Sunphotometer-Satellite Group

Group Members
Lead: Philip Russell (650-604-5404)
Robert Bergstrom (650-604-6261)
Cecilia Chang (650-604-5510)
Stephen Dunagan (650-604-4560)
Patrick Hamill (650-604-1710)
Roy Johnson (650-604-5933)
John Livingston (650-604-3386)
Stephanie Ramirez (650-604-3632)
Jens Redemann (650-604-5933)

Group Home Page

Research Objectives
The overall goal of the Sunphotometer-Satellite Group is to make major advances in understanding atmospheric composition and climate by studying how they are linked by solar energy. An important objective is to advance measurement science by designing and developing state-of-the-art instruments, by using them on aircraft, ground, and ship platforms, and by analyzing their data in conjunction with data from spacecraft and other suborbital measurements. More specific objectives include determining distributions of aerosols, water vapor, and ozone, as well as their radiative effects, in a variety of conditions and locations around the world to address questions posed in particular experiments. Example questions include:

  • How does the presence of a specific aerosol type (e.g., desert dust or organic aerosol) affect the agreement between satellite and sunphotometer measurements of aerosol optical depth?
  • Which wavelengths and types of satellite retrievals are most susceptible to errors when dealing with specific aerosol types and measurement conditions?
  • By how much do aerosols perturb the solar energy that drives climate (i.e., what is their radiative forcing) under particular conditions?
  • How do different types of radiometric measurements of water vapor (satellite and suborbital) compare to in situ measurements?
  • How do ozone gradients retrieved from space compare to those from airborne sunphotometric and in situ measurements?
  • How can the light-absorbing fraction of aerosols in their ambient state best be determined over broad wavelength ranges (ultraviolet-visible-infrared)?


Research Activities
Achieving the Group's objectives typically entails strong collaboration with a wide range of other measurers, analysts, and modelers in a variety of field experiments and other science team activities. Below we list experiments we participated in from 2004-present. For a complete list of previous experiments, see our website: . Our current and developing instruments are described at and respectively.

INTEX-B / MILAGRO: March 2006
Our airborne sunphotometer, AATS-14, flew on the Jetstream 31 (J31) aircraft based in Veracruz, Mexico, measuring aerosols and water vapor in outflow from Mexico City and biomass burning regions of Mexico and Central America.

ALIVE: September 2005
We performed the simultaneous validation of aerosol extinction profiles obtained from a Raman and a Micro Pulse Lidar using the NASA Ames Airborne Tracking 14-channel Sun photometer (AATS-14). During the Lidar Validation IOP, AATS-14 obtained extinction vertical profiles aboard the Jetstream 31 aircraft during spiral ascents and descents over the DOE SGP site.

INTEX-A / ITCT / ICARTT: July-August 2004
AATS-14 participated in INTEX-A and ITCT by flying on the twin turboprop Jetstream-31, based at Portsmouth, NH. Its goal was to help characterize aerosol radiative properties and effects in flights that sample polluted and clean air masses in coordination with measurements by other INTEX-ITCT platforms, including aircraft and a ship.

EVE: April 2004
The primary purpose of this experiment was to validate the over-ocean MODIS aerosol optical depth (AOD) measurements at 1.6 and 2.1micrometer ( m m) aboard the Terra and Aqua platform. The primary tool for validating the MODIS AOD is the 14-channel NASA Ames Airborne Tracking Sunphotometer, AATS-14, which flew aboard the CIRPAS Twin-Otter aircraft out of Monterey, CA.