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Home » Publication » Advanced imaging systems publications

Advanced imaging systems publications

National security publications March 1, 2014 Article

Tracking Elevated Pollution Layers with a Newly Developed Hyperspectral Sun/Sky Spectrometer (4STAR: Results from the TCAP 2012 and 2013 Campaigns

SRI International March 1, 2014

Total columnar water vapor (CWV), nitrogen dioxide (NO2), and ozone (O3) are derived from a newly developed, hyperspectral airborne Sun-sky spectrometer (4STAR) for the first time during the two intensive phases of the Two-Column Aerosol Project (TCAP) in summer 2012 and winter 2013 aboard the DOE G-1 aircraft. We compare results with coincident measurements. We find 0.045 g/cm2 (4.2%) negative bias and 0.28 g/cm2 (26.3%) root-mean-square difference (RMSD) in water vapor layer comparison with an in situ hygrometer and an overall RMSD of 1.28 g/m3 (38%) water vapor amount in profile by profile comparisons, with differences distributed evenly around zero. RMSD for O3 columns average to 3%, with a 1% negative bias for 4STAR compared with the Ozone Measuring Instrument along aircraft flight tracks for 14 flights during both TCAP phases. Ground-based comparisons with Pandora spectrometers at the Goddard Space Flight Center, Greenbelt, Maryland, showed excellent agreement between the instruments for both O3 (1% RMSD and 0.1% bias) and NO2 (17.5% RMSD and −8% bias). We apply clustering analysis of the retrieved products as a case study during the TCAP summer campaign to identify variations in atmospheric composition of elevated pollution layers and demonstrate that combined total column measurements of trace gas and aerosols can be used to define different pollution layer sources, by comparing our results with trajectory analysis and in situ airborne miniSPLAT (single-particle mass spectrometer) measurements. Our analysis represents a first step in linking sparse but intense in situ measurements from suborbital campaigns with total column observations from space.

Advanced imaging systems publications November 1, 2013 Article

Hyperspectral Aerosol Optical Depths from TCAP Flights

SRI International November 1, 2013

4STAR (Spectrometer for Sky-Scanning, Sun-Tracking Atmospheric Research), the world’s first hyperspectral airborne tracking sunphotometer, acquired aerosol optical depths (AOD) at 1 Hz during all July 2012 flights of the Two Column Aerosol Project (TCAP). Root-mean square differences from AERONET ground-based observations were 0.01 at wavelengths between 500-1020 nm, 0.02 at 380 and 1640 nm and 0.03 at 440 nm in four clear-sky fly-over events, and similar in ground side-by-side comparisons. Changes in the above-aircraft AOD across 3-km-deep spirals were typically consistent with integrals of coincident in situ (on DOE Gulfstream 1 with 4STAR) and lidar (on NASA B200) extinction measurements within 0.01, 0.03, 0.01, 0.02, 0.02, 0.02 at 355, 450, 532, 550, 700, 1064 nm, respectively, despite atmospheric variations and combined measurement uncertainties. Finer vertical differentials of the 4STAR measurements matched the in situ ambient extinction profile within 14% for one homogeneous column. For the AOD observed between 350-1660 nm, excluding strong water vapor and oxygen absorption bands, estimated uncertainties were ~0.01 and dominated by (then) unpredictable throughput changes, up to +/-0.8%, of the fiber optic rotary joint. The favorable intercomparisons herald 4STAR’s spatially-resolved high-frequency hyperspectral products as a reliable tool for climate studies and satellite validation.

Biomedical sciences publications August 1, 2013 Conference Paper

On the Potential to Enhance the Spatial Resolution of the Day/Night Band (DNB) Channel of the Visible and Infrared Imaging Radiometer Suite (VIRRS) for the Second Joint Polar Satellite System (JPSS-2) and Beyond

SRI International, Thomas Kilduff August 1, 2013

SRI Authors: Thomas Kilduff

Advanced imaging systems publications August 1, 2013 Article

Aberrant Basal Ganglia Metabolism in Fragile X Syndrome: A Magnetic Resonance Spectroscopy Study

SRI International August 1, 2013

Advanced imaging systems publications August 1, 2013 Article

Spectrometer for Sky-Scanning Sun-Tracking Atmospheric Research (4STAR): Instrument Technology

SRI International August 1, 2013

Advanced imaging systems publications August 1, 2013 Conference Paper

The Solar Orbiter Imager (SoloHI) Instrument for the Solar Orbiter Mission

SRI International August 1, 2013

Advanced imaging systems publications August 1, 2013 Conference Paper

Development and Test of an Active Pixel Sensor Detector for Heliospheric Imager on Solar Orbiter and Solar Probe Plus

SRI International August 1, 2013

Cyber & formal methods publications March 1, 2013 Conference Paper

Maximizing Availability of Content in Disruptive Environments by Cross-Layer Optimization

SRI International March 1, 2013

Advanced imaging systems publications May 1, 2011 Conference Paper

Comparison of 32 x 128 and 32 x 32 Geiger-Mode Apd FPAs for Single Photon 3D Ladar Imaging

SRI International May 1, 2011

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