Sensitivity studies of oxidative changes in the troposphere in 2100 using the GISS GCM

[摘要] We examine the relative importance of chemical precursor emissions affecting ozone(O₃) and hydroxyl (OH) for the year 2100. Runs were developed from the Comparison of TroposphericOxidants (Ox_Comp) modeling workshop year 2100 A2p emissions scenario, part of theIntergovernmental Panel on Climate Change (IPCC) third assessment report (TAR). While TARexamined only cumulative change, we examineindividual components (NO_x,CH₄, CO, etc.). Also, since there will be climate changes in 2100 (not accounted for by TAR), we investigate theeffect of changing our fixed SSTs/ocean ice from present day to 2100 conditions, as projected bya coupled ocean-atmosphere model with doubled CO₂. Unlike TAR we perform multiannual integrations and we include interactivelightning. Largest changes arose from the run with 2100 industrial NO_x(O₃=+16.9%, OH=+29.4% in July) and the run with 2100 methane (O₃=+17.4%, OH=-19.1% in July). In the latter run, large ozone increases in the NH upper troposphere appeared to repartitionHO₂ into OH to such an extent that the lowering in OH associated with increased methane was overwhelmed in that region. Incorporating all changescollectively led to the July tropospheric ozone burden increasingfrom 426 to601 Tg (+41.1%) and the July OH concentration increasing from 13.6 to15.2x10⁵ molecules/cm³ (+11.8%).

[学科分类] 大气科学