| 08 Oct 2026
A dataset of ground-based VCDs (O3, NO2, HCHO, HONO, SO2) and AOD observations from the hyperspectral vertical remote sensing network in China (2020–2025)
Abstract. With the rapid development of satellite observations of atmospheric composition and aerosols, long-term, independent, and standardized ground-based column measurements have become increasingly important for satellite product validation, retrieval error diagnosis, and multi-source data fusion. However, long-term ground-based column datasets covering multiple atmospheric constituents and processed using a unified framework remain limited in China. This study presents a ground-based dataset of multi-component vertical column densities (VCDs) and aerosol optical depth (AOD) from the Chinese Hyperspectral Vertical Remote Sensing Network for 2020–2025. The dataset includes VCDs of O3, NO2, HCHO, HONO, and SO2, together with AOD. It is based on observations from 53 MAX-DOAS sites across China, covering approximately 22.5–44.1° N and 80.1–122.7° E. The sites represent urban agglomerations, suburban transition zones, industrial areas, coastal and island environments, inland basins, arid and semi-arid regions, and the Tibetan Plateau. All observations were processed using a unified retrieval and quality-control framework to ensure consistency among sites and species. AOD has the broadest coverage, with 53 valid sites and 1073 valid site-months. NO2 and HCHO each cover 52 sites and more than 1000 valid site-months. SO2 and HONO cover 45 and 44 sites, respectively. O3 covers 29 sites and 588 valid site-months. For valid months, the median monthly completeness is 83.9 % for O3, NO2, HCHO, and SO2, and 86.7 % for HONO and AOD. Comparisons with independent observations show correlation coefficients of 0.899, 0.734, and 0.551 for MAX-DOAS NO2, HCHO, and O3 VCDs against satellite products, respectively. The correlation between AOD and AERONET is 0.879. Correlations of NO2, SO2, and O3 VCDs with CNEMC surface observations are 0.720, 0.624, and 0.678, respectively. This dataset provides a long-term, independent, and standardized ground-based reference for validating satellite VCD and AOD products, diagnosing retrieval biases, supporting satellite–AI integration and bias correction, and evaluating chemical transport models. The dataset is freely available at Zenodo (https://doi.org/10.5281/zenodo.22691855, Xing et al., 2026).
This manuscript presents a dataset of VCDs of O3, NO2, HCHO, HONO, and SO2, together with AOD, based on observations from 53 MAX-DOAS sites across China during 2020–2025. The dataset provides valuable long-term ground-based observations for satellite product validation, studies of atmospheric composition, and multi-source data fusion.
The manuscript is generally well organized, and a unified data processing framework has been applied across the observation network. The reliability of the dataset has also been evaluated through comparisons with satellite, AERONET, and surface monitoring observations. Overall, the dataset has considerable potential for future atmospheric research. However, several aspects of data quality assessment, retrieval methods, and validation procedures require further clarification to improve the reproducibility and usability of the dataset. I have the following specific comments.
Specific comments:
The manuscript states that all 53 sites use MAX-DOAS instruments and a unified data processing method. Please further clarify whether the main spectral parameters (e.g., spectral resolution) are consistent across sites and whether any measures were taken to ensure comparability of observations among sites.