the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 20 Aug 2025
Aerosol variability over oceans using micro-pulse lidar and photometer: Insights from TRANSAMA ship-based campaign
Abstract. The TRANSAMA campaign (Transit to AMARYLLIS-AMAGAS oceanographic cruise), conducted aboard the research vessel Marion Dufresne II investigated aerosol properties during its transit from La Reunion Island to Barbados (April–May 2023). A set of remote sensing instruments, including two CE318-T Sun-sky-lunar photometers and a CE370 single-wavelength elastic lidar, was deployed under the MAP-IO (Marion Dufresne Atmospheric Program–Indian Ocean) framework. Synergistic observations provided vertically resolved aerosol properties, such as extinction coefficients, alongside atmospheric structure, highlighting the marine boundary layer (MBL) top at 800 ± 300 m. While the photometer observations revealed very clean atmospheric conditions over the South Atlantic (AOD(440) = 0.08 ± 0.04), thin aerosol layers above the MBL were identified as long-range transported residual biomass-burning-urban aerosols from Southern Africa with effective LR of 33 ± 12 sr. Cloud layers covering a large range of altitudes (up to 16 km) were observed in 53 % of the lidar profiles with higher occurrence in low altitudes where the aerosol content was higher. These findings emphasize the impact of continental aerosols on remote oceanic regions, with implications on cloud formation and climate processes. The campaign also facilitated performance assessments of the deployed instrumentation, supporting the development of advanced mobile observatories for coupled lidar-photometer systems in marine environments.
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Status: final response (author comments only)
- RC1: 'Comment on egusphere-2025-3481', Anonymous Referee #1, 04 Sep 2025
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RC2: 'Comment on egusphere-2025-3481', Patrick Chazette, 05 Sep 2025
Although the geophysical conclusions drawn from this offshore campaign confirm existing knowledge, this article is relevant to AMT. The campaign demonstrates the value of lidar/photometer synergy in the regular monitoring of sparsely covered ocean areas. Such a deployment could complement Earth observation from space, as with the EarthCARE mission. This potential should be discussed.
The potential of the instruments should be given more emphasis, and the associated uncertainties should be discussed in greater detail. In particular, it is difficult to take measurements in a clean environment where AODs are often below 0.1. Given the significant uncertainty surrounding Ångström exponents and LR values, conclusions must take this limitation into account.
Using a combination of lidar and photometer instruments on vessels provides important additional data to existing land-based networks and spaceborne observations. The frequency with which such observations could be made should be estimated, taking into account the additional resources available beyond the Marion Dufresne vessel.
My comments and suggested corrections are highlighted in the associated file.
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EC1: 'Comment on egusphere-2025-3481', Lionel Doppler, 25 Sep 2025
I thank the authors of the paper "Aerosol variability over oceans using micro-pulse lidar and photometer: Insights from the TRANSAMA ship-based campaign" for their excellent work and valuable contribution. I fully agree with the reviewers that the manuscript convincingly demonstrates the synergy of lidar and photometer for the remote sensing of aerosols. In my opinion, it fits well within the scope of AMT and particularly this special issue. I also consider that the study and its survey are of high quality.
Nevertheless, I share the reviewers’ concern regarding Section 3, which is excessively long. It could be substantially shortened, potentially integrated into another section, allowing more emphasis on the discussion of the benefits of combining active remote sensing (lidar) with passive sensing (photometer), which constitutes the main strength of the paper. Figures 3 and 4, in my view, are not easily interpretable. I suggest providing accompanying tables with reducing the content to only the most relevant information, or removing them entirely if Section 3 undergoes major restructuring. The issues with these figures have also been noted by the reviewers.
Addressing these points should be the priority in any potential revision requested after acceptance.
I wish the authors every success in the revision process and sincerely thank and congratulate them for their work
Citation: https://doi.org/10.5194/egusphere-2025-3481-EC1
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