Trend detection and seasonal variation of tropospheric NO2 over China.

The growing economy of China and air pollution are both important global issues. Recently
the new air quality rules from the European Union make air pollution an important
economical and political topic in the Netherlands. China on the other hand is frequently in the
media due to the rapid development of the country and its accompanying opportunities.
This report brings air pollution and the economical development in China together. It focus on
one of the consequences of the rapid growth of the economy in China; increasing emissions of
pollutants. A closer look will be given on NO2, which is one of the constituents of air
pollution. The satellite instruments GOME and SCIAMACHY provide a dataset of almost ten
years of atmospheric information. This dataset is used to perform a trend study on the
tropospheric NO2 columns over China.

The study is part of the “Air quality Monitoring and Forecasting In China” (AMFIC) project
in the framework of the DRAGON programme. The DRAGON programme is the umbrella
project for joint Sino and European studies and is initiated by the European Space Agency
(ESA) and the Ministry of Science and Technology of China (MOST). The AMFIC project is
a cooperation between the Royal Dutch Meteorological Institute (KNMI), TNO-FEL, Belgian
Institute for Space Aeronomy (BIRA-IASB), Flemish Institute for Technological Research
(VITO), University of Bremen and the National Satellite Meteorological Centre of China
(NSMC).
In this report the results are presented of a one-year study carried out at the KNMI, of which
one month was spend at the NSMC in Beijing. The work presented in this report tries to
answer the next questions for China:

1. What is the trend in tropospheric NO2 and what is the significance of this trend in the
available nine years long dataset?
2. What is the seasonal variation of tropospheric NO2?
3. How can we interpret the trend and the seasonal variation in tropospheric NO2?

The first part of this report contains chapters with background information of the satellite
instruments and NO2 chemistry. Questions like; “What is the role of NO2 in the troposphere?”
and “How is NO2 measured?” are answered. The last chapter of the first part focuses on
present-day China to give the reader an impression of the recent economical developments in
China.

The second part of report is based on a paper, which will be submitted to the Journal of
Geophysical Research. It shows the input, methods and answers on the main questions of this
report. In the appendices extra derivations and figures are shown. They were not shown in the
article, but they complete the overview of the study.