Attributing Extreme Aerosol Events, Quantifying Their Emissions, and Better Understanding Associated Long-Range Transport and In-Situ Processing Using a New Co-Variability Approach across Multiple Satellites and Global Models

Remotely sensed observations reveal global trends and variation in aerosols. This forms a basis for determining when an event is abnormally intense, or uniquely distributed in space and time. Using multiple related measurements from multiple sensors, starting from 2006 to the present, allows for more information based on different chemical lifetimes of aerosols and related co-emitted species. We propose a new approach, using the simultaneous co-variability in the spatial and temporal distribution of these magnitudes across related measurements of aerosols and trace gasses. Model variability associated with different chemical and physical lifetimes of these different species, allows for us to infer long-range transport and and in-situ processing under specific conditions. Thankfully these conditions are relatively common and found throughout the globe.

This approach works with emissions and atmospheric processing from biomass burning and changing urban regions. Under highly polluted conditions, the amount of BC and inorganic aerosol can frequently be quantified. Such findings are robust across Asia, Africa, South America, and even North America and Europe (the latter two during biomass burning events), although results in general from North America and Europe, and always from Japan are not well constrained.

Out jointly variable model and measurement products based on OMI, MISR, MOPITT, and CALIOP, compare well when compared against MODIS and AERONET. Our results also provide deep insights into where current emission databases can be and should be improved, and what types of physical and chemical process also should be addressed. Under extreme conditions, while we match better in space and time, there still is much more to be done.

Our initial findings are: there are aerosol sources from regions previously thought to have no sources; urban emissions regions tend to spread more in space than in magnitude; vertical rise and subsequent middle-atmosphere transport is more important than previously thought; and finally that transported and in-situ aged aerosols are important even in urban areas where they were not expected to be important previously.