The Airborne and Satellite Investigation of Asian Air Quality (ASIA-AQ) was an international cooperative project focused on studying the factors influencing local air quality across Asia. Measurements from ASIA-AQ were collected to validate aerosol satellite observations from South Korea’s Geostationary Environment Monitoring Spectrometer (GEMS), the upcoming Multi-Angle Imager for Aerosols (MAIA) sensor, and other low-orbiting satellites. ASIA-AQ conducted one deployment from January to April 2024 across eastern Asia, mainly targeting South Korea, the Philippines, and Thailand. Multiple aircraft, including NASA’s DC-8 and G-III, were equipped with remote sensing and in situ sensors to measure various aerosols and trace gases. In addition, ground-based measurements from Pandora spectrometers, AErosol RObotic NETwork (AERONET), and ozonesondes were collected. ASIA-AQ was funded by NASA’s Tropospheric Composition Program.
2024-01-29 — 2024-04-01
East and Southeast Asia, Philippines, South Korea, Thailand
Ozonesondes are in situ balloon-borne instruments used to measure ozone concentration profiles. An ozonesonde consists of an electrochemical ozone sensor connected with a meteorological radiosonde to collect ozone, temperature, pressure, and humidity measurements as it ascends through the atmosphere. It provides ozone profile measurements at a resolution of 100 to 150 m. Ozonesondes have a typical measurement rate of 0.1 Hz and can collect profiles up to around 35 km.
Earth Science > Atmosphere > Atmospheric Water Vapor
Earth Science > Atmosphere > Atmospheric Pressure
Earth Science > Atmosphere > Atmospheric Water Vapor > Water Vapor Profiles
Earth Science > Atmosphere > Atmospheric Temperature > Upper Air Temperature > Vertical Profiles
The High Spectral Resolution Lidar 2 (HSRL-2) is an airborne lidar developed by NASA's Langley Research Center. HSRL-2 measures aerosol backscatter at 355, 532, and 1064 nm wavelengths and aerosol extinction at 355 and 532 nm wavelengths. It has a horizontal resolution of 1-2 km and a vertical resolution of 15 m, with measurements taken approximately every 0.5 seconds. It replaced the original High Spectral Resolution Lidar (HSRL).
Earth Science > Spectral/engineering > Lidar > Lidar Depolarization Ratio
GEOstationary Coastal and Air Pollution Events (GEO-CAPE) Airborne Simulator (GCAS) is an airborne push-broom instrument with two spectrometers. It was developed by the Radiometric Calibration and Flight Development Laboratory at Goddard Space Flight Center (GSFC) as a simulator for the GEO-CAPE mission. The first spectrometer in GCAS operates in the ultraviolet to visible (300-490 nm) range for air quality observations of nitrogen dioxide (NO2), ozone (O3), formaldehyde (HCHO), and other trace gases. The second spectrometer operates in the visible to near-infrared (480-900 nm) range to provide measurements of ocean color. GCAS has a typical spatial resolution of 250m across track and 500m along track at an altitude of 9 km, with a frame rate of 12 Hz.
The Picarro gas concentration analyzer is an in situ airborne or ground-based sensor manufactured by Picarro, Inc. It uses Wavelength-Scanned Cavity Ring Spectroscopy (WS-CRDS) to measure trace gases such as carbon dioxide, carbon monoxide, methane, and water vapor. For carbon dioxide measurements, the laser within Picarro operates at 1603 nm wavelength, while 1651 nm wavelength is used for methane and water vapor measurements. Picarro has a typical sampling time of 2.5 seconds. Depending on the model, Picarro can also provide measurements of carbon isotopes for gas concentrations.
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.
The Aircraft-Integrated Meteorological Measurement System (AIMMS) is an in situ airborne sensor developed by Aventech Research, Inc. It measures the aircraft's position, altitude, temperature, relative humidity, static pressure, and three-dimensional wind vector. The system includes an Inertial Measurement Unit (IMU), Global Positioning System (GPS), Air Data Probe (ADP), and a central processing module (CPM) for processing the GPS data. AIMMS provides data at a rate of up to 20 Hz and can operate in temperatures ranging from -20 to 50 degrees Celsius.
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.
The Aircraft-Integrated Meteorological Measurement System (AIMMS) is an in situ airborne sensor developed by Aventech Research, Inc. It measures the aircraft's position, altitude, temperature, relative humidity, static pressure, and three-dimensional wind vector. The system includes an Inertial Measurement Unit (IMU), Global Positioning System (GPS), Air Data Probe (ADP), and a central processing module (CPM) for processing the GPS data. AIMMS provides data at a rate of up to 20 Hz and can operate in temperatures ranging from -20 to 50 degrees Celsius.
