Preprints
https://doi.org/10.5194/egusphere-2023-155
https://doi.org/10.5194/egusphere-2023-155
03 Feb 2023
 | 03 Feb 2023

Radiative effect by cirrus cloud and contrails – A comprehensive sensitivity study

Kevin Wolf, Nicolas Bellouin, and Olivier Boucher

Abstract. Natural cirrus clouds and contrails cover about 30 % of the Earth's mid-latitudes and up to 70 % of its Tropics. Due to their widespread occurrence, cirrus have a considerable impact on the Earth energy budget, which, on average, leads to a warming net radiative effect (solar + thermal-infrared). However, whether the instantaneous radiative effect (RE) of natural cirrus or contrails is positive or negative depends on their microphysical, macrophysical, and optical, as well as radiative properties of the environment. This is further complicated by the fact that the actual ice crystal shape is often unknown and thus ice clouds remain one of the components that are least understood in the Earth's radiative budget.

The present study aims to separate the effect on cirrus RE of eight parameters: solar zenith angle, ice water content, ice crystal effective radius, cirrus temperature, surface albedo, surface temperature, liquid water cloud optical thickness of an underlying cloud, and three ice crystal shapes. In total, 94,500 radiative transfer simulations have been performed, spanning the parameter ranges that are typically associated with natural cirrus and contrails. The multi-dimensionality and complexity of the 8-dimension parameter space makes it impractical to discuss all potential configurations in detail. Therefore, specific cases are selected and discussed.

The ice crystal effective radius has the largest impact on solar, thermal-infrared (TIR), and net RE. The second most important parameter is the ice water content, which impacts the solar and terrestrial RE equally. Solar and TIR RE have opposite signs, meaning that the ice water content has a relatively small impact on net RE. Beyond the ice crystal effective radius and the ice water content, the solar RE of cirrus is determined by solar zenith angle, surface albedo, liquid cloud optical thickness, and the ice crystal shape in descending priority. RE in the TIR spectrum is dominated by the surface temperature, the ice cloud temperature, the liquid water cloud optical thickness, and the ice crystal shape. Net RE is controlled by the surface albedo, the solar zenith angle, and the surface albedo in decreasing importance. The relative importance of the studied parameters differs depending on the ambient conditions and during nighttime the net RE is equal to the TIR RE.

The data set generated in this work is publicly available. It can be used to compute the radiative effect of cirrus clouds, contrails, and contrail cirrus instead of full radiative transfer calculations.

Journal article(s) based on this preprint

09 Nov 2023
Sensitivity of cirrus and contrail radiative effect on cloud microphysical and environmental parameters
Kevin Wolf, Nicolas Bellouin, and Olivier Boucher
Atmos. Chem. Phys., 23, 14003–14037, https://doi.org/10.5194/acp-23-14003-2023,https://doi.org/10.5194/acp-23-14003-2023, 2023
Short summary

Kevin Wolf et al.

Interactive discussion

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2023-155', Anonymous Referee #1, 17 Feb 2023
    • AC1: 'Reply on RC1', Kevin Wolf, 11 May 2023
  • RC2: 'Comment on egusphere-2023-155', Andreas Macke, 21 Feb 2023
    • AC2: 'Reply on RC2', Kevin Wolf, 11 May 2023
  • RC3: 'Comment on egusphere-2023-155', Anonymous Referee #3, 07 Mar 2023
    • AC3: 'Reply on RC3', Kevin Wolf, 11 May 2023
  • CC1: 'Comment to Wolf et al., “Radiative effect by cirrus cloud and contrails – A comprehensive sensitivity study”, in review , egusphere-2023-155', Ulrich Schumann, 10 Mar 2023
  • CC2: 'Comment to Wolf et al., “Radiative effect by cirrus cloud and contrails – A comprehensive sensitivity study”, in review , egusphere-2023-155', Ulrich Schumann, 10 Mar 2023
    • AC4: 'Reply on CC2', Kevin Wolf, 11 May 2023

Interactive discussion

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2023-155', Anonymous Referee #1, 17 Feb 2023
    • AC1: 'Reply on RC1', Kevin Wolf, 11 May 2023
  • RC2: 'Comment on egusphere-2023-155', Andreas Macke, 21 Feb 2023
    • AC2: 'Reply on RC2', Kevin Wolf, 11 May 2023
  • RC3: 'Comment on egusphere-2023-155', Anonymous Referee #3, 07 Mar 2023
    • AC3: 'Reply on RC3', Kevin Wolf, 11 May 2023
  • CC1: 'Comment to Wolf et al., “Radiative effect by cirrus cloud and contrails – A comprehensive sensitivity study”, in review , egusphere-2023-155', Ulrich Schumann, 10 Mar 2023
  • CC2: 'Comment to Wolf et al., “Radiative effect by cirrus cloud and contrails – A comprehensive sensitivity study”, in review , egusphere-2023-155', Ulrich Schumann, 10 Mar 2023
    • AC4: 'Reply on CC2', Kevin Wolf, 11 May 2023

Peer review completion

AR: Author's response | RR: Referee report | ED: Editor decision | EF: Editorial file upload
AR by Kevin Wolf on behalf of the Authors (11 May 2023)  Author's response   Author's tracked changes   Manuscript 
ED: Referee Nomination & Report Request started (11 May 2023) by Matthias Tesche
RR by Andreas Macke (23 May 2023)
RR by David Mitchell (28 May 2023)
RR by Anonymous Referee #3 (27 Jun 2023)
ED: Reconsider after major revisions (27 Jun 2023) by Matthias Tesche
AR by Kevin Wolf on behalf of the Authors (18 Jul 2023)  Author's response   Author's tracked changes   Manuscript 
ED: Referee Nomination & Report Request started (24 Jul 2023) by Matthias Tesche
RR by Anonymous Referee #3 (18 Sep 2023)
ED: Reconsider after major revisions (19 Sep 2023) by Matthias Tesche
AR by Kevin Wolf on behalf of the Authors (25 Sep 2023)  Author's response   Author's tracked changes   Manuscript 
ED: Publish as is (26 Sep 2023) by Matthias Tesche
AR by Kevin Wolf on behalf of the Authors (27 Sep 2023)  Manuscript 

Journal article(s) based on this preprint

09 Nov 2023
Sensitivity of cirrus and contrail radiative effect on cloud microphysical and environmental parameters
Kevin Wolf, Nicolas Bellouin, and Olivier Boucher
Atmos. Chem. Phys., 23, 14003–14037, https://doi.org/10.5194/acp-23-14003-2023,https://doi.org/10.5194/acp-23-14003-2023, 2023
Short summary

Kevin Wolf et al.

Data sets

Simulated top-of-atmosphere (15 km) downward and upward solar and thermal-infrared irradiances and ice cloud optical thickness; calculated solar, TIR and net cloud radiative effect. Simulated with ice crystal properties for aggregates, droxtals, and plates based on Yang (2000). Wolf, K., Bellouin, N., and Boucher, O. https://doi.org/10.5281/zenodo.7593464

Kevin Wolf et al.

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Short summary
Cirrus and contrails considerably impact the Earths energy budget. Such ice clouds can have a positive (warming) or negative (cooling) net radiative effect (RE), which depends on cloud and ambient properties. The effect of 8 parameters on the cloud RE is estimated. In total, 94,500 radiative transfer simulations have been performed, spanning the typical parameter ranges associated with cirrus and contrails. Specific cases are selected and discussed. The generated data set is publicly available.