Preprints
https://doi.org/10.5194/amt-2020-492
https://doi.org/10.5194/amt-2020-492

  27 Jan 2021

27 Jan 2021

Review status: this preprint is currently under review for the journal AMT.

Evaluation of UV-visible MAX-DOAS aerosol profiling products by comparison with ceilometer, sun photometer, and in situ observations in Vienna, Austria

Stefan F. Schreier1, Tim Bösch2, Andreas Richter2, Kezia Lange2, Michael Revesz1, Philipp Weihs1, Mihalis Vrekoussis2,3, and Christoph Lotteraner4 Stefan F. Schreier et al.
  • 1Institute of Meteorology and Climatology, University of Natural Resources and Life Sciences, Vienna, Austria
  • 2Institute of Environmental Physics, University of Bremen, Germany
  • 3Climate and Atmosphere Research Center (CARE-C), The Cyprus Institute, Cyprus
  • 4Central Institute for Meteorology and Geodynamics, Vienna, Austria

Abstract. Since May 2017 and August 2018, two ground-based MAX-DOAS (Multi AXis Differential Optical Absorption Spectroscopy) instruments have been continuously recording daytime spectral UV-visible measurements in the north-west (University of Natural Resources and Life Sciences (BOKU) site) and south (Arsenal site) of the Vienna city centre (Austria), respectively. In this study, aerosol extinction (AE) profiles, aerosol optical depth (AOD), and near-surface AE are retrieved from MAX-DOAS measurements recorded on cloud-free days applying the Bremen Optimal estimation REtrieval for Aerosols and trace gaseS (BOREAS) algorithm. For the first time, measurements of atmospheric profiles of pressure and temperature obtained from routinely performed sonde ascents are used to calculate box-air-mass-factors and weighting functions for different seasons. The performance of BOREAS was evaluated against co-located ceilometer, sun photometer, and in situ instrument observations covering all four seasons. The results showed that the vertical AE profiles retrieved from the BOKU UV-visible MAX-DOAS observations are in very good agreement with data from the co-located ceilometer, reaching correlation coefficients (R) of 0.91–0.99 (UV) and 0.85–0.98 (visible) during fall, winter, and spring seasons. Moreover, AE extracted using the lowest part of MAX-DOAS vertical profiles (up to 100 m above ground) are highly consistent with near-surface ceilometer AE (R > 0.90 and linear regression slopes of ~0.90) during the fall season. A strong correlation is also found for the BOREAS-based AODs when compared to the AERONET ones. Notably, the highest correlation coefficients (R = 0.95 and R = 0.94 for UV and visible, respectively) were identified for the fall season. While high correlation coefficients are also found for the winter and spring seasons, the results are less reliable for measurements taken during summer. For the first time, the spatial variability of AOD and near-surface AE over the urban environment of Vienna is assessed by analyzing the retrieved and evaluated BOREAS aerosol profiling products in terms of different azimuth angles of the two MAX-DOAS instruments and for different seasons. We found that the relative differences of averaged AOD between different azimuth angles are 7–13 %, depending on the season. Larger relative differences of up to 32 % obtained for the different azimuthal directions are found for near-surface AE. This study revealed the strong capability of BOREAS to retrieve AE profiles, AOD, and near-surface AE over urban environments and demonstrated its use for identifying the spatial variability of aerosols, in addition to the temporal variation.

Stefan F. Schreier et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on amt-2020-492', Anonymous Referee #1, 26 Feb 2021
  • RC2: 'Comment on amt-2020-492', Anonymous Referee #2, 05 Mar 2021
  • RC3: 'Comment on amt-2020-492', Anonymous Referee #3, 24 Mar 2021

Stefan F. Schreier et al.

Stefan F. Schreier et al.

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Short summary
This paper reports on the evaluation of aerosol profiling products retrieved from ground-based MAX-DOAS instruments using the BOREAS algorithm. Aerosol extinction profiles, near-surface aerosol extinction, and aerosol optical depth are compared to measurements collected with ceilometer, sun photometer, and in-situ instruments. We show that these MAX-DOAS aerosol profiling products provide useful information to study spatial and temporal variations above the urban area of Vienna.