CV-990
Convair CV-990

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.

Gas Chromatography/Mass Spectrometry (GC-MS) is an in situ measurement technique used to analyze volatile organic compounds (VOCs) in the atmosphere. It employs gas chromatography to separate components of an air sample, and mass spectrometry to ionize, identify, and quantify gas species. GC-MS is utilized to detect VOCs, halocarbons, hydrocarbons, and various other pollutants. It can be used for ground-based or airborne operations.

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.

NOx/NOxy is an in situ chemiluminescence instrument that measures nitrogen oxides and ozone in the atmosphere. It offers a spatial resolution better than 100 meters at typical DC-8 research flight speeds. NOx/NOxy can be used on ground-based, airborne, and shipborne platforms, enabling it to support various atmospheric chemistry and air quality studies.

Spectrometers are instruments used to separate and analyze the spectral components of a substance. They usually measure the electromagnetic radiation that has been reflected, absorbed, or transmitted by the physical sample. Spectrometers can operate across the ultraviolet to infrared spectrum. The most common types include optical, nuclear magnetic resonance, and mass spectrometers. They can be used on aircraft, research vessels, vehicles, and other ground-based platforms.

The Forward Scattering Spectrometer Probe (FSSP) is an in situ airborne optical particle counter initially developed by Particle Measuring Systems, Inc. It determines particle size distribution by measuring the light intensity scattered by individual particles within the cloud. FSSP can detect particles ranging from 0.5 to 47 μm in diameter. It functions at a wavelength of 633 nm and typically samples at a rate of 1 Hz.

The Active Scattering Aerosol Spectrometer Probe (ASASP) is an airborne in-situ spectrometer made by Particle Measurement Systems, Inc. It measures the light intensity scattered by aerosol particles to determine particle size distribution and concentration. The wide-angle ASASP probes can detect light scattered between 35 and 120 degrees from the laser-beam axis.

The Georgia-Tech Laser Induced Fluorescence (GT-LIF) is an airborne in situ sensor that detects nitric oxide (NO), formaldehyde (HCHO), and nitrogen dioxide (NO2). It uses laser-induced fluorescence, which excites gas molecules to a higher energy state and then detects the emitted fluorescence as they return to a lower energy state. The emitted fluorescence helps determine gas concentrations and mixing ratios. For NO, molecules are excited at 226 nm, with fluorescence detected at 247 nm. HCHO is excited at 353 nm, and its fluorescence is detected at 400-450 nm, while NO2 is excited at 435 nm and detected around 780 nm.