Monday, 15 January 2007
The Atmospheric Radiation Measurement program Tandem Differential Mobility Analyzer: Instrument description and summary of 1st year of data
Exhibit Hall C (Henry B. Gonzalez Convention Center)
A differential mobility analyzer / tandem differential mobility analyzer (DMA / TDMA) system was integrated into the Aerosol Observing System trailer at the Atmospheric Radiation Measurement Southern Great Plains site in Oklahoma in September, 2005. This instrument is used to continuously characterize the size-resolved concentration, hygroscopicity, and volatility of submicron particles. These data are used to infer aerosol composition and are used to predict humidity-dependent light scattering properties and critical supersaturation-dependent CCN concentration. Currently, aerosol size distributions and size-resolved hygroscopicity at 7 particle sizes are measured roughly 25 times per day. Once-daily measurements of the size-resolved hydration state of the aerosol are made to facilitate comparison of in situ and remote sensing measurements when the ambient RH is intermediate of the efflorescence and deliquescence points of typical aerosol types. All measured distributions are fitted using series of lognormals to assist users in examining changes in aerosol concentration and properties occurring over a range of timescales. An overview of the DMA / TDMA system and a summary of the dataset acquired to date will be presented.