NASA - National Aeronautics and Space Administration

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.

In early 2000, the Ames Atmospheric Radiation Group completed the design and development of an all new Solar Spectral Flux Radiometer (SSFR). The SSFR is used to measure solar spectral irradiance at moderate resolution to determine the radiative effect of clouds, aerosols, and gases on climate, and also to infer the physical properties of aerosols and clouds. Additionally, the SSFR was used to acquire water vapor spectra using the Ames 25-meter base-path multiple-reflection absorption cell in a laboratory experiment. The Solar Spectral Flux Radiometer is a moderate resolution flux (irradiance) spectrometer with 8-12 nm spectral resolution, simultaneous zenith and nadir viewing. It has a radiometric accuracy of 3% and a precision of 0.5%. The instrument is calibrated before and after every experiment, using a NIST-traceable lamp. During field experiments, the stability of the calibration is monitored before and after each flight using portable field calibrators. Each SSFR consists of 2 light collectors, which are either fix-mounted to the aircraft fuselage, or on a stabilizing platform which counteracts the movements of the aircraft. Through fiber optic cables, the light collectors are connected to 2 identical pairs of spectrometers, which cover the wavelength range from (a) 350 nm-1000 nm (Zeiss grating spectrometer with Silicon linear diode array) and (b) 950 nm - 2150 nm (Zeiss grating spectrometer with InGaAs linear diode array). Each spectrometer pair covers about 95% of the incoming solar incident irradiance spectrum.

NASA’s Land, Vegetation and Ice Sensor (LVIS) is a wide-swath, high-altitude, full-waveform airborne laser altimeter and camera sensor suite designed to provide elevation and surface structure measurements over hundreds of thousands of square kilometers. LVIS is an efficient and cost-effective capability for mapping land, water, and ice surface topography, vegetation height and vertical structure, and surface dynamics. The LVIS Facility is comprised of two high-altitude scanning lidar systems plus cameras that have been integrated on numerous NASA, NSF, and commercial aircraft platforms providing a diverse and flexible capability to meet a broad range of science needs. The newest Facility lidar (LVIS-F) began operations in 2017 using a 4,000 Hz laser, and an earlier 1,000 Hz sensor built in 2010 has undergone various upgrades (LVIS-Classic). High-resolution, commercial off-the-shelf cameras are co-mounted with LVIS lidars providing geotagged image coverage across the LVIS swath. LVIS sensors have flown extensively for a wide range of science applications and have been installed on over a dozen different aircraft, most recently on NASA’s high-altitude Gulfstream-V jet based at Johnson Space Center

The LVIS lidars are full-waveform laser altimeters, meaning that the systems digitally record both the outgoing and reflected laser pulse shapes providing a true 3-dimensional record of the surface and centimeter-level range precision. Multiple science data products are available for each footprint, including the geolocated waveform vector, sub-canopy topography, canopy or structure height, surface complexity, and others. LVIS lidars map a ±6 degree wide data swath centered on nadir (e.g., at an operating altitude of 10 km, the data swath is 2 km wide). They are designed to fly at higher altitudes than what is typical for commercial lidars in order to map a wider swath with low incidence angles, avoid the need for terrain following, while operating at much higher speeds that maximize the range of the aircraft. Recent data campaigns include deployments to Antarctica, Greenland, Canada, Alaska, the conterminous US, Central America, French Guiana, and Gabon.

The DLH has been successfully flown during many previous field campaigns on several aircraft, most recently ACTIVATE (Falcon); FIREX-AQ, ATom, KORUS-AQ, and SEAC4RS (DC-8); POSIDON (WB-57); CARAFE (Sherpa); CAMP2Ex and DISCOVER-AQ (P-3); and ATTREX (Global Hawk). This sensor measures water vapor (H2O(v)) via absorption by one of three strong, isolated spectral lines near 1.4 μm and is comprised of a compact laser transceiver and a sheet of high grade retroflecting road sign material to form the optical path. Optical sampling geometry is aircraft-dependent, as each DLH instrument is custom-built to conform to aircraft geometric constraints. Using differential absorption detection techniques, H2O(v) is sensed along the external path negating any potential wall or inlet effects inherent in extractive sampling techniques. A laser power normalization scheme enables the sensor to accurately measure water vapor even when flying through clouds. An algorithm calculates H2O(v) concentration based on the differential absorption signal magnitude, ambient pressure, and temperature, and spectroscopic parameters found in the literature and/or measured in the laboratory. Preliminary water vapor mixing ratio and derived relative humidities are provided in real-time to investigators.

The Broadband Radiometers (BBR) consist of modified Kipp & Zonen CM-22 pyranometers (to measure solar irradiance) and CG-4 pyrgeometers (to measure IR irradiance) (see http://www.kippzonen.com/). The modifications to make these instruments more suitable for aircraft use include new instrument housings and amplification of the signal at the sensor. The instruments are run in current-loop mode to minimize the effects of noise in long signal cables. The housing is sealed and evacuated to prevent condensation or freezing inside the instrument. Each BBR has the following properties: Field-of-view: Hemispheric Temperature Range: -65C to +80C Estimated Accuracy: 3-5% Data Rate: 1Hz