Earth’s outgoing longwave radiation linear due to H<sub>2</sub>O greenhouse effect

Koll, Daniel D. B.; Cronin, Timothy W.

doi:10.1073/pnas.1809868115

Cited by 127 publications

(240 citation statements)

References 39 publications

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“…The ERA+RRTM sensitivity is broken down into contributions from water vapor (

\frac{\partial normalΔ {OLR}_{H_{2} normalO}}{\partial normalΔ T_{s}} = - 1.95 {W m}^{- 2} K^{- 1}

, negative of equation (7b)'s respective term), atmospheric temperature (

\frac{\partial normalΔ {OLR}_{T_{a}}}{\partial normalΔ T_{s}} = 2.70 {W m}^{- 2} K^{- 1}

, negative of equation (7b)'s respective term), and surface temperature (

\frac{\partial normalΔ {OLR}_{T_{s}}}{\partial normalΔ T_{s}} = 1.27 {W m}^{- 2} K^{- 1}

). Koll and Cronin () used an idealized atmospheric column and showed that there was a near‐perfect cancelation between the contributions from water vapor and atmospheric temperature to the feedback parameter, and only surface temperature contributes. However, in our ERA+RRTM calculations with real atmospheric conditions for columns across Earth, we show that this cancelation is imperfect with a 37% (

\frac{2.70 - 1.95}{2.02}

) contribution from atmospheric temperature to the total feedback parameter.…”

Section: Resultsmentioning

confidence: 99%

“…Hallberg and Inamdar (1993) focused on surface temperatures above 298 K, where G was found to nonlinearly increase. Recently, Koll and Cronin (2018) showed a nonlinear decrease in clear sky OLR at high temperatures, which can also be characterized as SGE. Past work on SGE has been based on idealized models that used a single global mean column and did not account for RH variations (Dewey & Goldblatt, 2018).…”

Section: Supporting Informationmentioning

confidence: 99%

“…The ERA+RRTM sensitivity is broken down into contributions from water vapor ( Koll and Cronin (2018) used an idealized atmospheric column and showed that there was a near-perfect cancelation between the contributions from water vapor and atmospheric temperature to the feedback parameter, and only surface temperature contributes. However, in our ERA+RRTM calculations with real atmospheric conditions for columns across Earth, we show that this cancelation is imperfect with a 37% ( 2.70−1.95 2.02 ) contribution from atmospheric temperature to the total feedback parameter.…”

Section: Sensitivity Of G and G To Surface Temperaturementioning

confidence: 99%

“…However, in our ERA+RRTM calculations with real atmospheric conditions for columns across Earth, we show that this cancelation is imperfect with a 37% ( 2.70−1.95 2.02 ) contribution from atmospheric temperature to the total feedback parameter. This implies that while changes in surface temperature are still the dominant contributor to changes in OLR ( 1.27 2.02 = 63%) as posited by Koll and Cronin (2018), atmospheric temperature plays an important role by outweighing water vapor's contributions. In the next section, we will see that locally, water vapor's radiative contributions overwhelm atmospheric temperature's contributions, which in turn helps generate the super greenhouse effect.…”

Section: Sensitivity Of G and G To Surface Temperaturementioning

confidence: 99%

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Quantifying the Drivers of the Clear Sky Greenhouse Effect, 2000–2016

2019

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The clear sky greenhouse effect (G) is defined as the trapping of infrared radiation by the atmosphere in the absence of clouds. The magnitude and variability of G is an important element in the understanding of Earth's energy balance; yet the quantification of the governing factors of G is poor. The global mean G averaged over 2000 to 2016 is 130–133 W m−2 across data sets. We use satellite observations from Clouds and the Earth's Radiant Energy System Energy Balance and Filled (CERES EBAF) to calculate the monthly anomalies in the clear sky greenhouse effect (ΔG). We quantify the contributions to ΔG due to changes in surface temperature, atmospheric temperature, and water vapor by performing partial radiation perturbation experiments using ERA‐Interim and Geophysical Fluid Dynamics Laboratory's Atmospheric Model 4.0 climatological data. Water vapor in the middle troposphere and upper troposphere is found to contribute equally to the global mean and tropical mean ΔG. Holding relative humidity (RH) fixed in the radiative transfer calculations captures the temporal variability of global mean ΔG while variations in RH control the regional ΔG signal. The variations in RH are found to help generate the clear sky super greenhouse effect (SGE). Thirty‐six percent of Earth's area exhibits SGE, and this disproportionately contributes to 70% of the globally averaged magnitude of ΔG. In the global mean, G's sensitivity to surface temperature is 3.1–4.0 W m−2 K−1, and the clear sky longwave feedback parameter is 1.5–2.0 W m−2 K−1. Observations from CERES EBAF lie at the more sensitive ends of these ranges and the spread arises from its cloud removal treatment, suggesting that it is difficult to constrain clear sky feedbacks.

