Subsonic Assessment (SASS) Ozone and Nitrogen Oxide Experiment

The Microwave Temperature Profiler (MTP) is an airborne microwave radiometer developed by the Jet Propulsion Laboratory and later modified by NCAR. It measures thermal emissions from oxygen molecules in the atmosphere to prove temperature profiles above, below, and at flight level. It operates between 55 to 59 GHz and provides profiles every 17 seconds with 4 km horizontal spacing. MTP has a vertical resolution of 150 m near the aircraft.

The SAFS instruments determine wavelength dependent actinic flux from 280-420 nm. The actinic flux in combination with the absorption cross section and quantum yield molecular data will be used to calculate the photolysis frequencies of multiple photochemically important molecular processes, including O3, NO2, HONO, CH2O, H2O2, CH3OOH, HNO3, PAN, CH3NO3, CH3CH2NO3, and CH3COCH3.

Generic-Chemistry Related Sensors (Gen-Chemistry) refers to non-specific instruments on a platform used for atmospheric chemistry measurements. These are typically in situ analyzers that measure various chemical compounds such as trace gases, halocarbons, volatile organic compounds, nitrates, aerosols, and other chemical species. Measurements can include mixing ratio, composition, particle size, optical properties, and particle size distribution.

Generic-Atmospheric State (Gen-AtmsState) refers to non-specific instruments on a platform used for measurements of atmospheric state parameters. These are typically in situ sensors that measure temperature, pressure, humidity, and wind speed/direction. Types of atmospheric state instruments include thermometers, hygrometers, barometers, and anemometers.

This information will be added in future versions.

Generic-Chemical Ionization Mass Spectrometry (Gen-CIMS) refers to a non-specific CIMS instrument on a platform. A CIMS is an in situ mass spectrometer that measures gas species by ionizing the molecules through chemical reactions. They provide measurements of trace gases, organic compounds, inorganic compounds, halogen species, and reactive nitrogen species.

The Passive-Cavity Aerosol Spectrometer Probe (PCASP) is an in situ airborne optical spectrometer manufactured by Droplet Measurement Technologies. It measures the light scattered by particles to determine the aerosol size distribution and concentration in the 0.1 to 3.0 μm size range. PCASP operates at the 632 nm wavelength and has a typical sampling rate of 10 Hz.

The Soluble Acidic Gases and Aerosols (SAGA) is an in situ airborne sampler owned and operated by the University of New Hampshire. It uses a mist chamber and ion chromatography to collect and analyze select aerosol species. It can provide samples of nitric acid, chloride, sulfates, nitrates, chloride, sodium, potassium, ammonium, and calcium. SAGA has a typical sampling frequency of 5 to 15 minutes and has a detection limit of 1 to 25 pptv depending on the sampled species.

The Differential Absorption Carbon monOxide Measurements (DACOM) is an airborne in situ spectrometer system. It uses the differential absorption technique and an infrared tunable diode laser (TDL) to collect measurements of nitrous oxide (N2O), carbon dioxide (CO2), carbon monoxide (CO), and methane (CH4) in the atmosphere. DACOM operates across the 4.7, 4.5, and 3.3 μm wavelengths to access the absorption lines for CO, N2O, and CH4. It has a measurement frequency of 5 Hz and a precision of about 1 ppbv.

The Airborne Tropospheric Hydrogen Oxides Sensor (ATHOS) is an in situ airborne sensor developed by Penn State University. ATHOS uses a laser-induced fluorescence (LIF) technique to measure hydroxide (OH) and hydroperoxyl (HO2) in the atmosphere. ATHOS operates near the 308 nm wavelength, has a pulse repetition frequency of 3 kHz, and has a typical time resolution of 20-30 s. It was designed to be equipped on NASA’s DC-8 aircraft and can collect measurements of OH and HO2 in clear sky and light cloud conditions.

The Differential Absorption Lidar (DIAL) is an airborne lidar system designed at NASA’s Langley Research Center (LaRC). It uses four lasers to detect lidar backscatter to provide profile measurements of ozone and aerosols in the atmosphere. DIAL operates in the ultraviolet (289-300 nm) for ozone measurements and operates in the visible (572-600 nm) and infrared (1064 nm) for aerosols. It has a horizontal spatial resolution of approximately 15 km and has a measurement accuracy of 5 ppbv.

The Whole Air Sampler (WAS) is an airborne in-situ instrument that collects samples of air for analysis of trace gases, such as nonmethane hydrocarbons (NMHCs), Halocarbons, Alkyl Nitrates, and various sulfur compounds that are present in the troposphere. Air samples collected via the WAS then undergo gas chromatography and mass spectrometry to determine which gasses are present in the sample. The WAS collects samples every minute, which enables scientists to get a clear picture of the chemical composition of the environment as research aircraft pass through.

This data will be added in future versions.

The Condensation Nuclei Counter (CNC) is optical method for counting atmospheric aerosol particles.

The Printed Optical Particle Spectrometer (POPS) is an in situ spectrometer that measures particle size and number concentration. POPS is capable of flying on UAVs or balloons, and it collects a vertical profile of particle measurements. With a typical operating wavelength of 405 nm, POPS obtains observations roughly every second and measures particles ranging in size from 140 nm to 3000 nm.

The Diode Laser Hygrometer (DLH) is an in situ airborne hygrometer developed by NASA’s Langley Research Center (LaRC). It uses tunable diode laser absorption to measure water vapor in the atmosphere. DLH operates in the near-infrared region at around 1.4 μm and has a measurement frequency of 100 Hz. It can provide accurate measurements of water vapor even while flying through clouds.

The Forward Scattering Spectrometer Probe (FSSP) is an in situ airborne optical particle counter originally designed by Particle Measuring Systems, Inc. It provides particle size distribution by measuring the intensity of the light scattered by individual particles within the cloud. FSSP can detect particles within a diameter range of 0.5 to 47 μm. It operates at a wavelength of 633 nm and has a typical sampling frequency of 1 Hz.

The Langley Aerosol Research Group Experiment (LARGE) is an in situ airborne instrument suite that measures aerosol and cloud microphysical and optical properties such as size distribution, number concentration, and scattering and absorption coefficient. LARGE consists of multiple instruments including the Ultra-High Sensitivity Aerosol Spectrometer (UHSAS), Particle-Into-Liquid Sampler (PILS), Particle Soot Absorption Photometer (PSAP), Cloud and Aerosol Spectrometer (CAS), Cloud Imaging Probe (CIP), and additional cloud and aerosol sensors. The LARGE instruments operate across the 450-700 nm wavelength range, can detect particles in the size range between 0.003-20μm, and have a measurement frequency of 1 Hz. It is typically used for airborne measurements, but it also can be deployed on ground-based platforms such as vehicles.

NOx/NOxy is an in situ chemiluminescence instrument. It provides measurements of nitrogen oxides and ozone in the atmosphere at a spatial resolution better than 100m for typical DC-8 research flight speeds. NOx/NOxy can be utilized on ground-based, airborne, and shipborne platforms allowing it to be used in various types of atmospheric chemistry and air quality studies.

The Meteorological Measurement System (MMS) is an in situ airborne instrument used for measuring atmospheric state parameters. MMS provides high-resolution and accurate measurements of atmospheric pressure, temperature, and wind direction/speed immediately around the plane. Additional parameters can be derived such as potential temperature, true airspeed, turbulence dissipation rate, and Reynolds number. Measurements of all parameters are typically collected at a rate of 20 Hz.