We apply two global observational data sets, gross primary productivity (GPP) and tropospheric formaldehyde column variability (HCHOv), to probe isoprene emission variability on large spatiotemporal scales. GPP and HCHOv are decoupled or weakly anticorrelated in regions and seasons when isoprene emission is high. Isoprene emission models that include soil moisture dependence demonstrate greater skill in reproducing observed seasonal GPP-HCHOv correlations in the southeast US and the Amazon.

We examine sensitivities in aerosol concentration and climate effects from biofuel combustion emissions. We find a strong sensitivity in the overall sign and magnitude of the direct radiative effect and cloud-albedo indirect effect due to uncertainties regarding emissions size distribution, composition, mass, and optical mixing state. This uncertainty limits our ability to evaluate black carbon mitigation strategies to counter warming effects from greenhouse gases.

We examine the responses of a range of meteorological and air quality indicators to the expansion of urban land using WRF/Chem. Sensitivity studies indicate that the responses of pollutant concentrations to the spatial extent of urbanization are linear near the surface but nonlinear at higher altitudes. The results of process analysis demonstrate that urban heat island circulation and a deeper boundary layer with stronger turbulent intensities play a significant role in relocating pollutants.

This study attempts to determine the feasibility of a new assimilation method of satellite measurements of CH4 and CO2 for optimization of their surface fluxes in a synthetic environment. Instead of their absolute concentrations, we assimilate the ratios of their concentrations (CH4/CO2) in our inversion. Doing so helps us to reduce the effect of atmospheric scattering on the measurements in our system. However, assimilation of the ratios makes the inversion non-linear.

We present an emission inventory with quantified uncertainties of organic carbon (OC) and elemental carbon (EC) in China. New emission factors from local measurements lead to lower OC emissions than previous studies. We use ground observations to test the levels, trends, and spatial pattern of the emissions. The improvement over prior inventories is indicated by inter-annual comparison and correlation analysis between emissions and observations. Sources with high primary OC/EC are underestimate.

The hygroscopicity of SE US aerosol is mostly water-soluble, with a hygroscopicity that is insensitive to partial volatilization in a thermodenuder. The most and least oxidized components of the aerosol are the most hygroscopic of organic constituents. No clear relationship was found between organic aerosol hygroscopicity and oxygen-to-carbon ratio. The aerosol factors covary in a way that induces the observed diurnal invariance in total organic hygroscopicity.

A remarkable major stratospheric sudden warming during the boreal winter 2008/09 is studied with the Chemical Lagrangian Model of the Stratosphere (CLaMS). We investigate how mixing triggered by this event correlates the wave forcing and how transport and mixing affect the composition of the whole stratosphere in the Northern Hemisphere, by using the tracer-tracer correlation technique.

We have introduced prognostic precipitation for both liquid (drizzle and rain) and solid (snow) phase precipitation into the global circulation model ECHAM5-HAM. This has a significant effect on the clouds and the parameterized collection rates, also reducing the sensitivity of the liquid water path to the anthropogenic aerosol forcing. Altogether the results suggest that the treatment of precipitation in global circulation models has a significant influence on the phase and lifetime of clouds.

This study estimated the contributions to mercury concentration and deposition in easter China from seven categories of emission sources by CMAQ-Hg. Also, this study focuses on diagnostic and process analyses for atmospheric mercury pollution formation and on identification of the dominant atmospheric processes for mercury.

1) Seasonal trends of SOA tracers and origins were studied in the remote TP for the first time. 2) Seasonal variation of isoprene SOA tracers was mainly influenced by emission. 3) Due to the transport of air pollutants from the Indian subcontinent, aromatics SOA tracer presented relatively higher levels in the summer and elevated mass fractions in the winter. 4) Biogenic SOC dominated over anthropogenic SOC in the remote TP.

