SAGE III Ozone Loss and Validation Experiment

The Airborne Chromatograph for Atmospheric Trace Species (ACATS) was an in situ airborne four-channel gas chromatograph. It used electron capture detection (ECD) to measure various halocarbons and trace gases in the stratosphere. Measurements are provided every 125 or 250 seconds, depending on the gas species. ACATS is now retired and has been replaced by the Uncrewed Aerial Systems (UAS) Chromatograph for Atmospheric Trace Species (UCATS).

The Microwave Temperature Profiler (MTP) is an airborne microwave radiometer developed by the Jet Propulsion Laboratory and later modified by NCAR. It measures brightness temperature from oxygen molecules at 56.363 GHz, 57.612 GHz, and 58.363 GHz. These measurements are converted into air temperature through a statistical retrieval process. It samples across 10 viewing angles and has a vertical resolution of 150 m near the aircraft. MTP provides profiles every 17 seconds with about 4 km of horizontal spacing.

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.

The Multiple-Angle Aerosol Spectrometer Probe (MASP) is an in situ airborne spectrometer. It measures the light intensity of scatter aerosol particles at 780 nm wavelength across multiple angles to determine particle size and concentration. It can detect particles within the 0.3 to 20 micron size range. MASP typically has a time resolution of 10 seconds.

The Focused Cavity Aerosol Spectrometer (FCAS) is an in situ airborne optical particle counter developed by Particle Measuring Systems, Inc. FCAS detects light scattered by individual aerosol particles to determine their size distribution. It can detect aerosol particles ranging from 0.06 to 2 μm in size and operate at altitudes up to 20 km. Typically, FCAS provides measurements every 10 seconds.

The High-Sensitivity Fast-Response CO2 Analyzer (Harvard CO2) is an in situ airborne spectrometer operated by Harvard University. It measures carbon dioxide (CO2) concentrations using a modified nondispersive infrared CO2 analyzer. CO2 mixing ratios are determined by measuring absorption at 4.26 μm. Harvard CO2 has a measurement sampling rate of 0.5 Hz and a precision of 0.05 ppm. Harvard is typically deployed on high-altitude aircraft like the ER-2, but it has been used for balloon-borne measurements.

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 NOAA Dual-Beam UV-Absorption Ozone Photometer (NOAA-O3) is an in situ optical balloon-borne and airborne instrument that measures ozone concentrations in the troposphere and lower stratosphere. It operates at a wavelength of 254 nm, enabling it to calculate ozone number density due to the precise ozone absorption cross section at that wavelength. It has a sampling rate of 2 Hz and a horizontal resolution of 100 to 200 meters during typical research flights.

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 Airborne Laser Infrared Absorption Spectrometer (ALIAS) is an in situ airborne spectrometer developed by the Jet Propulsion Laboratory. It can also be deployed on balloons. It uses mid-infrared (3.4–8 μm) absorption spectroscopy to measure atmospheric gases such as nitrous oxide (N2O), nitrogen dioxide (NO2), nitric acid (HNO3), hydrochloric acid (HCl), carbon monoxide (CO), and methane (CH4). ALIAS has a vertical resolution of 15 m and a time resolution of 3 seconds or less.

The Nucleation-mode Aerosol Size Spectrometer (NMASS) is an airborne, in situ spectrometer used to measure particle size distribution and cloud condensation nuclei (CCN). NMASS includes five parallel condensation nucleus counters (CNCs) that sample particles within the 3 to 60 nm diameter range. It can be mounted on various types of aircraft and is ideal for sampling cirrus clouds in the upper atmosphere. NMASS delivers rapid measurements with a temporal resolution of 10 Hz.

Harvard Water Vapor (HWV) is an in situ airborne hygrometer developed at Harvard University that measures water vapor mixing ratios in the upper troposphere and lower stratosphere. HWV includes two instruments with different methods for detecting water vapor: the Lyman-α photo-fragment fluorescence instrument (LyA) and a tunable diode laser direct absorption instrument (HHH -Harvard Herriott Hygrometer). By combining both instruments, HWV can identify and reduce systematic errors during flight. It provides measurements of water vapor mixing ratio from 1 to 1000 ppmv at 1 Hz and with an accuracy of 5%.

