evaluation of satellite no 2 columns over u. s. power plants using a regional atmospheric chemistry...
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Evaluation of Satellite NO2 Columns over U. S. Power Plants using a Regional Atmospheric
Chemistry Model
Si-Wan Kim
ESRL, NOAA and CIRES, U. of Colorado
Acknowledgements
SCIAMACHY Data: A. Heckel, A. Richter, and J. Burrows at Univ. of Bremen
OMI Data: J. Gleason at NASA
Emission Inventory and WRF-Chem model:
G. Frost, S. McKeen, E.-Y. Hsie, M. Trainer, G. Grell and S. Peckham at ESRL, NOAA and CIRES, U. of Colorado
Sep 10-12, 2007, Workshop at KNMI
1. Background 2. WRF-Chem model 3. Satellite instruments and retrievals4. NO2 columns over power plants5. Conclusions 6. Future Plans
Outline
Uncertainties in NOx emission inventory (“bottom-up emission”)
Evaluation of estimated NOx emissions with satellite observed NO2 columns
NOx emissions NO2 columns (Martin et al., 2003, Beirle et al., 2003, Richter et al., 2005, van
der A, 2006, Kim et al., 2006… ) For power plants, known NOx emissions
(CEMS) --> Accurate model NO2 columns --> Evaluation of satellite NO2 observations
1. Background
Western US Eastern US
BackgroundWhy Western U.S. ?
SCIAMACHY OMI
BackgroundObservation of NO2 Columns by Satellites
BackgroundIdentification of Sources (Power Plants)
North Valmy
Intermountain
Hunter /Huntington
Mohave
Navajo Four Corners/San Juan
Cholla/Coronado/ Springerville
Bonanza
Craig/Hayden
Jim Bridger/Naughton
Dave Johnston/Laramie River
Colstrip
Reid Gardener
BackgroundIdentification of Sources (Power Plants)
North Valmy
Intermountain
Hunter /Huntington
Mohave
Navajo Four Corners/San Juan
Cholla/Coronado/ Springerville
Bonanza
Craig/Hayden
Jim Bridger/Naughton
Dave Johnston/Laramie River
Colstrip
Reid Gardener
Weather Research and Forecasting – Chemistry model (www.wrf-model.org/WG11)
Simulate chemistry and aerosol online within WRF model Option to simulate coupling among chemistry, aerosol,
radiation and clouds. Various chemical mechanisms (kpp available) and aerosol
modules
Various physical packages: PBL, Microphysics, Radiation and Convective parameterizations
2. WRF-Chem Model
Period: 2005 Summer
Initial & Boundary Condition: NCEP GFS & Idealized chemical soundings
Emissions : NEI99 updated following CEMS 2005
PBL: YSU Microphysics: WSM5 Radiation: Dudhia shortwave Cumulus parameterization: Grell & Devenyi Land-Surface: Noah
Chemical mechanisms: RADM2, RACM, RACM-ESRL Aerosol: MADE-SORGAM
Advection scheme: Original & Positive Definite
WRF-Chem ModelSetup
WRF-Chem ModelDifference due to Chemical Mechanism
WRF-Chem Model
Four Corners & San Juan Power Plants
Difference due to Advection Scheme
• SCIAMACHY (ENVISAT) Period: March 2002 ~ Resolution: 60 x 30 km2
Global coverage at the equator: 6 days (due to alternate limb nadir viewing
Time: 10:30 LT
• OMI (EOS-Aura) Period: November 2004 ~ Nadir View Resolution: 13 x 24 km2 (nominal), 13 x 8 km2 (zoom-in) Global coverage: 1 day Time: 1:30 LT
• Sampling Clear Sky (Pixels with Cloud fraction < 0.15) For OMI, 10 < swath mode number < 50 are used.
3. Satellite instruments
Satellites
Subtraction of stratospheric NO2
Vertical sensitivity (AMF, Air Mass Factor) A priori NO2 profile Aerosols Terrain Height Albedo (Reflectivity)
Retrieval Issues: Tropospheric NO2 columns
Satellites
A priori NO2 profile SCIAMACHY MOZART NO2 profile SCIAMACHY WRF-Chem NO2 profile
Retrieval Issues (prof1)
Satellites
A priori NO2 profile
Retrieval Issues (prof2)
AMF-WRFprof
AMF-MOZprof
SatellitesSatellites
Aerosols
Retrieval Issues (aero1)
SatellitesSatellites
Aerosols
Retrieval Issues (aero2)
AMF-NoAerosol
AMF-EdgarAerosol
Satellites Retrieval Issues (terrain)
4. NO2 columns over power plants
SCIA
Mohave
Intermountain
Navajo
Four Corners/ San Juan
* Summer of 2005
WRF
OMI
WRF
Jim Bridger/ Naughton
Four Corners (SCIAMACHY)
Power plant emissions
* 14 day running mean
Model chemistry ~7%Model advection ~8%Satellite a priori profile ~6%Satellite aerosol ~3%
Four Corners (OMI)
Power plant emissions
Model Chemistry ~2%Model Advection ~11%
Jim Bridger & NaughtonPower plant emissions
IntermountainPower plant emissions
MohavePower plant emissions
NavajoPower plant emissions
Name of Plant
(size of box: lon. x lat. )
Satellite NO2 columns or Difference (WRF - Satellite) (1015 molec. cm-2)
SCIA1 WRF - SCIA1 SCIA2 WRF - SCIA2 OMI WRF - OMI
Four Corner/San Juan (2 x1)
Jim Bridg./Naught. (2.75 x 2)
Intermountain (1.5 x 1)
Mohave (1 x 0.788)
Navajo (1.5 x 0.625)
2.77
1.38
1.32
2.35
1.82
0.71 ( 25%)
0.04 ( 3%)
0.70 ( 53%)
1.41 ( 60%) 1.61 ( 89%)
2.59
1.10
1.14
2.41
1.78
0.88 ( 34%) 0.32 ( 29%)
0.88 ( 78%)
1.35 ( 56%)
1.66 ( 93%)
3.06
1.26
2.40
2.86
2.76
-0.14 ( -5%) -0.07 ( -6%)
-0.55 ( -23%)
-0.17 ( -6%)
0.17 ( 6%)
•SCIA1: MOZART NO2 profile / SCIA2: WRF-Chem NO2 profile•Model is overestimated to SCIA and is underestimated to OMI. However, both satellites show good agreement with model for Four Corners/San Juan power plants. In general, smaller boxes show higher biases for SCIA
Summary: Power Plants
5. Conclusions
* Satellite NO2 columns agree well with model NO2 columns over the regions where total NOx emission is dominated by power plants. For small size power plants, however, SCIAMACHY data are higher than the model results, while OMI and the model agree reasonably well, implying that the data frequency and resolution of SCIAMACHY limit the detection of these confined power plants.
* Applying positive advection scheme for RACM-ESRL (not done yet) may reduce discrepancy between SCIAMACHY and the model and increase discrepancy between OMI and the model.
* Inclusion of hourly and daily varying power plant emissions may reduce the discrepancy between model and satellites.
* The analysis can be extended to urban and highway emissions, which was known to be much more uncertain than those from power plants.
* Include daily variation of emissions from Four Corners and San Juan Power Plants: reductions in weekends and holidays by 25%
6. Future Plans