Global 0.1-Degree Monthly Mean Hourly Total Canopy Solar-Induced Chlorophyll Fluorescence Dataset Derived from Random Forest
Round 1
Reviewer 1 Report
Comments and Suggestions for Authorssee attatched file.
Comments for author File: 
Comments.pdf
Author Response
My response to your review comments is attached.
Author Response File: Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for AuthorsGeneral comments
This study develops a global, monthly mean hourly solar-induced chlorophyll fluorescence (SIF) dataset at 0.1° resolution, SIFo, using a Random Forest model to downscale existing data. Validated against ecosystem carbon flux measurements, SIFo demonstrates a strong correlation with photosynthetic activity (GPP), outperforming previous products. It effectively captures the widespread afternoon depression in photosynthesis across ecosystems. Analysis reveals soil moisture modulates this diurnal pattern, with SIF yield being more sensitive to water stress than light absorption. This dataset provides a valuable resource for monitoring global vegetation dynamics, assessing environmental stress, and improving carbon cycle models. This study demonstrates good in data quality and scientific insight, providing a valuable global SIF dataset.
Major Comments
- During the model training, the collinearity of the predictor variables was not analyzed.
- The importance of some predictor variables in the model is relatively low. It is necessary to evaluate the model's predictive performance and the computational time required for model construction after screening out these less important variables.
- Figure 9 exhibits longitudinal banding patterns. I suspect this is because the PAR data (and potentially other ERA5-Land data) used for modeling and calculating SIF yield were interpolated hourly (i.e., per 15 degrees of longitude) rather than for each 0.1-degree longitude grid cell. This approach is clearly unsuitable for a published data product. It is expected that the final results should be generated using auxiliary data interpolated to the 0.1-degree longitude resolution for both modeling and prediction.
Minor Comments
(1) I do not believe "SIFo" is an optimal abbreviation. Based on its definition, I consider "SIFtotal_01" to be a more appropriate designation.
(2) When discussing the response of productivity to drought, this paper needs to address: "Shifted trend in drought sensitivity of vegetation productivity from 1982 to 2020".
Author Response
My response to your review comments is attached.
Author Response File: Author Response.pdf
Reviewer 3 Report
Comments and Suggestions for AuthorsThe high resolution map of global SIF dataset is significant for many studies. Although the objective is meanful, the manuscript has some major flaws and many of expressions are not professional or accurate. Please consier the following comments.
- The abstract should be improved. Line 24 on page 1, what degree is the RMSE reduced by? Unit is necessay for RMSE (line 25). Line 31-32, what kind of research could be benefit from the improvement of the global SIF data?
- The section 2 is not well prepared. (1) The sections 2.1.1 and 2.1.2 have the same titles. (2) The SIF datasets with different subscrips are not clearly defined in section 2.1, espectially SIFz, SIFo, etc. (3) Please use a table to show all the data used in this study and the purposes. (4) The title of section 2.2 is still "Data"? (5) I don't think figure 2 belongs to method. It seems that it belongs to results.
- Many sentences are not professional, like Line 173 on page 5.
- For the title of section 2.2.3, it is better to use "Analysis of the afternoon depression of photosynthesis".
- Please invite a professional, native speaker to polish the entire manuscript.
- For results, R2 and adj R2 are the same for simple linear regression (one X, one Y). Please delete adj R2.
- It is unclear how to downscale the SIF data using RF. A flowchart of the manuscript is necessary.
The manuscript should be polished by a professional, native speaker.
Author Response
My response to your review comments is attached.
Author Response File: Author Response.pdf
Reviewer 4 Report
Comments and Suggestions for AuthorsThis manuscript presents the development of a global 0.1° monthly mean hourly solar-induced chlorophyll fluorescence (SIF) dataset (SIFo) downscaled from 0.5° SIFtotal using a random forest framework. The work is timely and significant, as it provides higher-resolution data for investigating diurnal photosynthetic processes at regional to global scales. The validation against eddy covariance GPP and the analysis of afternoon depression are well presented, and the dataset has clear potential applications in monitoring vegetation stress, evaluating Earth system models, and supporting climate research. However, I have some major concerns that may help improve the quality of this manuscript.