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“…The ERA+RRTM sensitivity is broken down into contributions from water vapor (

\frac{\partial normalΔ {OLR}_{H_{2} normalO}}{\partial normalΔ T_{s}} = - 1.95 {W m}^{- 2} K^{- 1}

, negative of equation (7b)'s respective term), atmospheric temperature (

\frac{\partial normalΔ {OLR}_{T_{a}}}{\partial normalΔ T_{s}} = 2.70 {W m}^{- 2} K^{- 1}

, negative of equation (7b)'s respective term), and surface temperature (

\frac{\partial normalΔ {OLR}_{T_{s}}}{\partial normalΔ T_{s}} = 1.27 {W m}^{- 2} K^{- 1}

\frac{2.70 - 1.95}{2.02}

) contribution from atmospheric temperature to the total feedback parameter.…”

Section: Resultsmentioning

confidence: 99%

Section: Supporting Informationmentioning

confidence: 99%

Section: Sensitivity Of G and G To Surface Temperaturementioning

confidence: 99%

Section: Sensitivity Of G and G To Surface Temperaturementioning

confidence: 99%

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Quantifying the Drivers of the Clear Sky Greenhouse Effect, 2000–2016

2019

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“…The linearization in Eq. 1 is justified, as Earth's outgoing longwave radiation does not follow classical Stefan-Boltzmann theory, but increases linearly with surface temperature (35) due to the watervapor feedback (36). A hypothetical jump in radiative forcing F by 1 W·m −2 will lead to global surface warming that reduces the PRI surplus until a balanced budget is reachieved again (3).…”

Section: Discussionmentioning

confidence: 99%

Earth’s radiative imbalance from the Last Glacial Maximum to the present

Baggenstos

Häberli

Schmitt

et al. 2019

Proc. Natl. Acad. Sci. U.S.A.

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The energy imbalance at the top of the atmosphere determines the temporal evolution of the global climate, and vice versa changes in the climate system can alter the planetary energy fluxes. This interplay is fundamental to our understanding of Earth’s heat budget and the climate system. However, even today, the direct measurement of global radiative fluxes is difficult, such that most assessments are based on changes in the total energy content of the climate system. We apply the same approach to estimate the long-term evolution of Earth’s radiative imbalance in the past. New measurements of noble gas-derived mean ocean temperature from the European Project for Ice Coring in Antarctica Dome C ice core covering the last 40,000 y, combined with recent results from the West Antarctic Ice Sheet Divide ice core and the sea-level record, allow us to quantitatively reconstruct the history of the climate system energy budget. The temporal derivative of this quantity must be equal to the planetary radiative imbalance. During the deglaciation, a positive imbalance of typically +0.2 W⋅m−2 is maintained for ∼10,000 y, however, with two distinct peaks that reach up to 0.4 W⋅m−2 during times of substantially reduced Atlantic Meridional Overturning Circulation. We conclude that these peaks are related to net changes in ocean heat uptake, likely due to rapid changes in North Atlantic deep-water formation and their impact on the global radiative balance, while changes in cloud coverage, albeit uncertain, may also factor into the picture.

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Dependence of Climate Sensitivity on the Given Distribution of Relative Humidity

Bourdin

Kluft

Stevens

2021

Preprint

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HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

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Earth’s outgoing longwave radiation linear due to H₂O greenhouse effect

Cited by 127 publications

References 39 publications

Quantifying the Drivers of the Clear Sky Greenhouse Effect, 2000–2016

Quantifying the Drivers of the Clear Sky Greenhouse Effect, 2000–2016

Earth’s radiative imbalance from the Last Glacial Maximum to the present

Dependence of Climate Sensitivity on the Given Distribution of Relative Humidity

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Earth’s outgoing longwave radiation linear due to H2O greenhouse effect

Cited by 127 publications

References 39 publications

Quantifying the Drivers of the Clear Sky Greenhouse Effect, 2000–2016

Quantifying the Drivers of the Clear Sky Greenhouse Effect, 2000–2016

Earth’s radiative imbalance from the Last Glacial Maximum to the present

Dependence of Climate Sensitivity on the Given Distribution of Relative Humidity

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Product

Resources

About

Earth’s outgoing longwave radiation linear due to H₂O greenhouse effect