Quantification of CO emission from large point sources using satellite measurements
Iris Dekker
Since a few years the urban population number exceeds that of the rural population and the amount of megacities has continued to grow. The densely populated (mega)cities are a significant source of all kinds of air pollutants. Carbon monoxide (CO) is a major air pollutant in cities. It is a toxic gas for humans on ground level, a precursor of ozone in the troposphere, and has an important role in the oxidizing power of the atmosphere. This all makes it important to monitor CO concentrations. The lifetime of carbon monoxide is several weeks, which makes its sources harder to detect than e.g. sources of NOx with a lifetime of hours to days. However, due to its relatively long lifetime, CO can be a good tracer of pollution transport. As the spatial resolution of satellites is improving, the detection and quantification of city CO emissions from space comes within reach. The MOPITT (Measurements Of Pollution In The Troposphere) instrument on the NASA’s Terra Satellite has a CO data record of more than 15 year and recently a data product with improved sensitivity to the Earth surface is released. This makes carbon monoxide data an interesting study object.
The aim of this project is to translate the relatively coarse satellite observed signals into emissions on city scale. For doing this, an atmospheric transport model, WRF-chem with a high resolution up to 1x1 km2 will be used. The method will be developed and tested using sources that are relatively well quantified, after which it will be applied to other sources that are much more uncertain. The benefit of using satellite and model data is that global coverage is reached, so that places without a dense network of air pollution measurement stations can be examined as well. In the future, the method will be applied to the data of TROPOMI, an ESA instrument on the Sentinel 5 satellites, to be launched in 2016. As TROPOMI’s resolution and coverage will be better than that of MOPITT, the possibilities will likely increase, so even smaller cities can be examined. TROPOMI will also provide data for other species such as NO2, and CH4 , so that emission ratios can be investigated as well.