The JPL Laser Hygrometer (JLH) is an in situ airborne hygrometer developed at the Jet Propulsion Laboratory (JPL). It uses a tunable diode laser operating at 1.37 μm to measure atmospheric water vapor in the upper troposphere and lower stratosphere. JLH has a minimum spatial resolution of 25 meters and a detection range of 1 to 500 ppmv. It typically samples at 1 Hz and can provide measurements with a precision of 0.05 ppmv.

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.

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.

The Harvard Hydroxyl Experiment (HOx) is an in situ laser-induced fluorescence (LIF) sensor developed by Harvard University. It uses LIF centered at 309 nm to measure hydroxyl radical (OH). The OH is then converted into its first electronic state using a tunable ultraviolet laser near 282 nm. The hydroperoxyl radical (HO2) is measured as OH after chemical titration with nitric oxide. HOx has a short integration time of less than 20 seconds.

The Chlorine Nitrate Instrument (ClONO2) is an in situ airborne analyzer used for the detection of nitrogen dioxide (NO2), chlorine monoxide (ClO), bromine monoxide (BrO), and chlorine nitrate (ClONO2). It used laser-induced resonance fluorescence (LIF) at 585 nm for the direct detection of NO2. It provides NO2 measurements in 10-second intervals with an accuracy of approximately 10%. It uses thermal dissociation and ultraviolet (118.9 nm) resonance fluorescence for the detection of ClO, BrO, and ClONO2. It provides ClO and ClONO2 measurements in 35-second intervals with a detection limit of 3 pptv and 10 pptv, respectively.

The Composition and Photodissociative Flux Measurement (CPFM) is an in situ airborne spectroradiometer used for the measurement of direct and scattered solar irradiance. It is based on a holographic, diffraction grating, and a 1024-element photodiode array detector. It measures the solar flux on a horizontal surface and the limb and apparent brightness below the flight level. CPFM operates in the 300-770 nm wavelength range. CPFM has also been used for ground-based measurements.

Argus is a two-channel, tunable diode laser instrument developed at NASA Ames Research Center. It collects in situ measurements of carbon monoxide (CO), nitrous oxide (N2O), and methane (CH4) in the atmosphere using second harmonic spectroscopy. Argus operates in the mid-infrared range (3.3 and 4.7 micrometers) and has an accuracy of about 3% for data rates between 0.1 and 0.5 Hz. Its lightweight and compact design makes it ideal for small payload platforms such as balloons and uncrewed aerial vehicles (UAVs).

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 Lidar Atmospheric Sensing Experiment (LASE) is an airborne lidar system developed at NASA's Langley Research Center (LaRC). LASE uses the differential absorption lidar technique to provide profile measurements of water vapor and aerosols in the atmosphere. LASE operates at the 815 nm wavelength and has a measurement frequency of 5 Hz. For aerosol scattering profiles, LASE has a horizontal resolution of 200 m and a vertical resolution of 30 m. It has a horizontal resolution of 5 km and a vertical resolution of 0.2 km for water vapor measurements.

The Airborne Raman Ozone, Temperature, and Aerosol Lidar (AROTAL) is an airborne lidar system operated by Goddard Space Flight Center (GSFC). It detects lidar backscatter to provide vertical profiles of ozone, temperature, and aerosols. It operates across four transmitted wavelengths: 308, 355, 532, and 1064 nm. It also collects Raman scattering at 332 nm and 387 nm. AROTAL has a horizontal resolution of about 4 to 7 km and a vertical resolution of 0.5 to 1.5 km.

The Microwave Temperature Profiler (MTP) is an airborne microwave radiometer developed by the Jet Propulsion Laboratory and later modified by NCAR. It measures brightness temperature from oxygen molecules at 56.363 GHz, 57.612 GHz, and 58.363 GHz. These measurements are converted into air temperature through a statistical retrieval process. It samples across 10 viewing angles and has a vertical resolution of 150 m near the aircraft. MTP provides profiles every 17 seconds with about 4 km of horizontal spacing.

