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PSAP modification, calibration and field test

PSAP modification, calibration and field test

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PSAP modification, calibration and field test

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  1. PSAP modification, calibration and field test • PSAP modification: optics, program • OEC modification • Campaign at DRI • Field test during NEAQS

  2. PSAP modifications:Light sourceHoles Detectors

  3. Detector-weighted mean wavelengths: Blue: 471 nm, Green: 543 nm, Red: 659 nm

  4. Electronics modification

  5. Principle of the 3wl PSAP

  6. OEC L = 660 cm

  7. Effective length reduction by purge air

  8. OEC at DRI OEC at UW

  9. Reno Aerosol Optics StudyJune, 2002 John Ogren NOAA/CMDL

  10. Objectives • Characterize new and existing instruments for measuring aerosol light absorption and extinction • Quantify the uncertainty in the measurements of aerosol light absorption coefficient used by NOAA and ARM • Derive methods for determining spectral aerosol absorption from multi-wavelength measurements of absorption and (extinction - scattering)

  11. Participants • NOAA/CMDL (Ogren, Sheridan) • DRI (Arnott, Moosmüller, Varma) • U. Washington (Covert, Virkkula, Ahlquist) • NASA/Ames (Strawa, Schmid) and Picarro Networks, Inc. (Owano, Provencal) • Thermo Andersen/DLR (Schloesser, Petzold) • Portland State U. (Atkinson)

  12. Absorption Coefficient Measurements • Photoacoustic • #1 532 nm • #2 1047 nm • Filter-based • Particle/soot absorption photometer (PSAP) • #1: 565 nm • #2 460, 540, 660 nm • Aethalometer • #1 370, 470, 521, 590, 660, 880, 950 nm • #2 370, 430, 470, 521, 565, 700, 950 nm • Carusso (multi-angle) • #1: 670 nm

  13. Extinction Coefficient Measurements • Folded path extinction cell (6.6 m path) • #1 460, 540, 660 nm • Cavity-ring down (CRD) • #1: 532 nm • #2: 690, 1550 nm • #3: 532, 1064 nm

  14. Scattering Coefficient Measurements • TSI 3563 integrating nephelometer • #1 450, 550, 700 nm • Radiance M903 integrating nephelometer • #1: 530 nm • DRI integrating sphere nephelometer • #1: 532 nm • NASA/Ames CRD nephelometer • #1: 690 nm

  15. Typical scattering and extinction data

  16. EC & SC calculations 1) STP 2) Drift correction for EC 3) SC truncation correction, J.O. 4) SC interpolation to EC wavelengths: 5) Time shifts to match EC & SC data

  17. Extinction by White Aerosols (532nm)

  18. Extinction by Gray Aerosols (532nm) Notes: Data points represent kerosene soot runs with varying amounts of ammonium sulfate. Scattering measured with TSI nephelometer, absorption with DRI photoacoustic instrument.

  19. Ammonium sulfate experiments, 1-min data, nominal wls

  20. Latex experiments, 1 min data

  21. AS, varying wavelengths

  22. OEC vs Neph in white experiments

  23. EC-SC vs PSAP, 1-min data, all experimentsPSAP data corrected according to Bond et al. (1999).

  24. EC-SC vs PSAP, 1-min data, good experimentsPSAP data corrected according to Bond et al. (1999).

  25. Looking for theloading correction function f(Tr), 1 When looking for f(Tr), use

  26. Looking for theloading correction function f(Tr), 2

  27. Looking for theloading correction function f(Tr), 3

  28. Looking for theloading correction function f(Tr), 4

  29. Looking for theloading correction function f(Tr), 5 Vary interpolation wavelengths => minimizing yields different values for k0, k1 & g

  30. Using f(Tr) = k0 + k1ln(Tr) - g ssp

  31. PSAP response to white aerosol, 1

  32. PSAP response to white aerosol, 2

  33. PSAP response to white aerosol, 3

  34. PSAP response to white aerosol, 4

  35. PSAP response to white aerosol, 5 Is fit 3 worth the extra work?

  36. Field test during NEAQS, 1

  37. Field test during NEAQS, 2

  38. Field test during NEAQS, 3 Noise