1 / 6

Elisabeth Andrews, University of Colorado CIRES & NOAA/ESRL/GMD

Tandem nephelometer humidograph system Hygroscopic growth can provide information about the composition of the aerosol particles. *Some aerosol components take up water easily – NaCl , (NH 4 ) 2 SO 4 * Other aerosol constituents do not – fresh soot, dust

kamin
Download Presentation

Elisabeth Andrews, University of Colorado CIRES & NOAA/ESRL/GMD

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Tandem nephelometerhumidograph system Hygroscopic growth can provide information about the composition of the aerosol particles. *Some aerosol components take up water easily – NaCl, (NH4)2SO4 *Other aerosol constituents do not – fresh soot, dust light scattering measurements at controlled humidity can be used to track changes in aerosol hygroscopicity Elisabeth Andrews, University of Colorado CIRES & NOAA/ESRL/GMD

  2. Tandem nephelometerhumidograph system (deployed at Appalachian State University) TSI nephelometer measures aerosol light scattering at low relative humidity (RH<40%) Humidifier exposes aerosol from TSI nephelometer to humidified air (RH~85%) RR nephelometer measures aerosol light scattering at high relative humidity (RH~85%) Aerosol rack RR neph TSI neph Humidifier Hygroscopic growth factor =f(RH) f(RH)=scattering (RH=85%) scattering (RH=40%)

  3. Check valve allows CO2 to bypass rotameter Gravity feed Check valve Water reservoir TSI neph RR neph (3 lpm) RH humidifier MFM Emergency drain To pump (30 lpm) (33 lpm) X Water drain Water trap This NO solenoid is in impactor box. NO solenoids NO During measurement, sample air follows flow path shown by black arrows. During span check, normally open (NO) solenoids close and CO2 flows through normally closed (NC) solenoid and backwards through system. Red arrows show where CO2 flow is different than sample flow. NC CO2 Flow diagram does NOT reflect recent design change!

  4. PRADACS hypothesis addressed: “LRTAD has unique chemical and physical properties which influence clouds and cloud processes” This plot shows that clean marine aerosol particles have a f(RH) of ~2.0 Aerosol with different composition (smoke, dust, polluted marine) have lower f(RH) values. Ervens et al. [2007] has shown that f(RH) in conjunction with size distribution measurements can be used to predict cloud condensation nuclei concentrations at some locations.

  5. NOAA/ESRL/GMD aerosol group characterize climate forcing properties of aerosol particles understand factors that control these properties Depending on aerosol type, humidity can have strong influence on radiative forcing efficiency. Clean Marine Polluted Dust Radiative forcing efficiency (W m-2 AOD-1) Continental Polluted Marine Relative Humidity (%)

  6. Other measurements that would be useful Aerosol chemistry, size distribution, air mass trajectories Other needs – sample air needs to be dry. If CSJ casita is significantly cooler than outside then the current dilution drying scheme is not enough. recommend purchase of dilution drying system from Twin Towers recommend having on hand critical spares for aerosol system (RH sensorsand pumps are the two most common failure points) Schedule March/April – install humidograph and train on use, upgrade system software Summer Campaign– will make sure aerosol system and humidographare operating properly prior to campaign. Fall Campaign- will make sure aerosol system and humidographare operating properly prior to campaign.

More Related