A31B-0028 Groundbreaking constraints on emissions from GEO-CAPE: Case studies of CH4, NH3, SO2, and NO2
GEO-CAPE Emission Working Group
Gill-Ran Jeong1, Jesse O. Bash2, Karen E. Cady-Pereira3, Daven K. Henze1, Ronald C. Cohen4, Lukas Valin4, Nickolay
Anatoly Krotkov5, Lok Lamsal6, Can Li7, Kevin Wecht8, John Worden9, Helen M. Worden10, and Andre Perkins11
1Mechanical Engineering, University of Colorado, Boulder, CO. 2. NERL/AMAD, US EPA, Research Triangle Park, NC. 3 Atmospheric and Environmental
Research Inc., Lexington, MA. 4Chemistry and Earth and Planetary Sciences, UC Berkeley, Berkeley, CA. 5Code 613.3, NASA/GSFC, Greenbelt, MD. 6USRA,
NASA/GSFC, Greenbelt, MD. 7ESSIC, NASA/GSFC, Greenbelt, MD. 8Earth and Planetary Sciences, Harvard University, Cambridge, MA. 9NASA/JPL,
Pasadena, CA. 10Atmospheric Chemistry Division, NCAR, Boulder, CO. 11University of Wisconsin, Madison, WI.
Introduction
Discussions and Conclusions
1.  Geostationary NH3 retrievals would be instrumental in
testing and evaluating NH3 air-surface exchange
algorithms and emissions inventories.
2.  OSSEs currently underway will define the set of
CH4 emissions related questions that can be
answered using GEO-CAPE observations.
3.  High-spatial
and
temporal
resolution
measurements will provide constraints on NOx
emission, export and chemical processing (e.g.,
HNO3, PAN, RONO2).
4.  Geostationary high spatial resolution (~4km) SO2
observations will expand satellite monitoring
capabilities beyond the largest point sources
currently observable and allow understanding of
SO2 removal processes for evaluation of AQ
models.
References
• Fioletov et al., Geophys. Res. Lett., 38, L21811, doi:10.1029/
2011GL049402, 2011.
• Fishman, J. et al., Bull. Amer. Meteor. Soc., 93, 1547–1566,
doi: http://dx.doi.org/10.1175/BAMS-D-11-00201.1, 2012.
• Henze, D. K. et al., Atmos. Chem. Phys., 7, 2413–2433, 2007.
• Howarth, R. W. et al., Climate Change, 106, 679–690, 2011.
• Katzenstein, A. S. et al., Proc. Natl. Acad. Sci. U.S.A., 100
(21), 11,975 – 11,979, 2003.
• Pétron, G., et al., J. Geophys. Res., doi:10.1029/2011JD
016360, 2012.
• Streets, D., in review, Atmos. Env.
Acknowledgement
This work was supported by funding from the NASA GEOCAPE Science Team.
NO3-­‐ μg/m3 • NH3 impacts PM2.5 concentrations by regulating NH4NO3.
• Uncertainty in NH3 fluxes limits understanding of how PM2.5 formation would
respond to controls on precursor emissions.
• Observations of nitrate (CSN:
Chemical Species Network) are
under-predicted with the standard
CMAQ model (Base), but better
estimated when accounting for bidirectional fluxes of NH3 (Bidi
and Bidi-F).
Constraining the emissions of CH4
from anthropogenic vs natural sources
• SCIAMACHY and in situ CH4 observations
suggest natural gas emissions are
underestimated [Katzenstein et al. 2003,
Pétron et al. 2012].
• CH4 emission rate from shale gas is highly
uncertain [Howarth et al. 2011].
Approach • Observation System Simulation Experiments
(OSSE) will test the ability of GEO-CAPE to
monitor anthropogenic and natural emissions
amidst uncertainties in both.
