| 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.
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?