Constraining Ammonia Emissions Through In-situ and Satellite Observations

Abstract

Atmospheric ammonia (NH3) affects air quality, climate, and biodiversity through aerosol particle formation and composition and nitrogen deposition into the biosphere. In this dissertation, I utilize NH3 observations from multiple platforms, including airborne measurements, ground monitoring network, and satellite retrievals, to better understand NH3 concentrations and associated emissions at fine scale. High resolution (~ 2 km) ammonia (NH3) column maps from IASI satellite retrievals are developed across the contiguous United States (CONUS) and the seasonality clusters are compared with both ground monitoring network observations and modeled results. The high spatial-resolution monthly NH3 maps serve as a constraint for model simulations and as a guide for the placement of future, ground-based network sites. A detailed intercomparison of seasonal and long-term trends of surface NH3 data from AMoN and satellite NH3 total columns in the CONUS are then performed to demonstrate the feasibility of using satellite NH3 columns to bridge the spatial gaps existing in the surface network NH3 concentrations. Increasing NH3 trends across the U.S. in the past decades stress the rising importance of NH3 in terms of nitrogen deposition. For the first time, large and episodic NH3 blooms are observed across the Midwest U.S. in each spring through satellite NH3 observations from both IASI and CrIS. The date of the first large NH3 peaks of the year correlate with the crop planting progress and this serves as an indicator of nitrogen fertilizer application. Finally, satellite-derived daily scale NH3 enhancement ratios during wildfire events are calculated and compared with airborne measurements, illustrating the feasibility of using satellite derived wildfire NH3 emissions as a substitute when in-situ measurements are unavailable.