This study presents a valuable dataset comprising vertical profiles of HONO and O₃ obtained from the Chinese Hyperspectral Vertical Remote Sensing Network between 2021 and 2024. The work addresses a critical gap in vertical observations of key photochemical species over China, offering substantial scientific insight into tropospheric atmospheric oxidative capacity and photochemical pollution mechanisms. The dataset spans 22 representative sites with extensive spatial and temporal coverage, and has been processed using a consistent and rigorous methodology, including the use of the TUV model to calculate photolysis frequencies and OH production rates. The manuscript is well‑structured, effectively supported by figures, and the independent validation results are compelling. The dataset holds high practical value for improving chemical transport models and informing air quality policy, and thus meets the journal's publication standards. However, several issues pertaining to the clarity of methodological descriptions and internal consistency of the data require the authors' attention, as detailed below.

1. Line 61: Could the authors clarify whether the dataset used in this study includes stations located in these regions?
2. Line 138: The authors should clarify the criteria used for selecting the monitoring sites (e.g., representativeness, pollution level, climate zone, or instrument deployment feasibility) to better justify the spatial representativeness of the dataset.
3. Lines 156-160: The Mount Tai (TS) site is defined as a clean background station. However, as a tourist attraction surrounded by industrial provinces, is there any interference in the observational data caused by tourism traffic or transport from surrounding industries? It is recommended to discuss the reliability of its background attributes.
4. Lines 185-187: The manuscript mentions the use of a standardized instrument configuration. Please supplement the specific brand and model of the spectrometers used at different sites (e.g., whether they are all the same model), which is crucial for assessing instrument consistency and data comparability.
5. Lines 188-190: Regarding the telescope design, please confirm whether “field of view <0.3°” refers to the full field of view or the half field of view.
6. Lines 190-191: The manuscript mentions that the spectrometer covers ultraviolet (296–408 nm) and visible (420–565 nm) ranges, with a gap of approximately 12 nm between them. Does this spectral gap affect the retrieval of specific species?
7. Lines 193-194: All sites employed an identical elevation scanning sequence, yielding a full scan cycle of ~12 min. Does this scan cycle refer to the total time to complete all elevation measurements (from 1° to 90°) and be ready to start the next round of scanning?
8. Line 199: “To minimize stratospheric contamination, spectra acquired at solar zenith angles greater than 75° were excluded.” Is this filtering criterion applied only to daytime measurement data, or does it also apply to nighttime measurements?
9. Lines 203-205: Please specify the exact version number of the QDOAS software, as different versions may contain different algorithm optimizations.
10. Lines 205-208: In the spectral retrieval section, it is explained that the zenith spectrum was used as the reference and subtracted from spectra at lower elevation angles. Is the zenith reference spectrum the 90° spectrum from the same scanning sequence, or an averaged or a specific time-interval zenith spectrum of the day?
11. Line 207: Using the zenith spectrum as a reference spectrum is a standard DOAS practice. Is the integration time for the zenith spectrum the same as for low-elevation spectra? If not, how are differences in signal-to-noise ratio handled?
12. Lines 262-264: Figure 2 summarizes the monthly data completeness. It is suggested that the authors analyze whether the main reasons for missing data at different sites show seasonal differences (e.g., heating season in North China or rainy season in South China) and briefly explain this in the manuscript.
13. Lines 268-270: It is mentioned that “more than ~85% of the sites operated for over one year, and ~60% for more than two years”. Does “operated” refer to completely continuous operation, or does it allow for interruptions while the data chain remains valid?
14. Lines 502-512: The peak J(HONO) at North China sites is approximately s⁻¹. How does this value compare with other similar studies (e.g., field measurements in urban Beijing)? Please add comparative discussion.
15. Lines 652-654: How were the CNEMC ground stations selected for comparison?
16. Lines 642-661: The validation section only presents comparative validation for O₃ data and does not cover HONO data. Is there any independent validation for HONO data (e.g., comparison with other instruments or methods)? If so, it is suggested to add it; if not, it is suggested to explain the reason.
17. Lines 658-660: Based on correlations of R = 0.62 and R = 0.66, the conclusion is that these validations “confirm the reliability” of the dataset. It is recommended to use more prudent wording, such as “confirm reasonable consistency”.
18. Lines 662-667: Figure 11c and 11d show site-specific correlations. It is recommended to briefly mention the names of the sites with the worst and best correlations in the text and analyze the reasons (e.g., complex terrain or excessive distance for comparison).
19. Lines 675-681: The summary emphasizes the extensiveness of the dataset. It is recommended to supplement the limitations of the dataset in terms of time span (e.g., limited to 2021–2024) so readers can make a comprehensive assessment.
20. Lines 700-709: Five main applications of the dataset are listed. It is recommended to add a sixth: the dataset plays an important role in assessing uncertainties in vertical parameterization schemes in atmospheric chemical mechanisms.