The Scanning Actinic Flux Spectroradiometer (SAFS) is an in situ airborne spectroradiometer developed by NCAR. It measures wavelength-dependent actinic flux from 280 to 420 nm. These measurements are used to calculate the photolysis frequencies for multiple species, including ozone, nitrogen dioxide, formaldehyde, nitric acid, and peroxyacetyl nitrate. SAFS has a measurement sampling rate of 0.1 Hz.

The Cryogenic Hygrometer (CRYO) is an in situ airborne hygrometer manufactured by Buck Research Instruments. It is a cryogenically cooled, chilled mirror hygrometer technique to measure the dew point or frost point temperature. These measurements are used to determine the water vapor mixing ratio. CRYO has a measurement range of -120 to 30 degrees Celsius and a typical response time of 10-20 seconds. It has an accuracy of 0.15 degrees Celsius.

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.

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 detects light scattered by particles to determine aerosol size distribution and concentration within the 0.1 to 3.0 μm range. PCASP operates at a wavelength of 632 nm and typically samples at 10 Hz.

The Focused Cavity Aerosol Spectrometer (FCAS) is an in situ airborne optical particle counter developed by Particle Measuring Systems, Inc. FCAS detects light scattered by individual aerosol particles to determine their size distribution. It can detect aerosol particles ranging from 0.06 to 2 μm in size and operate at altitudes up to 20 km. Typically, FCAS provides measurements every 10 seconds.

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 seconds. It was designed to be installed 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 developed at NASA’s Langley Research Center (LaRC). It uses four lasers to detect lidar backscatter and provide profile measurements of ozone and aerosols in the atmosphere. DIAL operates in the ultraviolet (289-300 nm) for ozone detection and in the visible (572-600 nm) and infrared (1064 nm) for aerosols. It has a horizontal spatial resolution of approximately 15 km and a measurement accuracy of 5 ppbv.

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 Nucleation-mode Aerosol Size Spectrometer (NMASS) is an airborne, in situ spectrometer used to measure particle size distribution and cloud condensation nuclei (CCN). NMASS includes five parallel condensation nucleus counters (CNCs) that sample particles within the 3 to 60 nm diameter range. It can be mounted on various types of aircraft and is ideal for sampling cirrus clouds in the upper atmosphere. NMASS delivers rapid measurements with a temporal resolution of 10 Hz.

The Tropospheric Ozone and Tracers from Commercial Aircraft Platforms (TOTCAP) is an in-situ airborne analyzer that measures tropospheric ozone, carbon dioxide, and water vapor. Ozone is measured using a dual-beam ultraviolet (254 nm) absorption analyzer. Water vapor is detected through second harmonic generation with a tunable diode laser spectrometer that uses a near-infrared (1.37 microns) laser. Carbon dioxide is measured by detecting its absorption in the infrared spectrum at 4.25 microns.

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 Fourier Transformation Spectrometer (FTS) is a high-resolution spectrometer used both in airborne and ground-based applications. FTS measures the solar radiance reflected from the surface, which can be used to estimate levels of carbon monoxide (CO), carbon dioxide (CO2), and methane (CH4) in the atmosphere. It offers a spatial resolution of approximately 100m by 1000m and operates at a measurement frequency of 1 Hz during typical research flights.

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.

The JPL Laser Hygrometer (JLH) is an in situ airborne hygrometer developed at the Jet Propulsion Laboratory (JPL). It uses a tunable diode laser operating at 1.37 μm to measure atmospheric water vapor in the upper troposphere and lower stratosphere. JLH has a minimum spatial resolution of 25 meters and a detection range of 1 to 500 ppmv. It typically samples at 1 Hz and can provide measurements with a precision of 0.05 ppmv.

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.

The High Spectral Resolution Lidar (HSRL) is an airborne lidar system developed at NASA Langley Research Center (LaRC). It uses the HSRL technique at 532 nm and the standard backscatter technique at 1064 nm to provide profile measurements of aerosol backscatter, extinction, and depolarization. The profiles of aerosol backscatter and depolarization typically have a vertical resolution of 30 m and a horizontal resolution of about 1 km. For the extinction profiles, the vertical resolution is 300 m with a horizontal resolution of approximately 6 km. HSRL is usually flown during investigations to validate observations from the CALIPSO spaceborne lidar.

