A long-term estimation of biogenic volatile organic compound (BVOC) emission in China from 2001–2016: the roles of land cover change and climate variability

Wang, Hui; Wu, Qizhong; Guenther, Alex B.; Yang, Xiaochun; Wang, Lanning; Xiao, Tang; Li, Jie; Feng, Jinming; Xu, Qi; Cheng, Huaqiong

doi:https://doi.org/10.5194/acp-21-4825-2021

Articles | Volume 21, issue 6

https://doi.org/10.5194/acp-21-4825-2021

© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

https://doi.org/10.5194/acp-21-4825-2021

© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 21, issue 6

Research article

|

29 Mar 2021

Research article |

| 29 Mar 2021

A long-term estimation of biogenic volatile organic compound (BVOC) emission in China from 2001–2016: the roles of land cover change and climate variability

Hui Wang, Qizhong Wu, Alex B. Guenther, Xiaochun Yang, Lanning Wang, Tang Xiao, Jie Li, Jinming Feng, Qi Xu, and Huaqiong Cheng

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Interactive discussion

Status: closed

AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment

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RC1: 'Comments', Anonymous Referee #1, 14 Apr 2020
- RC2: 'Review Report for Wang et al. manuscript', Anonymous Referee #2, 21 May 2020
  - AC2: 'Response to Referee #2 on "Land cover change dominates decadal trends of biogenic volatile organic compound (BVOC) emission in China"', Qizhong Wu, 07 Jul 2020
- AC1: 'Response to Referee #1 on "Land cover change dominates decadal trends of biogenic volatile organic compound (BVOC) emission in China"', Qizhong Wu, 06 Jul 2020

Peer-review completion

AR: Author's response | RR: Referee report | ED: Editor decision

AR by Qizhong Wu on behalf of the Authors (06 Oct 2020) Manuscript

ED: Referee Nomination & Report Request started (26 Oct 2020) by Eleanor Browne

RR by Anonymous Referee #1 (16 Nov 2020)

Suggestions for revision or reasons for rejection

First, thanks to the authors for the great efforts in revising the manuscript. I saw many places that have been changed, including newly-added tables and uncertainty discussion etc.
The title of this study is “Land cover change dominates decadal trends of biogenic volatile organic compound (BVOC) emission in China”. However, in this new version of figure 4, there is no clear trend in the total emissions (see S1 in Figure 4d), so for me, then the current title is misleading. This also goes to the descriptions in the abstract (Line 20-21). The significant trend found in S2 is with the fixed climate inputs to 2001, but cannot represent the modelled total emissions (i.e., S1). Then, my another concern with Figure 4 is that if we remove the first two years (i.e., 2001 and 2002), can we still see the increase trend for S2 and S5? If not, what does that mean? Does that mean the land use management mainly occurs before the year 2003 national-wide? And are these two years dominating the trend you actually detect for the whole time series? Or can you see the gradual changes from 2003 also contribute to the trend? On the same topic, now if we have a look at the significant trend of isoprene and HCHO in this study (figure 9), there are very few dots on both maps, meaning the majority does not have significant changing trend (not even mentioning increasing trend), right? Then just curiosu what causes the large decrease in emissions in Jiangxi, Hunan and Fujian areas.
I still think there should be a table that lists emission factors for those included compounds and for available PFTs. It provides basic information for readers to understand emission differences among differnet PFTs.
It is difficult to remember what processes are included or excluded for S1-S5, and I would suggest to use more meaningful names for these scenarios. Furthermore, it will be a good practice that all abbreviations in figures are explained in the caption.
Then about paper structure, the usage of HCHO is to evaluate the isoprene emission variability and trend, and for this, this should somehow present before analyzing the spatial and temporal changes of different scenarios.
P10, L8-9, “The interannual variability of isoprene emission estimated in this study ..” so do you mean that the modelled annual isoprene emission is evaluated with JJA HCHO datA? Why not look at the same months?
P10, L23, “low anthropogenic influence”, is there any reference that can back up this? As far as I know, some of these areas are highly developed and with heavy industry. Then the sentence after, I would also argue that this non-correlated area could be potentially linked to the less-constrained emission factor for crop PFTs, right?
P10, L33, when talking about the increasing trend, did the author only refer to the significant ones (dots in figure)? There are very few points are actually significant, even using the p threshold value of 0.1. Then I did not get what does the sentence starting with “the increasing trend pattern of isoprene emissions … ” mean?
What is the main reason for selecting different sizes of six regions to compare?

