This work addresses the relationship between major dynamical forcings and variability in NO column measurements. The dominating impact on Siberia is due to El Niño, on Indonesia, Northern Australia and South America is due to IOD,and on the remaining regions is due to NAO. That NO pollution in Indonesia is modulated by IOD contradicts previous work using AOD and El Niño. Simultaneous impacts of present and lagged forcings are derived using multi-linear regression, demonstrating El Niño impacts NO variability from 7 to 98 weeks ahead, while IOD and NAO are mostly impacted by past changes in NO variability. In all cases, lagged forcings exhibit more impact than present forcings, hinting at non-linearity. Finally, dynamical forcings are responsible for over 50% of the NO variability in most non-urban areas and over 40% in urban Indonesia and China. These results demonstrate the significance of climate forcing on short-lived air pollutants.

The contribution of biomass burning to the total aerosol loading over Monsoon Asia is both significant while also continuing to increase in recent decades. To better match the spatio-temporal distribution of aerosols and trace gasses observed in the free troposphere, this work applied a 3-D constrained emission inventory based on top-down remotely sensed NO2 measurement to investigate the most extreme of the annually occurring biomass burning seasons in Monsoon Asia. In 2016 this constituted an extreme event observed over a 6-day period covering millions of square kilometers, including over regions which are typically in the rainy phase of the Monsoon at this time. The results are shown to be consistent with respect to TRMM precipitation, AERONET measurements, MODIS AOD, MOPITT CO, and reanalysis meteorology, over both the biomass burning source as well as the millions of square kilometers downwind both to the East and to the Southwest. Reproducing the observed long-range transport pattern requires the time of biomass burning to be increased, regions not previously identified as burning to be actual source regions, and the emissions of BC to be 6.6 to 11.9 time larger than current inventories. The underlying mechanism for this long-range transport involves a new 3-D pathway that can occur during the transition from the North to the South Monsoon. The results are also consistent with the new idea that large loadings of BC in the lower free troposphere may significantly affect the meteorological field and the overall vertical distribution of aerosols in the tropical troposphere.