the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 22 Jul 2024
The long-term impact of BVOC emissions on urban ozone patterns over central Europe: contributions from urban and rural vegetation
Abstract. The paper evaluates the long-term (2007–2016) impact of Biogenic Volatile Organic Compounds (BVOC) emissions on urban ozone patterns over central Europe, specifically focusing on the contribution of urban vegetation using a regional climate model offline coupled to chemistry transport model. BVOCs are emitted by terrestrial ecosystems, with the prominent species being isoprene, monoterpenes, alcohols, carbonyls, and acids. Their impact is considered especially important over NOx-rich environments such as urban areas.
The study evaluates the impact of BVOC emissions on ozone (O3), formaldehyde (HCHO) and hydroxyl radical (OH) near surface concentrations, showing an increase in summer ozone by 6–10 % over large areas in central Europe due to BVOC emissions. It also demonstrates a substantial increase in formaldehyde concentrations. Additionally, the impact of BVOC emissions on hydroxyl radical concentrations shows a decrease over most of the domain by 20–60 %, with some increases over urban areas. Impacts on peroxy radicals (HO2 and higher RO2) are shown too.
Importantly, the study explores the partial role of urban vegetation in modulating ozone and evaluates its share in the overall ozone formation due to all BVOC emissions. The findings reveal that urban BVOC emissions contribute to around 10 % of the total impact on ozone and formaldehyde concentrations in urban areas, indicating their significant but localized influence.
The study also conducts sensitivity analyses to assess the uncertainty arising from the calculation of the urban fraction of BVOC emissions. The results show that the impact of urban BVOC emissions responds to their magnitude nearly linearly, with variations of up to fourfold, emphasizing the importance of accurately quantifying the urban BVOC fluxes. Overall, the study sheds light on the intricate relationship between urban vegetation, BVOC emissions, and their impact on atmospheric chemistry, providing valuable insights into the regional chemistry of BVOC emissions over central Europe and the causes of urban ozone pollution.
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Status: open (until 11 Oct 2024)
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RC1: 'Comment on egusphere-2024-2027', Anonymous Referee #1, 23 Aug 2024
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Liaskoni et al. study showed long-term (2007-2016) impact of Biogenic Volatile Organic Compounds (BVOC) emissions on urban ozone as well as formaldehyde and OH over central Europe. The study also explored the partial role of the urban vegetation and evaluated its share in the overall ozone formation due to all BVOC emissions. The study further assessed the changes in the oxidative capacity of the atmosphere by considering the oxidants e.g. OH and peroxy radicals and the dominant oxidation product of BVOCs (formaldehyde). Finally he study conducted a couple of sensitivity analyses to assess the uncertainty arising from the calculation of the urban fraction of BVOC emissions. This is an interesting paper as ozone can be considered as a regional problem, and the impact of vegetation emissions on urban areas is still unclear to some extent. Thus, the long-term regional impact of BVOC over decadal times-scales over central Europe can have a substantial contribution to scientific progress within the scope of this journal. The scientific approach and methods used in the study is perfect, but the paper is written in extremely bad English with grammatical errors and simple wording which doesn't go into the detail and causes confusion of the reader. Therefore, the article needs a major revision in its current form, after which it can be reviewed again for publication consideration.
The model validation results showed the overestimation of ozone in urban areas and even in rural areas. The explanation for the bias has been discussed with appropriate references. Can the authors include NOx model-measurement comparison to validate the model? NOx will play the major role for ozone variation in urban areas. This results can give more idea about the deviation of ozone in urban areas. It is also important to include how the model-measurement bias can impact on the overall results.
The details of the measurement data is absent in Method section. And also how the cities have been selected (on what parameters: NOx level or vegetation coverage)? Has the shading effect included in the MEGAN model? If not, how this can have impact on the overall emissions of BVOCs.
Some other comments:
Line 9: Most of the domain. What domain? Need to clarify.
