Submitted as: model description paper 22 Mar 2021

Submitted as: model description paper | 22 Mar 2021

Review status: a revised version of this preprint was accepted for the journal GMD.

Description and Evaluation of a Secondary Organic Aerosol and New Particle Formation Scheme within TM5-MP v1.1

Tommi Bergman1,2, Risto Makkonen2,3, Roland Schrödner4,5, Erik Swietlicki4, Vaughan T. J. Phillips6, Philippe Le Sager1, and Twan van Noije1 Tommi Bergman et al.
  • 1Royal Netherlands Meteorological Institute (KNMI), PO Box 201, 3730 AE De Bilt, the Netherlands
  • 2Climate System Research, Finnish Meteorological Institute, P.O. Box 503, FI-00101, Helsinki, Finland
  • 3Institute for Atmospheric and Earth System Research/Physics, Faculty of Science, University of Helsinki, P.O. Box 64, FI-00014, Finland
  • 4Department of Physics, Lund University, Box 118, 22100 Lund, Sweden
  • 5Institute for Tropospheric Research, Permoserstr. 15, 04318 Leipzig, Germany
  • 6Department of Physical Geography and Ecosystem Science, Lund University, Solvegatan 12, Lund 22362, Sweden

Abstract. We have implemented and evaluated a secondary organic aerosol scheme within the chemistry transport model TM5-MP in this work. In earlier versions of TM5-MP the secondary organic aerosol was emitted as Aitken sized particle mass emulating the condensation. In the current scheme we simulate the formation of SOA from oxidation of isoprene and monoterpenes by ozone and hydroxyl radicals which produce semi-volatile organic compounds and extremely low-volatility compounds. Subsequently, SVOC and ELVOC can condense on particles. Furthermore, we have introduced a new particle formation mechanism depending on the concentration of ELVOCs. For evaluation purposes, we have simulated the year 2010 with the old and new scheme, where we see an increase in simulated production of SOA from 39.9 Tg y−1 with the old scheme to 52.5 Tg y−1 with the new scheme. For more detailed analysis, the particle mass and number concentrations and their influence on the simulated aerosol optical depth are compared to observations. Phenomenologically, the new particle formation scheme implemented here is able to reproduce the occurrence of observed particle formation events. However, the concentrations of formed particles are clearly lower as is the subsequent growth to larger sizes. Compared to the old scheme, the new scheme is increasing the number concentrations across the observation stations while still underestimating the observations. The total aerosol mass concentrations in the US show a much better seasonal cycle and removal of a clear overestimation of concentrations. In Europe the mass concentrations are lowered leading to a larger underestimation of observations. Aerosol optical depth is generally slightly increased except in the northern high latitudes. This brings the simulated annual global mean AOD closer to observational estimate. However, as the increase is rather uniform, biases tend to be reduced only in regions where the model underestimates the AOD. Furthermore, the correlation against satellite retrievals and ground-based sun-photometer observations are improved. Although the process based approach to SOA formation causes reduction in model performance in some areas, overall the new scheme improves the simulated aerosol fields.

Tommi Bergman 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 gmd-2021-49', Anonymous Referee #1, 12 Apr 2021
    • AC2: 'Reply on RC1', Tommi Bergman, 23 Jun 2021
  • RC2: 'Comment on gmd-2021-49', Anonymous Referee #2, 14 Apr 2021
    • AC3: 'Reply on RC2', Tommi Bergman, 23 Jun 2021
  • CEC1: 'Comment on gmd-2021-49', Juan Antonio Añel, 20 Apr 2021
    • AC1: 'Reply on CEC1', Tommi Bergman, 23 Apr 2021
      • CEC2: 'Reply on AC1', Juan Antonio Añel, 23 Apr 2021
  • RC3: 'Comment on gmd-2021-49', Anonymous Referee #3, 21 Apr 2021
    • AC4: 'Reply on RC3', Tommi Bergman, 23 Jun 2021
  • RC4: 'Comment on gmd-2021-49', Anonymous Referee #4, 03 May 2021
    • AC5: 'Reply on RC4', Tommi Bergman, 23 Jun 2021

Tommi Bergman et al.

Data sets

Raw Model data from simulations Tommi Bergman

Tommi Bergman et al.


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Short summary
We describe in this paper the implementation of a process based secondary organic aerosol and new particle formation scheme within the chemistry transport model TM5-MP version 1.1. The performance of the model simulations for year 2010 are evaluated against in-situ observations, ground-based remote sensing and satellite retrievals. Overall, the simulated aerosol fields are improved although in some areas the model shows decline in performance.