Imagery

Pushbroom Imager for Cloud and Aerosol Research and Development - ARC

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)

Instrument Type
Spectrometer
Measurements
Imagery
Aircraft
ER-2 - AFRC
Point(s) of Contact
James D. Jacobson Jr.
(PI)
Pushbroom Imager for Cloud and Aerosol Research and Development - GSFC

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)

Instrument Type
Spectrometer
Measurements
Imagery
Aircraft
ER-2 - AFRC
Point(s) of Contact
Kerry G. Meyer
(PI)
Replaced By
PICARD ARC
Research Scanning Polarimeter

The NASA GISS Research Scanning Polarimeter (RSP) is a passive, downward-facing polarimeter that makes total radiance and linear polarization measurements in nine spectral bands ranging from the visible/near-infrared (VNIR) to the shortwave infrared (SWIR). The band centers are: 410 (30), 470 (20), 550 (20), 670 (20), 865 (20), 960 (20), 1590 (60), 1880 (90) and 2250 (130) nm where the full width at half maximum (FWHM) bandwidths of each channel is shown in parenthesis. Noise is minimized in the SWIR channels by cooling the detectors to less than 165K using a dewar of liquid nitrogen. The RSP measures the degree of linear polarization (DoLP) with an uncertainty of <0.2%. The polarimetric and radiometric intensity measurement uncertainties are each <3%. A full set of RSP’s design parameters are shown in Table 1 and more details on design and calibration can be found in Cairns et al. (1999) and Cairns et al. (2003).

The RSP is an along track scanning instrument that can make up to 152 measurements sweeping ± 60° from nadir along the aircraft's track every 0.8 seconds with each measurement having a 14 mrad (~0.8°) field-of-view. Each scan includes stability, dark reference and calibration checks. As the RSP travels aboard an aircraft, the same nadir footprint is viewed from multiple angles. Consecutive scans are aggregated into virtual scans that are reflectances of a single nadir footprint from multiple viewing angles. This format comprises the RSP’s Level 1C data.

RSP’s high-angular resolution and polarimetric accuracy enables numerous aerosol, cloud and ocean properties to be retrieved. These are Level 2 data products. A summary of the primary L2 aerosol, cloud and ocean data products retrieved by the RSP are shown in Table 3.

The RSP’s data archive is publicly available and organized by air campaign, each of which contain ReadMe files provided by the RSP team for their Level 1C and Level 2 data products, including important details about biases and uncertainties that data users should consult.

The RSP data archive is available at: https://data.giss.nasa.gov/pub/rsp/

A visualizer showing the times and locations of NASA Airborne Campaigns the RSP has taken part in is available at: http://rsp.apam.columbia.edu:3000

Table 1: RSP Design Parameters
Parameter Performance
Degree of Linear Polarization Uncertainty (%) <0.2
Polarization Uncertainty (%) <3.0
Radiometric Uncertainty (%) <3.0
Dynamic Range >104
Signal-to-Noise Ratio >2000 (with R=0.3)
Spectral Characteristics See table
Field of View >90o
Instantaneous FOV 14 mrad
Photodiode Detector Type:
·       Visible/NIR
·       Shortwave IR (temperature)		 Silicon
HgCdTe (165K)
SWIR Detector Cooling LN2 dewar
Data Rate <20 kbytes/sec
Size, W x L x H (cm) 40 x 64 x 34
Mass (kg) <20
Power (watts) <20 w/o heaters

 

Table 2: RSP Spectral Channels
Band ID λc (nm) Δλ (nm) Wavelength Type
V1 410 27 Visible
V2 470 20 Visible
V3 555 20 Visible
V4 670 20 Visible
V5 865 20 Near-IR
V6 960 20 Near-IR
S1 1590 60 Shortwave-IR
S2 1880 90 Shortwave-IR
S3 2250 130 Shortwave-IR

 

