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15 Years of Global PM 2.5 Estimates from Satellite. Aaron van Donkelaar with contributions from Randall Martin, and Brian Boys. Tuesday, June 10 th , 2014 Goldschmidt. PM 2.5 affects human health and longevity.
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15 Years of Global PM2.5 Estimates from Satellite Aaron van Donkelaar with contributions from Randall Martin, and Brian Boys Tuesday, June 10th, 2014 Goldschmidt
PM2.5 affects human health and longevity • Life expectancy increases 7 months per 10 μg/m3 decrease in long-term exposure Extinction due to aerosol in the atmospheric column is called Aerosol Optical Depth (AOD) Previous Global Burden of Disease report for 2000 (GBD2000) limited by insufficient ground-level observations of fine Particulate Matter (PM2.5) MODIS Aqua February 5th, 2006 GBD2010 estimates PM2.5 in urban and rural areas causes: • 3.2 million deaths (3%) Makes use of satellite-derived data for complete global coverage 0 0.2 0.4 0.6 0.8 1.0 Aerosol Optical Depth Cohen et al., 2005
AOD is related to PM2.5…but how to separate surface aerosol from column concentrations? • PM2.5 / AOD ratio is a function of: • vertical structure • aerosol type/hygroscopicity • meteorology Multiple approaches: • surface monitors calibration • empirical relations • model output 20 80 140 PM2.5 / AOD [μg/m3] GEOS-Chem v8-01-04
Model output can in used in different ways • “Unconstrained”: • Combined MODIS, MISR AOD • Apply simulated AOD/PM2.5 • van Donkelaar et al., EHP, 2010 • MODIS/MISR, 2001-2006 • Good representation of magnitude (error = 1μg/m3+27%) • Unavailable after 2006 • Boys et al., submitted • SeaWiFS&MISR, 1998-2012 • Successful representation of trends observed TOA reflectance a priori AOD a posteriori AOD observational error a priori error CALIOP Space-borne LIDAR Chemical Transport Model • “Optimal Estimation”: • Error-constrained MODIS, simulated AOD • AERONET-based error estimates • Consistent optical properties • Local reflectance information • CALIOP-adjusted AOD/PM2.5 • van Donkelaar et al., JGR, 2013 • 2004-2010 • Good representation of magnitude (error = 1μg/m3+25%) • Unavailable before 2004 Optimal estimation constrains AOD retrieval by error: MODIS Imaging Spectroradiometer SeaWiFS Imaging Spectroradiometer MISR Imaging Spectroradiometer
Combine PM2.5 to create a consistent 15 year dataset Unconstrained (UC) • 2001-2006 mass Optimal Estimation (OE) • 2004-2010 mass SeaWiFS&MISR • 1998-2012 annual variation/trend UC&OE • Weight by error over each land-cover type • 2001-2010 mass UC&OE + SeaWiFS&MISR • Apply relative variation from SeaWiFS/MISR • 1998-2012 annual mass Combined PM2.5 [μg/m3] PM2.5 (2001-2010) [μg/m3] In situ PM2.5 [μg/m3] van Donkelaar et al., submitted.
Consistent Trends in Satellite-Derived and In Situ PM2.5 1999-2012 Eastern US PM2.5 Anomaly (μg m-3) SeaWiFS& MISR In Situ In Situ In Situ (1999-2012) 0.37 ± 0.06 μg m-3 yr-1 Satellite-Derived (1999-2012) 0.36 ± 0.13 μg m-3 yr-1 Satellite-Derived Boys et al., submitted
Well correlated globally; potential bias at high PM2.5 200 150 100 50 0 1-σ error=1 μg/m3+47% y=0.68x+1.1 n=210 r=0.81 1-σ error=1 μg/m3+21% y=0.78x+1.7 n=512 r=0.73 40 30 20 10 0 Combined PM2.5 [μg/m3] Europe Global PM2.5 [μg/m3] 0 50 100 150 200 0 10 20 30 40 Ground Monitor PM2.5[μg/m3] van Donkelaar et al., submitted.
Time series highlight global changes van Donkelaar et al., submitted.
Significant global PM2.5 trends can be seen satellite @ in situ in situ PM2.5 [μg/m3] Boys et al., submitted.van Donkelaar et al., submitted.
Changes in Long-term Population-Weighted Ambient PM2.5Clean Areas are Improving; High PM2.5 Areas are Degrading 100 80 60 40 20 0 WHO Guidelines and Interim Targets 100 80 60 40 20 0 Asia, East +1.6 North America, High Income -0.3 2012 (70%) 1998 AQG 1998 (51%) Year Exceedance of WHO AQG drops from 62% to 19% Exceedance of WHO IT1 increases from 51% to 70% 2012 2005 1998 2012 IT3 80 60 40 20 0 Asia, South +1.0 Europe, Western -0.3 IT2 Percent of Population [%] Percent of Population [%] IT1 80 60 40 20 0 Europe, Central -0.2 North Africa,Middle East +0.4 Global: +0.6 5 10 15 25 35 50 100 5 10 15 253550 100 5 10 15 253550 100 Annual Mean Exposure [μg/m3] Annual Mean Exposure [μg/m3] 1998-2012 exposure trend [μg/m3/yr] van Donkelaar et al., submitted.
Global in situ monitors are sparse...and far from AERONET • PM2.5 estimates accuracy impacted by • AOD retrieval • Simulated aerosol vertical profile • Mass to extinction conversion • Sampling (clouds/snow) • Difficult to evaluate error sources • SPARTAN network collocates PM2.5 and AOD measurements • Satellite-derived PM2.5 evaluation, analysis, www.spartan-network.org Airphoton PM2.5 (Vanderlei Martins) Filter PM2.5 Filter PM10 3-λNephelometer AOD from CIMEL Sunphotometer (e.g. AERONET)
Global impact of global data Global Burden of Disease 2010 • 488 authors from 303 institutions in 50 countries • Inclusion of rural populations • PM2.5 causal role in 3 million deaths per year Lim et al., Lancet, 2012 • Inform Epidemiological Studies: • Global childhood asthma (Anderson et al., 2012) • Lung cancer in Canada (Hystad et al., 2012) • Mortality in California (Jerrett et al., 2013) • Diabetes(Brook et al., 2013; Chen et al., 2013) • Global adverse birth outcomes (Fleisher et al., in press) • Hypertension(Chen et al., in press) • Low PM2.5 cardiovascular mortality (Crouse et al., 2012) Crouse et al., EHP, 2012
Optimal estimation requires accurate error representation Error observed by AERONET Error is a function of species: • Emissions/chemistry • meteorology Estimate GC error: • Apply GC speciation • Inverse-distance / cross-correlation Observational error via brute force, extended via land cover van Donkelaar et al., JGR, 2013
Satellite-Derived PM2.5 Trends Inferred from SeaWiFS& MISR AOD and GEOS-Chem AOD/PM2.5 MISR 2000 -2012 SeaWiFS 1998 -2010 PM2.5 Trend [μg m-3 yr-1] Boys et al., submitted