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Determination of aerosol components from multiwavelength/depolarization measurements

GALION WS, 20-23 Sep 2010, Geneva. Determination of aerosol components from multiwavelength/depolarization measurements. Nobuo SUGIMOTO, Tomoaki Nishizawa, and Atsushi Shimizu National Institute for Environmental Studies nsugimot@nies.go.jp. Which parameter shall we compare with models?.

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Determination of aerosol components from multiwavelength/depolarization measurements

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  1. GALION WS, 20-23 Sep 2010, Geneva Determination of aerosol components from multiwavelength/depolarization measurements Nobuo SUGIMOTO, Tomoaki Nishizawa, and Atsushi Shimizu National Institute for Environmental Studies nsugimot@nies.go.jp

  2. Which parameter shall we compare with models? Lidar signal intensity (depolarization) S1 extinction coefficient distribution and characteristics of other aerosols assumption on external mixing dust extinction coefficient mass/extinction conversion factor optical characteristics of dust dust density Chemical Transport Model

  3. Method for estimating contributions of dust and air pollution The mixing ratio of dust, R, can be estimated from the observed aerosol depolarization ratio, da. where d1 and d2 are depolarization ratio of dust and other aerosols. We used d1~0.35 and d2~0.05 empirically determined from the histogram of observed aerosol depolarization ratio. [Sugimote et al. 2003; Shimizu et al. 2004]

  4. Method for estimating the extinction coefficients of dust and spherical aerosols using the depolarization ratio Dust March 21-31, 2004 Beijing Dust Spherical aerosols Air pollution

  5. Lidar dust and spherical extinction coefficients & OPC OPC data 0.3-1 mm Volume concentration 1-2 Size 2-3 3-4 4-5 > 5

  6. http://sprintars.riam.kyushu-u.ac.jp/indexe.html BC, OM, sulfate, sea salt, soil dust

  7. Development of data analysis methods 1β+1δ method to estimate dust and spherical aerosols (Sugimoto et al., 2003; Shimizu et al., 2004) 2β+1δ(switch) method to estimate dust (or sea-salt) and water soluble* (Nishizawa et al., 2007) 2β+1δ method (using spheroid model) to estimate dust, sea-salt and water soluble (Nishizawa et al.) 1α+2β+1δ(switch) method to estimate (dust or sea-salt), water soluble and black carbon (Nishizawa et al., 2008) 1α+2β+1δ to estimate dust, water soluble, black carbon or sea-salt (for EarthCARE ATLID, Nishizawa et al.) 2α+3β+2δ method to estimate dust, sea-salt, water soluble, black carbon and particle size of water soluble (being developed) The algorithm consider external mixing of aerosol components and prescribe the optical properties for each component *Water-soluble aerosol: a mixture of sulfate, nitrate, and organic carbon

  8. 1 + 1 2 532, DS Spherical 1064 532,|| Water-soluble + Dust (>0.1) or Water-soluble + Sea-salt (<0.1) Nishizawa et al. [2007] DS Spherical + Dust Sugimoto et al. [2003] 532 WS SS NIES aerosol classification algorithms using 2+1 Mie lidar WS: water-soluble particles SS: Sea-salt DS: Dust

  9. 532, DS 1064 532,|| SS WS Assumptions ・Log-normal size distribution ・Mode radius, standard deviation, refractive indexes are prescribed ・Spheroid particles for dust 2+1 algorithm Water-soluble + Dust + Sea-salt WS: water-soluble particles SS: Sea-salt DS: Dust

  10. a b [Dubovik et al. 2006] Spheroid model Axis Ratio  = a/b [Mishchenko et al. 1997] Lidar ratio Depolarization ratio

  11. DS 1064 532 532 WS BC Assumptions ・Log-normal size distribution ・Mode radius, standard deviation, refractive indexes are prescribed 1(532) + 2(532,1064) 1 + 2 algorithm Set S=50sr to consider the non-sphericity of dust Water-soluble + Dust + BC

  12. 2 2+1 Water-soluble Water-soluble Dust Dust Sea-salt Sea-salt Total Total AOT (532) Angstrom AOT (532) Angstrom 60% overestimation Agreement within 5% Comparison with Skyradiometer

  13. 1+1+ 1 algorithm: Absorption + Depolarization  Water-soluble* + Dust + Black carbon  Water-soluble* + Dust + Sea-salt Algorithm for ATLID The algorithm consider external mixing of aerosol components and prescribe the optical properties for each component *Water-soluble aerosol: a mixture of sulfate, nitrate, and organic carbon

  14. Over Land DS DS 355, 355, S > Sth 355,|| 355,|| S < Sth 355 355 SS WS WS BC Water-soluble + Dust + Sea-salt Water-soluble + Dust + Black carbon Over Sea NIES 1 + 1 + 1 algorithm Depolarization / absorption properties

  15. 1+2 algorithm 1+1+1 algorithm Water-soluble Water-soluble Demonstration of 1 + 1 + 1 algorithm Dust Dust Soot Soot • 1(532)+2(532,1064)+1(532)data measured with HSRL and MSL on Apr. 8 2005 were used in the analysis. • The aerosol properties at 532 nm used in 2+1 algorithm were used in the analysis using 1+1+1 algorithm

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