- Related Research Areas
- Atmospheric Composition
The detection of boundary layer ammonia by the NASA TES instrument provides unprecedented opportunity for reducing persistent uncertainties in our understanding of the distribution and impacts of atmospheric ammonia. Ammonia (NH3) affects air quality and climate through its role in the mass, composition and physical properties of tropospheric aerosol. In order to maximize the potential of TES observations to constrain model estimates of these important processes, we will take advantage of recently developed data assimilation tools and targeted in situ measurements of surface-level NH3 concentrations. To fully understand the role of NH3 on tropospheric aerosols, it is critical to analyze the surface fluxes and inorganic aerosol system at local, continental, and global scales; thus, observations and models will be used to address the following specific objectives:
Reduce uncertainty in the effective atmospheric lifetime of NH3 by constraining bi- directional NH3 flux from agricultural vs natural land types.
Provide observational constraints on the magnitude of NH3 sources and atmospheric NHx distributions first in a local case study in North Carolina and then throughout the Continental U.S.
Improve both spatial distribution and seasonal estimates of sources and fates of NHx in global models, quantifying how this alters global particle compositions and sensitivities to changing emissions.
For the first objective, special TES transect observations of NH3 will be compared both to
in situ measurements positioned directly within the satellite footprints across a region of
eastern North Carolina (where the county-level NH3 emission density is the highest in the
nation) and to CMAQ simulations employing a newly developed bi-directional flux model in order to estimate the impact of deposition and subsequent re-emission of NH3
from natural vs agricultural land types on the effective atmospheric lifetime and
distribution of NH3. An extended Kalman filter with CMAQ-DDM-3D sensitivities will
be used to constrain the magnitude of several key source sectors in North Carolina and
then throughout the U.S. Next, global scale analysis of NH3 emissions will be performed
using the 4D-Var technique with the GEOS-Chem adjoint model. For each of these
inverse modeling studies, considerable effort will be made to first characterize the
approach using model generated ("pseudo") observations, exploring the influence of prior
assumptions and covariances. The inverse modeling results will be evaluated through
comparison of subsequent model estimated NH3 and PM2.5 concentrations and nitrogen
deposition with additional observations.
This research will address several of the specific areas highlighted in ROSES solicitation A.15, such as factors influencing tropospheric air quality, aerosol processes, the climate impact of chemically active trace gases and aerosols, and the interaction between the regional and global scale atmosphere. The improved NH3 models proposed here will increase the effectiveness of emissions controls strategies to minimize harmful levels of PM2.5 exposure. They will also refine estimates of future reactive nitrogen deposition, which depend upon accurate representation of atmospheric NH3 transport. Constraining NH3 will help reduce uncertainty in anthropogenic climate forcing of aerosols through better estimates of aerosol ion concentrations that dictate particle phase, water uptake, and optical properties.
This proposal builds on a previous NASA proposal to develop TES NH3 retrievals (PI Shephard). Overall, the entire effort to constrain estimates of aerosol impacts on air quality and climate is enabled through utilization of new NH3 satellite observations and thus directly applies to NASA's strategic goal to advance scientific understanding and meet societal needs by studying planet Earth from space.
Project PI: Daven Henze/University of Colorado at Boulder
CU Mechanical Engineering Dept 1111 Engineering Drive ECME 114 Boulder, CO 80309
Phone: (303) 492-8716
Fax: (303) 492-3498
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