Shifting Patterns of Global Emissions and Ozone Chemical Regime Linked to Human Activity and Natural Processes Using a Decadal Chemical Reanalysis (Invited Presentation)

Changes in economic activity and emission controls over the past several decades have led to substantial changes in anthropogenic emissions globally. Meanwhile, climate change has been a key factor in increasing the risk and extent of natural processes such as extreme wildfire events. Satellite measurements have been used to explore these changing global patterns. However, the attribution to individual emission sources and chemical processes remains unclear due to the difficulty of combining multiple types of observations and the complex chemical mechanisms relating emissions to atmospheric concentrations.

We have developed a state-of-the-art chemical data assimilation (DA) system to combine various satellite observations with chemistry transport models. This framework has successfully been applied to quantify emission changes and their impacts on ozone for the past decade by ingesting a suite of satellite measurements including those from Aura, Aqua, and Terra (Miyazaki et al., 2020a, 2020b, 2020c, 2021, 2022), but a lack of information on pollutants that determine ozone chemical regime, aerosol formation, and oxidation capacity has been a key limitation for air quality and climate studies.

In this study, we extend the framework to utilize multi-sensor data from the new generation satellites, including Suomi-NPP CrIS and VIIRS and Sentinel-5P TROPOMI and from long-term satellite data from the Aura and other satellites to characterize processes that form ozone, aerosols, and other pollutants in the atmosphere and attribute changes in their concentrations to short- and long-term variations in human and natural activity. By utilizing the new generation satellite data, we simultaneously optimize anthropogenic and biogenic emissions of NOx, SO2, VOCs, CO, and aerosols to provide an improved representation of global tropospheric profiles and to better represent driving mechanisms of decadal changes of various chemical species, their chemical regime, and the oxidative capacity. We will also discuss recent applications of the extended chemical reanalysis, such as the impacts of COVID-19, wildfires, and decadal changes, to provide a greatly enhanced understanding of multi-year changes in air pollutants and their response to changes in emission efficiency and human activity.