Aerosol Observation System (AOS)
Instrument Categories: Aerosols
General Overview
The aerosol observation system (AOS) is the primary Atmospheric Radiation Measurement (ARM) platform for in situ aerosol measurements at the surface. The principal measurements are those of the aerosol absorption and scattering coefficients as a function of the particle size and radiation wavelength. Additional measurements include those of the particle number concentration, size distribution, hygroscopic growth, and inorganic chemical composition. The AOS measures aerosol optical properties to better understand how particles interact with solar radiation and influence the earth's radiation balance. The measurements are useful for calculating parameters used in radiative forcing calculations such as the aerosol single scattering albedo, asymmetry parameter, mass scattering efficiency, and hygroscopic growth. To learn more, see the preliminary data plots.
The system is located at the Southern Great Plains (SGP) site in Oklahoma and has been operational since the beginning of April 1996. The Aerosol Group at NOAA/Climate Monitoring and Diagnbostics Laboratory (CMDL), now the Global Monitoring Division (GMD), took over the mentorship of the AOS in early 1997. In March 2000, a long-term vertical profiling campaign began over the SGP site using a light aircraft. The measurements from the vertical profiles complement the surface measurements because the instrumentation on the airplane is similar to that at the SGP surface site. The aircraft measurements provide information on the aerosol vertical mixing. For more information, see the In-situ Aerosol Profiles (IAP) instrument page.
The IAP system underwent major upgrades in 2005 and 2006, including moving to a larger Cessna 206 airplane, installation of a more efficient inlet system that samples particles up to 8 um diameter, and addition of two more humidified nephelometers to allow better characterization of vertical profiles of aerosol hygroscopic growth. IAP data are available here.
Primary Measurements Taken
The following measurements are those considered scientifically relevant. Refer to the netCDF File Header Descriptions (Data Object Design Files) for the list of all available measurements, including those recorded for diagnostic or quality assurance purposes.
- Aerosol absorption
- Aerosol scattering
- Backscattered radiation
- Cloud condensation nuclei
- Hygroscopic growth
- Inorganic chemical composition
- Particle number concentration
- Particle size distribution
Available Value-Added Products
This instrument is an input to the following value-added products, which provide improved measurements or derived quantities.
- aip1ogren - AOS intensive properties
- aipavg1ogren - Derived: Hourly Averages of Aerosol intensive properties from AOS, Delene and Ogren et al, 2001
Available Datastreams
- aos - Aerosol Observing System (AOS): aerosol data, 1-min
- aosccn - Aerosol Observing System (AOS): cloud condensation nuclei data
Sites / Facilities
Note: Click the "
" to expand/collapse the list.
- North Slope Alaska (NSA)
- Southern Great Plains (SGP)
- Central Facility, Lamont, OK (C1)
- ARM Mobile Facility (FKB)
- Black Forest, Germany (M1)
- ARM Mobile Facility (NIM)
- Niamey, Niger (M1)
- ARM Mobile Facility (PYE)
- Point Reyes, CA (M1)
Mentor(s)
John Ogren
(303) 497-6210
John.A.Ogren@noaa.gov
Anne Jefferson
associate
(303) 497-6493
anne.jefferson@noaa.gov
Patrick Sheridan
associate
(303) 497-6672
patrick.sheridan@noaa.gov
