1. Mapping Surface NO 2 and PM 2.5 from Satellite Observations Randall Martin, Dalhousie University with contributions from Aaron van Donkelaar, Dalhousie U Lok Lamsal, Dalhousie U  NASA Goddard Colin Lee, U Toronto  Dalhousie U Environment Canada, Downsview 16 Jan 2011

2. Major Nadir-viewing Space-based Measurements of Air Quality (Not Exhaustive) SensorGOES Imager MOPITTMISRMODISAIRSSCIA- MACHY TESOMIPARA- SOL CALIOPGOME- 2 IASIVIIRS Platform (launch) GOES (varied) Terra Aqua (1999) ( 2002) Envisat (2002) Aura (2004) PARA- SOL (2004) Calipso (2006) MetOp (2006) NPP (2011) Equator Crossing n/a 10:30 1:3010:001:451:30 9:301:30 Typical Res (km) 4x422x2218x1810x1014 x1460x308x5>24x 13 18x1640x4080x4012 x12 6x6 Global Obs n/a3.57216n/a11 10.51 AerosolXXXXXXXXX NO 2 XXX HCHOXXX COXXXXX OzoneXXXXX SO 2 XXXX NH 3 XX Solar Backscatter & Thermal Infrared

3. General Approach to Estimate Surface NO 2 Concentration NO2 Column S → Surface Concentration Ω → Tropospheric column In Situ Model Model Profile Method: Solar backscatter Scattering by Earth surface and atmosphere   Idealized NO 2 absorption spectrum  

4. Afternoon Ground-Level NO 2 Inferred From OMI for 2005-2007 Lok Lamsal NO 2 [ppbv]

5. Ground-Level NO 2 Inferred From OMI for 2005 Temporal Correlation with In Situ Over 2005 ×  In situ —— OMI Works in Near-Real-Time! Values Estimated Using Monthly NO 2 Profiles for Different Year (2006) Insignificant change in results if profiles are daily coincident values from 2005 Lok Lamsal

6. Infer Ground-level NO 2 Between Monitors Using Empirical Column-to-Surface Ratio from In Situ Monitors Automatically Corrects for Bias in Satellite Column Lee et al., ACP, 2011 Passive Sites Permanent Sites

7. Combine both information sources (Model and In Situ) Explore with PM 2.5 inferred from MODIS & MISR AOD

8. RAW Has Significant Agreement with Long-Term (2001-2006) In situ Measurements Satellite Derived In-situ Satellite-Derived [ μ g/m3] In-situ PM 2.5 [μg/m 3 ] Annual Mean PM 2.5 [ μ g/m 3 ] (2001-2006) r MODIS AOD0.39 MISR AOD0.39 Combined AOD0.61 Combined PM 2.5 0.77 van Donkelaar et al., EHP, 2010

9. Significant Association of Long-Term PM 2.5 Exposure with Cardiovascular Mortality Crouse et al., EHP, submitted

10. RAW Has Limited Daily Skill Mean daily error can exceed 100%! Aaron van Donkelaar

11. Climatological Monitor Correction (CMC) to Correct Bias Regress 90-day running comparisons Make correction surface using IDW 2 weighted average

12. CMC Improves Daily Accuracy Reduces effects of climatological bias Reduces mean daily error to 40-60% Aaron van Donkelaar

13. IDW Inverse Distance Weighting of Satellite Estimate Improves Skill by Reducing Spatial Noise Regional mean daily error now ~40% Aaron van Donkelaar