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PROJECTS

Updated in 2016.5

On-going:     improving model simulation of BC wet scavenging (BC-cloud-radiation interactions) 

                      improving land surface model by accounting for BC/dust-snow-radiation interactions;

We develop and examine a microphysics-based black carbon (BC) aerosol aging scheme that accounts for condensation and coagulation processes in a global 3-D chemical transport model (GEOS-Chem) by interpreting the BC measurements from the HIAPER Pole-to-Pole Observations (HIPPO, 2009–2011) using the model. We convert aerosol mass in the model to number concentration by assuming lognormal aerosol size distributions and compute the microphysical BC aging rate explicitly from condensation of soluble materials onto hydrophobic BC and coagulation between hydrophobic BC and preexisting soluble particles. The results ...

A theoretical black carbon (BC) aging model is developed to account for three typical evolution stages, namely, freshly emitted aggregates, BC coated by soluble material, and BC particles undergoing further hygroscopic growth. The geometric-optics surface-wave (GOS) approach is employed to compute the BC single-scattering properties at each aging stage, which are subsequently compared with laboratory measurements. The results ... 

We estimate the snow albedo forcing and direct radiative forcing (DRF) of black carbon (BC) in the Tibetan Plateau using a global chemical transport model in conjunction with a stochastic snow model and a radiative transfer model. We also use the tag-tracer technique to  attribute BC forcings over the Tibetan Plateau to emissions from different regions (e.g., East Asia, South Asia, and others). The results ...

We systematically evaluate the black carbon (BC) simulations for 2006 over the Tibetan Plateau by a global 3-D chemical transport model (GEOS-Chem) driven by GEOS-5 assimilated meteorological fields, using in situ measurements of BC in surface air, BC in snow, and BC absorption aerosol optical depth (AAOD). Using improved anthropogenic BC emission inventories for Asia that account for rapid technology renewal and energy consumption growth and improved global biomass burning emission inventories that account for small fires, we find that ...

A stochastic approach has been developed to model the positions of black carbon (BC)/dust internally mixed with two snow grain types: hexagonal plate/column (convex) and Koch snowflake (concave). Subsequently, light absorption and scattering analysis can be followed by means of an improved geometric-optics surface-wave (GOS) approach coupled with Monte Carlo photon tracing to determine BC/dust single-scattering properties. Based on the stochastic and light absorption parameterizations and the adding/doubling method for spectral radiative transfer, we propose a two-layer spectral snow parameterization involving contaminated fresh snow on top of old snow for investigating the climatic impact of multiple BC/dust internal mixing associated with snow grain metamorphism, particularly over mountain topography. The results ...

Recent field, laboratorial and modeling studies have confirmed that in-cloud processes contribute to a large fraction of secondary organic aerosols (SOA) production with large space-time heterogeneity. This study evaluates the key factors that govern the production of cloud-process SOA (SOAcld) on a global scale based on the GFDL coupled chemistry-climate model AM3 in which full cloud chemistry is employed. The associations between SOAcld production rate and six factors (i.e., liquid water content, total carbon chemical loss rate, temperature, VOC/NOx, OH, and O3) are examined. We find that ...

We propose a new “three-layer” conceptual model for the air-sea exchange of organic gases, which includes a dynamic surface microlayer with photochemical and biological processes. A parameterization of this three-layer model is presented, which is used to calculate the air-sea fluxes of acetone over the Pacific Ocean.  Our model may help explain the discrepancies between measured and calculated acetone fluxes in previous studies. More measurements are needed to validate our conceptual model and provide constraints on the model parameters.

The effects of multi-wall carbon nanotube on soil microorganisms is systematically investigated from four aspects including biochemical reactions, enzyme activities, microbial biomass and community structure.Two group experiments are set up, i.e., the carbon nanotube group and the control group. In the carbon nanotube group, the multi-wall carbon nanotube was mixed well with the soil at a concentration of 1 mg carbon nanotube per gram soil. Peirodically (28 days), soils were analyzed using ecotoxicological parameters. We find that ...

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