Forcing radiative indirect

Jones, A., D. L. Roberts, and A. Slingo, A Climate Model Study of Indirect Radiative Forcing by Anthropogenic Sulphate Aerosols, Nature, 370, 450-453 (1994). 

Wang, W.-C., H. Mao, IS. A Isaksen, J. S. Fuglestvedt, and S. Karlsdottir, 1996 Indirect Effects of Increasing Atmospheric Methane on the Radiative Forcing Through Climate-Chemistry Interactions. Proceedings of XVIII Quadrennial Ozone Symposium-96, September 12-21,1996, L Aquila, Italy. 

Haywood, I, and Boucher, O. (2000). Estimates of the direct and indirect radiative forcing due to tropospheric aerosols a review. Rev. Geophys. 38,513-543. 

Such a complicated interactivity of processes can both directly and indirectly affect formation of the atmospheric greenhouse effect. Derwent et al. (2001) described a global 3-D Lagrangian chemistry transport model (STOCHEM) which reproduces chemical processes including MGC transport and can be used to reproduce interrelated fields of TO and methane concentration (Johnson et al., 2002) under conditions of emission to the atmosphere of short-lived TO precursors such as CH4, CO, NOx, and hydrogen. At the same time, the radiative forcing (RF) of NOx emissions depends on the location of emissions near the surface or in the upper troposphere, in the Northern or Southern Hemisphere. For each short-lived MGC/... 

The impact of secondary aerosols on indirect radiative forcing is the most variable and is the least understood [3]. The reasons why the indirect effect of secondary aerosols is so difficult to describe is that it depends upon [1] (1) a series of molecular-microphysical processes that connect aerosol nucleation to cloud condensation nuclei to cloud drops and then ultimately to cloud albedo and (2) complex cloud-scale dynamics on scales of 100-1000 km involve a consistent matching of multiple spatial and time scales and are extremely difficult to parameterize and incorporate in climate models. Nucleation changes aerosol particle concentrations that cause changes in cloud droplet concentrations, which in turn, alter cloud albedo. Thus, macro-scale cloud properties that influence indirect forcing result from both micro-scale and large-scale dynamics. To date, the micro-scale chemical physics has not received the appropriate attention. 

An understanding of the influence that aerosols have on climate has become increasingly important over the last several decades [3]. Primary and secondary aerosols can affect the Earth s radiative balance by scattering and absorbing light directly and can act indirectly as cloud condensation nuclei and therefore influence the distribution, duration, precipitation processes, and radiative properties of clouds. Thus, developing the ability to understand, model, and predict aerosol formation with confidence is essential to determine the impact of aerosol radiative forcing in climate models. 

Ghan SJ, Easter RC, Hudson J, Breon F-M (2001b) Evaluation of aerosol indirect radiative forcing in MIRAGE. J Geophys Res 106 5317-5334... 

Aerosol phase simulations. Atmos Environ 31 587-608 Jones A, Roberts DL, Slingo A (1994) A climate model study of indirect radiative forcing by anthropogenic sulphate aerosols. Nature 370 450 53... 

Boucher O., Moulin C., Belviso S., Aumont O., Bopp L., Cosme E., von Kuhlmann R., Lawrence C. G., Pham M., Redyy M. S., Sciare J., and Venkataraman C. (2002) Sensitivity study of dimethylsulphide (DMS) atmospheric concentrations and sulphate aerosol indirect radiative forcing to the DMS source representation and oxidation. Atmos. Chem. Phys. Discuss. 2, 1181-1216. 

Assume a planet in which the upper mantle has about 0.2% water, and the composition is broadly peridotitic, with heat production as on Earth. The geotherm depends on the vertical distribution of the heat production in the interior and on the surface temperature, and on the heat transfer controls. The surface temperature is maintained by the radiative balance of the atmosphere and any greenhouse increment, and is only indirectly dependent on interior processes. If the state of the atmosphere means that the surface is cold, say — 100°C to —200°C, then the lithosphere will be thick. The top of the mantle adiabat will be forced to cool. The deeper mantle will thus store heat until melting extracts it as... 

FIGURE 7 (a) Radiative forcing from greenhoitse gases, sulfate aerosols (direct and indirect effect),... 

Today, the anthropogenic emissions of SO, primarily from fossil fuel combustion, largely dominate the sulfur flux into in the atmosphere on the global scale. Climate models have determined the corresponding direct and indirect impacts on radiative forcing, but large uncertainties remain in these estimates. In fact, predictions of future climate need to account not only for the effects of sulfate aerosols, but also for the contributions of mineral dust, black carbon, organic carbon, and sea salt. The current view is that atmospheric particles should be treated as multicomponent, mul-... 

Direct radiative forcings affect directly the Earth s radiative balance for instance, added C02 absorbs infrared radiation. Indirect forcings lead to a radiative imbalance by first altering some component of the climate system that then leads to a change in radiative fluxes. An example of an indirect effect is increasing aerosol levels that produce clouds with smaller drops clouds with smaller drops are not as prone to produce precipitation, so the clouds persist longer and reflect and absorb more radiation. 

Methane oxidation leads to a net loss of OH in the atmosphere, thereby lengthening the lifetime of CH4 itself (we will discuss this later in this chapter). It is estimated that this longer lifetime increases the radiative forcing of CH4 by 25-35% over that in the absence of this feedback effect. Methane oxidation also leads to tropospheric O3 this indirectly increases the greenhouse effect by another 30-40% through the effect of the added O3 itself. Finally, increases in CH4 also indirectly lead to further climate forcing by increasing stratospheric H20 (about 7% of CH4 is oxidized in the upper troposphere). 

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