NO_x emission trends for China, 1995–2004: The view from the ground and the view from space

Abstract

[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.

Surface ozone background in the United States: Canadian and Mexican pollution influences

“…The scaled GEIA emissions for East Asia are consistent with TRACE-P aircraft observations in Asian outflow in 2001 (Heald et al, 2003), but NO x emissions in East Asia have grown rapidly since then (Zhang et al, 2007, Zhang et al, 2008. We also conducted a simulation using an (Zhang et al, 2007).…”

“…We also conducted a simulation using an (Zhang et al, 2007). We find that the effect of this increase on the mean North America background is less than 1 ppb anywhere in the US in summer.…”

NO<sub>2</sub> measurements in Hong Kong using LED based long path differential optical absorption spectroscopy

“…The results show that the VCDs would be 14.8 % higher in Summer and 16.9 % higher in Winter. As the NO x emissions over China has been reported to nearly doubled from 2000 to 2006 (Zhang et al, 2007), this suggests that the a-priori profile used in the OMI retrieval might be out of date and causing underestimation. The light gray and gray regions shown in Fig.…”

Ground‐level nitrogen dioxide concentrations inferred from the satellite‐borne Ozone Monitoring Instrument

“…Retrievals of tropospheric NO 2 columns from GOME and SCIAMACHY have been used to demonstrate the close relationship between land surface NO x emissions and tropospheric NO 2 columns [Leue et al, 2001;Martin et al, 2003aMartin et al, , 2006Jaeglé et al, 2005;Zhang et al, 2007]. Observations of a weekly pattern in GOME tropospheric NO 2 columns with significant reductions on weekends [Beirle et al, 2003], diurnal variation in NO 2 columns driven by emissions and photochemistry [Boersma et al, 2008a], and a large increase in tropospheric NO 2 columns over eastern China inferred from GOME and SCIAMACHY [Richter et al, 2005;van der A et al, 2006] demonstrate the capability of observing air pollution from space.…”