Measurements of urban and regional particulate using CAPS PMex-based aerosol light extinction measurements

 
Poster PDF

Authors

Andrew Freedman — Aerodyne Research, Inc.
Timothy B Onasch — Aerodyne Research, Inc.

Paul L Kebabian — Aerodyne Research, Inc.

Category

Aerosol Properties

Description

Time series of aerosol extinction and absorption at 532 nm during CalNex 2010.
We present results of optical property characterization of ambient particulate during two field deployments where measurements of aerosol light extinction were obtained by using an Aerodyne Cavity Attenuated Phase Shift Particle Extinction Monitor (CAPS PMex). The CAPS PMex is a lightweight, compact instrument able to perform precise and accurate measurements (3-sigma detection limit of 3 Mm-1 for 1s integration time) of atmospheric aerosol particles in field conditions. Two CAPS PMex instruments (measuring extinction at 630 and 532 nm) were also deployed during the CalNex 2010 study (May 14–June 16) at the CalTech ground site in Pasadena, California. During the same time, a photoacoustic spectrometer (PAS, DMT) and an aethalometer instrument (Magee Sci.) measured particle light absorption of submicron aerosol particles from the same sample line as the CAPS PMex monitors (see figure for time series of extinction and absorption at 532 nm during CalNex 2010). We combine the CAPS PMex and the aethalometer data to provide multi-wavelength particle single-scattering albedo trends for the one-month campaign. Two CAPS PMex measuring extinction at 630 are also currently deployed in Steamboat Springs, Colorado, as part of the STORMVEX campaign (November 2010–April 2011), for which a primary goal is to characterize the role of aerosols, both natural and anthropogenic, in cloud and precipitation processes. A first CAPS PMex instrument is located at the mountaintop site (Storm Peak Laboratory, SPL, elevation 3200 m), whereas a second CAPS is located at the nearby Christie Peak site (elevation 2400 m) as part the ARM Mobile Facility (AMF2) payload. At both sites, complementary optical measurements of aerosol absorption and scattering are also performed, along with ancillary measurements of aerosol size distribution and cloud condensation nuclei. This optimal setup allows comparing trends of the aerosol single-scattering albedo between the two locations. The influence of local meteorology (e.g. thermal inversion) on optical properties of the aerosols throughout the vertical profile will be also discussed.