Abstract. We simulated elemental carbon (EC) and organic carbon (OC) aerosols in China and compared model results to surface measurements at Chinese rural and background sites, with the goal of deriving "top-down" emission estimates of EC and OC, as well as better quantifying the secondary sources of OC. We included in the model state-of-the-science Chinese "bottom-up" emission inventories for EC (1.92 TgC yr −1 ) and OC (3.95 TgC yr −1 ), as well as updated secondary OC formation pathways. The average simulated annual mean EC concentration at rural and background sites was 1.1 µgC m −3 , 56 % lower than the observed 2.5 µgC m −3 . The average simulated annual mean OC concentration at rural and background sites was 3.4 µgC m −3 , 76 % lower than the observed 14 µgC m −3 . Multiple regression to fit surface monthly mean EC observations at rural and background sites yielded the best estimate of Chinese EC source of 3.05 ± 0.78 TgC yr −1 . Based on the topdown EC emission estimate and observed seasonal primary OC/EC ratios, we estimated Chinese OC emissions to be 6.67 ± 1.30 TgC yr −1 . Using these top-down estimates, the simulated average annual mean EC concentration at rural and background sites was significantly improved to 1.9 µgC m −3 . However, the model still significantly underestimated observed OC in all seasons (simulated average annual mean OC at rural and background sites was 5.4 µgC m −3 ), with little skill in capturing the spatiotemporal variability. Secondary formation accounts for 21 % of Chinese annual mean surface OC in the model, with isoprene being the most important precursor. In summer, as high as 62 % of the observed surface OC may be due to secondary formation in eastern China. Our analysis points to four shortcomings in the current bottom-up inventories of Chinese carbonaceous aerosols: (1) the anthropogenic source is underestimated on a national scale, particularly for OC; (2) the spatiotemporal distributions of emissions are misrepresented; (3) there is a missing source in western China, likely associated with the use of biofuels or other low-quality fuels for heating; and (4) sources in fall are not well represented, either because the seasonal shifting of Published by Copernicus Publications on behalf of the European Geosciences Union. T.-M. Fu et al.: Carbonaceous aerosols in Chinaemissions and/or secondary formation are poorly captured or because specific fall emission events are missing. In addition, secondary production of OC in China is severely underestimated. More regional measurements with better spatiotemporal coverage are needed to resolve these shortcomings.

Abstract. Using OMI (Ozone Monitoring Instrument) tropospheric NO 2 columns and a nested-grid 3-D global chemical transport model (GEOS-Chem), we investigated the growth in NO x emissions from coal-fired power plants and their contributions to the growth in NO 2 columns in 2005-2007 in China. We first developed a unit-based power plant NO x emission inventory for [2005][2006][2007] to support this investigation. The total capacities of coal-fired power generation have increased by 48.8 % in 2005-2007, with 92.2 % of the total capacity additions coming from generator units with size ≥300 MW. The annual NO x emissions from coal-fired power plants were estimated to be 8.11 Tg NO 2 for 2005 and 9.58 Tg NO 2 for 2007, respectively. The modeled summer average tropospheric NO 2 columns were highly correlated (R 2 = 0.79-0.82) with OMI measurements over grids dominated by power plant emissions, with only 7-14 % low bias, lending support to the high accuracy of the unitbased power plant NO x emission inventory. The ratios of OMI-derived annual and summer average tropospheric NO 2 columns between 2007 and 2005 indicated that most of the grids with significant NO 2 increases were related to power plant construction activities. OMI had the capability to trace the changes of NO x emissions from individual large power plants in cases where there is less interference from other NO x sources. Scenario runs from GEOS-Chem model suggested that the new power plants contributed 18.5 % and 10 % to the annual average NO 2 columns in 2007 in Inner Mongolia and North China, respectively. The massive new power plant NO x emissions significantly changed the local NO 2 profiles, especially in less polluted areas. A sensitivity study found that changes of NO 2 shape factors due to including new power plant emissions increased the summer average OMI tropospheric NO 2 columns by 3.8-17.2 % for six selected locations, indicating that the updated emission information could help to improve the satellite retrievals.

Whilst often discussed as non-trivial phases of low-dimensional ferroelectrics, modulated polar phases such as the dipolar maze and the nano-bubble state have been appraised as essentially distinct. Here we emphasize their topological nature and show that these self-patterned polar states, but also additional mesophases such as the disconnected labyrinthine phase and the mixed bimeron-skyrmion phase, can be fathomed in their plurality through the unifying canvas of phase separation kinetics. Under compressive strain, varying the control parameter, i.e., the external electric field, conditions the nonequilibrium self-assembly of domains, and bridges nucleation and spinodal decomposition via the sequential onset of topological transitions. The evolutive topology of these polar textures is driven by the (re)combination of the elementary topological defects, merons and antimerons, into a plethora of composite topological defects such as the fourfold junctions, the bimeron and the target skyrmion. Moreover, we demonstrate that these manipulable defects are stable at room temperature and feature enhanced functionalities, appealing for devising future topological-based nanoelectronics.

[1] We use a chemical transport model and its adjoint to examine the sensitivity of secondary inorganic aerosol formation to emissions of precursor trace gases from Asia. Sensitivity simulations indicate that secondary inorganic aerosol mass concentrations are most sensitive to ammonia (NH 3 ) emissions in winter and to sulfur dioxide (SO 2 ) emissions during the rest of the year. However, in the annual mean, the perturbations on Asian population-weighted ground-level secondary inorganic aerosol concentrations of 34% due to changing nitrogen oxide (NO x ) emissions are comparable to those from changing either SO 2 (41%) or NH 3 (25%) emissions. The persistent sensitivity to NO x arises from the regional abundance of NH 3 over Asia that promotes ammonium nitrate formation. IASI satellite observations corroborate the NH 3 abundance. Projected emissions for 2020 indicate continued sensitivity to NO x emissions. We encourage more attention to NO x controls in addition to SO 2 and NH 3 controls to reduce ground-level East Asian aerosol.