Synonyms: 
Water Vapor
Water

Turbulent Air Motion Measurement System

The TAMMS is composed of several subsystems including: (1) distributed pressure ports coupled with absolute and differential pressure transducers and temperature sensors, (2) aircraft inertial and satellite navigation systems, (3) a central data acquisition/processing system, and (4) water vapor instruments and potentially other trace gas or aerosol sensors.

Instrument Type: 
Point(s) of Contact: 

Uninhabited Aerial Vehicle Atmo Water Sensor Package

Measurements: 
Point(s) of Contact: 

Frost Point (NOAA)

The NOAA frost point instrument was designed to run unattended under the wing of NASA’s WB-57. An aircraft rated Stirling cooler provides cooling to 100 K. The cooler avoids consumables and provides a large temperature gradient that improves the response time. The vertical pylon houses the optics and provides aerodynamic pumping of the sample volume. At the bottom of the pylon there is a boundary layer plate and a vertical inlet that separates particles larger than 0.2 microns from the sampled air. There are two channels that use blue LEDs and scattered light to detect frost on the mirrors. Diamond mirrors are used for low thermal mass and high conductivity. The two channels are to be used to understand frost characteristics under flight conditions. High flow rates are used to decrease the shear boundary layer to facilitate diffusion through the boundary layer to the mirrors.

Measurements: 
Point(s) of Contact: 

Scanning High-Resolution Interferometer Sounder

The Scanning High-resolution Interferometer Sounder (S-HIS) is a scanning interferometer which measures emitted thermal radiation at high spectral resolution between 3.3 and 18 microns The measured emitted radiance is used to obtain temperature and water vapor profiles of the Earth's atmosphere in clear-sky conditions. S-HIS produces sounding data with 2 kilometer resolution (at nadir) across a 40 kilometer ground swath from a nominal altitude of 20 kilometers onboard a NASA ER-2 or Global Hawk.

Instrument Type: 
Measurements: 
Point(s) of Contact: 

NPOESS Airborne Sounder Testbed - Microwave

The NAST-M currently consists of two radiometers covering the 50-57 GHz band and a set of spectral emission measurements within 4 GHz of the 118.75 GHz oxygen line with eight single sideband and 9 double sideband channels, respectively. To be added prior to CRYSTAL-FACE are five double side band channels within 4 GHz of the 183 GHz water vapor line and a single band channel at 425 GHz. For clear air, the temperature and water vapor information provided by the 50-57 GHz, 118 GHz, and 183 GHz channels is largely redundant; but, for cloudy sky conditions the three bands provide information on the effects of precipitating clouds on the temperature and water vapor profile retrievals and enables sounding through the non-precipitating portion of the cloud, a feature particularly important for CRYSTAL-FACE.

Instrument Type: 
Measurements: 
Point(s) of Contact: 

Raman Airborne Spectroscopic Lidar

The Raman Airborne Spectroscopic Lidar (RASL) consists of a 15W ultraviolet laser, a 24-inch (61-centimeter) diameter Dahl-Kirkham telescope, a custom receiver package, and a structure to mount these components inside an aircraft. Both the DC-8 at NASA Dryden and the P-3 at NASA/Wallops are aircrafts that could carry RASL. The system is unique because it requires the largest window ever put into either of these aircraft. A fused-silica window, diameter of 27 inches (68.6 centimeters) and 2.375 inches (6 centimeters) thick is needed to withstand the pressure and temperature differentials at a 50,000-foot (15.2-kilometer) altitude.

In June through August of 2007, RASL flew numerous times on board a King Air B-200 aircraft out of Bridgewater, VA, in support of the 2007 Water Vapor Validation Experiments (WAVES) campaign. The WAVES campaign was a series of field experiments to validate satellite measurements. RASL data, along with data from ground-based and balloon-borne instruments, were used to assess the CALIPSO and TES instruments and for studies of mesoscale water vapor variability. During the test flights, RASL produced the first-ever simultaneous measurements of tropospheric water vapor mixing ratio and aerosol extinction from an airborne platform.

Instrument Type: 
Aircraft: 
Point(s) of Contact: 

