the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 05 Sep 2025
A localized plant species-specific BVOC emission rate library of China established using a developed statistical approach based on field measurements
Abstract. Precise quantification of biogenic volatile organic compound (BVOC) emissions is essential for effective control of ozone and aerosol pollution. However, the lack of localized and elaborate plant species-specific emission rate library pose significant challenges to its accurate emission estimates in China. Also, large uncertainty exited in the representative emission rate used in inventory compiling. Here a statistical approach of classifying emission intensity and assigning the representative emission rates in higher accuracy was developed, based on our and reported local field measurements. Furtherly, a localized plant species-specific BVOC emission rate library for China for 599 plant species was established. Critically, different reliability was given to each emission rate according to the measurement technique. Emission simulations were made to evaluate the performance of the developed library. By comparing with formaldehyde vertical column density observations, using our localized library improved the model performance in catching the spatial variations of isoprene emission. The newly estimated BVOC emissions were 27.70 Tg, 18 % higher than the estimations using the global library. The underestimates in the south and overestimates in the northeast and west could be abated by updating the localized emission rates. More local emission observations in higher reliability are encouraged to improve the accuracy of emission rates and further the emission estimates.
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Status: final response (author comments only)
- RC1: 'Comment on egusphere-2025-3354', Anonymous Referee #1, 06 Oct 2025
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RC2: 'Comment on egusphere-2025-3354', Anonymous Referee #3, 07 Oct 2025
The submitted manuscript presents a new data library of species-specific BVOC emission rates in China. The authors describe the statistical method of assigning emission rates to individual plant species based on field measurements. They also provide the final dataset with emission rates of isoprene, monoterpenes and sesquiterpenes for 599 plant species. I consider these efforts essential for the improvement of regional BVOC emission modelling as they can reduce errors introduced when global databases are used. This is demonstrated in the results where the authors apply their emission rates to modelling with the MEGANv3.2 model and show improved spatial correlation of BVOC emissions in China with satellite observations when compared to the use of a global library. The methods are described in sufficient detail and the results support the presented conclusions.
I recommend the manuscript for publication with the following comments:
- Section 3.1 on conversion of basal emissions - if there was a need to convert units of basal emissions from ug m-2 h-1 to ug g-1 h-1 , could the authors please specify what values of specific or dry leaf matter (g/m2) they used in conversion?
- Section 3.3.1 is a bit hard to comprehend, it could be reduced and clarified or perhaps visualized.
- In the modelled domain, what proportion of the area was covered with the emission rates with R-value 1?
- As the study also focuses on modelling with the MEGAN model, it would be interesting to see direct comparison of emission rates estimated in this study with those in the MEGANv3 global library (eg. by summarizing key differences) and/or with other available emission inventories.
- Section 4.2, the BVOC emission total in China is presented as 27.7 Tg / year 2020. Could the authors specify the unit, Tg of what? If different BVOC species (with different molecular masses) are to be summed, they need be converted to Tg of carbon before the summation. Please check and correct throughout the text. Same applies to Figs. 5 and 6. Also, if the BVOC split to percentage is to be presented as in Figure S4, first the units need to be harmonised to Tg (C), otherwise the masses are not comparable and the percentage is not valid. How are total BVOC emissions defined, which species are included in the sum?
- Section 4.2 - I’d suggest to move Table S3 from Supplementary material to the main text. It would help the reader to better understand definition of different simulations.
- Conclusions section, line 590: The authors say their localised dataset “Undeniably helps to improve the accuracy of the determined emission rates and furtherly the emission estimates.” While I think this study as well as database of emission rates is very valuable, this is a rather strong statement. The results presented in the paper do not give a proof of improving the accuracy of the emission rates or estimates. Please rephrase.
- Supplement, line 42: Could the authors please add a figure of HCHO values to illustrate the spatial correlation with their results?