We show that simplified chemical mechanisms break down VOC into smaller sized degradation products on the first day faster than the near-explicit MCM chemical mechanism which would lead to an underprediction of ozone levels downwind of VOC emissions, and an underestimation of the VOC contribution to tropospheric background ozone when using simplified chemical mechanisms in regional or global modelling studies.

The numerical model WRF-Chem is used to estimate the contribution of anthropogenic emissions to BC, aerosol optical depth and atmospheric heating rates over southern Africa. An evaluation of the model with observational data including long-term BC measurements shows that the basic meteorology is reproduced reasonably well but simulated near-surface BC concentrations are underestimated by up to 50%. It is found that up to 100% of the BC in highly industrialized regions is of anthropogenic origin.

The polar orbiting MODIS instruments provide four daily observations of the fire diurnal cycle, resulting in erroneous fire radiative energy (FRE) estimates. Using geostationary SEVIRI data, we explore the fire diurnal cycle and its drivers for Africa to develop a new method to estimate global FRE in near real-time using MODIS. The fire diurnal cycle varied with climate and vegetation type, and including information on the fire diurnal cycle in the model significantly improved the FRE estimates.

Our manuscript describes the hygroscopic properties of accumulation- and coarse-mode aerosol particles sampled at the ZOTTO in central Siberia (61º N, 89º E). The hygroscopic growth measurements were supplemented with chemical analyses of the samples. In addition, the microstructure and chemical composition of aerosol particles were analyzed by x-ray micro-spectroscopy (STXM-NEXAFS) and transmission electron microscopy (TEM).

Isoprene epoxydiols (IEPOX) are major gas-phase products from the atmospheric oxidation of isoprene that yield secondary organic aerosol (SOA) by reactive uptake onto acidic sulfate aerosol. We report a substantial contribution of IEPOX-derived SOA to the total fine aerosol collected during summer. IEPOX-derived SOA measured by online and offline mass spectrometry techniques is correlated with acidic sulfate aerosol, demonstrating the critical role of anthropogenic emissions in its formation.

Ozone holds a certain fascination in atmospheric science. It is ubiquitous in the atmosphere, central to tropospheric oxidation chemistry, and yet harmful to human and ecosystem health as well as being an important greenhouse gas. It is not emitted into the atmosphere but is a byproduct of the very oxidation chemistry it largely initiates. This review examines current understanding of the processes regulating tropospheric ozone at global to local scales from both measurements and models.

This work investigates hygroscopic properties of internally mixed organic/inorganic aerosol particles. Aerosol particles containing organic and inorganic components can phase separate under certain relative humidity conditions, creating particles with an inorganic core and an organic shell. This paper explores whether water uptake from gaseous phase still occurs in such phase-separated systems. It finds that phase separation does not inhibit water uptake for the five systems that were studied.

Twelve trace elements in fine particles and clouds at a mountain site in southern China were investigated. Long-range transport contributed the most to element concentrations, whereas the YRD and the area around Mt. Lushan exhibited the highest element solubility. We demonstrated that cloud processing can enhance aerosol element solubility and increase sulfate concentration correspondingly, by irreversibly altering the morphology of metal particles in cloud droplet residues.

Stable-boundary-layer processes have been analysed using BLLAST data. Shallow drainage flows were formed at some locations after the near calm stage of the late afternoon. This stage ended with the arrival of a deeper wind associated with the mountain-plain circulation. At the same time, gravity waves were detected with an array of microbarometers. The interaction of these processes with turbulence was studied through multi-resolution flux decomposition at different sites and heights.

The seasonal cycle and optical properties of mineral dust aerosols in northern Africa were simulated for the period from 2006 to 2010 using the numerical atmospheric model ALADIN (Aire Limitée Adaptation dynamique Développement InterNational) coupled to the surface scheme SURFEX (SURFace EXternalisée). These simulations aim to quantify the dust emission and deposition and establish a three-dimensional dust aerosol distribution and extinction climatology over northern Africa.