JPL Mark IV Balloon Interferometer

The MkIV interferometer operates in solar absorption mode, meaning that direct sunlight is spectrally analyzed and the amount of various gases at different heights in the Earth's atmosphere is derived from the shapes and depths of their absorption lines. The optical design of the MkIV interferometer is based largely on that of the ATMOS instrument, which has flown four times on the Space Shuttle. The first three mirrors in the optical path comprise the suntracker. Two of these mirrors are servo-controlled in order to compensate for any angular motion of the observation platform. The subsequent wedged KBr plates, flats, and cube-corner retro-reflectors comprise a double-passed Michelson interferometer, whose function is to impart a wavelength-dependent modulation to the solar beam. This is achieved by sliding one of the retro-reflectors at a uniform velocity so that the recombining beams interfere with each other. A paraboloid then focusses the solar beam onto infrared detectors, which measure the interferometrically modulated solar signal. Finally, Fourier transformation of the recorded detector outputs yields the solar spectrum. An important advantage of the MkIV Interferometer is that by employing a dichroic to feed two detectors in parallel, a HgCdTe photoconductor for the low frequencies (650-1850 cm-1) and a InSb photodiode for the high frequencies (1850-5650 cm-1), the entire mid-infrared region can be observed simultaneously with good linearity and signal-to-noise ratio. In this region over 30 different gases have identifiable spectral signatures including H2O, O3, N2O, CO, CH4, NO, NO2, HNO3, HNO4, N2O5, H2O2, ClNO3, HOCl, HCl, HF, COF2, CF4, SF6, CF2ClCFCl2, CHF2Cl, CF2Cl2, CFCl3, CCl4, CH3Cl, C2H2, C2H6, OCS, HCN, N2, O2, CO2 and many isotopic variants. The last three named gases, having well known atmospheric abundances, are important in establishing the observation geometry of each spectrum, which otherwise can be a major source of uncertainty. Similarly, from analysis of T-sensitive CO2 lines, the temperature profile can be accurately determined. The simultaneity of the observations of all these gases greatly simplifies the interpretation of the results, which are used for testing computer models of atmospheric transport and chemistry, validation of satellite data, and trend determination.

Although the MkIV can measure gas column abundances at any time during the day, the highest sensitivity to atmospheric trace gases is obtained by observing sunrise or sunset from a balloon. The very long (~ 400 km) atmospheric paths traversed by incoming rays in this observation geometry also make this so-called solar occultation technique insensitive to local contamination.

Instrument Type: 
Aircraft: 
Balloon, DC-8 - AFRC
Point(s) of Contact: 

Harvard Integrated Cavity Output Spectroscopy

The Harvard CRDS/ICOS instrument is an absorption spectrometer that uses the relatively new and highly sensitive techniques of integrated cavity output spectroscopy (ICOS) and cavity ringdown spectroscopy (CRDS) with a high-finesse optical cavity and a cw quantum cascade laser (QCL) source. The primary spectroscopic technique employed is ICOS, in which intra-cavity absorption is measured from the steady-state output of the cavity. Light from a high power, tunable, single mode, solid-state laser source is coupled into a cavity consisting of two concave, highly reflective mirrors (R ≈ 0.9999), through which air continuously flows. The laser is scanned over a spectral region of 1–2 cm-1 containing an absorption feature, and the cavity output is detected by an LN2-cooled HgCdTe detector. The resultant output approximates an absorption spectrum with an effective pathlength of > 5 km, far greater than that of standard multipass Herriott or White cells.

Instrument Type: 
Measurements: 
Point(s) of Contact: 

Harvard Lyman-α Photofragment Fluorescence Hygrometer

The Harvard Water Vapor (HWV) instrument combines two independent measurement methods for the simultaneous in situ detection of ambient water vapor mixing ratios in a single duct. This dual axis instrument combines the heritage of the Harvard Lyman-α photo-fragment fluorescence instrument (LyA) with the newly designed tunable diode laser direct absorption instrument (HHH). The Lyman-α detection axis functions as a benchmark measurement, and provides a requisite link to the long measurement history of Harvard Lyman-α aboard NASA’s WB-57 and ER-2 aircraft [Weinstock et al., 1994; Hintsa et al., 1999; Weinstock et al., 2009]. The inclusion of HHH provides a second high precision measurement that is more robust than LyA to changes in its measurement sensitivity [Smith et al., in preparation]. The simultaneous utilization of radically different measurement techniques facilitates the identification, diagnosis, and constraint of systematic errors both in the laboratory and in flight. As such, it constitutes a significant step toward resolving the controversy surrounding water vapor measurements in the upper troposphere and lower stratosphere.

Instrument Type: 
Measurements: 
Point(s) of Contact: 

JPL Laser Hygrometer

The JPL Laser Hygrometer (JLH) is an autonomous spectrometer to measure atmospheric water vapor from airborne platforms. It is designed for high-altitude scientific flights of the NASA ER-2 aircraft to monitor upper tropospheric (UT) and lower stratospheric (LS) water vapor for climate studies, atmospheric chemistry, and satellite validation. JLH will participate in the NASA SEAC4RS field mission this year. The light source for JLH is a near-infrared distributed feedback (DFB) tunable diode laser that scans across a strong water vapor vibrational-rotational combination band absorption line in the 1.37 micrometer band. Both laser and detector are temperature‐stabilized on a thermoelectrically-cooled aluminum mount inside an evacuated metal housing. A long optical path is folded within a Herriott Cell for sensitivity to water vapor in the UT and LS. A Herriott cell is an off-axis multipass cell using two spherical mirrors [Altmann et al., 1981; Herriott et al., 1964]. The laser beam enters the Herriott cell through a hole in the mirror that is closest to the laser. The laser beam traverses many passes of the Herriott cell and then returns through the same mirror hole to impinge on a detector.

Instrument Type: 
Measurements: 
Point(s) of Contact: 

Pages

Subscribe to RSS - H2O