Constraints on instantaneous ozone production rates and regimes during DOMINO derived using in-situ OH reactivity measurements

Abstract

Abstract. In this study air masses are characterized in terms of their total OH reactivity which is a robust measure of the "reactive air pollutant loading". The measurements were performed during the DOMINO campaign (Diel Oxidant Mechanisms In relation to Nitrogen Oxides) held from 21/11/2008 to 08/12/2008 at the Atmospheric Sounding Station -El Arenosillo (37.1 • N-6.7 • W, 40 m a.s.l.). The site was frequently impacted by marine air masses (arriving at the site from the southerly sector) and air masses from the cities of Huelva (located NW of the site), Seville and Madrid (located NNE of the site). OH reactivity values showed strong wind sector dependence. North eastern "continental" air masses were characterized by the highest OH reactivities (average: 31.4 ± 4.5 s −1 ; range of average diel values: 21.3-40.5 s −1 ), followed by north western "industrial" air masses (average: 13.8 ± 4.4 s −1 ; range of average diel values: 7-23.4 s −1 ) and marine air masses (average: 6.3 ± 6.6 s −1 ; range of average diel values: below detection limit −21.7 s −1 ), respectively. The average OH reactivity for the entire campaign period was ∼18 s −1 and no pronounced variation was discernible in the diel profiles with the exception of relatively high values from 09:00 to 11:00 UTC on occasions when air masses arrived from the north western and southern wind sectors. The measured OH reactivity was used to constrain both diel instantaneous ozone production potential rates and regimes. Gross ozone production rates at the site were generally limited by the availability of NO x with peak values of around 20 ppbV O 3 h −1 . Using the OH reactivity based approach, derived ozone production rates indicate that if NO x would no longer be the limiting factor in air masses arriving from the continental north eastern sector, peak ozone production rates could double. We suggest that the new combined approach of in-situ fast measurements of OH reactivity, nitrogen oxides and peroxy radicals for constraining instantaneous ozone production rates, could significantly improve analyses of upwind point sources and their impact on regional ozone levels.

OH reactivity in a South East Asian tropical rainforest during the Oxidant and Particle Photochemical Processes (OP3) project

“…As a general trend, it has been found that our understanding is best in clean marine or high NO x environments, where the reaction of OH and NO 2 is the main constituent of the total OH loss (Ren et al, 2003;Di Carlo et al, 2004;Lee et al, 2009;Lou et al, 2010;Dolgorouky et al, 2012). The greatest discrepancies between measured and calculated OH reactivity are usually found under low NO x conditions in the presence of elevated levels of volatile organic compounds (VOCs), typical of those found in forested locations (Di Carlo et al, 2004;Sinha et al, 2008Sinha et al, , 2010Nölscher et al, 2012), or in highly processed continental air masses (Dolgorouky et al, 2012;Sinha et al, 2012).…”

“…Although high OH reactivities have been observed in both urban and forested environments (Shirley et al, 2006;Sinha et al, 2008Sinha et al, , 2010Sinha et al, , 2012Dolgorouky et al, 2012;Di Carlo et al, 2004), the ability of models to simulate these OH reactivity observations varies greatly. As a general trend, it has been found that our understanding is best in clean marine or high NO x environments, where the reaction of OH and NO 2 is the main constituent of the total OH loss (Ren et al, 2003;Di Carlo et al, 2004;Lee et al, 2009;Lou et al, 2010;Dolgorouky et al, 2012).…”

How the OH reactivity affects the ozone production efficiency: case studies in Beijing and Heshan, China

“…By directly measuring the total OH reactivity, VOC reactivity can be obtained by deducting the inorganic reactivity from the total OH reactivity, which provides a constraint for evaluating the roles of reactive VOCs in air chemistry (Sadanaga et al, 2005;Sinha et al, 2012;. This paper presents field data in China from two intensive observations conducted in August 2013 in Beijing and October to November 2014 in Heshan, Guangdong, focusing on OH reactivity and related species.…”

“…While the ozone concentration exceeds Grade II of China's National Ambient Air Quality Standard (2012; 93 ppbV) frequently in summer in the Beijing-Tianjin-Hebei area and the Pearl River Delta (PRD) region (Wang et al, 2006;Zhang et al, 2008), it appears there is an increasing trend for ozone in Beijing and other areas in recent years (Zhao et al, 2009;Zhang et al, 2014). Compared to traditional empirical kinetic model approach (EKMA; Dodge et al, 1977), the OH reactivity due to VOCs (termed VOC reactivity) rather than VOC mixing ratio was used in the calculation of ozone production rate (Geddes et al, 2009;LaFranchi et al, 2011;Sinha et al, 2012;Zhang et al, 2014). Due to the limitation of current measurement techniques, some VOC species which could not be quantified so far and there- Figure 1.…”

Oxidation processes in the Eastern Mediterranean atmosphere: Evidence from the Modelling of HO<sub>x</sub> Measurements over Cyprus

“…The OH reactivity calculated from the trace gases measured during CYPHEX varied between 1-2 s -1 during the study period (Figure 4), which is comparable to reactivity measurements made in the free troposphere (Mao et al, 2009). During the TORCH-2 campaign in Weybourne, England and the DOMINO campaign in El Arenosillo, Spain, the total reactivity was generally <5 s -1 when air masses originated from the sea (Lee et al, 2009;Sinha et al, 2012). The OH 10 reactivity measured in sub-urban regions is generally higher than 5 s -1 (Yang et al, 2016).…”