NASA - National Aeronautics and Space Administration

This is a stratospheric lidar which is configured to fly on the NASA DC-8. It is a zenith viewing instrument, which makes vertical profile measurements of ozone, aerosols and temperature. Stratospheric ozone can be measured at solar zenith angles greater than ~30 degrees, while temperature and aerosols require SZA > 90 degrees. The SNR is maximized under dark coonditions. The measurement of Near-field water vapor measurements is being investigated and could be readily implemented. The instrument utilizes a XeCl excimer laser and a Nd-YAG laser to make DIAL, Raman DIAL, and backscatter measurements. A zenith viewing 16" telescope receives the lidar returns.

The APS is a passive sensor designed to gather high altitude dust particles for laboratory research. An APS paddle is deployed from a wingtip pod into stratosphere once the ER-2 has reached cruising altitude, and is retracted before descent. Both wire impactor and oil-film paddles are used. After approximately 40 hours of exposure, the sealed units are returned to the investigator for examination by an electron microscope. The returned particles can be the by-products of meteor decomposition in the upper atmosphere, or the products of massive volcanic eruptions.

The AOCI is a high altitude multispectral scanner built by Daedalus Enterprises, designed for oceanographic remote sensing. It provides 10-bit digitization of eight bands in the visible/near-infrared region of the spectrum, plus two 8-bit bands in the near and thermal infrared.

The Autonomous Modular Sensor (AMS) is an airborne scanning spectrometer that acquires high spatial resolution imagery of the Earth's features from its vantage point on-board low and medium altitude research aircraft. Data acquired by AMS is helping to define, develop, and test algorithms for use in a variety of scientific programs that emphasize the use of remotely sensed data to monitor variation in environmental conditions, assess global change, and respond to natural disasters.

The AMPR is a total power passive microwave radiometer producing calibrated brightness temperatures (TB) at 10.7, 19.35, 37.1, and 85.5 GHz. These frequencies are sensitive to the emission and scattering of precipitation-size ice, liquid water, and water vapor. The AMPR performs a 90º cross-track data scan perpendicular to the direction of aircraft motion. It processes a linear polarization feed with full vertical polarization at -45º and full horizontal polarization at +45º, with the polarization across the scan mixed as a function of sin2, giving an equal V-H mixture at 0º (aircraft nadir). A full calibration is made every fifth scan using hot and cold blackbodies. From a typical ER-2 flight altitude of ~20 km, surface footprint sizes range from 640 m (85.5 GHz) to 2.8 km (10.7 GHz). All four channels share a common measurement grid with collocated footprint centers, resulting in over-sampling of the low frequency channels with respect to 85.5 GHz.

The Airborne Multichannel Microwave Radiometer (AMMR) measures thermal microwave emission (in degrees Kelvin of brightness temperature) from surface and atmosphere. The up-looking radiometer at 21 and 37 GHz is a component of AMMR that was developed in the 1970's for precipitation measurements from an aircraft. The entire AMMR assembly covers a frequency range of 10-92 GHz. The 21/37 GHz unit has been flown in many types of aircraft during the past three decades in various field campaigns. It was refurbished during the year 2000 and is ready for flight again.

The fixed-beam Dicke radiometer has a beam width of about 6 degrees and is currently programmed with radiometric output every second. The temperature sensitivity is < 0.5 K, and the calibration accuracy is about ±4 K. The calibration is performed on the ground by viewing targets of known brightness (e.g., sky and absorber with known brightness temperature). The unit can be installed in one of the windows of the NASA P-3 aircraft so that it views at an angle of about 15º from zenith. Thus, it is necessary to spiral the aircraft gradually down to region below the freezing level in order to make measurements effectively. Ideally, the aircraft descends at the rate of about 1 km per 5 minutes. The system requires a bottle of N2 gas to keep the wave guides dry during the in-flight operation.

Isotopic CO2 measurements have been identified as an important component of NASA's Earth Science Enterprise's Carbon Cycle Initiative as part of its program in global climate change. The isotopic composition of atmospheric CO2, and especially its 13CO2/ 12CO2 ratio, is an established tool for understanding the details of the global carbon cycle, since this ratio can distinguish between oceanic and terrestrial biospheric sinks of CO2.

The Airborne Laser Infrared Absorption Spectrometer (ALIAS-II) is a very high resolution scanning tunable diode laser spectrometer which makes direct, simultaneous measurements of selectable combinations of HCl, NO2, CO, CO2, CH4, and N2O at sub-part-per-billion levels over a 3-30 second integration time. The measurement technique is based upon using tunable lead-salt and/or quantum cascade lasers operating from 3.4 to 8 microns wavelength scanning over absorption lines at 10 Hz recording second harmonic spectra. The instrument features an open-cradle multipass Herriott absorption cell with 15.24-cm diameter spherical zerodur mirrors coated with gold on chrome. The separation between the mirrors is adjustable allowing for a relatively small cell (0.75-m to 1.5-m) to contain an optical path length up to 120-m, depending on the spacing of the mirrors. Lasers and detectors are contained in a lightweight aluminum liquid nitrogen Dewar which can achieve a 28-hour hold time with only a 2 liter charge of liquid nitrogen. The instrument features custom laser current drives, signal chains, InSb detectors and preamps, 16-bit signal averager, analog signal conditioner, and digital I/O which are controlled by an onboard Pentium processor. Data is written to a ruggedized 2-Gb hard disk every 30 seconds and simultaneously transmitted via telemetry to ground station computers which provide backup storage of the data. The instrument weighs 36 kg and requires <56 watts for operation. Additional power up to 250 watts is available for structural heaters and current draw varies with atmospheric conditions.

ALIAS (Aircraft Laser Infrared Absorption Spectrometer) measures total water, total water isotopes, carbon monoxide, and carbon dioxide isotope ratios. No other instrument provides real-time measurements of carbon dioxide isotope ratios which are clear identifiers of atmospheric transport (18O/17O/16O for stratospheric intrusion, 13C/12C for anthropogenic signals). ALIAS easily adapts to changing mission priorities and can be configured to measure HCl, CH4, SO2, and N2O by simply replacing a semiconductor laser. These measurements contribute to Atmospheric Composition Focus Area research by providing key data on how convective processes affect stratospheric composition, the development of cirrus particles and their affect on Earth's radiative balance, and health of the ozone layer through measurement of chlorine partitioning.

The Airborne Synthetic Aperture Radar (AIRSAR) was an all-weather imaging tool able to penetrate through clouds and collect data at night. The longer wavelengths could also penetrate into the forest canopy and in extremely dry areas, through thin sand cover and dry snow pack. AIRSAR was designed and built by the Jet Propulsion Laboratory (JPL) which also manages the AIRSAR project. AIRSAR served as a NASA radar technology testbed for demonstrating new radar technology and acquiring data for the development of radar processing techniques and applications. As part of NASA’s Earth Science Enterprise, AIRSAR first flew in 1988, and flew its last mission in 2004.