Increase in tropospheric nitrogen dioxide over China observed from space

Area of Science:

• Atmospheric Chemistry
• Environmental Science
• Remote Sensing

Background:

• Combustion emissions impact air quality and global tropospheric chemistry.
• Nitrogen oxides (NOx) drive ozone production, leading to smog and increased tropospheric ozone.
• NOx emissions contribute to nitric acid deposition and local radiative forcing.

Purpose of the Study:

• To analyze tropospheric nitrogen dioxide (NO2) column amounts from 1996-2004.
• To compare satellite-retrieved data with existing emission inventories.
• To assess regional trends in NOx emissions, particularly in industrializing Asia.

Main Methods:

• Retrieval of tropospheric NO2 column densities using data from GOME and SCIAMACHY satellite instruments.
• Analysis of spatial and temporal trends over the 1996-2004 period.
• Comparison of observed trends with bottom-up emission inventory estimates.

Main Results:

• Observed substantial reductions in NO2 concentrations over parts of Europe and the USA.
• Documented a significant increase of approximately 50% in NO2 over industrial areas of China.
• Identified an accelerating annual growth rate in Chinese NO2 emissions, surpassing inventory projections.

Conclusions:

• Satellite observations provide critical insights into regional NOx emission trends.
• Economic development in Asia, particularly China, is driving a rapid increase in NOx emissions.
• Discrepancies between satellite data and inventories highlight the need for improved emission monitoring in developing regions.