Limb sounding and monitoring of surface air quality

Limb sounding and monitoring of surface air quality Chris Mc. Linden Air Quality Research Division, Environment Canada with material from Jeff Brook (EC), Randall Martin (Dalhousie) Atmospheric Limb Sounding Satellite meeting Cdn Space Agency 5 -6 December 2013

Background • Environment Canada seeks to monitor and forecast air quality (AQ) and convey this information to the public – Deaths from traffic Pollution are 9 times higher than from traffic Accidents (Brauer et al. , Canadian Medical Association Journal, 2013) – ~21, 000 Canadian deaths due to air pollution in 2008; $8 B in treatment (National Post, November 2011) – WHO International Agency for Research on Cancer declares air pollution is a carcinogen (Oct 2013) • Communication to the public is through the “Air Quality Health Index” (AQHI) – A 10 -point scale that links AQ to health risks associated with a three-pollutant mix (O 3, NO 2, PM 2. 5) – Based on Canadian multi-city mortality/morbidity studies of short term health effects

Background • Monitoring is done primarily through • NAPS stations, 2009 the NAPS (National Air Pollution Surveillance) network These stations generally located near urban or industrial areas http: //www. ec. gc. ca/rnspa-naps/ • NAPS and the GEM-MACH model used to produce objective analyses

Background • Satellites are seen as an option to supplement the monitoring network over rural / background regions – Provide large-scale coverage – Derive surface concentrations; deposition rates OMI (2005 -08) with GEOS-Chem Courtesy Randall Martin

Links between surface AQ and limb sounding • Issues arise however when significant amounts of the absorber are present in the stratosphere, so called “stratospheric-tropospheric separation” – NO 2 – Aerosol, particularly following volcanic eruptions • Cirrus cloud • Lightning-NOx C

Improved Retrievals of NO 2 Nadir Limb Environment Canada is, where necessary, making improvement to exploring L 2 nadir data products Nadir L 1 L 2 processing sequence Level 1, calibrated spectra NASA Spectral analysis KNMI Removal of stratosphere: high pass filtering Removal of stratosphere: modelling stratospheric NO 2 Calculation of Air Mass Factors Level 2, tropospheric VCD Use existing KNMI retrieval, redo 3 rd step EC Calculation of Air Mass Factors Level 2, tropospheric VCD

NO 2 Original New EC Reprocessing leads to significant increases in NO 2 and SO 2 100% increase SO 2 Validation in the oil sands 40% increase

Removal of the stratospheric NO 2 signal • Fraction of total NO 2 column in the troposhere – Urban/Industrial areas: 30 -80%; Rural/background areas: 10 -30% – With most of Canada <20%, it is critical to have an unbiased method for removing stratospheric NO 2 – At 20% in strat: a 10% high bias in strat-NO 2 a 40% low bias in trop-NO 2 Annual mean, from OMI (2009) Fraction NO 2 profiles from GEOS-Chem (troposphere) and box model (stratosphere)

Improved Retrievals of NO 2 Nadir Limb Environment Canada is, where necessary, making improvement to exploring L 2 nadir data products Nadir L 1 L 2 processing sequence Level 1, calibrated spectra NASA Spectral analysis KNMI Removal of stratosphere: high pass filtering Removal of stratosphere: modelling stratospheric NO 2 Calculation of Air Mass Factors Level 2, tropospheric VCD Use existing KNMI retrieval, redo 3 rd step Can we improve this step? EC Calculation of Air Mass Factors Level 2, tropospheric VCD We are exploring the potential of using stratospheric NO 2 profile measurements from the OSIRIS instrument to remove the stratospheric NO 2 from OMI

Canadian AQ Forecast Suite : Operational Configuration: GEM-MACH 10 Global Environmental Multi-scale model - Modelling Air quality and CHemistry • GEM-MACH options chosen to meet EC’s operational AQ forecast needs; key characteristics include: – limited-area (LAM) configuration where grid points are co-located with operational met-only GEM which supplies initial conditions and lateral boundary conditions for GEM-MACH 10 – 10 -km horizontal grid spacing, 80 vertical levels to 0. 1 h. Pa – 2 -bin sectional representation of PM size distribution (i. e. , 0 -2. 5 and 2. 5 -10 μm) with 9 chemical components – Some processes resolved with increased number of bins GEM-10 grid (blue) ; GEM-MACH 10 grid (red) – Full process representation of oxidant and aerosol chemistry: gas-, aqueous- & heterogeneous chemistry mechanisms § aerosol dynamics § dry and wet deposition (including in and below cloud scavenging) §

Dry Deposition of NO 2 and SO 2 Inferred from OMI (2005 -08) with GEOS-Chem Vertical Profile & Deposition Velocity Courtesy of Randal Martin Nowlan et al. , in prep

• Multi-instrument / joint retrievals are becoming increasingly common to remove

Missions UV/visible nadir-viewing instruments

Original New EC Reprocessing leads to significant increases in NO 2 and SO 2 100% increase 40% increase

• Lightning NOx (NO 2, HNO 3) in the upper troposhere OMI OSIRIS

Parameter Current NO 2 Current SO 2 New EC Absorber Profile TM 4 (2 x 3 ) or GMI (2 x 2. 5 ) Single profile GEM-MACH (15 x 15 km); GEOS-CHEM (1/2 x 2/3 ) [2010 -2011] Surface Albedo OMI monthly climatology (0. 5 x 0. 5 ) Single value MODIS monthly (5 km x 5 km) Surface pressure TM 4 / GMI constant value GEM-MACH temperature TM 4 / GMI Single profile GEM-MACH Snow detection NISE snow/ice product none IMS snow/ice product Snow albedo Constant, 0. 6 none MODIS (5 km x 5 km) General theme: higher spatial and temporal resolution