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.

ACLAIM is a 2-micron lidar operating at 100 pulses per second using an 8 cm diameter expanded beam. It was developed for advanced turbulence detection with applications to supersonic inlet control, mitigation of aircraft gust response and aircrew / passenger warning for improved seatbelt utilization.

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 Broadband CO2 lidar instrument operates on the principle of differential absorption. This means that the instrument examines the transmission of light through the atmosphere at two or more different wavelengths that are absorbed differently by the species one wishes to measure. There are then two principal elements involved in the measurement—the source and the detector. Passive systems use natural processes such as sunlight or atmospheric emission to generate a number of different wavelengths which are separated for analysis by the detector. Most laser based systems (eg. DIAL lidars) use two or more different laser sources to provide different wavelengths. These systems then might use the same detector for the multiple wavelengths using time separation or modulation to differentiate the signals coming from the different lasers.

This system, however, uses as a detector that can differentiate wavelengths just as conventional passive sensors. The detector was originally developed as the Fabry-Perot passive sensor measuring CO2 using reflected sunlight. Our new approach is made possible by the emergence of a new type of source—the superluminescent light emitting diode (SLED). The SLED has the same high brightness and collimation characteristics as a conventional laser but it emits light over a broader range of wavelengths than conventional lasers. This permits a differential absorption measurement employing a single source with wavelength differentiation in the detector.

ATHOS uses laser-induced fluorescence (LIF) to measure OH and HO2 simultaneously. OH is both excited and detected with the A2Σ+ (v’=0) → X2π (v”=0) transition near 308 nm. HO2 is reacted with reagent NO to form OH and is then detected with LIF. The laser is tuned on and off the OH wavelength to determine the fluorescence and background signals. ATHOS can detect OH and HO2 in clear air and light clouds from Earth's surface to the lower stratosphere. The ambient air is slowed from the aircraft speed of 240 m/s to 8-40 m/s in an aerodynamic nacelle. It is then pulled by a vacuum pump through a small inlet, up a sampling tube, and into two low-pressure detection cells - the first for OH and the second for HO2. Detection occurs in each cell at the intersection of the airflow, the laser beam, and the detector field-of-view.

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 utility of millimeter-wave radars have been successfully used for cloud sensing and cloud microphysical studies. Studies of the impact of cloud feedbacks on the earth's radiation budget have underscored the importance of having a means of measuring the vertical distribution of clouds. Millimeter-wave radars can provide this information under most conditions, with high resolution, using a relatively compact system.

The Airborne Cloud Radar (ACR) for profiling cloud vertical structure was developed by the Jet Propulsion Laboratory and the University of Massachusetts in 1996. It is a W-band (95 GHz) polarimetric Doppler radar designed as a prototype airborne facility for the development of the 94 GHz Cloud Profiling Radar (CPR) for NASA CloudSat mission.

The ACR is a third-generation millimeter-wave cloud radar. While adopting the well tested techniques used by its predecessors, ACR also has a number of new features including an internal calibration loop, frequency agility, digital I and Q demodulation, digital matched filtering, and a W-band low-noise amplifier.