EvaluaJon of U.S. NO x Emissions with Satellite- based ObservaJons and Model SimulaJons

Transcription

1 EvaluaJon of U.S. NO x Emissions with Satellite- based ObservaJons and Model SimulaJons Gregory Frost*, Si- Wan Kim*, Stuart McKeen*, Eirh Yu Hsie*, Claire Granier*, & Michael Trainer Chemical Sciences Division, NOAA Earth System Research Laboratory, Boulder, Colorado, USA *also at CooperaNve InsNtute for Research in Environmental Sciences, University of Colorado, Boulder, Colorado, USA also at Université Pierre et Marie Curie and LATMOS- CNRS, Paris, France Andreas Heckel, Andreas Hilboll, Andreas Richter, & John Burrows InsNtute of Environmental Physics & InsNtute of Remote Sensing, University of Bremen, Germany James Gleason NASA Goddard Space Flight Center, Greenbelt, Maryland, USA Approach: Top- down assessment of sector- wide NO x emissions using atmospheric NO 2 columns retrieved from satellites and calculated by a regional chemical- transport model 3 examples of applicaaons of this approach: NO x emission controls at Eastern US power plants (S.- W. Kim et al., Geophys. Res. Le7., 2006) NO x emissions from Western US power plants and urban areas (S.- W. Kim et al., J. Geophys. Res, 2009) NO x emissions over Texas power plants, urban areas, and industrial faciliaes 2009 GEIA- ACCENT Open Conference, October 2009, Oslo, Norway

2 EPA Assessments of US NO x Emission Trends Highway Power generaaon Highway NO x emission trends from US EPA boyom- up inventories US NO x emissions have decreased >20% since 1999 Largest decreases in two biggest sectors Highway and other sources: emission process models Electric power generaaon: in- stack measurements Power generaaon now smaller contributor to US total NO x Power generaaon EPA NaNonal Emissions Inventory (NEI) Air Pollutant Emissions Trends Data h7p://

3 Top- Down Emissions Assessment by Satellites NO x emissions NO 2 columns (summer day short NO x lifeame) Satellite- observaaons of NO 2 columns in combinaaon with chemical- transport models Understand and improve NO x emissions (MarAn et al., 2003; Beirle et al., 2003; Richter et al., 2005; van der A, 2006; Kim et al., 2006 & 2009; ) UncertainAes in satellite retrieval and modeling (Boersma et al., 2004; Kim et al. 2009) US power plant measure their NO x emissions in- stack (CEMS) More accurate modeled NO 2 columns Evaluate & calibrate satellite NO 2 columns over power plants with regional model Satellite- retrieved NO 2 columns used to evaluate inventories for other NO x sources

4 Satellite NO 2 Column Retrievals Satellite Instrument Period Overpass Ame Global coverage Pixel size GOME (ERS- 2) 1995/4-2003/6 10:30 LT 3 days 340 x 40 km 2 SCIAMACHY (ENVISAT) OMI (AURA) GOME- 2 (METOP) 2002/3- present 10:00 LT 6 days 60 x 30 km /7- present 13:30 LT 1 day 27 x 13 km 2 (nominal) 2007/3- present 09:30 LT 1.5 days 80 x 40 km 2 NO 2 Column Retrieval Process 1. Spectral fi_ngs to get NO 2 slant column (S) 2. SubtracAon of stratospheric NO 2 column 3. CalculaAon and applicaaon of air mass factor (AMF) to get NO 2 veracal column (V) V = S / AMF AMF calculaaon: A priori NO 2 profile: chemical- transport models A priori aerosol profile Aerosol opacal depth Terrain height Surface albedo Temperature & Pressure RadiaAve transfer equaaon: LOWTRAN, etc

5 WRF- Chem Modeling of NO 2 VerJcal Columns Weather Research and ForecasAng - Chemistry model model.org/wg11 Simulates atmospheric chemistry online within WRF meteorological model Can choose between various modules for gas and aerosol chemistry, planetary boundary layer dynamics, aerosol and cloud microphysics, radiaaon, and convecaon Setup for these case studies Eastern US Summer 2004 simulaaon period 27 x 27 km 2 horizontal resoluaon Western US Summer 2005 simulaaon period 15 x 15 km 2 horizontal resoluaon Texas Summer 2006 simulaaon period Model resoluaon: 20 x 20 km 2 Emissions EPA NEI1999 and NEI2005 CEMS power plant emissions NOAA ESRL High Performance CompuAng System WRF- Chem Summer 2004 Average NO 2 VerAcal Columns