Earth Science > Atmosphere > Atmospheric Temperature > Upper Air Temperature
Earth Science > Atmosphere > Atmospheric Temperature
The Single Particle Soot Photometer (SP2) is an in situ laser-induced photometer developed by Droplet Measurement Technologies. SP2 measures the black carbon (BC) mass in individual aerosol particles, along with their optical and physical properties that contain BC. The device detects aerosol particles with diameters of 200-400 nm and can analyze up to 25,000 particles per second. It operates at a sampling rate of 1 Hz and uses a wavelength of 1.06 μm. It can be used on airborne or ground-based platforms and paired with a Humidified-Dual SP2 (HD-SP2).
The Pandora Spectrometer System is a ground-based UV-VIS spectrometer designed to measure column amounts of trace gases in the atmosphere. It employs total optical absorption spectroscopy for retrievals of ozone, nitrogen dioxide, formaldehyde, and other trace gases. Pandora operates within the 280-525 nm spectral range at a resolution of 0.6 nm. It can perform both direct sun and all-sky radiance measurements, with an overall measurement time of 80 seconds. Pandora is part of a network of identical instruments called the Pandonia Global Network.
The AErosol RObotic NETwork (AERONET) is a federated network of ground-based remote sensing aerosol sensors established by NASA and the PHOtométrie pour le Traitement Opérationnel de Normalisation Satellitaire (PHOTONS) in 1993. Each AERONET site includes a CIMEL Electronique sunphotometer that measures sun irradiance and sky radiances. These measurements are used to determine aerosol properties such as aerosol optical depth and extinction. The sunphotometers operate at nine wavelengths (340, 380, 440, 500, 675, 870, 937, 1020, and 1640 nm) and provide aerosol data approximately every 15 minutes. AERONET sites are distributed worldwide, enabling mapping of about 90% of the Earth’s surface.
The Los Gatos Research Ammonia Analyzer - Trace (LGR-AAT) is an in situ airborne analyzer developed by Los Gatos Research, Inc. It uses the Off-Axis Integrated Cavity Output Spectroscopy (OA-ICOS) technique to measure ammonia (NH3) in ambient air. It has a measurement range of 0.5 ppb - 10 ppm and an operational range of 0 to 100 ppm. LGR-AAT has a data rate up to 10 Hz and a precision of 0.2 ppb in 1 second.
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.
The Tricolor Absorption Photometer (TAP) is an in situ optical sensor produced by Brechtel Manufacturing, Inc. It measures aerosol black carbon and light absorption by light transmission through a filter. It detects light absorption at three wavelengths: 467 nm, 528 nm, and 652 nm, providing data every second. TAP has been used for both ground-based and airborne observations.
The Aircraft-Integrated Meteorological Measurement System (AIMMS) is an in situ airborne sensor developed by Aventech Research, Inc. It measures the aircraft's position, altitude, temperature, relative humidity, static pressure, and three-dimensional wind vector. The system includes an Inertial Measurement Unit (IMU), Global Positioning System (GPS), Air Data Probe (ADP), and a central processing module (CPM) for processing the GPS data. AIMMS provides data at a rate of up to 20 Hz and can operate in temperatures ranging from -20 to 50 degrees Celsius.
Earth Science > Atmosphere > Atmospheric Temperature > Upper Air Temperature
Earth Science > Atmosphere > Atmospheric Temperature
The Los Gatos Research (LGR) Greenhouse Gas Analyzer (GGA) is a portable analyzer suitable for in situ measurements, either airborne or ground-based. It utilizes off-axis integrated cavity output spectroscopy (OA-ICOS) technology to simultaneously measure methane (CH4), carbon dioxide (CO2), and water vapor (H2O). It can detect CH4 levels up to 100 ppm, CO2 up to 20,000 ppm, and H2O up to 30,000 ppm. The device offers a selectable measurement rate ranging from 0.01 to 1 Hz, with some models featuring a fast flow option capable of rates up to 10 Hz.
Thermo Scientific Gas Analyzers are in situ gas analyzers manufactured by ThermoFisher Scientific. They provide precise measurements of various trace gases such as ozone, carbon dioxide, carbon monoxide, and sulfur dioxide. Thermo Scientific Gas Analyzers can be deployed on aircraft, research vessels, and ground-based platforms.
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.
