Contribution to: SciDAC Progess Report - Collaborative Design and Development of the Community Climate System Model for Terascale Computing

[摘要] Since pre-industrial times, the concentrations of various aerosol types (e.g., sulfate, black carbon, and mineral dust) and several key greenhouse gases such as methane (CH{sub 4}), nitrous oxide (N{sub 2}O), and ozone (O{sub 3}), have been changing because of anthropogenic activities. Collectively, the magnitude of the climate forcing from these species is larger than that of carbon dioxide (CO{sub 2}) although some are positive and some are negative (see Fig. 27). The behavior and effect of these non-CO{sub 2} species is more complicated than for CO{sub 2} because they are affected by atmospheric chemistry and aerosol microphysics, so their distributions are more heterogeneous. There are also feedbacks between climate, chemistry, and aerosols that further increase the importance of chemistry and aerosols, e.g. a change in any one of stratospheric ozone, stratospheric temperature, or stratospheric dynamics will feedback on the other two. For aerosols, in addition to the direct effect of scattering and absorbing light, they act indirectly by serving as cloud condensation nuclei (CCN), leading to clouds with more (but smaller) droplets that reflect more sunlight and last longer, thus cooling the atmosphere. Aerosols and atmospheric chemistry can also have an impact through interaction with the biosphere, e.g., fertilization of the land with nitrogen species and fertilization of the oceans with Iron from mineral dust. There is also chemical production of CO{sub 2} in the atmosphere through oxidation of species such as CH{sub 4}, CO and terpenes. Thus, to predict and understand future climates, the radiative forcing from these non-CO{sub 2} gases and aerosols, as well as their feedbacks into the radiative, dynamical, and biogeochemical balances, must be taken into account. The non-CO{sub 2} species are also important because they should be more amenable to anthropogenic control measures trying to mitigate climate change (Hansen et al., 2000) than CO{sub 2} because they have shorter atmospheric lifetimes.

[发布日期] 2003-10-17 [发布机构] Lawrence Livermore National Laboratory

[关键词] Nitrous Oxide;Aerosols;99 General And Miscellaneous//Mathematics, Computing, And Information Science;Carbon Dioxide;Design