6 NO x Controls at Eastern US Power Plants Effects of NO x controls on large point sources in the Eastern US beginning in the late 1990s NaAonal and regional polluaon control programs Focus on coal- burning power plants Improved burner technology, post- burner ammonia scrubbers ConJnuous Emission Monitoring Systems (CEMS) Stack measurements of hourly NO x, SO 2, and CO 2 emissions made by unlity companies Data for 966 facilines in 1999 and 1427 facilines in 2004 CEMS data show: SubstanAal NO x emission reducaons since late 1990 s Amount of electric power generated has increased US NO x Emissions, 10 6 ton Annual NO x Emissions (US) = - 36% (Ohio River) = - 45% US Total Ohio River Region Ohio River Region NO x Emissions, 10 6 ton US Heat Input, mmbtu Annual Heat Input EPA Clean Air Markets Division Emissions Query Wizard hlp://camddataandmaps.epa.gov/gdm/index.cfm? fuseacaon=emissions.wizard Ohio River Region Heat Input, mmbtu Year Year

7 Eastern US Power Plant NO x Controls Detected by Satellite Summer 2004 Average NO 2 VerNcal Columns SCIAMACHY WRF- Chem, Reference Emissions (NEI 99) Northeast Urban Corridor Ohio River Valley Model reproduces satellite NO 2 veracal columns over urban areas Model NO 2 columns too large over power plants using 1999 emissions S.- W. Kim et al., Geophys. Res. Le7., 2006

8 Eastern US Power Plant NO x Controls Detected by Satellite SCIAMACHY Summer 2004 Average NO 2 VerNcal Columns WRF- Chem, Updated Power Plant Emissions Power plants = CEMS 2004 monthly averages All other sources = NEI 1999 S.- W. Kim et al., Geophys. Res. Le7., 2006 Model with summer 2004 power plant emissions agrees much beler with satellite NO 2 columns over power plants Satellite detects changes in Ohio River Valley from recent power plant NO x emission controls

9 Trends in Eastern US Satellite NO 2 and NO x Emissions Northeast Urban Corridor E(NO x ) < 20% power plant Satellite NO 2 columns: GOME ( ) & SCIAMACHY ( ) Ohio River Valley 1997 E(NO x ) ~ 50% power plant BoYom- up NO x emissions trend derived from monthly CEMS reports assuming all other NO x sources constant at summer 1999 June- August averages trends normalized to 1999 value Ohio River Valley 2005 E(NO x ) ~ 20% power plant Similar trends in satellite NO 2 columns and NO x emissions Power plant NO x controls have decreased NO 2 columns Mobile NO x emission changes smaller than those from power plants S.- W. Kim et al., Geophys. Res. Le7., 2006

10 NO x Emissions from Western US Power Plants Isolated plants have discrete signatures in satellite retrievals Power plant emissions are measured connnuously at each stack Currently no NO x pollunon controls on large coal- burning plants in the West CalibraNon for satellite- model comparison North Valmy Colstrip Intermountain Hunter / HunAngton Reid Gardener Dave Johnston/ Laramie River Jim Bridger/ Naughton Craig/Hayden Mohave Bonanza Navajo Cholla/Coronado/ Springerville SCIAMACHY, Summer 2005 Four Corners/ San Juan S.- W. Kim et al., J. Geophys. Res., 2009

11 Satellite - Model NO 2 Column Comparison: Power Plants Model uses observed emissions (CEMS) over power plant areas. Good agreement between satellite and model NO 2 columns over Western US power plants OpAmize satellite column retrievals and model parameterizaaons Model enables comparison of different satellite retrieval approaches Consistency for different retrievals gives confidence in conclusions about emissions S.- W. Kim et al., J. Geophys. Res., 2009

12 NO x Emissions from Western US Urban Areas Build on satellite- model comparisons for power plants Evaluate urban area emission inventories and monitor changes Denver Boise Salt Lake City Reno Sacramento San Francisco Fresno Albuquerque / Santa Fe Bakersfield Los Angeles Las Vegas Phoenix Tucson El Paso SCIAMACHY, Summer 2005 S.- W. Kim et al., J. Geophys. Res., 2009

