Constraints on Southern Ocean Shortwave Cloud Feedback from the Hydrological Cycle
Shifts in Southern Ocean (SO, $40 - 85^{o}S$) shortwave cloud feedback ($SW_{FB}$) toward more positive values are the dominant contributor to higher effective climate sensitivity (ECS) in Coupled Model Intercomparison Project phase 6 (CMIP6) models. To provide an observational constraint on the SO...
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crwinnower:10.22541/essoar.170158311.16527130/v1 2024-06-02T08:14:46+00:00 Constraints on Southern Ocean Shortwave Cloud Feedback from the Hydrological Cycle Tan, Chuyan McCoy, Daniel Thompson Elsaesser, Gregory 2023 http://dx.doi.org/10.22541/essoar.170158311.16527130/v1 unknown Authorea, Inc. posted-content 2023 crwinnower https://doi.org/10.22541/essoar.170158311.16527130/v1 2024-05-07T14:19:10Z Shifts in Southern Ocean (SO, $40 - 85^{o}S$) shortwave cloud feedback ($SW_{FB}$) toward more positive values are the dominant contributor to higher effective climate sensitivity (ECS) in Coupled Model Intercomparison Project phase 6 (CMIP6) models. To provide an observational constraint on the SO $SW_{FB}$, we use a simplified physical model to connect SO $SW_{FB}$ with the response of column-integrated liquid water mass (LWP) to warming and the susceptibility of albedo to LWP in 50 CMIP5 and CMIP6 GCMs. In turn, we predict the responses of SO LWP using a cloud-controlling factor (CCF) model. The combination of the CCF model and radiative susceptibility explains about $50$\% of the variance in the GCM-simulated $SW_{FB}$ in the SO. Observations of SW radiation fluxes, LWP, and CCFs from reanalysis are used to constrain the SO $SW_{FB}$. The response of SO LWP to warming is constrained to $2.76\ -\ 4.19$ $g\ m^{-2}\ K^{-1}$, relative to a GCM prior of $0.64\ -\ 9.33$ $g\ m^{-2}\ K^{-1}$. The susceptibility of albedo to LWP is constrained to be $0.43\ -\ 0.90$ $ (kg\ m^{-2})^{-1}$, relative to $0.30\ -\ 3.91$ $(kg\ m^{-2})^{-1}$. The overall constraint on the contribution of SO to global mean $SW_{FB}$ is $-0.168\ -\ 0.051$ $W\ m^{-2}\ K^{-1}$, relative to $-0.277\ -\ 0.270$ $ W m^{-2} K^{-1}$. In summary, observations suggest SO $SW_{FB}$ is less likely to be as extremely positive as predicted by some CMIP6 GCMs, but more likely to range from moderate negative to weakly positive. Other/Unknown Material Southern Ocean The Winnower Southern Ocean |
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Shifts in Southern Ocean (SO, $40 - 85^{o}S$) shortwave cloud feedback ($SW_{FB}$) toward more positive values are the dominant contributor to higher effective climate sensitivity (ECS) in Coupled Model Intercomparison Project phase 6 (CMIP6) models. To provide an observational constraint on the SO $SW_{FB}$, we use a simplified physical model to connect SO $SW_{FB}$ with the response of column-integrated liquid water mass (LWP) to warming and the susceptibility of albedo to LWP in 50 CMIP5 and CMIP6 GCMs. In turn, we predict the responses of SO LWP using a cloud-controlling factor (CCF) model. The combination of the CCF model and radiative susceptibility explains about $50$\% of the variance in the GCM-simulated $SW_{FB}$ in the SO. Observations of SW radiation fluxes, LWP, and CCFs from reanalysis are used to constrain the SO $SW_{FB}$. The response of SO LWP to warming is constrained to $2.76\ -\ 4.19$ $g\ m^{-2}\ K^{-1}$, relative to a GCM prior of $0.64\ -\ 9.33$ $g\ m^{-2}\ K^{-1}$. The susceptibility of albedo to LWP is constrained to be $0.43\ -\ 0.90$ $ (kg\ m^{-2})^{-1}$, relative to $0.30\ -\ 3.91$ $(kg\ m^{-2})^{-1}$. The overall constraint on the contribution of SO to global mean $SW_{FB}$ is $-0.168\ -\ 0.051$ $W\ m^{-2}\ K^{-1}$, relative to $-0.277\ -\ 0.270$ $ W m^{-2} K^{-1}$. In summary, observations suggest SO $SW_{FB}$ is less likely to be as extremely positive as predicted by some CMIP6 GCMs, but more likely to range from moderate negative to weakly positive. |
format |
Other/Unknown Material |
author |
Tan, Chuyan McCoy, Daniel Thompson Elsaesser, Gregory |
spellingShingle |
Tan, Chuyan McCoy, Daniel Thompson Elsaesser, Gregory Constraints on Southern Ocean Shortwave Cloud Feedback from the Hydrological Cycle |
author_facet |
Tan, Chuyan McCoy, Daniel Thompson Elsaesser, Gregory |
author_sort |
Tan, Chuyan |
title |
Constraints on Southern Ocean Shortwave Cloud Feedback from the Hydrological Cycle |
title_short |
Constraints on Southern Ocean Shortwave Cloud Feedback from the Hydrological Cycle |
title_full |
Constraints on Southern Ocean Shortwave Cloud Feedback from the Hydrological Cycle |
title_fullStr |
Constraints on Southern Ocean Shortwave Cloud Feedback from the Hydrological Cycle |
title_full_unstemmed |
Constraints on Southern Ocean Shortwave Cloud Feedback from the Hydrological Cycle |
title_sort |
constraints on southern ocean shortwave cloud feedback from the hydrological cycle |
publisher |
Authorea, Inc. |
publishDate |
2023 |
url |
http://dx.doi.org/10.22541/essoar.170158311.16527130/v1 |
geographic |
Southern Ocean |
geographic_facet |
Southern Ocean |
genre |
Southern Ocean |
genre_facet |
Southern Ocean |
op_doi |
https://doi.org/10.22541/essoar.170158311.16527130/v1 |
_version_ |
1800738743091462144 |