use of space-based tropospheric no 2 observations in regional air quality modeling
DESCRIPTION
Use of space-based tropospheric NO 2 observations in regional air quality modeling. Robert W. Pinder 1 , Sergey L. Napelenok 1 , Alice B. Gilliland 1 , Randall V. Martin 2 Atmospheric Sciences and Modeling Division, NOAA, in partnership with USEPA - PowerPoint PPT PresentationTRANSCRIPT
Use of space-based tropospheric NO2 observations in regional air
quality modelingRobert W. Pinder1, Sergey L. Napelenok1,
Alice B. Gilliland1, Randall V. Martin2
1. Atmospheric Sciences and Modeling Division, NOAA, in partnership with USEPA2. Dalhouise University and Harvard-Smithsonian Center for Astrophysics
TROPOMI WorkshopKNMI, Utrecht, The Netherlands
March 5-6, 2008
Case Study: NOx State Implementation Plan Call
• From 2002 – 2005, NOx emission reductions from power plants in Midwestern United States (22% ↓)
• Simultaneous gradual reduction in vehicle NOx emissions (18% ↓)
• Goal: Use satellite data to infer emission changes
Surface change in total nitrate, 2002-05
Tools:• CMAQ:
Community Multi-scale Air Quality Model
• Surface networks: HNO3, O3, deposition
• Can satellite data augment these tools?
2003 2004 2005SCIAMACHY
2003 2004 2005SCIAMACHY
2003 2004 2005SCIAMACHY
How does the change in the satellite observations correspond to
changes in emissions?
(1) Develop method using air quality model to relate emissions to column density
(2) Apply method to relate trend in satellite data to trend in emissions (in development)
Use Air Quality Model and Satellite Data to Infer Emission Change
• Begin with a priori emission estimate• Use emissions as input to CMAQ to estimate
NO2 column density
• Based on difference between CMAQ estimate and observed value, use an inverse technique to derive a new emission estimate
• Repeat until emission estimate converges (a posteriori)
Focus on Southeast United States in 2004
• Isolated urban areas
• Good spatial coverage in satellite data
• High quality surface NO2 observations
Continental US Southeast USC
MA
QS
CIA
MA
CH
Y
Missing NO2 Aloft
• When paired with aloft measurements from NASA INTEX, CMAQ underpredicts NO2 above the mixed layer
• On average 1.07 (1015 molecules cm-2)
Singh, et al. (2007) Reactive Nitrogen Distribution and Partitioning in the North American Troposphere andLowermost Stratosphere
Similar error found in other models
SC
IAM
AC
HY
CM
AQ
Continental US Southeast US+
IN
TE
X
Emissions
(tons NOx day-1)
Comparison of CMAQ and SCIAMACHY
r2
Atla
nta
Birm
ingh
am
Ge
org
ia
Alab
am
a
a priori 0.68 513 202 574 852
a posteriori
CMAQ0.89 482 182 1171 1718
a posteriori
CMAQ + INTEX0.93 435 138 364 782
RESULTS
Urban areas decrease;consistent with updatedemissions data
Rural areas aresensitive to NO2 aloft
Inverse improves surface concentrations
• Inverse-adjusted emissions improves agreement with independent surface NO2 observations
• Sensitivity test demonstrates proper accounting of NO2 aloft is importantNO2
Work in Progress: Next Steps
• More information is available on ACPD (Napelenok et al., A method for evaluating spatially-resolved NOx emissions using Kalman filter inversion, direct sensitivities, and space-based NO2 observations)
• Improve simulation of NOx above the planetary boundary layer
• Improve inverse methods to better quantify uncertainty
• Apply method to trends in 2003, 2004, and 2005
• Beyond SCIAMACHY NO2 data
Considerations for Future Missions
• Consistency across multiple years• Horizontal and vertical resolution• Reduce uncertainty and global daily coverage• Multiple observations per day, but need to
consider chemical state
• Harmonizing regional models and retrieval• More transparency in retrieval methods and
uncertainty calculations to ease interpretation and comparison
ACKNOWLEDGEMENTS: Aloft NOx measurements collected by Ron Cohen and the NASA INTEX team.
Helpful comments and advice from Rynda Hudman, Dev Roy, Robin Dennis, David Mobley, and Ann Marie Carlton.
DISCLAIMER: The research presented here was performed under the Memorandum of Understanding between the U.S. Environmental Protection Agency (EPA) and the U.S. Department of Commerce's National Oceanic and Atmospheric Administration (NOAA) and under agreement number DW13921548. This work constitutes a contribution to the NOAA Air Quality Program. Although it has been reviewed by EPA and NOAA and approved for publication, it does not necessarily reflect their policies or views.