DRI Aerosol Optics at the SGP CART Site and on the Twin Otter

1. DRI Aerosol Optics at the SGP CART Site and on the Twin Otter Objectives: Quantify aerosol scattering and absorption at the ground and aloft. Link laboratory (Reno Aerosol Optics Experiment), ground-based, and aircraft measurements to assist with understanding instrument issues. Use complementary measurements from diverse instruments to compare and contrast opinions about aerosol optics. Use closure in the form of Extinction = Scattering + Absorption where possible to sort good and bad measurements. Pat Arnott, John Walker, Hans Moosmüller Desert Research Institute University of Nevada Reno NV

2. CART SITE IN-SITU AEROSOL OPTICS • AbsorptionDRI Photoacoustic: 532 nm and 1047 nm.**DRI 7 wavelength Aethalometer 370, 470, 521, 590, 660, 880, 950 nm.UNIV. WA Custom PSAP 467, 530, 660 nm.NOAA Standard PSAP 550 nm.* • ScatteringNOAATSI Nephelometer 450, 550, 700 nm. (Backscatter fraction as well.)*DRI Integrating Sphere Nephelemeter, 532 nm. Laser-based instrument with forward truncation angle ≈ 1 deg**THERMOANDERSON MIE instrument operating at 2 wavelengths. • ExtinctionDRI Cavity Ringdown Instrument, 532 nm. Modified from RAOS for more effective aerosol sampling, and to reduce the need for purge flow corrections.** * Instruments at both the GIF and AOS trailer (standard setup).** Instruments for closure comparison at 532 nm.

3. Aerosol Optics Instruments at the SGP CART SITE DRI PA absorption at 532 nm, 1047 nm, CRD, and IS Neph and PSAPs

4. Aerosol Absorption at the CART site: Time Series. Event around day 143 UTC most well-defined and agreed upon. 23 May 2003.

5. Aerosol Absorption at the CART site: Scatter Plots. Message: Agreement among PSAP’s, and between PA is less good than we have seen in the past.

6. Aerosol Optics Closure at the CART site: 532 nm Time Series

7. Aerosol Optics Closure at the CART site: 532 nm Scatter Plot

8. Aerosol Scattering at the CART site: 532 nm, DRI IS and TSI Interpolated Data (10 um cut on AOS, no cut on DRI).

9. Aerosol Scattering at the CART site: 532 nm, DRI IS and TSI Interpolated Data

10. 532 nm Single Scatter Albedo Histograms SGP CART SITE

11. IN-SITU AEROSOL OPTICS ALOFT • AbsorptionDRI Photoacoustic: 676 nm.UNIV. WA Custom PSAP 467, 530, 660 nm. • ScatteringUNIV. WA TSI NEPH 450, 550, 700 nm, and Humidification System.(More details from the UW).NASA AMESReciprocal Nephelometer 676 nm. • ExtinctionNASA AMES Cavity Ringdown Instrument, 676 nm.

12. Photoacoustic Measurements of Aerosol Light Absorption at 676 nm from the Twin Otter Aircraft

13. Pancakes Layers of Asian Smoke from the Air 27 May 3(Photo by Roy the Co-pilot)

14. May 27th: Layers Aloft Aerosol Optics at 660 nm.

15. May 27th: Layers Aloft Aerosol Light Absorption at 660 nm and 676 nm

16. Example of Photoacoustic Data Quality Metric Aloft.

17. A Single Layer was observed on 28 May 2003

18. Time series of light absorption from the 28th of May

19. CART SITE: ‘Validate’ the TSI and DRI neph comparisons. Compare light absorption values with the UW PSAP that was in the GIF trailer. (Hourly averages of all DRI Aerosol Optics Data are in the archive) To Do And Possible Papers AIRCRAFT: Comb cabin files for aircraft altitude and ambient pressure versus time to better assign an ambient Babs value to the photoacoustic data. (raw data and draft 2 minute time average data are in the archive.) (Collective Job) Assign time intervals to all legs, and do leg averages. Combine with CART SITE data when the aircraft was low over the site to compare data. PAPERS Instrument comparison from CART SITE data. 2. Measurements of aerosol optics aloft (instrument comparison and case studies), especially light absorption.

20. Thanks for your attention…