Preprints
https://doi.org/10.5194/amt-2023-106
https://doi.org/10.5194/amt-2023-106
30 Jun 2023
 | 30 Jun 2023
Status: a revised version of this preprint was accepted for the journal AMT and is expected to appear here in due course.

Aerosol properties derived from COCCON ground-based Fourier Transform spectra

Óscar Álvarez, África Barreto, Omaira E. García, Frank Hase, Rosa D. García, Julian Gröbner, Sergio F. León-Luis, Eliezer Sepúlveda, Virgilio Carreño, Antonio Alcántara, Ramón Ramos, A. Fernando Almansa, Stelios Kazadzis, Noémie Taquet, Carlos Toledano, and Emilio Cuevas

Abstract. Fourier Transform Infrared (FTIR) spectroscopy is particularly relevant for climate studies due to its ability to provide information on both fine absorption structures (i.e. trace gases) and broadband continuum signatures (i.e. aerosols or water continuum) across the entire infrared (IR) domain. In this context, this study assesses the capability of the portable and compact EM27/SUN spectrometer, used within the research infrastructure COCCON (COllaborative Carbon Column Observing Network), to retrieve spectral aerosol properties from low-resolution FTIR solar absorption spectra. The study focuses on the retrieval of Aerosol Optical Depth (AOD) and its spectral dependence in the 873–2314 nm spectral range from COCCON measurements at the subtropical high-mountain Izaña Observatory (IZO, Tenerife, Spain), which were coincidentally carried out with standard sun photometry within the Aerosol Robotic Network (AERONET) in the 3-year period from December 2019 to September 2022. The co-located AERONET-COCCON database in the 2021–2022 period (post-COVID-19 lockdown) was used to cross-validate these two independent techniques in the common spectral range (870–1640 nm), demonstrating an excellent agreement at the near-coincident spectral bands (mean AOD differences limited to 0.005, standard deviations up to 0.019 and Pearson regression coefficients up to 0.99). This indicates that the low-resolution COCCON instruments are suitable for detecting the aerosol broadband signal contained in the IR spectra in addition to the retrieval of precise trace gas concentrations provided that its calibration is performed frequently enough to compensate for the optical degradation of the external system (approx. 0.6 % per month). The study also assesses the capability of the EM27/SUN to simultaneously infer aerosols and trace gases, and relate their common emission sources in two case study events: a volcanic plume from the La Palma eruption in 2021 and a nearby forest fire in Tenerife in 2022. Overall, our results demonstrate the potential of the portable low-resolution COCCON instruments to enhance the multi-parameter capability of the FTIR technique for atmospheric monitoring.

Óscar Álvarez et al.

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on amt-2023-106', Anonymous Referee #1, 19 Jul 2023
    • AC1: 'Reply on RC1', África Barreto, 17 Aug 2023
  • RC2: 'Comment on amt-2023-106', Anonymous Referee #2, 21 Jul 2023
    • AC2: 'Reply on RC2', África Barreto, 17 Aug 2023

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on amt-2023-106', Anonymous Referee #1, 19 Jul 2023
    • AC1: 'Reply on RC1', África Barreto, 17 Aug 2023
  • RC2: 'Comment on amt-2023-106', Anonymous Referee #2, 21 Jul 2023
    • AC2: 'Reply on RC2', África Barreto, 17 Aug 2023

Óscar Álvarez et al.

Óscar Álvarez et al.

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Short summary
In this work, we have extended the capabilities of a portable FTIR, which was originally designed to provide high-quality greenhouse gas monitoring within the COCCON network. The extension allows the spectrometer to now also provide coincidentally column-integrated aerosol information. This addition of a reference instrument to a global network will be utilized to enhance our understanding of atmospheric chemistry by adding multiparameter capabilities to the existing ground-based networks.