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Aerosol and Cloud Microphysics Group
Atmospheric Physics Branch
Earth Science Division
Last Modified: Jan, 2006
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Cadenza
 Cavity Ring-Down Technology Applied to the Measurement of Aerosol Optical Properties

     Cadenza employs innovative cavity ring-down technology to make in-situ measurement of aerosol extinction and scattering coefficients. The instrument was developed for NASA-Ames Research Center by Picarro, Inc. under SBIR. Cadenza recently flew as part of the Asian Dust Above Monterey (ADAM) and the DOE Aerosol Intensive Operat-Ing Period flight experiments aboard the Naval Research Laboratory Twin-Otter aircraft.

     Cadenza measures extinction at two wavelengths: 675 nm and 1550 nm. An example of Cadenza extinction coefficient measurement is plotted at right. On May 25, 2003 Cadenza sampled this aerosol layer at about 620 mbar (about 12,500 ft altitude) over Oklahoma. It is expected that measurements such as these will help reduce the current uncertainty in estimates of the effect that aerosols have on climate, help pinpoint sources and effects of pollution, and provide valuable data needed for satellite validation.


 • Simultaneous measurement of aerosol extinction and scattering coefficient at 675 nm and extinction at 1550 nm
 • Derived quantities of Absorption Coefficient and single scattering albedo at 675 nm
 • Employs Continuous Wave Cavity Ring-Down (CW-CRD) technique
 • Accuracy: 1% at 1.0x10-6 m-1 (1.0 Mm-1) for 10 sec sample time
 • Small size: The instrument dimensions are: 19”Wx24”Lx8’H
 • Associated electronics rack: 35” High
 • Weight: 90 kg
 • Developed by Picarro, Inc. and NASA Ames Research Center
 • Applications: studies of visibility, climate forcing by aerosol, and the validation of aerosol retrieval schemes from satellite data.
 • Participation in
   – Reno Aerosol Optics Study, 2002, Lab intercomparison
   – DOE: Aerosol IOP, 2003; flight experiment on Twin Otter
   – Aerosol Dust Above Monterey (ADAM), 2003; flight experiment on Twin Otter
   – Extended MODIS wavelength Validation Experiment, 2004.
   – Caldecott Tunnel Experiment
   – Atmospheric Brown Cloud Post-Monsson Experiment, Maldives, 2004.