The Airborne SUbmillimeter Radiometer (ASUR) is a passive airborne radiometer developed at the University of Bremen. It measures the thermal emissions of trace gases in upper atmosphere across the 604.3 to 662.3 GHz frequency range. It is typically used for the detection of ozone, water vapor, and species important for ozone chemistry. ASUR provides vertical profiles from 15 to 50 km with a vertical resolution of approximately 6km and 12km for the lower and upper stratosphere, respectively.

The Multiple Axis Resonance Fluorescence Chemical Conversion Detector for ClO and BrO (ClO/BrO) is an in situ airborne analyzer operated by Harvard University. It provides measurements of chlorine monoxide (ClO) and bromine monoxide (BrO) in the upper troposphere and lower stratosphere. ClO and BrO are converted to chlorine (Cl) and bromine (Br) through the addition of nitric oxide (NO) in the sample air. Cl and Br concentrations are detected through resonance scattering in the vacuum ultraviolet (119 nm) to determine ClO and BrO concentrations. ClO/BrO has a detection limit greater than 1 pptv.

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.

The Ozone Lidar Experiment (OLEX) is an airborne lidar system operated by the German Aerospace Center (DLR). It measures atmospheric backscatter at four wavelengths (308, 355, 532, and 1064 nm) to provide profiles of ozone and aerosols. It views from zenith and has a measurement range from 2 km above the flight altitude up to around 30 km. It operates at a repetition rate of 10 Hz, with a horizontal resolution of 20 m and a vertical resolution of 15 m at a typical aircraft speed of 200 meters per second. OLEX is designed to operate on the DLR Falcon research aircraft.

Differential Optical Absorption Spectroscopy (DOAS) is a passive spectrometer technique used to measure trace gas concentrations. It detects trace gases by measuring specific, narrow-band absorptions in the ultraviolet and visible light spectrum. DOAS is typically used to detect ozone (O3), nitrogen dioxide (NO2), formaldehyde (CH2O), and sulfur dioxide (SO2). It is suitable for both airborne and ground-based applications.

Generic-Radiometers refer to non-specific radiometers on a platform. These are typically passive microwave radiometers that measure brightness temperature. Radiometers can be used to retrieve temperature and water vapor profiles, soil moisture content, ocean salinity, precipitation and cloud properties, and vegetation.

The Fourier Transformation Spectrometer (FTS) is a high-resolution spectrometer used both in airborne and ground-based applications. FTS measures the solar radiance reflected from the surface, which can be used to estimate levels of carbon monoxide (CO), carbon dioxide (CO2), and methane (CH4) in the atmosphere. It offers a spatial resolution of approximately 100m by 1000m and operates at a measurement frequency of 1 Hz during typical research flights.

The Raman Lidar (RL) is a ground-based lidar system operated by the Department of Energy’s (DoE) Atmospheric Radiation Measurement (ARM) User Facility. It detects Raman backscatter in the ultraviolet range (355 nm) to provide profiles of water vapor, temperature, and aerosol and cloud optical properties. It also detects Raman backscatter from water vapor at 408 nm and molecular nitrogen at 387 nm to help derive aerosol optical properties and water vapor mixing ratios. It has a range resolution of 7.5 m, a time resolution of 10 seconds, and a pulse repetition frequency of 30 Hz. RL can deliver profile measurements from approximately 200 m up to 10 km above ground level.

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

Sunphotometers are passive optical sensors that measure the amount of sunlight. They are pointed directly at the sun to measure direct sunlight and not sunlight scatter from aerosols. These measurements can be used to determine the aerosol optical depth by following Beer’s Law. Sunphotometers have been deployed on aircraft, research vessels, and field sites for aerosol research and monitoring.