While the product is presented as “hourly,” the fact that it is based on monthly means reduces the temporal representativeness of true diurnal variability. This averaging may smooth out key short-term physiological responses to environmental stress. The authors should discuss more explicitly the actual value and limitations of using a “monthly mean hourly” dataset for studies focused on diurnal dynamics.
Given the increasing availability of OCO-3 and geostationary SIF observations, is it feasible to attempt a downscaling toward daily or even sub-daily (e.g., half-hourly) scales, perhaps by integrating SIF with meteorological drivers or harmonized high-frequency products? Even if not currently implemented, discussing this possibility would strengthen the contribution and guide future work.
Since the downscaling framework uses both spatial and temporal predictors (e.g., hour, month, latitude, longitude), the current random cross-validation may overestimate model generalization. I recommend performing spatial-based and temporal-based cross-validation (e.g., leave-one-site-out or leave-one-year-out schemes) to test whether the model maintains robustness when extrapolating to unseen locations or time periods.
Addressing these issues would increase the transparency, robustness, and practical usability of the dataset. Overall, the study represents an important step forward in monitoring diurnal vegetation activity at global scales.
Author Response
My response to your review comments is attached.
Author Response File: Author Response.pdf
Round 2
Reviewer 3 Report
Comments and Suggestions for AuthorsThank you for improving the manuscript. All my concerns are sovled. I only have a few comments.
- For figure 5, the legend still says "SIFo", not "SIFtotal_01".
- Since it is a product-related paper, please publish the Global 0.1-degree monthly mean hourly total canopy solar-induced chlorophyll fluorescence dataset in the section of "Data availability statement".
Author Response
Reviewer Comments Response (Round 2)
Comments from the Reviewer(s):
We sincerely thank the reviewer for their positive feedback and valuable comments on our revised manuscript. We are delighted to hear that all previous concerns have been addressed. We have carefully attended to the final minor points raised, as detailed below. The corresponding changes have been incorporated into the manuscript.
Response to Reviewer Comments:
Comment 1: For figure 5, the legend still says "SIFo", not "SIFtotal_01".
Response 1: We sincerely apologize for this oversight during the revision. Thank you for pointing it out. We have now corrected the legend of Figure 5 from "SIFo" to "SIFtotal_01" in the updated manuscript.
Comment 2: Since it is a product-related paper, please publish the Global 0.1-degree monthly mean hourly total canopy solar-induced chlorophyll fluorescence dataset in the section of "Data availability statement".
Response 2: We fully agree with the reviewer on the importance of data availability for a product-related paper. In response to this suggestion, we have taken immediate action to prepare our dataset for public release.
The dataset has been prepared and is ready for upload to National Ecosystem Research Network of China.
Regarding the timing of the public release, most reputable data repositories require the DOI of the accepted manuscript to establish a permanent and bidirectional link between the data and the publication. Therefore, the formal upload process to assign a persistent DOI to the dataset is contingent upon the final acceptance of our manuscript.
We have now updated the "Data Availability Statement" in the manuscript to clearly reflect this plan. The statement now reads:
*"The Global 0.1-degree monthly mean hourly total canopy solar-induced chlorophyll fluorescence dataset (SIFtotal_01) generated in this study will be made publicly available upon publication through the [National Ecosystem Research Network of China] repository. The DOI link will be provided here once it is assigned. The website of our team on the National Ecosystem Research Network of China is https://www.nesdc.org.cn/otherProject/index?menuId=team& projectId=1328."*
Our commitment is as follows:
Upon formal acceptance of the manuscript, we will promptly complete the data upload, obtain the data DOI, and update the "Data Availability Statement" in the final proofs with the active, permanent link. We assure you and the editors that there will be no delay in this process.
Once again, we extend our deepest gratitude to the reviewer for their thorough review and constructive suggestions, which have significantly improved the quality of our work.
Reviewer 4 Report
Comments and Suggestions for AuthorsThanks for the revision! Great work!
Author Response
We are delighted to hear that the reviewer finds our work to be "Great work". We sincerely appreciate their time and encouraging comments.
