Recent model calculations of the global mean radiative forcing from tropospheric ozone since preindustrial times fall in a relatively narrow range, from 0.3 to 0.5 W m . These calculations use preindustrial ozone elds that overestimate observations available from the turn of the nineteenth century. Although there may be calibration problems with the observations, uncertainties in model estimate...

[1] We use a global chemical transport model (GEOS-Chem) driven by a general circulation model (NASA Goddard Institute for Space Studies GCM) to investigate the effects of 2000–2050 global change in climate and emissions (the Intergovernmental Panel on Climate Change A1B scenario) on the global tropospheric ozone budget and on the policy-relevant background (PRB) ozone in the United States. The...

A survey of existing data reveals that tropospheric ozone is fairly uniformly distributed within the hemispheres, but that the hemispheres are well separated. Within the northern hemisphere representative data of tropospheric ozone exhibit a uniform seasonal variation the phase of which is delayed by about 2 months with respect to the injection into the troposphere. It is suggested that this de...

The new generation GISS climate model includes fully interactive chemistry related to ozone in historical and future simulations, and interactive methane in future simulations. Evaluation of ozone, its tropospheric precursors, and methane shows that the model captures much of the largescale spatial structure seen in recent observations. While the model is much improved compared with the previou...

this study utilizes a decade long (2005-2014) monthly data of total column tropospheric ozone (tcto) in dubson units to evaluate the spatial and temporal trend of lao over some major cities of west africa, namely lagos, accra, niamey, abuja, bamako, dakar, agadez, conakry, kano, and ouagadougou which are either capital cites or major commercial hubs, where the population ranges from 0.09 millio...

[1] We examine the impact of assimilating ozone observations from the Tropospheric Emission Spectrometer (TES) on North American surface ozone abundances in the GEOS-Chem model in August 2006. The assimilation reduces the negative bias in the modeled free tropospheric ozone, which enhances the ozone flux into the boundary layer. Surface ozone abundances increased by as much as 9 ppb in western ...

Accurate and temporally resolved fields of freetroposphere ozone are of major importance to quantify the intercontinental transport of pollution and the ozone radiative forcing. We consider a global chemical transport model (MOdèle de Chimie Atmosphérique à Grande Échelle, MOCAGE) in combination with a linear ozone chemistry scheme to examine the impact of assimilating observations from the Mic...

A regional air quality simulation framework including the Weather Research and Forecasting modeling system (WRF), the Community Multi-scale Air Quality modeling system (CMAQ), and precursor emissions to simulate tropospheric ozone over South and East Asia is introduced. Concentrations of tropospheric ozone and related species simulated by the framework are validated by comparing with observatio...

Aircraft and satellite observations indicate the presence of ppt (ppt ≡ pmol/mol) levels of BrO in the free troposphere with important implications for the tropospheric budgets of ozone, OH, and mercury. We can reproduce these observations with the GEOS-Chem global tropospheric chemistry model by including a broader consideration of multiphase halogen (Br-Cl) chemistry than has been done in the...

The impact of surface emissions on the zonal structure of tropical tropospheric ozone and carbon monoxide is investigated for November 2004 using satellite observations, in-situ measurements, and chemical transport models in conjunction with inverse-estimated surface emissions.Vertical ozone profiles from the Tropospheric Emission Spectrometer (TES) and ozone sonde measurements from the Souther...