Earth Science > Atmosphere > Atmospheric Water Vapor
Earth Science > Atmosphere > Atmospheric Pressure
Earth Science > Atmosphere > Atmospheric Water Vapor > Water Vapor Indicators > Humidity
Earth Science > Atmosphere > Atmospheric Temperature > Surface Temperature > Air Temperature
The Cloud Droplet Probe (CDP) is an in situ cloud probe manufactured by Droplet Measurement Technologies. It measures the particle size distribution and concentration for cloud particles in the 2-50 μm size range. CDP detects pulses of light scattered from a laser (658 nm) to count and size individual cloud droplets. CDP has a typical measurement rate of 1 Hz and can detect concentrations of up to 2000 particles per cubic centimeter.
The Aerosol Mass Spectrometer (AMS) is an in situ spectrometer developed by Aerodyne Research. It employs quadrupole mass spectrometry to measure aerosol chemical composition and properties. It can detect particles ranging from 40 nm to 1 micron in size and has a time resolution of up to 10 Hz. It can be installed on aircraft, research vessels, mobile laboratories, or other ground-based platforms.
Earth Science > Atmosphere > Aerosols > Chemical Composition
Condensation Particle Counters (CPCs) are in situ sensors that measure aerosol particle concentrations. CPCs determine aerosol levels by condensing fluid onto particles, causing them to grow to sizes detectable by optical scattering. Typically, CPCs can detect particles ranging from 7 nm to 3 μm, measure concentrations up to 100,000 particles per cubic centimeter, and provide readings every second. CPCs are manufactured by TSI Incorporated and can be used on airborne, shipborne, and ground-based platforms.
The Los Gatos Research Ammonia Analyzer - Trace (LGR-AAT) is an in situ airborne analyzer developed by Los Gatos Research, Inc. It uses the Off-Axis Integrated Cavity Output Spectroscopy (OA-ICOS) technique to measure ammonia (NH3) in ambient air. It has a measurement range of 0.5 ppb - 10 ppm and an operational range of 0 to 100 ppm. LGR-AAT has a data rate up to 10 Hz and a precision of 0.2 ppb in 1 second.
The Particle Soot Absorption Photometer (PSAP) is an in situ airborne photometer manufactured by Radiance Research. It applies Beer's Law to measure the change in light transmission of aerosol particles. These measurements help determine aerosol absorption and extinction. PSAP operates across three wavelengths (467, 530, and 660 nm) and has a 1-second time resolution. It is usually deployed on aircraft, but it can also be used on ships and vehicles.
The Proton Transfer Mass Spectrometer (PTR-MS) is an in situ spectrometer used both on aircraft and ground, developed by the University of Innsbruck in Austria. It detects volatile organic compounds (VOCs) without the need for sample preparation at very low concentrations. PTR-MS employs chemical ionization mass spectrometry, enabling quick and highly sensitive VOC detection. It has a signal integration time ranging from 0.5 to 1 second.
The Georgia Institute of Technology Chemical Ionization Mass Spectrometer (GT-CIMS) is an in situ airborne spectrometer. It employs a lower-pressure flow tube reactor to detect reactive nitrogen species such as nitric acid and peroxyacetyl nitrate (PAN) in the lower atmosphere. GT-CIMS typically has a temporal resolution of 1 second and a detection limit of 10 pptv.
The Trace Organic Gas Analyzer (TOGA) is an in situ airborne analyzer that measures volatile organic compounds (VOCs) in the atmosphere. It combines fast gas chromatography and mass spectrometry to provide atmospheric mixing ratios of VOCs. It can detect a wide range of VOCs with high precision (<3%) and accuracy (20% or better), with a time resolution of 40 seconds for a 2-minute cycle.
LI-COR Gas Analyzer is an in situ gas analyzer manufactured by LI-COR. They can be deployed on aircraft, research vessels, vehicles, balloons, and ground-based platforms. They provide measurements of various trace gases such as carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), and water vapor (H2O). Most models use Optical Feedback-Cavity Enhanced Absorption Spectroscopy (OF-CEAS) to collect measurements. LI-COR gas analyzers have a typical measurement rate of 1 Hz and an operating temperature range of -25 to 45 degrees Celsius.
The Multicompound Gas Analyzer (MGA) is an in situ spectrometer manufactured by MIRO Analytical. It uses mid-infrared laser absorption spectroscopy with Quantum Cascade Lasers (QCL) to measure greenhouse gases such as methane (CH4), carbon monoxide (CO), nitrous oxide (N2O), and water vapor (H2O). It has a precision of 3 ppb for CH4 and 0.09 ppb for CO and N2O. MGA has a sampling rate of 1 to 10 Hz.
