High-resolution (0.05°  ×  0.05°) NO_x emissions in the Yangtze River Delta inferred from OMI

Abstract

Emission datasets of nitrogen oxides (NO x ) at high horizontal resolutions (e.g., 0.05 • × 0.05 • ) are crucial for understanding human influences at fine scales, air quality studies, and pollution control. Yet high-resolution emission data are often missing or contain large uncertainties especially for the developing regions. Taking advantage of longterm satellite measurements of nitrogen dioxide (NO 2 ), here we develop a computationally efficient method of estimating NO x emissions in major urban areas at the 0.05 • × 0.05 • resolution. The top-down inversion method accounts for the nonlinear effects of horizontal transport, chemical loss, and deposition. We construct a two-dimensional Peking University High-resolution Lifetime-Emission-Transport model (PHLET), its adjoint model (PHLET-A), and a satellite conversion matrix approach to relate emissions, lifetimes, simulated NO 2 , and satellite NO 2 data. The inversion method is applied to the summer months of 2012-2015 in the Yangtze River Delta (YRD; 29-34 • N, 118-123 • E) area, a major polluted region of China, using the NO 2 vertical column density data from the Peking University Ozone Monitoring Instrument NO 2 product (POMINO). A systematic analysis of inversion errors is performed, including using an independent test based on GEOS-Chem simulations. Across the YRD area, the summer average emissions obtained in this work range from 0 to 15.3 kg km −2 h −1 , and the lifetimes (due to chemical loss and deposition) range from 0.6 to 3.3 h. Our emission dataset reveals fine-scale spatial information related to nighttime light, population density, road network, maritime shipping, and land use (from a Google Earth photo). We further compare our emissions with multiple inventories. Many of the fine-scale emission structures are not well represented or not included in the widely used Multi-scale Emissions Inventory of China (MEIC).

NOx Emission Reduction and Recovery during COVID-19 in East China

“…Nitrogen oxides (NOx = NO + NO 2 ) is an excellent tracer of human activity as NOx is primarily emitted as NO from anthropogenic combustion sources, including transportation, powerplants, industries, and residential combustion [6,7]. Natural sources of NOx include soil, lightning, and wildfire [7][8][9][10][11][12][13][14][15][16][17]. NO 2 is primarily produced from the oxidation of NO, which is produced from atmospheric nitrogen and oxygen at high temperatures [7,11,17].…”

“…Natural sources of NOx include soil, lightning, and wildfire [7][8][9][10][11][12][13][14][15][16][17]. NO 2 is primarily produced from the oxidation of NO, which is produced from atmospheric nitrogen and oxygen at high temperatures [7,11,17]. NO x is a major precursor of particulate matter and ozone [17].…”

“…NO 2 is primarily produced from the oxidation of NO, which is produced from atmospheric nitrogen and oxygen at high temperatures [7,11,17]. NO x is a major precursor of particulate matter and ozone [17]. NO 2 can cause respiratory diseases and is also detrimental to the ecosystems through the formation of nitric acid and acid rain [11,13].…”

Long-Term (2005–2017) View of Atmospheric Pollutants in Central China Using Multiple Satellite Observations

“…By contrast, emission sources of sulfate and nitrate's gaseous precursors, SO 2 and NO x , are mostly from coal-burning power plants and industry activities, which are the main control targets of the government due to the practicability for unified management. Since the short lifetime of SO 2 and NO 2 , satellite VCD products of SO 2 and NO 2 are usually used to map anthropogenic emission sources as well as their emission levels [13,17]. To have a long-term view of the changes in the overall SO2 level in central China, spatial means of OMI SO2 compared with statistical SO2 emission amount during 2005-2017 ( Figure 4).…”

“…The heavy air pollution in China has drawn the attention of numerous observational studies from various perspectives. Besides ground-based measurements and chemistry model simulations, satellite studies have greatly renewed knowledge concerning spatial distribution of air pollution hotspots and variations of their major emissions in northern China [14][15][16], the Yangtze River Delta (YRD) [17], and Pearl River Delta (PRD) [18]. However, previous studies mostly focused on economically developed regions with extensive urban agglomeration.…”