Atmospheric Radiation Measurement Climate Research Facility US Department of Energy
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aoshtdma

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AOS Humidified Tandem Differential Mobility Analyzer (aoshtdma)

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The humidified tandem differential mobility analyzer (HTDMA) is part of the aerosol observing system (AOS).

It measures how aerosol particles of different initial dry sizes grow or shrink when exposed to changing relative humidity (RH). It uses two different mobility analyzers (DMA) and a humidification system to make the measurements.

One DMA selects a narrow size range of dry aerosol particles, which are exposed to varying RH conditions in the humidification system. The second (humidified) DMA scans the particle size distribution output from the humidification system.

Scanning a wide range of particle sizes enables the second DMA to measure changes in size or growth factor (growth factor = humidified size/dry size) due to water uptake by the particles. A condensation particle counter (CPC) downstream of the second DMA counts particles as a function of selected size in order to obtain the number size distribution of particles exposed to different RH conditions.

Measurements

Concentration of aerosol
Total scan concentration over all bins

Location

ACAPEX (ARM Cloud Aerosol Precip Experiment); Mobile Facility
  • Latitude: None
  • Longitude: None
  • Publication Date: 2015-01-05
  • Start Date: 2015-01-05
  • End Date: 2015-02-11
  • Last Updated: 2017-09-25

Instrument Mentor

https://www.arm.gov/connect-with-arm/organization/instrument-mentors/list#htdma

Gunnar Senum
Brookhaven National Laboratory
Daniel Cziczo
Massachusetts Institute of Technology
Cynthia Salwen
Brookhaven National Laboratory
Janek Uin
Brookhaven National Laboratory

DOI / Citation

http://dx.doi.org/10.5439/1095581
Atmospheric Radiation Measurement (ARM) user facility. 2015, updated hourly. Humidified Tandem Differential Mobility Analyzer (AOSHTDMA). 2015-01-05 to 2015-02-11, ARM Mobile Facility (ACX) Off the Coast of California - NOAA Ship Ronald H. Brown; AMF2 (M1). Compiled by J. Uin, D. Cziczo, C. Salwen and G. Senum. ARM Data Center. Data set accessed at http://dx.doi.org/10.5439/1095581.