Monthly patterns of ammonia over the contiguous United States at 2 km resolution

Rui Wang (1) , Xuehui Guo (1) , Da Pan (1) , James T. Kelly (2) , Jesse O. Bash (2) , Kang Sun (2) , Fabien Paulot (3) , Lieven Clarisse (4) , Martin Van Damme (4) , Simon Whitburn (4) , Pierre-François Coheur (4) , Cathy Clerbaux (5, 4, 6) , Mark A. Zondlo (1)

1 Department of Civil and Environmental Engineering [Princeton]
2 EPA - US Environmental Protection Agency
3 GFDL - NOAA Geophysical Fluid Dynamics Laboratory
4 SQUARES - Spectroscopy, Quantum Chemistry and Atmospheric Remote Sensing
5 TROPO - LATMOS
6 IPSL (FR_636) - Institut Pierre-Simon-Laplace

Monthly, high resolution (∼2 km) ammonia (NH3) column maps from the Infrared Atmospheric Sounding Interferometer (IASI) were developed across the contiguous United States and adjacent areas. Ammonia hotspots (95th percentile of the column distribution) were highly localized with a characteristic length scale of 12 km and median area of 152 km2. Five seasonality clusters were identified with k‐means++ clustering. The Midwest and eastern United States had a broad, spring maximum of NH3 (67% of hotspots in this cluster). The western United States, in contrast, showed a narrower mid‐summer peak (32% of hotspots). IASI spatiotemporal clustering was consistent with those from the Ammonia Monitoring Network. CMAQ and GFDL‐AM3 modeled NH3 columns have some success replicating the seasonal patterns but did not capture the regional differences. 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.

Domains: Atmospheric and Oceanic Physics [physics.ao-ph]; Ocean, Atmosphere

Rui Wang, Xuehui Guo, Da Pan, James T. Kelly, Jesse O. Bash, et al.. Monthly patterns of ammonia over the contiguous United States at 2 km resolution. Geophysical Research Letters, 2021, 48 (5), pp.e2020GL090579. ⟨10.1029/2020GL090579⟩. ⟨insu-03086947v2⟩