Spectrometer

The Pushbroom Imager for Cloud and Aerosol Research and Development is a V/SWIR imaging spectrometer designed to support atmospheric research. It features an undistorted wide field of view, and 50 meter resolution pixels when flown on the ER-2 aircraft. It is intended to simulate existing satellite imager products (MODIS/VIIRS,) and to validate radiances and geophysical retrievals, with an emphasis on cloud and aerosol science. It will also be used to prototype future imager requirements and algorithms, and to contribute to multi-disciplinary NASA field studies. Instrument Type: Dual Offner Imaging spectrometer Measurements: V/SWIR imagery (205 bands, 400 – 2450nm, 50 deg. FOV)

Air-LUSI makes highly-accurate, SI-traceable measurements of lunar spectral irradiance.  These measurements can be used to validate or adjust current models of lunar spectral irradiance used for calibration Earth observing satellites.  Air-LUSI is initially being used to address the current 5-10% uncertainty in knowledge of exo-atmospheric spectral lunar irradiance. Improved lunar spectral irradiance model accuracy will help satellite instruments to use the Moon as an absolute calibration reference, greatly improving the versitility and speed of on-orbit satellite calibration.  Air-LUSI has two main subsystems:

• IRIS - IRradiance Instrument Subsystem is a non-imaging telescope with an integrating sphere feeding light via fiber optics to a spectrometer.
• ARTEMIS - Autonomous, Robotic TElescope Mount Instrument Subsystem keeps telescope fixed on the Moon to within less than 0.1°.  This system uses a tracking camera on the telescope and control computer.

We are targeting lunar phases withing 5° to 90° of the Full Moon.  Air-LUSI measurements lunar spectral irradiance with spectral resolution of 3.7 nm with 0.8 nm sampling from 300 nm to 1100 nm, with accuracy target of better than 1% (k=1).  Future system performance will include measurements out to 2500 nm with ≤ 10 nm resolution.  Demonstration flights with the Air-LUSI provided an unprecedented sub-percent level of accuracy <0.8% (k=1) relative uncertainty from 400 nm to 950 nm.  Future measurement accuracy is expected to be <0.5% (k=1).

Chi-WIS is a mid-infrared tunable diode laser off-axis integrated cavity output absorption spectrometer (ICOS) instrument for measurement of H2O and HDO in the upper troposphere and lower stratosphere. The high precision of the measurement allows detection of small changes in the HDO/H2O ratio that can be used to study water transport pathways and characterize the extent to which convection-driven water vapor perturbations propagate through the UT/LS to contribute to the overall stratospheric water budget. Chi-WIS participated in the 2017 StratoClim campaign onboard the M-55 Geophysica high altitude research aircraft measuring the isotopic composition of water vapor between 12 and 20 kilometers inside the Asian Summer Monsoon anticyclone.

The Pushbroom Imager for Cloud and Aerosol Research and Development is a V/SWIR imaging spectrometer designed to support atmospheric research. It features an undistorted wide field of view, and 50 meter resolution pixels when flown on the ER-2 aircraft. It is intended to simulate existing satellite imager products (MODIS/VIIRS,) and to validate radiances and geophysical retrievals, with an emphasis on cloud and aerosol science. It will also be used to prototype future imager requirements and algorithms, and to contribute to multi-disciplinary NASA field studies. Instrument Type: Dual Offner Imaging spectrometer Measurements: V/SWIR imagery (205 bands, 400 – 2450nm, 50 deg. FOV)

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

The Enhanced MODIS Airborne Simulator (EMAS) is a multispectral scanner configured to approximate the Moderate-Resolution Imaging Spectrometer (MODIS), an instrument orbiting on the NASA Terra and Aqua satellites. MODIS is designed to measure terrestrial and atmospheric processes. The EMAS was a joint development project of Daedalus Enterprises, Berkeley Camera Engineering, the USU Space Dynamics Laboratory, and Ames Research Center. The EMAS system acquires 50-meter spatial resolution imagery, in 38 spectral bands, of cloud and surface features from the vantage point of the NASA ER-2 high-altitude research aircraft.

Instrument Type: Multispectral Imager
Measurements: VNIR/SWIR/LWIR Imagery

The Enhanced MODIS Airborne Simulator (EMAS) is a multispectral scanner configured to approximate the Moderate-Resolution Imaging Spectrometer (MODIS), an instrument orbiting on the NASA Terra and Aqua satellites. MODIS is designed to measure terrestrial and atmospheric processes. The EMAS was a joint development project of Daedalus Enterprises, Berkeley Camera Engineering, the USU Space Dynamics Laboratory, and Ames Research Center. The EMAS system acquires 50-meter spatial resolution imagery, in 38 spectral bands, of cloud and surface features from the vantage point of the NASA ER-2 high-altitude research aircraft.

Instrument Type: Multispectral Imager
Measurements: VNIR/SWIR/LWIR Imagery

mini-DOAS uses the Differential Optical Absorption Spectroscopy (DOAS) technique to identify and quantify trace gases using their narrow band absorptions.

This instrument studies:

1) the transport of short-lived halogenated species and their decay products to the stratosphere and the subsequent influence to the photochemistry and budget of Bromine (BrO) in the TTL.
2) the potential impact of halogen oxides to directly destroy UT/LS ozone.

This optical spectrometer measures the size and shape of particles from 100 to 6200 µm in diameter.