Earth Science > Atmosphere > Atmospheric Water Vapor > Water Vapor Indicators > Water Vapor
The Scanning Mobility Particle Sizer (SMPS) is an in situ aerosol sensor that can be operated on airborne or ground-based platforms, manufactured by TSI Incorporated. SMPS uses a differential mobility analyzer (DMA) to measure the electrical mobility diameter of aerosol particles, which helps determine the size distribution. It also counts the number of aerosol particles using a condensation particle counter (CPC). It detects particles in the size range of 10-1000 nm and typically takes about 10 seconds to complete each scan.
Earth Science > Atmosphere > Aerosols
Earth Science > Atmosphere > Aerosols > Chemical Composition
The Tunable Infrared Laser Direct Absorption Spectrometer (TILDAS) is an in situ spectrometer developed by Aerodyne Research. It measures gas concentrations by determining how much light the species absorbs at a specific wavelength. TILDAS is used to detect various trace gases, including methane, nitrous oxide, nitrogen dioxide, carbon monoxide, carbon dioxide, formaldehyde, and ammonia. The laser operates within the mid-infrared spectrum and is tuned to a specific wavelength based on the target species. It provides measurements at a data rate of up to 10 Hz. TILDAS can be deployed on aircraft, ships, trucks, and other ground-based platforms.
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 Open-Path Ammonia Laser Spectrometer (OPALS) is an in situ airborne spectrometer developed by Princeton University. It is a quantum cascade laser-based spectrometer that detects ammonia (NH3) at the 9.06 μm wavelength. It can measure a wide range of NH3 mixing ratios and offers improved capabilities for emission source characterization and flux measurements. OPALS has a precision of 0.15 ppbv, an accuracy of 10%, and a time resolution 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 specific aerosol species. It can provide samples of nitric acid, chloride, sulfates, nitrates, sodium, potassium, ammonium, and calcium. SAGA has a typical sampling interval of 5 to 15 minutes and a detection limit of 1 to 25 pptv, depending on the sampled species.
The Compact Airborne NO2 Experiment (CANOE) is an in situ analyzer developed at Goddard Space Flight Center (GSFC). It uses non-resonant laser-induced fluorescence (LIF) to measure nitrogen dioxide (NO2) throughout the troposphere and lower stratosphere. A 532 nm laser detects the fluorescence from NO2 molecules to determine the concentration. CANOE provides measurements at a rate of 1 Hz.
The Ultra-High Sensitivity Aerosol Spectrometer (UHSAS) is an in situ spectrometer developed by Droplet Measurement Technologies. It can be used on both airborne and ground-based platforms to measure aerosol size distribution and concentration. UHSAS determines particle size by detecting the peak light signals from aerosol particles illuminated by a 1054 nm laser. It can sample particles in the 60–1000 nm size range and operates at a sampling frequency of 10 Hz.
The Single Particle Soot Photometer (SP2) is an in situ laser-induced photometer developed by Droplet Measurement Technologies. SP2 measures the black carbon (BC) mass in individual aerosol particles, along with their optical and physical properties that contain BC. The device detects aerosol particles with diameters of 200-400 nm and can analyze up to 25,000 particles per second. It operates at a sampling rate of 1 Hz and uses a wavelength of 1.06 μm. It can be used on airborne or ground-based platforms and paired with a Humidified-Dual SP2 (HD-SP2).
The Whole Air Sampler (WAS) is an airborne in-situ instrument that collects air samples for analyzing trace gases, such as nonmethane hydrocarbons (NMHCs), halocarbons, alkyl nitrates, and various sulfur compounds found in the troposphere. Air samples collected by the WAS are then analyzed using gas chromatography and mass spectrometry to identify the gases present. The WAS collects samples every minute, allowing scientists to get a clear picture of the environment's chemical composition as research aircraft pass through.
The Aerodynamic Particle Sizer (APS) is an in situ spectrometer manufactured by TSI Instruments. APS measures aerodynamic particles in the 0.5-20 μm size range. It also measures the light-scattering intensity of the particles in the 0.37-20 μm optical size range. APS provides particle size distributions for 52 channels at a typical sampling time of 1 second. It uses a laser diode operating at 655 nm and has a size resolution of 0.02 μm at 1 μm. APS can be deployed on aircraft, ships, or ground-based platforms.
The Condensation Nuclei Counter (CNC) is an in situ optical sensor produced by Droplet Measurement Technologies. It detects cloud condensation nuclei (CCN) by supersaturating the sampled air, allowing CCN particles to become detectable. The particles are then measured with an optical particle counter (OPC). CNC can detect particles from 0.75 to 10 μm in diameter and operates at a sampling rate of 1 Hz. It is suitable for both airborne and ground-based operations.