13 Satellite - Model NO 2 Column Comparison: Urban Areas Note: weekend days are omiled in this analysis Large satellite - model NO 2 column differences over many Western US ciaes Urban emissions not well represented by 1999 inventory Model NO 2 columns for ciaes are % higher than the satellite retrievals Trends in NO x emissions since 1999? Are emission changes mostly due to motor vehicles? S.- W. Kim et al., J. Geophys. Res., 2009

14 Day- of- Week Trends in Urban Satellite NO 2 Columns Satellites show weekend decline in urban NO 2 columns Reduced traffic, paracularly heavy- duty diesel vehicles Lower mobile source NO x emissions on weekends Consistent with roadside monitoring Clear day- of- week trends in satellite NO 2 columns, but model did not consider weekly variaaons of NOx emissions Day of week changes in satellite NO 2 columns first reported by: S. Beirle et al. (2003), Weekly cycle of NO 2 by GOME measurements: a signature of anthropogenic sources, Atmos. Chem. Phys., 3, S.- W. Kim et al., J. Geophys. Res., 2009

15 Year- to- Year Trends in Urban Satellite NO 2 Columns %/yr (SCIA) %/yr (SCIA) %/yr (UB OMI) %/yr (NASA OMI) Lev axis: NO 2 columns averaged over box %/yr (SCIA) %/yr (UB OMI) %/yr (NASA OMI) %/yr (SCIA) Year- to- year declines in satellite NO 2 columns in many Western US ciaes Coincide with NO x declines seen by roadside monitoring (Ban- Weiss et al., 2008; Bishop and Stedman, 2008). Effect of cleaner engines, especially light- duty gasoline vehicles Declining trends in aerosols are not included in retrievals Declines in satellite NO 2 column might be underesamated %/yr (SCIA) %/yr (UB OMI) %/yr (NASA OMI) %/yr (SCIA) S.- W. Kim et al., J. Geophys. Res., 2009

16 Improved Modeled NO2 Columns with Updated Emissions WRF- Chem:NEI99 WRF- Chem:NEI05 Modeled NO2 Column Difference (%) = (NEI05 - NEI99) / NEI99 Max = 92 (%) / Min = - 78(%)

17 EvaluaJng NO x Source Regions in Texas NASA OMI Summer of 2006 (Jul/26- Oct/6) Urban areas: Dallas AusAn San Antonio Houston (urban + industrial) Power plants: MarAn Lake MonAcello and Welsh Big Brown and Limestone Tolk Harrington

18 Houston Texas Model vs. Satellite NO2 Columns SCIAMACHY, NASA OMI, UB OMI Mexican Power Plant Houston Mexican power plant is not included in scaler plot. Model and satellite NO2 columns agree well except Houston and Mexican power plant areas Model columns are ~factor of 2 higher than satellite column in Houston UncertainAes in industrial emissions? Dall Hous Aust SanA BigB Tolk Harr Mont Mart Mexi

19 Model vs. NOAA P- 3 Aircrae ObservaJons Preliminary results m AGL 10AM- 6PM LT 10 flights 11 Sept Sept2006 Observed median = ppbv RACM- ESRL RADM2 Model NO 2 = 2 Aircrae observed NO 2 IndicaAon of overesamaaon of NOx emissions in Houston? LimitaNons Errors in model boundary layer height, cloud, and veracal mixing DiluAon and convecaon need fine- resoluaon simulaaons CancellaAon of errors need to examine individual flights

20 Conclusions The combinaaon of space- based instruments and regional model provides a useful evaluaaon of NO x emission inventories and trends Effects of major NO x emission reducaons at Eastern US power plants Point source polluaon control strategies have resulted in widespread changes to atmospheric NO x levels that satellites can measure ContribuAons from Western US NO x power plants and urban areas Power plants serve as calibraaon for NO 2 veracal columns Impact of cleaner motor vehicles on urban to regional scale measured by satellites Satellites see day- of- week changes associated with motor vehicle emissions Impact of aerosol on satellite- derived NO 2 column trends needs to be invesagated Large urban and power plant sources in Texas Industrial NO x emissions from Houston may be overesamated In- situ aircrav observaaons help confirm findings from satellite- model comparison