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Satellite Remote Sensing of Ozone-NOx-VOC Sensitivity
Randall Martin Aaron Van Donkelaar Arlene Fiore
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Ozone Control Strategies Require Independent Information on Effectiveness of Reducing NOx or VOCs
HCHO/NOy Ratio Used as Indicator Would like to Observe from Space… (ppbv) NOx-Saturated NOx-Sensitive Sillman and He, 2002
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Conduct Three Simulations With GEOS-CHEM Model
Base Case Reduce Anthropogenic NOx Emissions by 50% Reduce Anthropogenic VOC Emissions by 50%
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Tropospheric HCHO/NO2 Column Ratio Is an Indicator of the Sensitivity of Afternoon Surface Ozone to NOx and VOC Emissions in a Well-mixed Environment GEOS-CHEM Model Calculation For Polluted Regions, Mar-Nov NOx Saturated NOx Sensitive
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Tropospheric NO2 and HCHO Columns Largely Confined Near the Surface Also Closely Related to NOx and VOC Emissions Tropospheric NO2 column ~ ENOx Tropospheric HCHO column ~ EVOC Boundary Layer CO NO2 NO/NO2 W ALTITUDE NO hours HCHO OH HO2 hours VOC hours HNO3 Emission Emission Nitrogen Oxides (NOx) Volatile Organic Compounds (VOC)
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Retrieve Tropospheric NO2 and HCHO Columns from GOME Largest Errors (from AMF) Cancel in the Ratio
Solar Io Backscattered intensity IB Spectral Fit (UV/Vis) Total HCHO & NO2 Slant Column Remove Stratosphere Tropospheric NO2 Slant Column Scattering by Earth surface and by atmosphere Calculate AMF Tropospheric NO2 & HCHO Column
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GOME Observations Show NOx-Sensitive Conditions Over Most Polluted Regions During August Major Industrial Areas are Clear Exceptions White areas indicate clouds or data below the GOME detection limit August
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Biomass Burning Emissions are Clearly NOx-Sensitive, In Contrast with NOx-Saturated Conditions Over the Industrial Highveld Also observe plume evolution August
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Seasonal Evolution from NOx-Sensitive to NOx-Saturated Conditions in Fall
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GOME Observations Provide Confidence in a Recent Model Prediction NOx-Sensitive in the South and NOx-Saturated in the North in Fall Seasonal Maximum in Surface Ozone in Urban China Occurs in Fall (More High-Pressure Systems) GOME Model Luo et al., JGR, 2000
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Conclusions Satellite Observations of the Tropospheric HCHO/NO2 Column Indicate Ozone-NOx-VOC Sensitivity Errors in Ratio Less Than for Individual Species Sensitive Tool for Ozone Model Evaluation OMI Will Be Launched in June 40 Times Higher Spatial Resolution Less sub-grid scale variation Afternoon observation time
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