Atmospheric Radiation Measurement Climate Research Facility US Department of Energy

ISDAC / RISCAM - Humidified Tandem Differential Mobility Analyzer (HTDMA)

1 April 2008 - 30 June 2008

Lead Scientist: Don Collins

Observatory: NSA

In conjunction with the ISDAC project, a Humidified Tandem Differential Mobility Analyzer (HDTMA) was used to characterize the size-resolved hygroscopicity of an aerosol. When coupled with a concurrently measured aerosol size distribution, these data can be employed: i) to predict the humidity dependent optical properties and CCN spectra of the aerosol population; ii) to constrain the atmospheric processes responsible for changes in particle size and properties; and iii) to isolate the properties and impact of a single particle type that is present in an external mixture. These measurements were particularly valuable for quantifying the contribution of specific classes of particles to the total CCN concentration.


Um J, GM McFarquhar, Y Hong, S Lee, C Jung, R Lawson, and Q Mo. 2015. "Dimensions and aspect ratios of natural ice crystals." Atmospheric Chemistry and Physics, 15(7), 10.5194/acp-15-3933-2015.
Research Highlight


Lawson RP. 2011. "Effects of ice particles shattering on the 2D-S probe." Atmospheric Measurement Techniques, 4(7), 10.5194/amt-4-1361-2011.

Vaden TD, D Imre, J Beranek, and A Zelenyuk. 2011. "Extending the capabilities of single particle mass spectrometry: I. Measurements of aerosol number concentration, size distribution, and asphericity." Aerosol Science and Technology, 45(1), 10.1080/02786826.2010.526155.


Roeder LR. 2008. 2008 Annual Report. DOE ARM Climate Research Facility. DOE/SC-ARM-0805.

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Campaign Data Sets

IOP Participant Data Source Name Final Data
Don Collins Tandem Differential Mobility Analyzer Order Data