Table 3: Summary of L2 Data Products
Property Type Property Uncertainty Reference
Aerosol Aerosol Optical Depth for fine & coarse modes (column) 0.02/7% Stamnes et al., 2018
Aerosol Aerosol Size: effective radius for fine and coarse modes (column) 0.05 µm/10% Stamnes et al., 2018
Aerosol Aerosol Size: effective variance for fine and coarse modes (column) 0.3/50% Stamnes et al., 2018
Aerosol Aerosol Single Scatter Albedo (column) 0.03 Stamnes et al., 2018
Aerosol Aerosol Refractive Index (column) 0.02 Stamnes et al., 2018
Aerosol Aerosol Number Concentration 50% Schlosser et al., 2022
Aerosol Aerosol Top Height < 1 km Wu et al., 2016
Aerosol Surface Wind Speed 0.5 m s-1 Stamnes et al., 2018
Ocean Chlorophyll-A Concentration 0.7 mg m-3 Stamnes et al., 2018
Ocean Ocean diffuse attenuation coefficient 40% Stamnes et al., 2018
Ocean Ocean hemispherical backscatter coefficient 10% Stamnes et al., 2018
Cloud Cloud Flag 10%  
Cloud Cloud Albedo 10%  
Cloud Cloud Top Phase Index 10% van Diedenhoven et al., 2012
Cloud Cloud Top Effective Radius 1 um/10% Alexandrov et al., 2012a/b
Cloud Cloud Top Effective Variance 0.05/50% Alexandrov et al., 2012a/b
Cloud Cloud Mean Effective Radius 20% Alexandrov et al., 2012a/b
Cloud Cloud Optical Depth 10% Nakajima & King, 1990
Cloud Liquid Water Path 25% Sinclair et al., 2021
Cloud Columnar Water Vapor (Above Surface or Cloud) 10% Nielsen et al., 2023 (to be submitted)
Cloud Cloud Top Height 15% Sinclair et al., 2017
Cloud Cloud Droplet Number Concentration 25% Sinclair et al., 2021; Sinclair et al., 2019

 

Table 4: References
Alexandrov, M. D., Cairns, B., & Mishchenko, M. I. (2012). Rainbow fourier transform. Journal of Quantitative Spectroscopy and Radiative Transfer, 113(18), 2521-2535.
Alexandrov, M. D., Cairns, B., Emde, C., Ackerman, A. S., & van Diedenhoven, B. (2012). Accuracy assessments of cloud droplet size retrievals from polarized reflectance measurements by the research scanning polarimeter. Remote Sensing of Environment, 125, 92-111.
Cairns, B., E.E. Russell, and L.D. Travis, 1999: The Research Scanning Polarimeter: Calibration and ground-based measurements. In Polarization: Measurement, Analysis, and Remote Sensing II, 18 Jul. 1999, Denver, Col., Proc. SPIE, vol. 3754, pp. 186, doi:10.1117/12.366329.
Cairns, B., E.E. Russell, J.D. LaVeigne, and P.M.W. Tennant, 2003: Research scanning polarimeter and airborne usage for remote sensing of aerosols. In Polarization Science and Remote Sensing, 3 Aug. 2003, San Diego, Cal., Proc. SPIE, vol. 5158, pp. 33, doi:10.1117/12.518320.
Nakajima, T., & King, M. D. (1990). Determination of the optical thickness and effective particle radius of clouds from reflected solar radiation measurements. Part I: Theory. Journal of Atmospheric Sciences, 47(15), 1878-1893.
Schlosser, J. S., Stamnes, S., Burton, S. P., Cairns, B., Crosbie, E., Van Diedenhoven, B., ... & Sorooshian, A. (2022). Polarimeter+ lidar derived aerosol particle number concentration. CHARACTERIZATION OF REMOTELY SENSED, MODELED, AND IN-SITU DERIVED AMBIENT AEROSOL PROPERTIES.
Sinclair, K., Van Diedenhoven, B., Cairns, B., Yorks, J., Wasilewski, A., & McGill, M. (2017). Remote sensing of multiple cloud layer heights using multi-angular measurements. Atmospheric Measurement Techniques, 10(6), 2361-2375.
Sinclair, K., Van Diedenhoven, B., Cairns, B., Alexandrov, M., Moore, R., Crosbie, E., & Ziemba, L. (2019). Polarimetric retrievals of cloud droplet number concentrations. Remote Sensing of Environment, 228, 227-240.
Sinclair, K., van Diedenhoven, B., Cairns, B., Alexandrov, M., Dzambo, A. M., & L'Ecuyer, T. (2021). Inference of precipitation in warm stratiform clouds using remotely sensed observations of the cloud top droplet size distribution. Geophysical Research Letters, 48(10), e2021GL092547.
Stamnes, S., et al. "Simultaneous polarimeter retrievals of microphysical aerosol and ocean color parameters from the “MAPP” algorithm with comparison to high-spectral-resolution lidar aerosol and ocean products." Applied optics 57.10 (2018): 2394-2413.
van Diedenhoven, B., Fridlind, A. M., Ackerman, A. S., & Cairns, B. (2012). Evaluation of hydrometeor phase and ice properties in cloud-resolving model simulations of tropical deep convection using radiance and polarization measurements. Journal of the Atmospheric Sciences, 69(11), 3290-3314.
Wu, L., Hasekamp, O., van Diedenhoven, B., Cairns, B., Yorks, J. E., & Chowdhary, J. (2016). Passive remote sensing of aerosol layer height using near‐UV multiangle polarization measurements. Geophysical research letters, 43(16), 8783-8790.
Instrument Type
Polarimeter
Measurements
Imagery
Aircraft
ER-2 - AFRC,
P-3 Orion - WFF,
C-130- WFF,
King Air B-200 - LaRC,
J-31
Point(s) of Contact
Brian Cairns
(PI)
Enhanced MODIS Airborne Simulator

