04 Oct 2023
 | 04 Oct 2023

On the sensitivity of aerosol-cloud interactions to changes in sea surface temperature in radiative-convective equilibrium

Suf Lorian and Guy Dagan

Abstract. Clouds play a crucial role in regulating Earth's energy balance and are influenced by anthropogenic aerosol concentration (Na) and sea surface temperature (SST) changes. However, these two factors – aerosols and SST – are typically studied independently. In this study, we employ idealized cloud-resolving, radiative-convective-equilibrium simulations to explore aerosol-cloud interactions (ACI) under different SSTs. Our findings reveal that ACIs are dependent on the prescribed SST, even at equilibrium conditions. Specifically, we show that increasing Na leads to a decline in top-of-atmosphere (TOA) energy gain across SSTs due to changes in the cloud radiative effect, both in the short-wave and the long-wave parts of the spectrum. TOA short-wave flux changes with an increase in Na are found to be more sensitive to the underlined SST conditions compared to long-wave radiation. The variations in how the clouds' short-wave radiative effect responds to Na at various SSTs are explained by variations in the sensitivity of the water content in the cloud. Specifically, the sensitivity of the water content to Na decreases with SST due to deepening of the warm, liquid portion of the cloud. This deepening results in clouds that are less responsive to aerosol-induced warm rain suppression. Furthermore, with an increase in Na, we observe an increase in latent heat release at the upper troposphere associated with heightened production of snow and graupel. We show that this trend, which is consistent across all SSTs, affects the anvil cloud cover by affecting the static–stability at the upper troposphere via a similar mechanism to the iris–stability effect, resulting in a decline in TOA long-wave energy gain. In conclusion, under the ongoing climate change, studying the sensitivity of clouds to aerosols and SST should be conducted concomitantly as mutual effects are expected.

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Suf Lorian and Guy Dagan

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2023-2096', Blaž Gasparini, 26 Oct 2023
  • RC2: 'Comment on egusphere-2023-2096', Anonymous Referee #2, 02 Nov 2023
  • AC1: 'Comment on egusphere-2023-2096', Suf Lorian, 05 Mar 2024
  • AC2: 'Comment on egusphere-2023-2096 - corrected file', Suf Lorian, 06 Mar 2024
Suf Lorian and Guy Dagan
Suf Lorian and Guy Dagan


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Short summary
We examine the combined effect of aerosols and sea surface temperature (SST) on clouds under equilibrium conditions in cloud-resolving radiative-convective equilibrium simulations. We demonstrate that the aerosol-cloud interaction effect on top-of-atmosphere energy gain strongly depends on the underlying SST, while the short-wave part of the spectrum is significantly more sensitive to SST. Furthermore, increasing aerosols influences upper troposphere stability and thus anvil cloud fraction.