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Synonyms: 
DOE G-1
Associated content: 
Gulfstream G-1

B200 turn reversal seen from the DOE G-1

Spectrometer for Sky-Scanning, Sun-Tracking Atmospheric Research

4STAR (Spectrometers for Sky-Scanning Sun-Tracking Atmospheric Research; Dunagan et al., 2013) is an airborne sun-sky spectrophotometer measuring direct solar beam transmittance (i.e., 4STAR determines direct solar beam transmission by detecting direct solar irradiance) and narrow field-of-view sky radiance to retrieve and remotely sense column-integrated and, in some cases, vertically resolved information on aerosols, clouds, and trace gases. The 4STAR team is a world leader in airborne sun-sky photometry, building on 4STAR’s predecessor instrument, AATS-14 (the NASA Ames Airborne Tracking Sun photometers; Matsumoto et al., 1987; Russell et al. 1999, and cited in more than 100 publication) and greatly expanding aerosol observations from the ground-based AERONET network of sun-sky photometers (Holben et al., 1998) and the Pandora network of ground-based direct-sun and sky spectrometer (e.g, Herman et al., 2009).

4STAR is used to quantify the attenuated solar light (from 350 to 1650 nm) and retrieve properties of various atmospheric constituents: spectral Aerosol Optical Depth (AOD) from ultraviolet to the shortwave infrared (e.g., LeBlanc et al., 2020, Shinozuka et al., 2013); aerosol intensive properties - Single Scattering Albedo (SSA; e.g., Pistone et al., 2019), asymmetry parameter, scattering phase function, absorption angstrom exponent, size distribution, and index of refraction; various column trace gas components (NO2, Ozone, Water Vapor; e.g., Segal-Rosenheimer et al., 2014, with potential for SO2 and CH2O); and cloud optical depth, effective radius and thermodynamic phase (e.g., LeBlanc et al., 2015).

Some examples of the science questions that 4STAR have pursued in the past and will continue to address:

  • What is the Direct Aerosol Radiative Effect on climate and its uncertainty? (1)
  • How much light is absorbed by aerosol emitted through biomass burning? (1)
  • How does heating of the atmosphere by absorbing aerosol impact large scale climate and weather patterns? (1)
  • How does aerosol spatial consistency of extensive and intensive properties compare? (2)
  • How does the presence of aerosol impact Earth’s radiative transfer, with co-located high concentration of trace gas? (3, 5)
  • What is the impact of air quality from long-range transport of both aerosol particulates and column NO2 and Ozone, and their evolution? (3, 6)
  • What are the governing properties and spatial patterns of local and transported aerosol? (1)
  • How are cloud properties impacted near the sea-ice edge? (4)
  • In heterogeneous environments where clouds and aerosols are present, how much solar radiation is impacted by 3D radiative transfer? And how does that impact the aerosol properties? (5)

(1) ORACLES: Zuidema et al., doi:10.1175/BAMS-D-15-00082.1., 2016; LeBlanc et al., doi:10.5194/acp-20-1565-2020, 2020; Pistone et al., https://doi.org/10.5194/acp-2019-142, 2019;Cochrane et al., https://doi.org/10.5194/amt-12-6505-2019, 2019; Shinozuka et al., https://doi.org/10.5194/acp-20-11275-2020, 2020; Shinozuka et al., https://doi.org/10.5194/acp-20-11491-2020, 2020
(2) KORUS-AQ:  LeBlanc et al., doi:https://doi.org/10.5194/acp-22-11275-2022, 2022

(3) KORUS-AQ: Herman et al., doi:10.5194/amt-11-4583-2018, 2018
(4) ARISE: Smith et al., https://doi.org/10.1175/BAMS-D-14-00277.1, 2017; Segal-Rosenheimer et al., doi:10.1029/2018JD028349, 2018
(5) SEAC4RS: Song et al., doi: 10.5194/acp-16-13791-2016, 2016; Toon et al., https://doi.org/10.1002/2015JD024297, 2016
(6) TCAP: Shinozuka et al., doi:10.1002/2013JD020596, 2013; Segal-Rosenheimer et al., doi:10.1002/2013JD020884, 2014

Instrument Type: 
Spectrometer
Measurements: 
NO2, O3, H2O, Spectral Aerosol Optical Depth, Aerosol Extinction Angstrom Exponent, Aerosol Single Scattering Albedo, Aerosol Asymmetry Parameter, Aerosol Scattering phase function, Aerosol Size Distribution, Aerosol Complex Refractive Index, Cloud Optical Depth, Cloud droplet effective radius, Cloud Thermodynamic Phase, Cloud Liquid Water Content
Aircraft: 
P-3 Orion - WFF, C-130H - WFF, Convair 580 NRC, Gulfstream G-1 (DOE), DC-8 - AFRC
Point(s) of Contact: 
Meloe S. Kacenelenbogen (Co-I)

Gulfstream G-1

The Battelle G-1 has been operated as a Research Aircraft Facility at Pacific Northwest National Laboratory since 1991. The platform has provided steady support for the Department of Energy's (DOE) Atmospheric Science Program (ASP), the long-term goal of which is developing comprehensive understanding of the atmospheric processes that control the transport, transformation, and fate of energy related trace chemicals and particulate matter; the current focus of which is aerosol radiative forcing of climate: aerosol formation and evolution and aerosol properties that affect direct and indirect influences on climate and climate change. The platform is also available to non-DOE agencies (has flown for EPA, e.g.), and state and private entities, and now to NASA researchers through this Catalog. The aircraft’s 165 square feet of interior space is configured for maximum utility. Internal removable instrumentation racks and seats enable rapid reconfiguration as necessary. Inlets and sensors are mounted on aluminum inserts that replace selected windows. An onboard data acquisition system accommodates a wide range of analog and digital inputs. Instrumentation for measurement of state variables, including turbulent quantities, as well as navigation data are included in the base configuration.

Owner/Operator: 
Battelle, Pacific Northwest Division
Type: 
Conventional Aircraft, twin turboprop
Duration: 
6.0 hours (payload and weather dependent)
Useful Payload: 
3 078 lbs
Gross Take-off Weight: 
36 000 lbs
Onboard Operators: 
7 (including flight crew)
Max Altitude: 
25,000 MSL
Air Speed: 
250 knots
Range: 
1 500 Nmi
Power: 
400 A, 28VDC (up to 4KVA, 115VAC; up to 4KVA, 230 VAC)
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