Journal cover Journal topic
Geoscientific Model Development An interactive open-access journal of the European Geosciences Union
Journal topic

Journal metrics

IF value: 5.240
IF5.240
IF 5-year value: 5.768
IF 5-year
5.768
CiteScore value: 8.9
CiteScore
8.9
SNIP value: 1.713
SNIP1.713
IPP value: 5.53
IPP5.53
SJR value: 3.18
SJR3.18
Scimago H <br class='widget-line-break'>index value: 71
Scimago H
index
71
h5-index value: 51
h5-index51
Preprints
https://doi.org/10.5194/gmd-2020-357
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/gmd-2020-357
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Submitted as: development and technical paper 12 Nov 2020

Submitted as: development and technical paper | 12 Nov 2020

Review status
This preprint is currently under review for the journal GMD.

Implementing a sectional scheme for early aerosol growth from new particle formation in the Norwegian Earth System Model v2: comparison to observations and climate impacts

Sara M. Blichner1, Moa K. Sporre2, Risto Makkonen3,4, and Terje K. Berntsen1 Sara M. Blichner et al.
  • 1Department of Geosciences, University of Oslo, Oslo, Norway
  • 2Department of Physics, Lund University, Lund, Sweden
  • 3Institute for Atmospheric and Earth System Research/Physics, Faculty of Science, University of Helsinki, Finland
  • 4Climate System Research, Finnish Meteorological Institute, Helsinki, Finland

Abstract. Aerosol-cloud interactions contribute with a large portion of the spread in estimates of climate forcing, climate sensitivity and future projections. An important part of this uncertainty is how much new particle formation (NPF) contributes to cloud condensation nuclei (CCN), and furthermore, how this changes with changes in anthropogenic emissions. Incorporating NPF and early growth in Earth System Models (ESMs) is, however, challenging both due to uncertain parameters (e.g. participating vapours), structural challenges (numerical description of growth from ∼1 to ∼100 nm), and due to large scale of ESM grid compared to NPF scale.A common approach in ESMs is to represent the particle size distribution by a certain number of log-normal modes. Sectional schemes on the other hand, where the size distribution is represented by bins, are considered closer to first principles because they do not make an a priori assumption about the size distribution.

In order to improve the representation of early growth, we have implemented a sectional scheme for the smallest particles (5–39.6 nm diameter) in the Norwegian Earth System Model (NorESM), feeding particles into the original aerosol scheme. This is, to our knowledge, the first time such an approach has been tried. We find that including the sectional scheme for early growth improves the aerosol number concentration in the model when comparing against observations, particularly in the 50–100 nm diameter range. Furthermore, we find that the model with the sectional scheme produces much less particles than the original scheme in polluted regions, while it produces more in remote regions and the free troposphere, indicating a potential impact on the estimated aerosol forcing. Finally, we analyse the effect on cloud-aerosol interactions and find that the effect of changes in NPF efficiency on clouds is highly heterogeneous in space. While in remote regions, more efficient NPF leads to higher cloud droplet number concentration (CDNC), in polluted regions the opposite is in fact the case.

Sara M. Blichner et al.

Interactive discussion

Status: open (until 07 Jan 2021)
Status: open (until 07 Jan 2021)
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
[Subscribe to comment alert] Printer-friendly Version - Printer-friendly version Supplement - Supplement

Sara M. Blichner et al.

Data sets

Data for: Implementing a sectional scheme for early aerosol growth from new particle formation in the Norwegian Earth System Model v2: comparison to observations and climate impacts Sara Marie Blichner https://doi.org/10.11582/2020.00056

Model code and software

Model code and configuration/setup instruction (OAS-Code-Setup) Sara Marie Blichner https://doi.org/10.5281/zenodo.4265057

Post-processing code (OAS-DEV) Sara Marie Blichner https://doi.org/10.5281/zenodo.4265033

Sara M. Blichner et al.

Viewed

Total article views: 157 (including HTML, PDF, and XML)
HTML PDF XML Total Supplement BibTeX EndNote
127 29 1 157 10 0 0
  • HTML: 127
  • PDF: 29
  • XML: 1
  • Total: 157
  • Supplement: 10
  • BibTeX: 0
  • EndNote: 0
Views and downloads (calculated since 12 Nov 2020)
Cumulative views and downloads (calculated since 12 Nov 2020)

Viewed (geographical distribution)

Total article views: 110 (including HTML, PDF, and XML) Thereof 106 with geography defined and 4 with unknown origin.
Country # Views %
  • 1
1
 
 
 
 

Cited

Saved

No saved metrics found.

Discussed

No discussed metrics found.
Latest update: 01 Dec 2020
Publications Copernicus
Download
Short summary
Aerosol-cloud interactions is the largest contributor to climate forcing uncertainty. In this study we combine two common approaches to aerosol representation in global models: A sectional scheme, which is closer to first principals, for the smallest particles forming in the atmosphere and a log-modal scheme, which is faster, for the larger particles. With this approach, we improve the aerosol representation compared to observations, while only increasing the computational cost by 15 %.
Aerosol-cloud interactions is the largest contributor to climate forcing uncertainty. In this...
Citation