the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 17 Apr 2025
The complete 3-year dataset of 4STAR sky-scans from ORACLES 2016–2018
Abstract. The NASA ORACLES (ObseRvations of Aerosols above CLouds and their intEractionS) airborne field campaigns deployed a 4STAR (Spectrometer for Sky-Scanning, Sun-Tracking Atmospheric Research) instrument onboard a P-3 aircraft to measure columnar optical properties of biomass burning aerosol smoke plumes over the Southeast Atlantic Ocean from 2016 to 2018. Although 4STAR’s retrievals of aerosol optical properties from direct solar irradiances and diffuse sky radiances were performed, analyzed, and compared against other field campaigns via Single Scattering Albedo (SSA) campaign medians by Pistone et al., 2019 for ORACLES 2016, such an analysis was not extended to 2017 and 2018 due to previously unquantified instrument performance issues. As a result, only the 4STAR 2016 dataset was available to the public via https://doi.org/10.5067/Suborbital/ORACLES/P3/2016_V3 (ORACLES Science Team, 2021a). The instrument issues were diagnosed and mitigated through use of a four-wavelength set, instead of the previous five-wavelength set. Uniform Quality Control (QC) standards were established to ensure consistent data quality across all three campaigns. This resulted in research-quality, four-wavelength 4STAR datasets for 2017 and 2018 that have since been archived along with the original five-wavelength 4STAR 2016 dataset on the NASA Earth Science Project Office website, replacing the older versions at https://doi.org/10.5067/Suborbital/ORACLES/P3/2017_V3 (ORACLES Science Team, 2021b) and https://doi.org/10.5067/Suborbital/ORACLES/P3/2018_V3 (ORACLES Science Team, 2021c). The four-wavelength 4STAR 2016 dataset, although not on the archival site, is also publicly available via https://doi.org/10.5281/zenodo.14659686 (Mitchell, 2025). Potential improvements to these initial releases, such as broadening the spectral range, substituting for missing flight-level albedo, and removing unreliable scattering angles, are discussed. The complete 3-year ORACLES 4STAR 2016–2018 has many uses, including the determination of subseasonal changes in aerosol properties, modelling aerosol evolution, and the validation of satellite-retrieved aerosol products.
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Status: final response (author comments only)
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RC1: 'Comment on essd-2025-31', Anonymous Referee #1, 11 Jun 2025
The manuscript is well-written and clearly expresses the methodology and results. I appreciated the authors efforts to provide a comprehensive product for the entire 3 years of the campaign, especially given the issues with an instrument artifact. Providing the data both on the ESPO website and in Zenodo seemed like a logical choice to increase the accessibility of the data. Researchers familiar with the data would go to the ESPO website while others may find it in Zenodo. It would be good to provide more context about the data on the Zenodo page. I would recommend linking to this manuscript in the Zenodo metadata so that researchers can learn more about the context of the data.
Citation: https://doi.org/10.5194/essd-2025-31-RC1 -
AC2: 'Reply to RC1', Logan Mitchell, 19 Jun 2025
Thank you for the comment. I have linked the preprint DOI on Zenodo.
Citation: https://doi.org/10.5194/essd-2025-31-AC2
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AC2: 'Reply to RC1', Logan Mitchell, 19 Jun 2025
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RC2: 'Comment on essd-2025-31', Anonymous Referee #2, 15 Jun 2025
This manuscript provides the data from the NASA ORACLES airborne filed campains that deployed a 4STAR instrument onboard a P-3 aircarft to measure columnar optical properties of biomass burning aerosol smoke plumes over the Southeast Atlantic Ocean from 2016 to 2018. The authors well describe the wavelength selection and quality control criteria, however, I think it is better to show a period of the data or a single case for example may help the readers to better understanding the quality control or what the data is about. On the whole, this is a good manuscript that provides valuable data.
Citation: https://doi.org/10.5194/essd-2025-31-RC2 -
AC3: 'Reply to RC2', Logan Mitchell, 19 Jun 2025
Thank you for the comment. We highlight a single case in Figures 1-3 and each ORACLES campaign in Figure 5. But additional context is also now available via our new supplemental tables (attached to AC1).
