Satellite measurements of tropospheric trace gas distributions on a regional and urban scale
利用衛星測量技術探測區域及城市中污染物的分佈
Student thesis: Doctoral Thesis
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Award date | 3 Oct 2014 |
Link(s)
Permanent Link | https://scholars.cityu.edu.hk/en/theses/theses(d784c8c4-2a67-4c75-9d04-35287be5cd50).html |
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Other link(s) | Links |
Abstract
Air pollutant is a serious problem in many urbanised areas. The recent increase in the
spatial resolution of satellite instruments has made it feasible to study the regional distribution
of air pollutants from space. In this thesis, I developed a novel gridding algorithm
and studied the feasibility for evaluating a regional chemistry transport model using a
regional OMI NO2 product. The objective is to contribute to the current effort to make
satellite measurements more suitable on the local and regional scale.
A new gridding algorithm was developed to map measurements from the instrument's
frame of reference (level 2) onto a longitude-latitude grid (level 3). It was designed for
OMI and can easily be employed for similar instruments. The algorithm reconstructs
the trace gas distribution by a parabolic spline surface by accounting for the instrument's
spatial sensitivity within each ground pixel. A comparison with an established gridding
algorithm shows improved performance for small to moderate measurement errors due to
better parametrisation of the distribution. The resulting maps are smoother and extreme
values are more accurately reconstructed.
To study the feasibility for evaluating a regional chemistry transport model with satellite
measurements, a new regional OMI NO2 product was developed for the Pearl River
Delta (PRD) region. The NO2 retrieval was improved by using high-resolution ancillary
parameters of surface reflectance, NO2 profile shapes and aerosol extinction coefficients
to recalculate air mass factors (AMF). The new product reduces the bias between satellite
and ground measurements. The CMAQ model was evaluated with the new satellite
product and the ground measurements. The mean bias between model and satellite product
is consistent with the bias between model and ground network. Therefore, satellite
measurements can not only be used to study the trace gas distribution but also be used to estimate the model bias.
The novel gridding algorithm and the results of the model evaluation, presented in this
thesis, can be very helpful for future studies of air pollutants on local and regional scale.
- Urban pollution, Air, Artificial satellites in air pollution control, Pollution, Measurement