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Abstract This study investigates the formation mechanism of the ocean surface warming pattern in response to a doubling CO2with a focus on the role of ocean heat uptake (or ocean surface heat flux change, ΔQnet). We demonstrate that thetransientpatterns of surface warming and rainfall change simulated by the dynamic ocean–atmosphere coupled model (DOM) can be reproduced by theequilibriumsolutions of the slab ocean–atmosphere coupled model (SOM) simulations when forced with the DOM ΔQnetdistribution. The SOM is then used as a diagnostic inverse modeling tool to decompose the CO2-induced thermodynamic warming effect and the ΔQnet(ocean heat uptake)–induced cooling effect. As ΔQnetis largely positive (i.e., downward into the ocean) in the subpolar oceans and weakly negative at the equator, its cooling effect is strongly polar amplified and opposes the CO2warming, reducing the net warming response especially over Antarctica. For the same reason, the ΔQnet-induced cooling effect contributes significantly to the equatorially enhanced warming in all three ocean basins, while the CO2warming effect plays a role in the equatorial warming of the eastern Pacific. The spatially varying component of ΔQnet, although globally averaged to zero, can effectively rectify and lead to decreased global mean surface temperature of a comparable magnitude as the global mean ΔQneteffect under transient climate change. Our study highlights the importance of air–sea interaction in the surface warming pattern formation and the key role of ocean heat uptake pattern.
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This content will become publicly available on August 15, 2026
An Observational Estimate of the Pattern Effect on Climate Sensitivity: The Importance of the Eastern Tropical Pacific and Land Areas
Abstract The patterns associated with the top-of-the-atmosphere radiative responseRto surface temperatureTare typically explored through two relationships: 1) the spatially varying radiative response to spatially varying changes in temperature (ΔRi/ΔTi) and 2) the spatially varying radiative response to global-mean changes in temperature (ΔRi/ΔT). Here, we explore the insights provided by an alternative parameter: the global-mean radiative response to changes in spatially varying temperature (ΔR/ΔTi). The pattern ΔR/ΔTiindicates regions where surface temperature covaries withRand thus provides a statistical analog to the causal response functions derived from atmospheric Green’s function experiments. The pattern can be transformed so that it can be globally averaged and thus indicates the local contribution to the global feedback parameter. The transformed version of ΔR/ΔTicorresponds to the pattern in surface temperature whose expansion coefficient time series explains the maximum fraction of the covariance betweenRandTi. It explains roughly the same fraction of internal variability inRas that explained by the Green’s function approach. We focus on the physical insights provided by ΔR/ΔTiwhen it is estimated from regression analyses of monthly mean observations. Consistent with the results of Green’s function experiments, the observational analyses indicate negative contributions to the global internal feedback parameter over the western Pacific and positive contributions over the southeastern tropical Pacific. Unlike the results of such experiments, the analyses indicate notable negative contributions to the global feedback parameter over land areas. When estimated from observations, temperature variability over the land areas accounts for ∼70% of the negative global internal feedback, whereas variability over the southeastern tropical Pacific reduces the global-mean negative internal feedback by ∼10%.
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- Award ID(s):
- 2116186
- PAR ID:
- 10654004
- Publisher / Repository:
- AMS
- Date Published:
- Journal Name:
- Journal of Climate
- Volume:
- 38
- Issue:
- 16
- ISSN:
- 0894-8755
- Page Range / eLocation ID:
- 4233 to 4249
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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