollution, J. Air Waste Manage., Monge, M. E., D’Anna, B., Mazri, L., Giroir-Fendler, A., Ammann, M., Donaldson, D. J., and 5 5 20 25 15 30 30 10 25 20 15 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | , , 2014. , 2008. , 2011. 10.5194/acp-3-2067-2003 , 2007. 10.5194/acp-14-6089-2014 , 2013. 10.1029/2010JD014735 20794 20793 10.5194/acp-8-2595-2008 and its precursors in Beijing in summertime between 3 10.5194/acp-7-557-2007 , 2009. 10.5194/acp-13-8551-2013 10.5194/acp-9-5131-2009 Wang, J. L., Gao, D. F., Shao, M., Fan, S. J., and Liu, S. C.: Regional ozone pollution and Lanzhou, Res. Environ. Sci., 13, 18–21, 2000. in air-quality models, Atmos. Chem. Phys., 3, 2067–2082, doi: doi: Liu, S. C.: Variations of ground-level2005 O and 2011, Atmos. Chem. Phys., 14, 6089–6101, doi: observation-based approach for analyzingPRD2004 ozone-precursor campaign, relationship Atmos. during Environ., 42, the 6203–6218, PRIDE- 2008. Zuo, H. C., Chen,acetyl J. M., nitrate Zhang, (PAN) in X.228–237, suburban C., 2009. and and Fan, remote S. areas J.: of Continuous western measurement China, of Atmos. peroxy- Environ., 43, 2003. Park, I. S., Reddy, S., Fu,emissions J. in S., Chen, 2006 D., Duan, for L., Lei, the Y., Wang, NASA L. T., INTEX-B and Yao, mission, Z. L.: Atmos. Asian Chem. Phys., 9, 5131–5153, So, K. L.: Ozonemos. production Chem. and Phys., hydrocarbon 7, reactivity 557–573, in doi: Hong Kong, Southern China, At- Wu, W. S., Tang, J.,nitrogen Zhang, speciation at Q. Mount Z., Waliguan in andstudy, western J. Wang, China: Geophys. W. new Res.-Atmos., X.: insights 116, from Source doi: the of 2006 summer surface ozone andWang, W. X.: reactive Sources and photochemistrysphere of volatile of organic western compounds in China: the13, results remote 8551–8567, atmo- from doi: the Mt. Waliguan Observatory, Atmos. Chem. Phys., ozone at a regionalAtmos. background Chem. station Phys., 8, in 2595–2607, eastern doi: China 1991–2006: enhanced variability, Zhang, Y. H., Su, H., Zhong, L. J., Cheng, Y. F., Zeng, L. M., Wang, X. S., Xiang, Y. R., Zhang, L., Brook, J. R., and Vet, R.: A revised parameterization for gaseous dry deposition Zhang, Q., Yuan, B., Shao, M., Wang, X., Lu, S., Lu, K., Wang, M., Chen, L., Chang, C.-C., and Zhang, L., Chen, C. H., Li, S. X., and Zhang, F.: Air pollution and potential control schemes in Zhang, J. M., Wang, T., Ding, A. J., Zhou, X. H., Xue, L. K., Poon, C. N., Wu, W. S., Gao, J., Zhang, Q., Streets, D. G., Carmichael, G. R., He, K. B., Huo, H., Kannari, A., Klimont, Z., Zhang, J., Wang, T., Chameides, W. L., Cardelino, C., Kwok, J., Blake, D. R., Ding, A., and Xue, L. K., Wang, T., Zhang, J. M., Zhang, X. C., Deliger, Poon, C. N., Ding, A. J., Zhou, X. H., Xu, X., Lin, W., Wang, T., Yan, P., Tang, J., Meng, Z., and Wang, Y.: Long-term trend of surface Xue, L. K., Wang, T., Guo, H., Blake, D. R., Tang, J., Zhang, X. C., Saunders, S. M., and 5 20 30 25 15 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper |

(ppbv) 3 Maximum hourly O a 3 emissions over China. The x episode days

. 25 Fig 20796 20795 21 Jun–31 Jul 20054 May–1 Jun 2005 1820 Apr–26 May 2004 619 Jun–16 7 Jul 2006 286 8 127 178 143 E, E, E, E, ◦ ◦ ◦ ◦ N N N N ◦ ◦ ◦ ◦ 40.35 31.45 22.70 36.13 116.30 121.10 113.55 103.69 Map showing the study areas and anthropogenic NO Overview of ozone pollution conditions in four Chinese cities. Beijing CP Shanghai Taicang Guangzhou WQS Lanzhou RSP Site Location Observation period Number of O The ozone episode day is deﬁned here as the one with the maximum hourly ozone exceeding 100 ppbv. a emission data was obtained from Q. Zhang et al. (2009). Figure 1. Table 1.

CO in the four cities. The data (b) and y

2 3 NO

2 3

. . . . 26 (a) 26 Fig Fig Fig Fig 20798 20797 Average OH reactivities of major hydrocarbons at the four cities. The error bar is Observed average diurnal proﬁles of

standard error. Figure 3. Figure 2. time interval is 10 min, and the error bar is standard error.

Guangzhou the AHC sub- (c) (b)

Shanghai (7 May 2005), precursor groups and 3

(b) 5 6

. . 4

28 27 Fig Fig Fig major O 20800 20799 (a) Beijing (9 July 2005), (a) Lanzhou (11 July 2006). Note that the blue bars are added to the red events in Shanghai, Guangzhou and Lanzhou. 3 (d)

accumulation and contributions from in-situ chemistry, regional transport, and de- 3 The OBM-calculated RIRs for O Figure 5. (24 May 2004), and ones. Figure 4. position during episodes in groups during high O

production 3 concentrations and O 2 with aerosol surface. The error bars production rates by including ClNO 2 3

5 6 8

. . . . 28 29 Fig Fig Fig Fig 20802 20801 from 0.02 to 0.4 during episodes at four cities. Also shown are the ob- 2 0.6) during episodes at four cities. Also shown are the model-simulated HO γ = concentrations and the product of NO 2 2 ClNO ϕ Average increase in the daytime-average O Average reductions in the daytime-average HO Figure 7. rates by adjusting served aerosol surface area concentrations (notethe that measurements the at data a in nearby Guangzhou station was in inferred from Hong Kong). The error bars are standard deviations. Figure 6. nighttime ClNO formation ( are standard deviations. The number in parentheses gives the increase in percentage.

Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper |

production rate by including HONO 3

8 7

. . 29 Fig Fig 20803 reactions during episodes at four cities. Also shown are the 2 Average increase in the daytime-average O Figure 8. modeled daytime-average HONO concentrations. Thenumber error in bars parentheses are gives the standard increase deviations. in The percentage. formation from heterogeneous NO