1. Simulate “true” atmosphere: perturb
natural gas emissions in red box for 2 weeks
2. Generate GEO-CAPE observations: sample
“true” atmosphere with observation operator
3. Assimilate observation to recover perturbed
emission distribution: 4D-Var inversion with
GEOS-Chem adjoint [Henze et al. 2007]
• Observations from a remote sensing geostationary instrument are simulated for
several model atmospheres. They could help constrain the mechanistic models of
NH3 fluxes, as the differences between base case simulations (Base), those with
bidirectional exchange (Bidi) and bidirectional exchange with a modified fertilizer
input (Bidi-F) are clearly discernible in the figures shown above.
• A geostationary instrument could quantify differences in NH3 concentrations due
to changes in the mechanistic processes governing NH3 deposition and evasion. Form local to continental: NOx emissions,
transport, and chemistry
Future study • Add realistic complexity
• Random and potential systematic errors in
observations
•  Uncertainty in nested model boundary and
initial conditions
•  Uncertainty in other emission types
0.95 1.15 Resulting CH4 enhancement
0 0.1 ppb Optimized : prior Total CH4 missions
0.95 1.15 Constraining the lifetime of SO2
•  Detection limit for SO2 point pollution sources using satellite pixel averaging
technique [Fioletov et al., 2011] critically depends on sensor ground resolution.
•  Current observations from OMI with spatial resolution of 13km by 24km
(>300km2) allow detection of sources larger than ~70 kt/yr.
Detecting SO2 point sources
• The NO2 column simulated at 4 × 4 km2 horizontal resolution over the Four
Corners Power Plant (NM, USA) from 9AM – 1PM on a day when winds are fast
(top) and when winds are slow (bottom).
• Large day-to-day differences of the NO2 column (top-row vs. bottom-row) are
caused by day-to-day differences in transport and chemistry. GEO-CAPE will
measure the NO2 column with spatial detail comparable to the simulation shown
above providing an opportunity to distinguish these differences.
• NOx is removed from the atmosphere primarily by reaction of NO2 with OH. Due
to the nonlinear dependence of OH on NOx, the removal of NOx is slow where
NOx is high, but is fast where NOx is lower near the plume edge. GEO-CAPE will
observe the NO2 column with a spatial resolution sufficient to observe the plume
edge (4 – 10 km).
• Hourly measurements will enable investigation of diurnal patterns of NOx
emissions and chemistry.
Case studies over isolated power plants, where
emissions are known, will improve our understanding of the diurnal evolution of
the NO2 vertical distribution.
Perturbed : prior Total CH4 emissions
• With GEO-CAPE’s 20 times better
ground resolution (~16 km2 ) than OMI
observations, point SO2 emissions < 10
kT/year
will be detectable (with
averaging), which constitutes majority
of point source SO2 emissions over
GEO-CAPE domain (US).
Detec%ng GEO-­‐CAPE While existing remote sensing measurements currently
provide valuable sources of top-down constraints on a
wide range of emissions of air pollutants and
greenhouse gases, geostationary observations hold the
potential to significantly advance our scientific
understanding of constituent sources in several ways.
Over North America, the proposed GEO-CAPE
instrument will allow replacement of monthly mean
and annual average estimates of emissions, ones that
are tuned to current and/or historical observations, with
detailed mechanistic models that are capable of
projecting outside the envelope of current
observations. GEO-CAPE observations are expected
to be a major leap forward in observations that can test
and constrain such models. In this manner, GEOCAPE will also allow development of high space and
time resolution emission fields that will enable
detailed evaluation of other components of a chemical
transport model (e.g., boundary layer fluid dynamics).
Here we present case studies of the expected benefits
of GEO-CAPE observations. In each case, we
illustrate the ways in which geostationary observations
provide insight beyond current capabilities with low
earth orbit satellites.
Constraining bi-directional fluxes of NH3
: OMI : additions with GEO-CAPE
Detecting SO2 emission
• With GEO-CAPE’s hourly daytime
observations one can directly monitor
dispersion of SO2 plumes from
individual power plants. Combing GEOCAPE pollution measurements with
available meteorological information
and accurate bottom-up hourly emission
data (CEM: continuing emission
monitors installed inside power plant
stacks), one can better estimate SO2 lifetime.
•  GEO-CAPE SO2 data can be used to
evaluate sulfur removal processes
incorporated in 4D modeling.