This manuscript presents and publicly releases a valuable dataset derived from the Chinese Hyperspectral Vertical Remote Sensing Network, featuring vertical profiles of O₃ and HONO acquired from 22 representative sites between 2021 and 2024. This dataset fills a critical gap in the long-term, vertical observations of key photochemical species over China, holding significant scientific value for understanding the evolution of tropospheric oxidative capacity. Overall, it represents a high-quality data paper. However, several details in the manuscript still require further refinement to enhance the overall quality and readability of the paper.

1. Lines 85-86: The word “generally” in “but generally lacks observations of key photochemical precursors such as HONO and volatile organic compounds (VOCs)” could be ambiguous. It is suggested to change to “but lacks observations of key photochemical precursors such as HONO and volatile organic compounds (VOCs)”.
2. Lines 120-121: “the contribution of HONO photolysis to boundary-layer OH” could be changed to “the contribution of HONO photolysis to the boundary-layer OH budget” for greater precision.
3. Lines 186-187: The manuscript mentions a “standardized instrument configuration”. Please explicitly state whether the spectrometers and telescopes used at all 22 sites are of the exact same brand and model.
4. Line 194: The elevation scanning sequence includes 1°, 2°, …, 90°. Low elevation signals (e.g., 1°) are susceptible to obstructions, during the processing, were strict obstruction checks performed for low-elevation observations at all sites? If obstructions were present, were the relevant data excluded?
5. Line 195: “The integration time at each elevation was 1 min” refers to the integration time for observation at each elevation angle. It is suggested to change to “The integration time at each elevation angle was 1 min”.
6. Line 197: “The instruments also operated at night to record dark current…”. This phrasing might mislead readers into thinking the instruments were conducting routine atmospheric composition observations at night. It is recommended to explicitly state that nighttime operation was strictly for instrument calibration and did not produce scientific data.
7. Line 207: The manuscript mentioned that the zenith spectrum (90°) was used as the reference. Please clarify whether the reference spectrum is from the same scanning cycle or if a fixed reference was used.
8. Line 268: In “More than ~85% of the sites operated for over one year”, “~” indicates an approximation, which is slightly redundant when used with “more than”. It is suggested to change to “Over 85% of the sites operated for more than one year”.
9. Line 335: Please pay attention to the subscripts for NO2; it should be written as “NO₂”. Please check the full manuscript to ensure all instances of NO₂ are written correctly.
10. Line 412: “the pronounced O₃ enhancements observed at 3–4 km at sites such as CQ, GZ_TM and SUIST” – here “SUIST” should be “SUST”. Please verify.
11. Line 543: The manuscript reads “reaching 1.0×10⁴–5.5×10⁴ ppb·s⁻¹”. This should likely be 10^-4. It appears to be a typographical error. Please verify and correct.
12. Line 572-573: “underscoring the near-surface confinement of both HONO and its photolytic OH production.” “its photolytic OH production” could be changed to “OH production from its photolysis” for clarity.
13. Line 616: There are two periods in “Figures S29–S32..”. One should be removed.
14. Line 643: The validation section only presents the validation of O₃ data and does not cover the validation of HONO data. Is this because there is no verifiable data for HONO, or is it due to other reasons?
15. Lines 652-655: “Song et al. (2023b)” is cited as the criterion for site selection. For readers unfamiliar with this work, it is recommended to briefly summarize the main content of the selection criteria so that readers can understand the spatial representativeness of the validation data.

This study presents a dataset of vertical profiles of HONO and O₃ derived from the China Ground-based Hyperspectral Vertical Remote Sensing Observation Network. The dataset covers 22 representative sites, featuring an extended temporal span and broad spatial coverage. This dataset fills a critical observational gap and holds significant value for investigating boundary layer photochemical processes and improving our understanding of tropospheric oxidative capacity. The manuscript is well structured, with detailed methodological descriptions, comprehensive result presentation, and thorough data validation, and overall represents a high-quality data paper. However, there remains room for improvement in terms of clarity of expression, logical rigor, completeness of methodological details, and adherence to formatting conventions. Specific comments and suggestions are provided below to further enhance the quality and readability of the manuscript.

