Synonyms: 
DC8
DC-8
NASA DC8
Associated content: 

High Frame Rate Slit-less Spectrograph

Provides spectral (and imaging) information at a rate of 1000 frames per second for detection of ablation anomalies, flicker in bowshock emissions, spacecraft rotation, and wake.

The instrument consists of a digital intensified CCD camera capable of 1000 frames per second, equipped with a 600 l/mm objective transmission grating.

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HR-732 Aerial Cameras

Hycon HR-732 cameras are used to acquire high resolution photography in a 9 x 18 inch format. These cameras can be flown in pairs or one camera may be paired with an RC-10 mapping camera. The HR-732s acquire high resolution photography with twenty-four inch focal length lenses providing an image scale of half-mile to the inch. The large scale high resolution photography provided by these cameras is used by agencies such as the Forest Service for timber resource management and by the Fish and Wildlife Service for wetlands inventories and wildlife habitat mapping.

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Goodrich Clear Air Turbulence Data Collection

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Georgia Tech NO Instrument

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Georgia Tech Laser-Induced Fluorescence

The Georgia Tech Laser-Induced Fluorescence instrument measures nitric oxide (NO), formaldehyde (HCHO), and nitrogen dioxide (NO2). Each species is measured by laser-induced fluorescence at reduced pressure. Ambient air is drawn in through a pinhole orifice into a pair of multipass White cells. The pressure in the White cells is maintained at 5-10 mbar to extend the fluorescence lifetime, and the multiple passes (typically 32-40) effectively extends the probe interaction volume. The ambient air is probed at 90o from the flow and the fluorescence collected at 90o to the flow and probe.

NO is probed at the 226 absorption line and monitored at the 247 nm fluorescence. The laser pulse and scattering will be time-gated out using microchannel plate detectors. The expected 2-sigma limit of detection is 5 pptv/min. Formaldehyde is probed at 353 nm and the fluorescence monitored in a range from 400 to 450 nm. The expected performance is 10 pptv/min. NO2 will be probed near 435 nm and the fluorescence around 780 nm collected. Its expected performance is 15 pptv/min. In each case, the probe wavelength will be alternately switched from the absorption feature to a nearby “off-line” position to determine the background. The actual frequency will be monitored in reference cells. Calbration is done by standard addition to the airflow. The light sources used are custom-built cavities pumped by a diode-pumped Nd:YAG laser operating at ~10 kHz.

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Direct beam Irradiance Airborne Spectrometer

A solar tracking Direct beam Irradiance Airborne Spectrometer (DIAS) is used for calculation of line of sight ozone and wavelength dependent aerosol optical depths.

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Forward Scattering Spectrometer Probe

The FSSP is of that general class of instruments called optical particle counters (OPCs) that detect single particles and size them by measuring the intensity of light that the particle scatters when passing through a light beam. A Helium Neon laser beam is focused to a diameter of 0.2 mm at the center of an inlet that faces into the oncoming airstream. This laser beam is blocked on the opposite side of the inlet with an optical stop, a "dump spot" to prevent the beam from entering the collection optics. Particles that encounter this beam scatter light in all directions and some of that scattered in the forward direction is directed by a right angle prism though a condensing lens and onto a beam splitter. The "dump spot" on the prism and aperture of the condensing lens define a collection angle from about 4º - 12º.

The beam splitter divides the scattered light into two components, each of which impinge on a photodetector. One of these detectors, however, is optically masked to receive only scattered light when the particles pass through the laser beam displaced greater than approximately 1.5 mm either side of the center of focus. Particles that fall in that region are rejected when the signal from the masked detector exceeds that from the unmasked detector. This defines the sample volume needed to calculate particle concentrations.

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Dual Channel Airborne tunable diode Laser Spectrometer

The instrument uses two-tone frequency modulation (TTFM) with signal detection at approximately equals 12 MHz. Multiplexing is achieved using a dichroic optical element and a mechanical chopper which blocks each beam alternately. A control program running on a dedicated digital signal processor (DSP) allows the registration of the full absorption line shape each millisecond and simultaneous zero overhead on-line data reduction using a multiple linear regression algorithm. Gas exchange through the compact multireflection cell (2.71 volume, total path 53 m.) takes place in approximately equals 200 ms and thus determines the instrument response time.

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Alan Fried (Co-I)

Chemical Ionization Mass Spectrometer

The CIMS instrument consists of a low pressure ion molecule reactor (IMR) coupled to a quadrupole mass filter by an actively pumped collisional dissociation chamber (CDC) and an octopole ion guide. The vacuum system is a 100 mm outer diameter stainless steel chamber evacuated with two small turbo pumps (70 l s-1). The mass filter is a set of 9.5 mm diameter quadrupole rods housed in the main vacuum chamber. The CDC is a short 80 mm diameter chamber that houses an octopole ion guide and is evacuated with a hybrid molecular drag pump. The IMR is evacuated with a scroll pump (300 l min-1) that also serves as the backing pump for the mass spectrometer.

Click here for the Collaborative Ground and Airborne Observations description page.

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DC-8 - AFRC, Gulfstream V - NSF
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Gas and Aerosol Measurement Sensor/Langley Airborne A-Band Spectrometer

GAMS/LAABS is a combination of the Gas and Aerosol Measurement System (GAMS) and the Langley Airborne A-Band Spectrometer (LAABS). The instruments are optically co-aligned and use a common pointing system to track the Sun through an aircraft view port. In the field the instrument provides line-of-sight (LOS) O3, NO2, O4, and water vapor measurements using both a SAGE III-like multiple linear regression algorithm and a full spectrum algorithm. Aerosol may also be derived for ‘enhanced’ conditions including polar stratospheric clouds and optically thin cirrus. Using profile data (1-D/2-D) transformed to GAMS/LAABS LOS geometry, quick-look validation/comparison products for SAGE III, AROTAL, AATS-14, SCIAMACHY, and other instruments will be obtained. The data from GAMS/LAABS will make possible crucial evaluations of SAGE III data processing possible following deployment. These activities include SAGE III etaloning/mirror correction validation, O2 spectroscopy and forward model verification, ozone spectroscopy near the O2 A band and 940-nm water vapor features, evaluation of the relative strength of spectroscopic features (e.g., water vapor features at 600 nm and 940 nm) and altitude registration validation using oxygen measurements.

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Gas and Aerosol Measurement Sensor (GAMS)

o Solar spectrometer with 1024 channels from ~ 430 to 1030 nm
o Provides measurements of LOS transmission spectra and
differential O3, H2O, O2, O4, and aerosol
o Solar imager to monitor scene homogeneity
o Focus on UV-Vis-Near-IR solar occultation only
o Designed to extend the technique into the troposphere
o Built space flight-like spectrometer, telescope, photon-to-bits
boards, & MCM (detector controller).
o COTS imager to establish imager performance requirements

Langley Airborne A-Band Spectrometer (LAABS)

• High spectral resolution (~0.035 nm) grating spectrometer with > 800
channels from ~759 to 771 nm
• Provides measurements of LOS transmission spectra for evaluation of
SAGE III O2 A-band forward model
• Originally developed to support CALIPSO (formerly PICASSO-CENA)
spaceborne A-band spectrometer
• Designed and fabricated by BATC to provide high spectral resolution
(~0.035 nm) radiance measurements in O2 A-band spectral region
(~765 nm)

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