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 detect water vapor in the atmosphere. DLH operates in the near-infrared range at about 1.4 μm and has a measurement frequency of 100 Hz. It can deliver precise measurements of water vapor even when flying through clouds.
Earth Science > Atmosphere > Atmospheric Water Vapor
Earth Science > Atmosphere > Atmospheric Water Vapor > Water Vapor Indicators > Water Vapor
Earth Science > Atmosphere > Atmospheric Water Vapor > Water Vapor Indicators > Humidity > Relative Humidity
Earth Science > Atmosphere > Atmospheric Water Vapor > Water Vapor Indicators > Humidity
The In Situ Airborne Formaldehyde (ISAF) is an airborne optical sensor developed by NASA's Goddard Space Flight Center (GSFC). ISAF uses laser-induced fluorescence (LIF) to measure formaldehyde throughout the troposphere and lower stratosphere. It operates at a wavelength of 353 nm and has a sampling frequency of 1 Hz. ISAF can detect formaldehyde concentrations from 10 pptv to hundreds of ppbv with an accuracy of 10%.
The Rapid OZone Experiment (ROZE) is an airborne in situ instrument that measures ozone levels in the troposphere and lower stratosphere. It employs the incoherent broadband cavity-enhanced absorption spectroscopy (IBBCEAS) technique to determine ozone concentrations in the sampled volume. ROZE utilizes a light-emitting diode (LED) in the ultraviolet (UV) spectrum at 265 nm. ROZE operates with a measurement sampling rate of 10 Hz and an accuracy of 6.2%.
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.
Earth Science > Atmosphere > Air Quality > Nitrogen Oxides
The Meteorological Measurement System (MMS) is an in situ airborne instrument used to measure atmospheric state parameters. MMS provides high-resolution, accurate measurements of atmospheric pressure, temperature, and wind direction and speed immediately around the plane. Additional parameters that can be derived include potential temperature, true airspeed, turbulence dissipation rate, and Reynolds number. Measurements of all parameters are typically collected at a rate of 20 Hz.
Nephelometers are in situ optical sensors that can be airborne or ground-based. They measure the total scattering and backscattering of aerosol particles in the atmosphere. Nephelometers operate at three wavelengths: 450 nm, 550 nm, and 700 nm, with a typical time resolution of 1 Hz.
The Aerosol Sampling for Transmission Electron Microscopy (AS-TEM) is an airborne aerosol sampler. It collects and filters aerosol samples using an impactor, which are then analyzed with transmission electron microscopy (TEM) to determine the particles' size, shape, composition, and mixing state. It can sample fine (100-700 nm) and coarse particles (>700 nm). AS-TEM can also be used for ground-based sampling.
Earth Science > Atmosphere > Aerosols
The Airborne Cavity Enhanced Spectrometer (ACES) is a two-channel spectrometer designed for aircraft measurements of glyoxal (CHOCHO), methylglyoxal (CH3COCHO), nitrous acid (HONO), nitrogen dioxide (NO2), and water vapor (H2O). ACES provides high-sensitivity measurements of trace gases and aerosols by passing light through an optical cavity equipped with a grating spectrometer and a charge-coupled device. It operates across two wavelength ranges (361-389 nm and 438-468 nm) and offers high precision and rapid measurement frequency.
The Charged-couple device (CCD) Actinic Flux Spectroradiometer (CAFS) is an in situ airborne spectroradiometer developed by the Atmospheric Radiation Investigations and Measurements (ARIM) laboratory at NCAR. CAFS measures spectrally resolved ultraviolet and visible actinic flux between 280-650 nm. These measurements can be used to derive the photolysis frequencies for several chemical compounds such as ozone, nitrogen dioxide, formaldehyde, and nitrate. CAFS has a temporal resolution of 1 Hz and a wavelength resolution of about 1.8 nm at 297 nm.
The CalTech Chemical Ionization Mass Spectrometer (CIT-CIMS) is an in situ airborne single-mass spectrometer. CIT-CIMS uses CF3O-ion chemistry and compact time-of-flight and triple quadrupole spectrometers to measure specific atmospheric trace gases such as nitric acid, hydrogen peroxide, and sulfur dioxide. It was designed with rapid scan capabilities, enabling it to operate at a high temporal resolution (10 Hz) and detect a wide range of masses. CIT-CIMS is typically used for airborne observations but can also be employed for ground-based measurements.
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 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 coefficients. LARGE includes several instruments, such as 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 over the 450-700 nm wavelength range, detect particles ranging from 0.003 to 20 μm, and measure at a frequency of 1 Hz. It is primarily used for airborne measurements but can also be deployed on ground-based platforms like vehicles.
