UV absorption cross sections of nitrous oxide (N&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt;O) and carbon tetrachloride (CCl&amp;lt;sub&amp;gt;4&amp;lt;/sub&amp;gt;) between 210 and 350 K and the atmospheric implications

Carlon, N. Rontu; Papanastasiou, Dimitrios K.; Fleming, Eric L.; Jackman, Charles H.; Newman, Paul A.; Burkholder, James B.

doi:10.5194/acp-10-6137-2010

Cited by 31 publications

(28 citation statements)

References 35 publications

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“…The lifetime is computed as the atmospheric burden (total number of molecules) divided by the loss rate, both of which are vertically integrated and globally/annually averaged. We have recently shown the impact of new photolysis cross sections on the modelcomputed lifetime of CCl 4 (Rontu Carlon et al, 2010). Here we examine the time dependence of the lifetimes of various compounds in more detail.…”

Section: Photochemical Lifetimesmentioning

confidence: 98%

A model study of the impact of source gas changes on the stratosphere for 1850–2100

et al. 2011

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Abstract. The long-term stratospheric impacts due to emissions of CO 2 , CH 4 , N 2 O, and ozone depleting substances (ODSs) are investigated using an updated version of the Goddard two-dimensional (2-D) model. Perturbation simulations with the ODSs, CO 2 , CH 4 , and N 2 O varied individually are performed to isolate the relative roles of these gases in driving stratospheric changes over the 1850-2100 time period. We also show comparisons with observations and the Goddard Earth Observing System chemistry-climate model simulations for the time period 1960-2100 to illustrate that the 2-D model captures the basic processes responsible for longterm stratospheric change.The ODSs, CO 2 , CH 4 , and N 2 O impact ozone via several mechanisms. ODS and N 2 O loading decrease stratospheric ozone via the increases in atmospheric halogen and odd nitrogen species, respectively. CO 2 loading impacts ozone by: (1) cooling the stratosphere which increases ozone via the reduction in the ozone chemical loss rates, and (2) accelerating the Brewer-Dobson circulation (BDC) which redistributes ozone in the lower stratosphere. The net result of CO 2 loading is an increase in global ozone in the total column and upper stratosphere. CH 4 loading impacts ozone by: (1) increasing atmospheric H 2 O and the odd hydrogen species which decreases ozone via the enhanced HOx-ozone loss rates; (2) increasing the H 2 O cooling of the middle atmosphere which reduces the ozone chemical loss rates, partially offsetting the enhanced HOx-ozone loss; (3) converting active to reservoir chlorine via the reaction CH 4 +Cl→HCl+CH 3 which leads to more ozone; and (4) increasing the NO x -ozone production in the troposphere.Correspondence to: E. L. Fleming (eric.l.fleming@nasa.gov)The net result of CH 4 loading is an ozone decrease above 40-45 km, and an increase below 40-45 km and in the total column.The 2-D simulations indicate that prior to 1940, the ozone increases due to CO 2 and CH 4 loading outpace the ozone losses due to increasing N 2 O and carbon tetrachloride (CCl 4 ) emissions, so that total column and upper stratospheric global ozone reach broad maxima during the 1920s-1930s. This precedes the significant ozone depletion during ∼1960-2050 driven by the ODS loading. During the latter half of the 21st century as ODS emissions diminish, CO 2 , N 2 O, and CH 4 loading will all have significant impacts on global total ozone based on the Intergovernmental Panel on Climate Change (IPCC) A1B (medium) scenario, with CO 2 having the largest individual effect. Sensitivity tests illustrate that due to the strong chemical interaction between methane and chlorine, the CH 4 impact on total ozone becomes significantly more positive with larger ODS loading. The model simulations also show that changes in stratospheric temperature, BDC, and age of air during 1850-2100 are controlled mainly by the CO 2 and ODS loading. The simulated acceleration of the BDC causes the global average age of air above 22 km to decrease by ∼1 yr from 1860-2100. The photochemical lifeti...

