Greenhouse gas radiative forcing: Effects of averaging and inhomogeneities in trace gas distribution

FRECKLETON, RS; HIGHWOOD, EJ; Shine, Keith P.; WILD, O; Law, Kathy S.; SANDERSON, MG

doi:10.1256/smsqj.55013

Cited by 22 publications

(40 citation statements)

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“…The differences were significantly higher (5-7%) for CFC-11, CFC-12, HFC-22, HFC-23, and H-1301, mainly because these gases decay much more rapidly in the stratosphere. Similar results have also been found by Freckleton et al [1998], who estimated the differences in radiative forcings between GAM and LAS cases to be about 6-7% for CFC-11 and CFC-12. For other gases with higher stratospheric lifetimes, the differences are relatively small.…”

Section: Diffusivity Factor-based Versus Angular Integration-based Rasupporting

confidence: 88%

“…Radiative forcing for most of the greenhouse gases is noticeably sensitive to the LAS mean greenhouse gas distributions and atmospheric conditions. Estimated forcings for CO2, CH4, and N20 based on a single GAM profile were lower than the LAS case, whereas the single-profile forcings were higher for halocarbons and perfluorocarbons, consistent with the findings of Freckleton et al [1998]. This is due to the fact that the tropopause height in the GAM profile is relatively higher than the LAS case, and hence the stratospheric adjustment takes place at a lower pressure level.…”

Section: Diffusivity Factor-based Versus Angular Integration-based Rasupporting

confidence: 79%

“…Myhre and Stordal [1997] show that assuming a fixed global-mean tropopause height for each latitude belt can produce errors of up to 10% in the instantaneous global-mean forcing. Moreover, Freckleton et al [1998] have shown that the choice of tropopause definition can influence the radiative forcing results by up to 9%. In this study we define the tropopause at each latitude as a level where the minima in temperature occurs.…”

Section: Introductionmentioning

confidence: 99%

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Radiative forcings and global warming potentials of 39 greenhouse gases

Jain¹,

Briegleb²,

Minschwaner³

et al. 2000

J. Geophys. Res.

133

181

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Abstract. The radiative forcings and global warming potentials for 39 greenhouse gases are evaluated using narrowband and broadband radiative transfer models. Unlike many previous studies, latitudinal and seasonal variations are considered explicitly, using distributions of major greenhouse gases from a combination of chemical-transport model results and Upper Atmosphere Research Satellite (UARS) measurements and cloud statistics from the International Satellite Cloud Climatology Project. The gases examined include CO2, CH4, N20, plus a number of chlorofiuorocarbons, hydrochlorofiuorocarbons, hydrofiuorocarbons, hydrochlorocarbons, bromocarbons, iodocarbons, and perfiuorocarbons (PFCs). The model calculations are performed on a 5 ø latitude grid from 82.5øS to 82.5øN. The radiative forcings determined by the model are then used to derive global warming potential for each of the compounds, which are compared with prior analyses. In addition, the latitudinal and seasonal dependence of radiative forcing since preindustrial time is calculated. The vertical profiles of the gases are found to be important in determining the radiative forcings; the use of height-independent vertical distributions of greenhouse gases, as used in many previous studies, produce errors of several percent in estimated radiative forcings for gases studied here; the errors for the short-lived compounds are relatively higher. Errors in evaluated radiative forcings caused by neglecting both the seasonal and the latitudinal distributions of greenhouse gases and atmospheres are generally smaller than those due to height-independent vertical distributions. Our total radiative forcing due to increase in major greenhouse gas concentrations for the period 1765-1992 is 2.32 Wm -2, only 2% higher than other recent estimates; however, the differences for individual gases are as large as 23%.

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Section: Diffusivity Factor-based Versus Angular Integration-based Rasupporting

confidence: 88%

Section: Diffusivity Factor-based Versus Angular Integration-based Rasupporting

confidence: 79%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Radiative forcings and global warming potentials of 39 greenhouse gases

Jain¹,

Briegleb²,

Minschwaner³

et al. 2000

J. Geophys. Res.

133

181

View full text Add to dashboard Cite

show abstract

“…This is based on the GAM profile of Christidis et al (1997) with some additional high altitude data from Jain et al (2000). Surface albedo is set as 0.125 (Trenberth et al, 2009 Calculating radiative forcings on a single profile does introduce some error relative to using a set of profiles for various latitudes (Myhre and Stordal, 1997;Freckleton et al, 1998;Jain et al, 2000). However, as this is a methodological paper concerning single column radiative-convective models, it is the appropriate approach for our purposes.…”