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

Instrument Type
Spectrometer
Measurements
Imagery
Aircraft
ER-2 - AFRC
Point(s) of Contact
Steve Platnick
(Co-I)
Enhanced MODIS Airborne Simulator

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

Instrument Type
Spectrometer
Measurements
Imagery
Aircraft
ER-2 - AFRC
Point(s) of Contact
Steve Platnick
(Co-I)
Three-View Cloud Particle Imager

The Three-View Cloud Particle Imager (3V-CPI) measures the size, shape and concentration of water drops and ice particles in clouds. The probe is a combination of three imaging instruments. Two of them comprise a 2D-S (Two- Dimensional Stereo hydrometeor spectrometer), in which two high-resolution (about 9 mm resolution) 2D probes image particles as they pass through laser beams that are orthogonal to each other. If particles also lie in the intersection of the sensitive areas of the two beams, they are seen by both 2D probes. In that case, the third instrument, a Cloud Particle Imager (CPI), is triggered to take a high-resolution picture, via a briefly illuminated high-resolution imaging array. This image has a pixel size of about 2.3 µm and so provides very high resolution for determining shapes and habits of ice crystals. The probe is particularly suited to imaging such crystals, but also provides good detection of other hydrometeors including large cloud droplets, drizzle and small rain drops, and other precipitation particles.

Instrument Type
Particle imager,
Spectrometer (in situ)
Measurements
Imagery
Aircraft
Gulfstream V - NSF
Point(s) of Contact
Jorgen Jensen
(PI)
WB-57 Ascent Video Experiment

The WB-57 Ascent Video Experiment (WAVE) provides both ascent and entry imagery and enables better observation of the Shuttle on days of heavier cloud cover and areas obscured from ground cameras by the launch exhaust plume. WAVE comprises a 32-inch-ball turret system mounted on the nose of two WB-57 aircraft. The turret houses an optical bench, providing installation of both HDTV and infrared cameras. Optics consist of an 11-inch-diameter, 4.2 meter fixed-focal-length lens. The system can be operated in both auto track and manual modes.

Instrument Type
Camera
Measurements
Imagery
Aircraft
WB-57 - JSC
Point(s) of Contact
Marty Ross
(PI)
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