Radiative forcing due to stratospheric water vapour from CH<sub>4</sub> oxidation

Myhre, Gunnar; Nilsen, Jørgen Skredsvig; Gulstad, Line; Shine, Keith P.; Rognerud, B.; Isaksen, I. S. A.

doi:10.1029/2006gl027472

Cited by 62 publications

(79 citation statements)

References 33 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Stated RFs are based on composition changes in the troposphere and do not include stratospheric response, although some studies also include the lower stratosphere, where aviation NOx also increases O 3 (e.g., 15) and the greenhouse effect is similar to the upper troposphere. The CH 4 RF here also excludes changes to stratospheric water vapor, which are estimated to increase RF cooling by about 15% (24). Transient CH 4 perturbations for any particular year are always less than predicted at steady state due to the decadal lifetime of CH 4 and the steadily increasing aviation emissions (25).…”

Section: Rf Uncertainty From Model Ensemblesmentioning

confidence: 99%

Uncertainties in climate assessment for the case of aviation NO

Holmes

Tang²,

Prather³

2011

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

122

View full text Add to dashboard Cite

Nitrogen oxides emitted from aircraft engines alter the chemistry of the atmosphere, perturbing the greenhouse gases methane (CH 4 ) and ozone (O 3 ). We quantify uncertainties in radiative forcing (RF) due to short-lived increases in O 3 , long-lived decreases in CH 4 and O 3 , and their net effect, using the ensemble of published models and a factor decomposition of each forcing. The decomposition captures major features of the ensemble, and also shows which processes drive the total uncertainty in several climate metrics. Aviation-specific factors drive most of the uncertainty for the short-lived O 3 and long-lived CH 4 RFs, but a nonaviation factor dominates for long-lived O 3 . The model ensemble shows strong anticorrelation between the short-lived and long-lived RF perturbations (R 2 ¼ 0.87). Uncertainty in the net RF is highly sensitive to this correlation. We reproduce the correlation and ensemble spread in one model, showing that processes controlling the background tropospheric abundance of nitrogen oxides are likely responsible for the modeling uncertainty in climate impacts from aviation.aviation emissions | error correlation | model sensitivity Q uantifying uncertainties in climate processes is a major priority for climate research, as exemplified by the widespread use of probability distributions and uncertainties in the Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report (1). To understand and attribute changes in the greenhouse gases and aerosols that force climate change, we rely on chemistry-transport models (CTMs), which require further characterization of their errors (e.g., 2-5). Aviation emissions are estimated to contribute 5% of anthropogenic climate forcing, with a nearly threefold uncertainty (6). This forcing occurs mainly through aviation-induced cloudiness and emissions of CO 2 and nitrogen oxides. Climate impacts of other aviation emissions-CO, SO 2 , soot, hydrocarbons, and water vapor-are highly uncertain, but estimated to be much smaller (6). In this paper we quantify one type of climate forcing and its uncertainty, the impact of aviation emissions on the greenhouse gases ozone (O 3 ) and methane (CH 4 ).Aircraft engines emit NO and NO 2 (NOx), which are indirect greenhouse gases through their chemical reactions impacting O 3 production and the CH 4 lifetime. As an O 3 precursor, NOx emissions increase the tropospheric column of O 3 and its radiative forcing. Aviation NOx emissions have a stronger impact on O 3 than surface emissions on a per molecule basis because they occur at high altitudes (7). Previous model-based estimates of the amount of O 3 generated by aviation NOx emissions vary by up to 100% and these differences have been attributed to a range of causes: e.g., the ratios of NO∶NO 2 and OH∶HO 2 , background NOx levels (8), location and time of emissions (9-11), the amount of sunlight (12), and atmospheric mixing (13,14).Early work on climate forcing by aviation assumed that the impacts would be short-lived and limited to the northern latitudes ...

show abstract

Section: Rf Uncertainty From Model Ensemblesmentioning

confidence: 99%

Uncertainties in climate assessment for the case of aviation NO

Holmes

Tang²,

Prather³

2011

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

122

View full text Add to dashboard Cite

show abstract

“…It is also possible to have a two-stage process, where convection lofting parcels and ice rise to the upper troposphere, followed by gradual dehydration as the parcels ascend into the stratosphere (Rosenlof 2003). The 3 rd pathway has been considered as insignificant in the lower stratosphere (e.g., Rosenlof 2003;Myhre et al 2007). This leaves either the first or the second pathway and no definite conclusion has been reached as to which is the major pathway for water to rise into the stratosphere .…”

Section: Introductionmentioning

confidence: 99%

Cross Tropopause Transport of Water by Mid-Latitude Deep Convective Storms: A Review

Wang¹,

Su²,

Charvát³

et al. 2011

Terr. Atmos. Ocean. Sci.

View full text Add to dashboard Cite

Recent observational and numerical modeling studies of the mechanisms which transport moisture to the stratosphere by deep convective storms at mid-latitudes are reviewed. Observational evidence of the cross-tropopause transport of moisture by thunderstorms includes satellite, aircraft and ground-based data. The primary satellite evidence is taken from both conventional satellite of thunderstorm images and CloudSat vertical cloud cross-section images. The conventional satellite images show cirrus plumes above the anvil tops of some of the convective storms where the anvils are already at the tropopause level. The CloudSat image shows an indication of penetration of cirrus plume into the stratosphere. The aircraft observations consist of earlier observations of the "jumping cirrus" phenomenon reported by Fujita and recent detection of ice particles in the stratospheric air associated with deep convective storms. The ground-based observations are video camera records of the jumping cirrus phenomenon occurring at the top of thunderstorm cells. Numerical model studies of the penetrative deep convective storms were performed utilizing a three-dimensional cloud dynamical model to simulate a typical severe storm which occurred in the US Midwest region on 2 August 1981. Model results indicate two physical mechanisms that cause water to be injected into the stratosphere from the storm: (1) the jumping cirrus mechanism which is caused by the gravity wave breaking at the cloud top, and (2) an instability caused by turbulent mixing in the outer shell of the overshooting dome. Implications of the penetrative convection on global processes and a brief future outlook are discussed.

show abstract

“…16,[24][25][26] However, it was shown that a computed stratospheric temperature change caused by increasing stratospheric water vapor is strongly dependent on the temporal and spatial variation of stratospheric water vapor changes. 22,63,64 A more realistic change in the stratospheric water vapor profiles yields a weaker stratospheric cooling than for a constant profile. 22,63,64 In particular, Myhre et al 64 (2007) calculated a stratospheric cooling of about 0.0 K to 0.2 K in the lower polar stratosphere (z15-25 km) caused by stratospheric water vapor increase due to CH 4 oxidation based on observational data for the time period from 1979 until 2000.…”

Section: Impact On Ozone-climate Interactionsmentioning

confidence: 99%

“…22,63,64 A more realistic change in the stratospheric water vapor profiles yields a weaker stratospheric cooling than for a constant profile. 22,63,64 In particular, Myhre et al 64 (2007) calculated a stratospheric cooling of about 0.0 K to 0.2 K in the lower polar stratosphere (z15-25 km) caused by stratospheric water vapor increase due to CH 4 oxidation based on observational data for the time period from 1979 until 2000. The amount and the spatial distribution of stratospheric water increase calculated by Myhre et al 64 (2007) are comparable to the water vapor increase inferred for a potential future hydrogen economy (see Fig.…”

Section: Impact On Ozone-climate Interactionsmentioning

confidence: 99%