Section: Global Annual Mean Atmospherementioning

confidence: 99%

Clouds and the Faint Young Sun Paradox

Goldblatt

Zahnle

2011

Clim. Past

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Abstract. We investigate the role which clouds could play in resolving the Faint Young Sun Paradox (FYSP). Lower solar luminosity in the past means that less energy was absorbed on Earth (a forcing of −50 W m −2 during the late Archean), but geological evidence points to the Earth having been at least as warm as it is today, with only very occasional glaciations. We perform radiative calculations on a single global mean atmospheric column. We select a nominal set of three layered, randomly overlapping clouds, which are both consistent with observed cloud climatologies and reproduced the observed global mean energy budget of Earth. By varying the fraction, thickness, height and particle size of these clouds we conduct a wide exploration of how changed clouds could affect climate, thus constraining how clouds could contribute to resolving the FYSP. Low clouds reflect sunlight but have little greenhouse effect. Removing them entirely gives a forcing of +25 W m −2 whilst more modest reduction in their efficacy gives a forcing of +10 to +15 W m −2 . For high clouds, the greenhouse effect dominates. It is possible to generate +50 W m −2 forcing from enhancing these, but this requires making them 3.5 times thicker and 14 K colder than the standard high cloud in our nominal set and expanding their coverage to 100% of the sky. Such changes are not credible. More plausible changes would generate no more than +15 W m −2 forcing. Thus neither fewer low clouds nor more high clouds can provide enough forcing to resolve the FYSP. Decreased surface albedo can contribute no more than +5 W m −2 forcing. Some models which have been applied to the FYSP do not include clouds at all. These overestimate the forcing due to increased CO 2 by 20 to 25% when pCO 2 is 0.01 to 0.1 bar.

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“…However, this method is too time-consuming. Researchers thus use a globally averaged atmospheric profile or an average for certain profiles [28][29][30]. Here, we use three model atmospheric profiles (tropical (TRO), mid-latitude summer (MLS), and mid-latitude winter (MLW)) (Anderson et al [31]) to determine the global mean radiative flux.…”

Section: Radiative Forcing Gwp and Gtp Due To Nfmentioning

confidence: 99%

Inhomogeneous Radiative Forcing of NF3

Zhang

2017

Atmosphere

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Nitrogen trifluoride (NF 3 ) has the potential to make a growing contribution to the Earth's radiative budget. In this study, the global mean radiative efficiency of NF 3 is calculated as 0.188 W·m −2 ·ppb −1 by line-by-line method. Global warming potentials of 14,700 for 100 years and global temperature potentials of 16,600 for 100 years are calculated. At the same time, inhomogeneous instantaneous radiative forcing of NF 3 at the top of the atmosphere and its relationship to other atmospheric and surface variables are studied. A total of 42 atmospheric profiles are used. The results show NF 3 instantaneous radiative efficiency range from 0.07 W·m −2 ·ppb −1 to 0.50 W·m −2 ·ppb −1 in clear sky conditions. The mean value is 0.25 W·m −2 ·ppb −1 . In clear sky conditions, the correlation coefficient between surface temperature and NF 3 instantaneous radiative forcing is 0.94 and the partial correlation coefficient is −0.88 between integrated water content and NF 3 instantaneous radiative forcing. A regression model is constructed for NF 3 instantaneous radiative forcing based on surface temperature and integrated water content. The average value of the relative error is 6.17% based on LBLRTM (Line-by-Line Radiative Transfer Model) results. The correlation coefficient is 0.985 between cloud radiative forcing and the difference of NF 3 instantaneous radiative forcing between clear sky and all cloudy sky conditions. A regression model is constructed for NF 3 instantaneous radiative forcing in all cloudy sky. The average relative error is 5.9% based on LBLRTM results.

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Greenhouse gas radiative forcing: Effects of averaging and inhomogeneities in trace gas distribution

Cited by 22 publications

References 0 publications

Radiative forcings and global warming potentials of 39 greenhouse gases

Radiative forcings and global warming potentials of 39 greenhouse gases

Clouds and the Faint Young Sun Paradox

Inhomogeneous Radiative Forcing of NF3

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