Line 25-26: Will they be monoterpenes, sesquiterpenes?
Line 38-39: This statement should be applicable at high NOx condition which needs to be mentioned.
Line 39: a comma (,) or first bracket () need to be added after organic peroxy radicals.
Line 43: ‘nitrate radical (NO3)’ has already been defined before, so you can remove ‘nitrate radical’ from here.
Line 49-50: This has already been written in Line 38-39. You can delete anyone.
Line 83: (Richards et al., 2013) will be Richards et al. (2013).
Line 93: ‘to’ needs to be added after ‘due’.
Line 109: ‘Nowak et al. (2000), analysing various micro-climatic conditions above the urban domain of Washington DC to Massachussets, showed that’ can be written as ‘Nowak et al. (2000) showed by analysing various micro-climatic conditions above the urban domain of Washington DC to Massachussets that’
Line 143: To used BVOC emissions model?- Please correct the sentence.
Line 155: ‘as well’ will be ‘as well as’.
Line 179: typo ‘inbtermediates’
Line 170: which monoterpene as a representative of monoterpenes is used in the mechanism? There is a large variation of rate coefficients and products for different monoterpenes oxidation process. How can this impact on the overall results?
Line 182: HOx recycling and its impact on NOx-ozone chemistry (Archibald et al., 2010) has been updated in Khan et al. (2021). You could include this information in here.
Ref: Khan et al. (2021) Changes to simulated global atmospheric composition resulting from recent revisions to isoprene oxidation chemistry. Atmospheric Environment 244, 117914.
Line 197: ‘sesquiterpene’ will be ‘sesquiterpenes’.
Line 234: Please define ‘JJA’ when you use it first time.
Line 236: ‘of’ needs to be added after role.
Line 249: ‘on’ needs to be added after depending.
Line 258: ‘some’ needs to be removed.
Line 260: the has been written two times.
Line 297: ‘then’ will be ‘than’
Line 301: ‘here’ should be replaced by the figure number ‘Figure 5 to Figure 9’.
Line 305: Need to mention the figure number 5 in this sentence.
Line 307: ‘norther’ will be ‘northern’
Line 317: The sentence is not complete.
Line 318: ‘ozone’ needs to be added after MDA8.
Line 319: You could include the names of the urban areas in here.
Line 321: ‘that’ has been written two times.
Line 347: ‘well know’ will be ‘well known’.
Line 382: ‘reaches’ has been written two times.
Line 384: ‘as’ will be ‘us’.
Line 392: Impact on hydrogen oxide radicals. Why RO2 has been added in HOx?
Line 410: ‘to’ needs to be added after up.
Line 426: unit missing after 0.02-0.04.
Line 427: The sentence ‘Thus, again, half and twice of the default case, respectively’ does not make any sense.
Line 437: Is the sentence ‘overestimation over rural areas up to 20 µgm−3 while up to 30 µgm−3)’ correct?
Line 440: The sentence has grammatical error.
Line 443: Im et al. (2015) needs to be changed with (Im et al., 2015).
Line 443: ‘out’ will be ‘our’.
Line 449: The sentence with reference Zhu et al. (2024) is not clear to me.
Line 457: Grammatical error. Need to add ‘have’ after We
Line 474: The sentence is not correct. There or Therefore?
Line 481: chemical can be written as ‘species’.
Line 484: ‘os’ will be ‘is’
Line 512: causes will be cause
Line 520: ‘Crigee’ will be ‘Criegee’
Line 521: ‘pof’ will be ‘of’
Line 532: unit missing after 0.2 to 0.8
Figure 17: ‘in’ should be included after ‘Unites are’
Figure 16 and Figure 5 OH distribution should be similar? If they are similar, why they are shown in two places?
Peroxydes and hydroperxydes need to be corrected by Peroxides and hydroperoxides throughout the manuscript.
Citation: https://doi.org/10.5194/egusphere-2024-2027-RC1
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