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Section: Photochemical Lifetimesmentioning

confidence: 98%

A model study of the impact of source gas changes on the stratosphere for 1850–2100

et al. 2011

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“…Solar radiation is weakened by absorption and scattering between TOA and the surface. This process for clear-sky days can be described by the Beer-Lambert-Bouguer law (Rontu Carlon et al, 2010), which uses the extinction coefficient ε and ε respectively, depending on the condition of the atmosphere (e.g. aerosols and water vapour content):…”

Section: Radiation Model For a Horizontal Planementioning

confidence: 99%

“…For this method, which uses the solar position algorithm (SPA) (Reda and Andreas, 2008) to calculate the solar radiation on top of the atmosphere (TOA), the general form of the Lambertian cosine law is used:…”

Section: Radiation Model For a Horizontal Planementioning

confidence: 99%

Correction of broadband snow albedo measurements affected by unknown slope and sensor tilts

et al. 2016

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Abstract. Geometric effects induced by the underlying terrain slope or by tilt errors of the radiation sensors lead to an erroneous measurement of snow or ice albedo. Consequently, artificial diurnal albedo variations in the order of 1-20 % are observed. The present paper proposes a general method to correct tilt errors of albedo measurements in cases where tilts of both the sensors and the slopes are not accurately measured or known. We demonstrate that atmospheric parameters for this correction model can either be taken from a nearby well-maintained and horizontally levelled measurement of global radiation or alternatively from a solar radiation model. In a next step the model is fitted to the measured data to determine tilts and directions of sensors and the underlying terrain slope. This then allows us to correct the measured albedo, the radiative balance and the energy balance. Depending on the direction of the slope and the sensors a comparison between measured and corrected albedo values reveals obvious over-or underestimations of albedo. It is also demonstrated that differences between measured and corrected albedo are generally highest for large solar zenith angles.

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“…GSFC 2-D model simulations suggest that lifetimes will not change substantially in this century in response to projected greenhouse gas changes. For example, the CCl 4 stratospheric lifetime is projected to decrease by 6% (51-48 years) from 2010-2100 (Rontu Carlon et al, 2010), and the lifetimes of CFC-11, CFC-12, and N 2 O are projected to decrease by 3-5% over this time period. Furthermore, the N 2 O distribution and other transport-sensitive features of both models compare well to observations (Garcia et al, 1992;Fleming et al, 2007), suggesting the transport calculations are sufficiently accurate for this study.…”

Section: Ozone Calculationsmentioning

confidence: 99%

Options to accelerate ozone recovery: ozone and climate benefits

et al. 2010

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Abstract. Hypothetical reductions in future emissions of ozone-depleting substances (ODSs) and N 2 O are evaluated in terms of effects on equivalent effective stratospheric chlorine (EESC), globally-averaged total column ozone, and radiative forcing through 2100. Due to the established success of the Montreal Protocol, these actions can have only a fraction of the impact on ozone depletion that regulations already in force have had. If all anthropogenic ODS and N 2 O emissions were halted beginning in 2011, ozone is calculated to be higher by about 1-2% during the period 2030-2100 compared to a case of no additional restrictions. Direct radiative forcing by 2100 would be about 0.23 W/m 2 lower from the elimination of anthropogenic N 2 O emissions and about 0.005 W/m 2 lower from the destruction of the chlorofluorocarbon (CFC) bank. Due to the potential impact of N 2 O on future ozone levels, we provide an approach to incorporate it into the EESC formulation, which is used extensively in ozone depletion analyses. The ability of EESC to describe total ozone changes arising from additional ODS and N 2 O controls is also quantified.

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UV absorption cross sections of nitrous oxide (N<sub>2</sub>O) and carbon tetrachloride (CCl<sub>4</sub>) between 210 and 350 K and the atmospheric implications

Cited by 31 publications

References 35 publications

A model study of the impact of source gas changes on the stratosphere for 1850–2100

A model study of the impact of source gas changes on the stratosphere for 1850–2100

Correction of broadband snow albedo measurements affected by unknown slope and sensor tilts

Options to accelerate ozone recovery: ozone and climate benefits

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