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RR by Anonymous Referee #2 (02 Dec 2020)

Suggestions for revision or reasons for rejection

The revised manuscript by Wang and co-workers is clearly improved and the majority of my previous concerns have been adequately addressed. I have however doubts regarding (i) the high magnitude of the LULC-induced isoprene trends derived from this study, as illustrated in Figure 4; (ii) the fact that adding up the trends due to LULC (0.64%/yr, S2), LAI (+0.21%/yr, S5), and meteorology (-0.08%/yr in S3 or -0.01%/yr in S4), does not result in the trend of the full model simulation (0.64%/yr, S1), as one would expect. Regarding the first point, the authors should include additional evidence for the very strong trend LULC by e.g. providing MODIS LULC trend maps. The second point casts doubt on the interpretation of the results and the conclusions drawn. These two points need to be better explained and clarified in the next version.

Another question concerns the trends in surface temperature and radiation and their comparison to the trends at the sites shown in Figure 3. The upper panels of this figure are not very clear and the comparison is not quantitative. I recommend to provide a more quantitative comparison, as e.g. time series of modelled and observed temperature and radiation fluxes averaged over different large regions. In addition, you should compare the respective trends quantitatively, averaged over the same regions.

Specific comments/Language corrections

p.3, l.33: Add references, e.g. Palmer et al. (2003), Marais et al. (2012), Stavrakou et al. (2009), see below
p.6, l.6-14: Most of this text can be found in Table 1, could be shortened
p.6, l.17: Replace 'which means the meteorological' by 'which means that the meteorological'
p.6, l.15-19: 'is not considered in this study' is mentioned twice in the same paragraph. Check and rephrase.
p.6, l.23-24: Provide reference for the Theil-Sen and Mann-Kendall estimation methods.
p.7, l.19: Add 's' in 'demonstrate'
p.7, l.5: Here and elsewhere 'didn't' should read 'did not'
p.8, l.2: 'national wide' should be 'nationwide', here and elsewhere
p.8, l.6: 'comparing to S2', read 'compared to S2'
p.8, l.7-9: Something is missing in this sentence. Reread and rephrase.
p.8, l.12: 'faction', should be 'fraction'
p.8, l.17: read 'six regions of interest', and 'the six regions include'
p.8, l.29: 'at a rate'
p.9, l.13: Correct 'significantly trend' by 'significant trend'
p.9, l.19: 'comparing that', replace by 'compared to that'
references: use abbreviations of journal names
figure 5 caption: 'the rest columns', read 'the rest of the columns'; replace 'showed' by 'shown'; replace 'test were used' by 'test was used'

References

Marais, E. A., Jacob, D. J., Kurosu, T. P., Chance, K., Murphy, J. G., Reeves, C., Mills, G., Casadio, S., Millet, D. B., Barkley, M. P., Paulot, F., and Mao, J.: Isoprene emissions in Africa inferred from OMI observations of formaldehyde columns, Atmos. Chem. Phys., 12, 6219-6235, https://doi.org/10.5194/acp-12-6219-2012, 2012.

Palmer, P. I, D. J. Jacob, A. M. Fiore, R. V. Martin, K. Chance, T.P. Kurosu: Mapping isoprene emissions over North America using formaldehyde
column observations from space, J. Geophys. Res., 108, D6, 4180, doi:10.1029/2002JD002153, 2003.

Stavrakou, T., Müller, J.-F., De Smedt, I., Van Roozendael, M., van der Werf, G. R., Giglio, L., and Guenther, A.: Evaluating the performance of pyrogenic and biogenic emission inventories against one decade of space-based formaldehyde columns, Atmos. Chem. Phys., 9, 1037-1060, https://doi.org/10.5194/acp-9-1037-2009, 2009.

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ED: Reconsider after major revisions (08 Dec 2020) by Eleanor Browne

AR by Qizhong Wu on behalf of the Authors (20 Jan 2021) Author's response Author's tracked changes Manuscript

ED: Publish subject to minor revisions (review by editor) (07 Feb 2021) by Eleanor Browne

AR by Qizhong Wu on behalf of the Authors (17 Feb 2021) Author's response Author's tracked changes Manuscript

ED: Publish as is (17 Feb 2021) by Eleanor Browne

AR by Qizhong Wu on behalf of the Authors (18 Feb 2021)

Short summary

We assessed the influence of the greening trend on BVOC emission in China. The comparison among different scenarios showed that vegetation changes resulting from land cover management are the main driver of BVOC emission change in China. Climate variability contributed significantly to interannual variations but not much to the long-term trend during the study period.