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Monitoring the Climate Forcing Properties of Aerosols

Monitoring the Climate Forcing Properties of Aerosols. John A. Ogren NOAA Earth System Research Laboratory Global Monitoring Division (GMD) ( formerly CMDL). http://www.cmdl.noaa.gov/aero/. Legend NOAA affiliate short-term former sites. ESRL/GMD Aerosol Network. ALT. ALT. BRW. WSA.

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Monitoring the Climate Forcing Properties of Aerosols

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  1. Monitoring the ClimateForcing Properties of Aerosols John A. OgrenNOAA Earth System Research Laboratory Global Monitoring Division (GMD) ( formerly CMDL) http://www.cmdl.noaa.gov/aero/

  2. Legend NOAA affiliateshort-term former sites ESRL/GMD Aerosol Network ALT ALT BRW WSA BND WLG THD SGP KOS CSJ MLO NIM KCO SMO CPT SPO

  3. On-going Collaborative Stations ALT Environment Canada Chinese Academy of Meteorological Science DOE/ARM Univ. of Puerto Rico DOE/ARM South African Weather Service

  4. Clear-sky Aerosol RadiativeForcing over North Indian Ocean energy loss at top of atmosphere due to backscattering of sunlight to space -7.0 ± 1 W m-2 TOA heating of atmosphere due to aerosol absorption of sunlight +16.0 ± 2 W m-2 ATM cooling of surface due to aerosol absorption and backscattering -23 ± 2W m-2 SFC Source: Ramanathan et al., J. Geophys. Res., 2001 average for Jan - March, 1999; 0 - 20°N; a = 0.3

  5. Direct Aerosol Forcing of Climate • What are we after? • Change in surface and top-of-atmosphere energy budget due to scattering and absorption of sunlight by anthropogenic aerosols, for the entire globe. • What do we need to measure? • AEROSOL AMOUNT • Anthropogenic aerosol optical depth, a • Chemical measurements to determine anthropogenic fraction • AEROSOL PROPERTIES • absorption vs. scattering • scattering vs. angle • water uptake • What is our strategy? • Models+satellites provide global distribution of AMOUNT • Monitoring from surface and airplanes gives • validation data for models and satellites • climatology of aerosol PROPERTIES • Radiative transfer models derive forcing from AMOUNT and PROPERTIES • International collaborations are needed to determine the aerosol properties in relevant regions

  6. Collaborating Stations for Aerosols • ALT: Alert, Canada • GAW Global station, aerosols upgraded 2004 with NOAA/SEARCH funds • CPT: Capt Point, South Africa • GAW Global station, aerosols upgraded 2005 with U.S. State Dept. funds through GCOS • France (CNRS/Cachier) will provide chemical samplers • CSJ: Cape San Juan, Puerto Rico • NOAA/GMD regional station, established 2004 with GMD base funds and Univ. Puerto Rico instruments • WLG: Mt. Waliguan, China • GAW Global station, upgraded mid-90’s with GEF funds, upgraded 2005 with U.S. State Dept. funds through GCOS • Chinese Academy of Meteorological Sciences providing aerosol mass and composition measurements • Finnish Meteorological Institute providing aerosol size distribution measurements

  7. Collaborations Work at the PI Level • Host institute provides station infrastructure, sample inlet stack and tower, on-site operations, data QC, submission to GAW archive. • ESRL/GMD provides sampling system design, data acquisition software, data processing hardware and software, and operations support (advice, troubleshooting) • ESRL/GMD builds sampling system, both partners install system jointly.

  8. What Parameters are Measured? • Primary quantities • light scattering (ssp) and backscattering (sbsp) aerosol cross-sectional area for scattering per unit volume of air (m2 m-3,10-6 m-1 = 1 Mm-1) • light absorption coefficient (sap) • particle number concentration • Sampling conditions for ssp, sbsp, and sap • sample heating to keep RH <= 40% • switched impactors to provide two particle size ranges, D < 1 m and D < 10 m • three wavelengths, ca. 450, 550, and 700 nm • Derived properties • single-scattering albedo (scattering vs. absorption) • submicron scattering fraction (size dependence) • hemispheric backscatter fraction and asymmetry parameter (angular dependence) • Ångström exponent (wavelength dependence) • radiative forcing efficiency

  9. KEY FEATURES OF GMDAEROSOL SAMPLING SYSTEM • Heated inlet, so that all size cuts and optical measurements are performed at a low relative humidity. The sample is heated just enough to maintain the RH below 40% and the temperature below 40° C. • Measurements performed on two size-fractions, Dp < 1.0 mm (fine particles) and 1 < Dp < 10 mm (coarse particles) diameter. • Optical and chemical measurements can be synchronized so that they can be related quantitatively. • Real-time contamination control is possible, using Ntot, wind speed, and wind direction. • Highly-automated so that minimal operator attention is required.

  10. PSAP CPC Nephelometer GMD Basic Aerosol Sampling System MFC+Pump Inlet flow 150 lpm = 5*30 lpm at splitter System footprint is 0.9 x 0.6 m. Neph PSAP PM1 PM10 CPC A/D, PID, PC Drier switched impactors RH Splitter Inlet Heater

  11. GMD Aerosol Sampling System Exterior external pumpbox, filtered exhaust, thermostat-controlled cooling fan 10-m stack, 20-cm dia PVC pipe, 1000 lpm, Re=7100 base of stack showing access port for 5-cm dia stainless steel heated inlet (150 lpm) and bypass tee (850 lpm) Copies of this inlet system are deployed at NOAA (BRW, MLO, THD, BND, CSJ), ARM (SGP, AMF), and GAW (ALT, CPT, WLG) stations

  12. Rain Hat: Stainless Steel Cooking Pot

  13. Installation at Mt. Waliguan, China

  14. Installation at Cape Point

  15. NOAA Aerosol Inlet Passing Efficiency

  16. Construction Schematic (example) ftp://ftp.cmdl.noaa.gov/aerosol/doc/drawings

  17. Data Acquisition Software on Boot CD ftp://ftp.cmdl.noaa.gov/aerosol/etc/cpd/cpdlive.iso

  18. Quicklook Plots on Web http://www.cmdl.noaa.gov/aero/net/wlg/data.html

  19. Data Visualization

  20. Data Editing

  21. firewall GAW workstationat NOAA NOAA/GAW Aerosol Data Flow NOAA server Field data system ftp ssh + VNC ssh + rsync ssh + VNC ftp WDCAarchive ftp ssh + NX sftp World Data Center for Aerosols Site operator(local or remote)

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