Please double check for language and typing errors, some of which are pointed out below:
- Line 19: pose -> poses
- Line 20: exited -> existed
- Line 104: on -> of
- Line 151: environment -> environmental
- Line 162: remove space after )
- Line 200: rates(a-e -> rates (a-e
- Line 254: were -> was
- Sentence on lines 413-416 is somewhat unclear and possibly missing a verb
- Line 461: less -> lower
- Line 524: emission -> emissions
- Sentence on lines 528-529 is somewhat unclear
- Sentence on lines 547-549 - missing verb
Citation: https://doi.org/10.5194/egusphere-2025-3354-RC2
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- 1
The study by Han et al. presents the development of a plant species-specific BVOC emission rate library for China, based on a combination of literature data and new measurements. The authors employ a statistical approach to classify emission intensities, define representative emission rates, and assign reliability levels depending on the measurement technique. They then implement the new emissions in MEGAN v3.2 and assess its performance against formaldehyde satellite observations. The topic is timely and relevant, as accurate biogenic emission inventories remain a major uncertainty in atmospheric chemistry. The manuscript compiles an impressive amount of local data that will be valuable for the community. However, in its current form, the study is not suitable for publication, and substantial revisions are required before it can be considered further.
General comments
Specific comments
L18. Aerosol pollution is mainly due to direct emissions. Please revise to clarify that BVOCs contribute significantly to the production of ozone and secondary organic aerosols.
L26. Consider replacing the performance with sensitivity or implications.
L31-33. Consider moving this sentence to the conclusions or removing it entirely, keeping the final paragraph of the introduction focused on the study objectives.
L39. The cited reference is not relevant to BVOC reactivity. Please consider citing a more appropriate chemical reactivity source, such as https://doi.org/10.1021/cr0206420
L58 and below. Replace errors with uncertainties. The term error would only be appropriate if the correct reference values were known.
L86-87. A reference is needed.
L110/Figure S2. I recommend moving this figure to the main text.
L110-113. Teflon bags are widely used in BVOC research due to their chemical inertness and negligible BVOC emissions. Please clarify how you further “passivated” them.
L173. How do these 79 species compare? Consider adding an analysis or figure that enables the derivation of research conclusions.
L192. Please clarify what is meant by regular in distribution.
L200/Fig.1. Consider homogenizing the y-axis scales and grouping by species to improve visual clarity.
L218 and generally. Consider using medians instead of means, as they are more representative for this type of dataset.
L249/Fig. 2. Please correct the English and refine the caption to improve clarity.
L277. This sentence (“Generally, most plant species performed low and moderate intensity of isoprene.”) clearly illustrates how the English phrasing can make it difficult to understand the meaning of several statements in the paper.
L305. Perhaps this recent review (https://doi.org/10.1038/s43247-023-01175-9) is more suitable for supporting this statement.
L310/Fig.3. Consider removing the lines connecting the medians of each bar and removing the dashed box. Homogenizing the y-axes would also improve clarity.
L314. The text refers to boxplots, but Figure 3 shows bars. Please clarify.
L312. Consider citing a more general or representative publication. E.g. https://doi.org/10.1016/j.tplants.2009.12.005
L343. The word anyway is typically used in informal communication and should be avoided in research writing. This is another example of the linguistic revisions needed throughout the manuscript.
L350/Fig. 4. The concept of this figure is good, but in practice it is difficult to follow all the drawn lines.
L366-367. Please show this through a figure and strengthen the scientific interpretation.
L382. These are not the only variables used in MEGAN. In addition, the meteorological parameters are not included directly in the MEGAN code but must be derived from external atmospheric data.
L402. Please clarify how you updated plant species when MEGAN operates on plant functional types.
L410-418. This section is very hard to follow. Please rewrite and consider adding a table to improve clarity.
L427. Butanes are primarily emitted from anthropogenic sources, with very minor contributions from vegetation. How can they emerge as the most important BVOCs? Such a statement reduces confidence in the scientific assessment and falls under General Comment 2.
L466-468. In such an anthropogenically dominated region, formaldehyde (HCHO) observations carry significant uncertainties that must be discussed.
L473-474 & L549-551. If I understand correctly, the values of R=1 together with R=2 provide the best result (simulation 1). If that is the case, how was the conclusion reached regarding important differences between static and dynamic measurements?