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[1] A rapid increase of NO 2 columns over China has been observed by satellite instruments in recent years. We present a 10-a regional trend of NO x emissions in China from 1995 to 2004 using a bottom-up methodology and compare the emission trends with the NO 2 column trends observed from GOME and SCIAMACHY, the two spaceborne instruments. We use a dynamic methodology to reflect the dramatic change in China's NO x emissions caused by energy growth and technology renewal. We use a scenario analysis approach to identify the possible sources of uncertainties in the current bottom-up inventory, in comparison with the satellite observation data. Our best estimates for China's NO x emissions are 10.9 Tg in 1995 and 18.6 Tg in 2004, increasing by 70% during the period considered. NO x emissions and satellite-based NO 2 columns show broad agreement in temporal evolution and spatial distribution. Both the emission inventory data and the satellite observations indicate a continuous and accelerating growth rate between 1996 and 2004 over east central China. However, the growth rate from the emission inventory is lower than that from the satellite observations. From 1996 to 2004, NO x emissions over the region increased by 61% according to the inventory, while a 95% increase in the NO 2 columns measured by satellite was observed during the same period. We found good agreement during summertime but a large discrepancy during wintertime. The consistency between the summertime trends suggests that the bias cannot be due to systematic error of activity data or emission factors. The reasons for the discrepancy cannot yet be fully identified, but possible explanations include an underestimation in seasonal emission variations, variability of meteorology, NO x injection height, and the increasing trend of sulfate aerosols.

Abstract. Using observations from the Cheeka Peak Observatory in northwestern Washington

[1] Continuous observations of aerosols in China and Japan were made by polarization lidars during March to May 2001, corresponding with the Asian Pacific Regional Aerosol Characterization Experiment (ACE-Asia) field campaign period. Lidars in Beijing, Nagasaki, and Tsukuba were continuously operated regardless of weather conditions. Scatterers in the atmosphere were categorized for all vertical profiles, and occurrence frequencies of dust, spherical aerosols, and clouds up to 6 km were calculated. The frequency of dust was highest in Beijing for the whole height range. There was a peak of dust occurrence near the ground in Nagasaki. Dust was frequently detected in the free troposphere in Tsukuba. The contributions of dust and spherical aerosols to the total backscattering coefficient were estimated from the depolarization ratio with the assumption of the external mixture of both kinds of aerosols. Vertical profiles of backscattering by dust and by spherical aerosols represented the different characteristics of these aerosols. The monthly averaged backscattering coefficients by dust near the surface were 0.003/km/sr in Beijing, 0.001-0.002/km/sr in Nagasaki, and 0.0006/km/sr in Tsukuba. The backscattering coefficients by spherical aerosols near the surface were 0.002-0.004/km/sr at all three observatories. We compared the derived backscattering coefficients with aerosol mass concentrations calculated by a numerical model, Chemical Weather Forecasting System (CFORS). CFORS reproduced well the vertical structures of the tall dust events and the enhancements of spherical aerosols throughout the observation period. A specific dust event on 16-19 May 2001 was analyzed by using five lidars in Japan, and its fine structure is described.

A large international field experiment and use of transport modeling has yielded physical, chemical, and radiative properties of the abundant aerosols originating from Asia.