Routinely, we have treated land segments as silos and gravitated our perspectives towards fluxes that are directed upward and downward. If you have ever had a leaky sink, one way to fix it would be to put a bucket underneath. But wouldn’t it make more sense to find and fix the core problem that is causing the leak? Nature perhaps is similar to the leaky sink, but on a far more complex scale, and the core problems are often from many different sources and sinks. So, what cause(s) our control volume to leak and unable to conserve energy?

Cities have a complex mix of land uses, from commercial districts with dining and shops to residential neighborhoods linked by travel corridors, as well as industrial areas such as ports and factories. All of these different land uses lead to a diversity of urban sources that emit volatile organic compounds (VOCs) and greenhouse gasses such as carbon dioxide (CO2) and methane (CH4). Direct measurements and analysis of these species over time helps us understand human interactions with climate and air pollution.