1. Line 23: The phrase “primary source” is somewhat absolute. OH production involves multiple pathways; consider revising to “one of the primary sources” or specifying conditions (e.g., polluted boundary layer).
2. Lines 57-58: The statement “ozone (O3)… has continued to increase” is overly absolute. It is recommended to add qualifiers such as “in some regions” or “on average” to more accurately reflect the complex trends of ozone pollution in China.
3. Lines 97-98: The word “pronounced” in “preclude resolving the pronounced diurnal variability” is somewhat subjective. It is suggested to replace it with more objective terms like “strong” or “fine-scale”.
4. Lines 117-118: In “to quantify the altitude-dependent production of OH radicals,” the term “altitude-dependent” might be ambiguous (dependent on altitude vs. varying with altitude). It is recommended to change it to “altitude-resolved” or “vertical variations in.”
5. Lines 122-124: The order of region names “North, East, South, Central, and Southwest China” is not entirely consistent with the order presented later in Table 1 and the main text (e.g., Southwest China appears after South China in Table 1). It is recommended to unify the listing order of region names throughout the article.
6. Lines 146-148: In “stations at the Chinese Academy of Meteorological Sciences (CAMS1, CAMS2) and the University of Chinese Academy of Sciences (UCAS), located in and around Beijing…”, the phrase “in and around Beijing” is slightly ambiguous, as both stations are within the municipality of Beijing. It is recommended to change it to “located within Beijing”.
7. Lines 156-157: The sentence “The summit of Mount Tai (TS; 1,500 m a.s.l.) offers vertical profiles under clean, high-altitude background conditions.” is not entirely accurate, as TS, being a major tourist destination, is subject to tourism activities and regional transport influences and is not pristine. It is recommended to change “clean” to “relatively clean background conditions”.
8. Lines 186-200: Are the specifications of the instruments employed at each of the 22 sites consistent?
9. Lines 193-194: Following “All sites employed an identical elevation scanning sequence…,” it is recommended to add a brief explanation of the scientific rationale or optimization considerations for selecting these specific elevation angles (e.g., 1°, 2°, …90°).
10. Line 204: In the spectral retrieval section, please specify the version number of the QDOAS software used.
11. Lines 206-208: Please clarify whether the zenith reference spectrum is the 90° spectrum from the same scanning sequence, or a daily average or zenith spectrum from a specific time period.
12. Lines 213-214: In “using a fifth-order polynomial, allowing accurate separation of narrow-band molecular absorption,” the subject of “allowing” is unclear. It is recommended to change it to “This allows for the accurate separation…” or merge it with the preceding sentence.
13. Lines 215-217: After “Strict quality control was applied: only retrievals with a root-mean-square (RMS) fitting residual below 1 × 10^-3 were retained,” it is recommended to add the basis or reference for setting this specific RMS threshold.
14. Lines 307-309: In “without a persistent mid-level enhancement,” the word “persistent” may not be accurate, as the dataset presents a multi-year mean state. It is suggested to change it to “without a distinct mid-level enhancement.”
15. Lines 334-336: In the sentence “This pattern reflects nocturnal accumulation driven by heterogeneous conversion… and after sunrise…,” the two clauses connected by “and” are at different logical levels. It is recommended to separate them with a semicolon or restructure the sentence.
16. Lines 347-348: For the statement “Sites with dense vegetation or agricultural land use (LA and CF) may receive contributions from biogenic VOC-related chemistry,” it is recommended to provide a reference for research on the influence of biogenic VOCs on HONO formation.
17. Lines 411-412: In the sentence “The pronounced O3 enhancements observed at 3–4 km at sites such as CQ, GZ_TM and SUIST are therefore likely linked to…,” “SUIST” should be “SUST” (the site for Southern University of Science and Technology). Please correct this.
18. Lines 476: The phrase “using in situ concentration profiles” is incorrect, as MAX-DOAS observations are remote sensing retrievals, not “in situ” measurements. It is recommended to change it to “using retrieved concentration profiles” or simply “using concentration profiles”.
19. Lines 504-505: The manuscript states “J(HONO) exhibits a pronounced diurnal cycle, increasing during the morning (08:00–10:00) with rising solar radiation.” In fact, J values begin to rise immediately after sunrise. The fastest increase may occur during 08:00–10:00, but the peak is usually around noon. It is recommended to change it to “increasing after sunrise” for accuracy.
20. Line 543: The manuscript states “reaching 1.0×10⁴–5.5×10⁴ ppb s^-1”. For OH production P(OH) = J(HONO) * [HONO], if J is taken as ~10^-3 s^-1 and HONO as 0.3–0.5 ppb, then P(OH) should be approximately 3×10^-4–5×10^-4 ppb s^-1. The value in the text is 8 orders of magnitude larger, indicating a severe typo. Please verify and correct this.
21. Line 549: The manuscript states “exceeding 3.0×10⁴ ppb s^-1”. This also contains an order-of-magnitude error; it should be “exceeding 3.0×10^-4 ppb s^-1” or a similar magnitude.
22. Lines 615-616: The manuscript reads “at the 22 sites ，and seasonal mean diurnal”. A Chinese full-width comma “，” is used here; it should be changed to an English half-width comma.The manuscript reads “presented in Figures S29–S32..”. There are two periods at the end of the sentence; it should be changed to one.
23. Line 653: Regarding the comparison with CNEMC surface station data, please detail the methodology used to select the CNEMC stations.
24. Line 660: The manuscript states “confirm the reliability of the dataset used in this study”. It is recommended to add a note regarding HONO data validation, as the text only presents validation for O₃, whereas HONO is another critical data product.
25. Line 681-682: The statement “represents one of the most extensive collections in China” should be verified. It is recommended to change it to “one of the most extensive publicly available collections” for greater rigor.