Citation: https://doi.org/10.5194/essd-2025-31-AC3
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AC3: 'Reply to RC2', Logan Mitchell, 19 Jun 2025
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RC3: 'Comment on essd-2025-31', Anonymous Referee #3, 16 Jun 2025
This manuscript presents a complete and consistent three-year dataset of 4STAR sky-scan measurements from the ORACLES 2016-2018 campaigns, addressing previous data gaps by resolving instrument artifacts and applying uniform quality control. To further enhance its quality and utility for researchers, consider expanding on the technical details behind the instrument issue resolution, particularly the scientific rationale for selecting the four specific wavelengths used for the 2017 and 2018 data, and briefly describing the applied calibration methods. Additionally, improve the clarity of the quality control (QC) criteria by providing more quantitative thresholds or logical rules, ideally complemented by illustrative examples showing the impact of QC on data, such as visualizing outlier removal. For improved data accessibility and usability, detail the specific file formats and variable naming conventions used in the archived datasets on ESPO and Zenodo. Finally, offer a quantitative summary of the dataset's spatiotemporal coverage, including total measurement or flight hours and geographic ranges for each year, to help users quickly grasp the dataset's scale and characteristics.
Citation: https://doi.org/10.5194/essd-2025-31-RC3 -
AC4: 'Reply to RC3', Logan Mitchell, 19 Jun 2025
Thank you for the comment. We explain the scientific rationale behind the wavelength selection in the Introduction, but have added text reiterating it in the Methods. We have also added information regarding 4STAR calibration. We hope that the new supplemental tables (attached to AC1) are helpful in clarifying the QC criteria. We have added the file formats and variable naming conventions to the Introduction section. We are also working to create a supplemental table describing the spatiotemporal coverage of the 4STAR retrievals during ORACLES.
Citation: https://doi.org/10.5194/essd-2025-31-AC4
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AC4: 'Reply to RC3', Logan Mitchell, 19 Jun 2025
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AC1: 'Updates regarding essd-2025-31', Logan Mitchell, 19 Jun 2025
I am writing this comment to inform everyone of some minor changes to our dataset.While working on a separate analysis, we discovered that our 4STAR altitude values were incorrect. We determined that pressure altitude was erroneously reported instead of GPS altitude for ORACLES 2017 and 2018. As such, we corrected it and reuploaded as v3 on Zenodo. The overall state of the 4STAR data is the same, as evidenced by the SSA campaign medians being virtually unchanged in our updated Figure 5.We also created a metadata table outlining the data quality for every sky-scan. It is available via an ODS spreadsheet also included in our v3 Zenodo upload.To increase the visibility of our data quality, we have also converted the ODS spreadsheet into four tables (one per campaign dataset) within a new supplement (attached).
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RC4: 'Comment on essd-2025-31', Anonymous Referee #4, 15 Jul 2025
The manuscript presents a valuable extension of the 4STAR retrievals to the ORACLES 2017 and 2018 campaigns by addressing instrument artifacts and establishing automated quality control standards. The work is well-motivated and provide important dataset for the study of biomass burning aerosols and their climate impacts. However, several areas require clarification to enhance the manuscript's scientific rigor and usability for potential data users.
1. The manuscript briefly mentions the shift from a five-wavelength to a four-wavelength set to avoid instrument artifacts but lacks a detailed theoretical discussion. The authors should clarify how the removal of 400 nm affects the inversion of aerosol's properties to help potential users better understand its quality. In addition, the authors should discuss the potential biases introduced by the 4wl set, particularly the noted slight decrease in SSA at 500 nm. Is this systematic?
2. The manuscript would benefit from a case study or example analysis showcasing how the dataset can be applied. The authors can consider include a brief case study of biomass burning event to illustrate its practical applications.
3. To enhance the dataset's accessibility, I recommend including a detailed summary table listing key metadata such as variables names, temporal and spatial coverage. This will allow users to quickly evaluate the data's applicability for their research needs.
Citation: https://doi.org/10.5194/essd-2025-31-RC4 -
AC5: 'Reply to RC4', Logan Mitchell, 18 Jul 2025
Thank you for the comment. We have added a theoretical discussion regarding why 500 nm was specifically the most affected wavelength to the results section, along with recommended work for determining if the shift is systematic in the future improvements subsection. We are also adding a practical application subsection to the discussion, where we will discuss a recent publication that made use of our ORACLES 4STAR datasets, in alignment with your comment and that of RC2. We have also created supplemental tables listing the spatiotemporal variability and variable names, in alignment with your comment and that of RC3.
Citation: https://doi.org/10.5194/essd-2025-31-AC5
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AC5: 'Reply to RC4', Logan Mitchell, 18 Jul 2025
- AC6: 'Final response for essd-2025-31', Logan Mitchell, 27 Jul 2025
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ORACLES 2016-2018 4STAR Dataset, Version 2 Logan Mitchell https://doi.org/10.5281/zenodo.14659686
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