Data Acquisition
The primary spatial data in this project is the concentration of NO2 in different time range. All data is acquired from the NASA Earth Data website which is a public open-access for providing satellite image data. The specific variable type in our research is the ‘Tropospheric NO2 Column’ (30% Cloud Screened) rather than the ‘Total NO2 Column’ because tropospheric change particularly indicates the NO2 pollution from human activities.
Data Visualization
ArcGIS, QGIS, Adobe Photoshop were the main software in the process of data visualization for our poster. Additionally, web-mapping was mainly conducted in Visual Studio Code (VSC) with JavaScript libraries and HTML/CSS. The raw satellite images data were firstly converted into the tiff format for further analysis. Afterwards, they were interpolated by using the Kriging interpolation method to smooth the interval between pixels and enhance linear between maximum and minimum values, which gave a better visualization on final result. It is important to mentioned that, owing to the worldwide research scale, all maps’ projections were ‘customized’ for eliminating distortions. For instance, large area countries with east-west orientation such as China and USA were projected in conic conformal projection.