Rapid saturation of cloud water adjustments to shipping emissions

Manshausen, Peter; Watson-Parris, Duncan; Christensen, Matthew W.; Jalkanen, Jukka-Pekka; Stier, Philip

doi:https://doi.org/10.5194/acp-23-12545-2023

Articles | Volume 23, issue 19

https://doi.org/10.5194/acp-23-12545-2023

© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.

https://doi.org/10.5194/acp-23-12545-2023

© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 23, issue 19

ACP Letters

| Highlight paper

|

09 Oct 2023

ACP Letters | Highlight paper |

| 09 Oct 2023

Rapid saturation of cloud water adjustments to shipping emissions

Peter Manshausen, Duncan Watson-Parris, Matthew W. Christensen, Jukka-Pekka Jalkanen, and Philip Stier

Data sets

Invisible Tracks: Collocation of wind-advected ship locations and shipping emissions with data from the MODIS cloud product P. Manshausen, D. Watson-Parris, M. Christensen, J.-P. Jalkanen, and P. Stier https://doi.org/10.5285/2d0f8bb3927b4f75ae75276705858f68

ERA5 hourly data on pressure levels from 1940 to present H. Hersbach, B. Bell, P. Berrisford, G. Biavati, A. Horányi, J. Muñoz Sabater, J. Nicolas, C. Peubey, R. Radu, I. Rozum, D. Schepers, A. Simmons, C. Soci, D. Dee, and J.-N. Thépaut https://doi.org/10.24381/cds.bd0915c6

MODIS atmosphere L2 cloud product (06_L2) S. Platnick, S. A. Ackerman, M. D. King, K. Meyer, W. P. Menzel, R. E. Holz, B. A. Baum, and P. Yang https://doi.org/10.5067/MODIS/MOD06_L2.006

Model code and software

ManshaP/invisible_tracks: Release_paper P. Manshausen https://doi.org/10.5281/zenodo.6556425

Executive editor

Ship tracks are enhanced regions of cloud brightness that trail behind ships that are known to be created by their effluent. They are widely used as observational test beds to deepen understanding of how pollution might affect cloud microphysical processes and climate at larger regional and global scales. This study uses satellite observations of cloud properties and records of ship position and their effluent to assess perturbations from ship emissions on cloud droplet number and liquid water path. The study found that, as expected, the droplet number perturbation in shiptracks scales with ship emission rates of aerosol particles. Surprisingly, however, the liquid water path in drizzling clouds increased by an amount that was nearly fixed. The observation points to novel non-linear threshold behaviours of relevance to representations of aerosol indirect effects in climate models.