The Esrange MST Radar (ESRAD) is a ground-based, mesosphere-stratosphere-troposphere (MST) radar located at Esrange, Sweden. It was designed to provide details about atmospheric winds and turbulence from the troposphere to the mesosphere. ESRAD measures radar backscatter at 52 MHz, which can be used to retrieve profiles of turbulence, vertical wind, and wind speed/direction. ESRAD can sample heights from 100 m to 128 km and has a range resolution of 75 m to 3 km. A typical cycle takes about 1 to 2 minutes in each scanning mode.

The Alfred Wegener Institute (AWI) Differential Absorption Lidar (DIAL) is a ground-based lidar system located in Ny-Alesund, Spitsbergen, within the Network for the Detection of Stratospheric Change (NDSC). It is a multi-wavelength lidar that measures backscatter to retrieve aerosol and ozone profiles. It uses the DIAL technique to measure ozone at 308 and 353 nm. It detects aerosols at 353 nm, 532 nm, and 1064 nm wavelengths. It also detects Raman scattering light at the 607 nm wavelength. Its resolution ranges from 600 meters to 6 km, depending on the altitude.

The Airborne Raman Ozone, Temperature, and Aerosol Lidar (AROTAL) is an airborne lidar system operated by Goddard Space Flight Center (GSFC). It detects lidar backscatter to provide vertical profiles of ozone, temperature, and aerosols. It operates across four transmitted wavelengths: 308, 355, 532, and 1064 nm. It also collects Raman scattering at 332 nm and 387 nm. AROTAL has a horizontal resolution of about 4 to 7 km and a vertical resolution of 0.5 to 1.5 km.

The Microwave Temperature Profiler (MTP) is an airborne microwave radiometer developed by the Jet Propulsion Laboratory and later modified by NCAR. It measures brightness temperature from oxygen molecules at 56.363 GHz, 57.612 GHz, and 58.363 GHz. These measurements are converted into air temperature through a statistical retrieval process. It samples across 10 viewing angles and has a vertical resolution of 150 m near the aircraft. MTP provides profiles every 17 seconds with about 4 km of horizontal spacing.

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.

The Direct beam Irradiance Airborne Spectrometer (DIAS) was a passive airborne spectrometer operated by NCAR. It measured direct beam solar irradiance from 280 to 650 nm. These measurements were used to calculate the line-of-sight ozone and wavelength-dependent aerosol optical depths (AOD). DIAS had a spectral resolution of approximately 1 nm.

The Gas and Aerosol Measurement Sensor/Langley Airborne A-Band Spectrometer (GAMS/LAABS) is an airborne spectrometer system designed at Langley Research Center (LaRC). It is a combination of the GAMS and LAABS instruments and provides line-of-sight (LOS) transmission spectra measurements of aerosols, water vapor, and oxygen compounds. These measurements are used to determine aerosol optical depth. GAMS operates across 1024 spectral channels in the 430 to 1030 spectral range and acquires data at a rate of 180 Hz. LAABS operates across over 800 channels in the 759 to 771 nm spectral range at a resolution of about 0.035 nm and has an integration time of 1.5 seconds.

The Cloud Aerosol and Precipitation Spectrometer (CAPS) is an in situ airborne spectrometer manufactured by Droplet Measurement Technologies. It combines the Cloud Imaging Probe (CIP), the Cloud and Aerosol Spectrometer (CAS), and the Hotwire Liquid Water Content (LWC) Sensor into a single instrument. CAPS measures the size distribution of aerosol, cloud, and liquid droplets for particles between 50-1600 μm in size, with a time resolution of 1 Hz. It can also capture images of cloud particles and provide measurements of temperature, pressure, and LWC.

The Focused Cavity Aerosol Spectrometer (FCAS) is an in situ airborne optical particle counter developed by Particle Measuring Systems, Inc. FCAS detects light scattered by individual aerosol particles to determine their size distribution. It can detect aerosol particles ranging from 0.06 to 2 μm in size and operate at altitudes up to 20 km. Typically, FCAS provides measurements every 10 seconds.

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

The PAN and Trace Hydrohalocarbon ExpeRiment (PANTHER) is an in situ airborne analyzer. It uses electron capture detection and gas chromatography techniques to measure various trace gases such as methane, peroxyacyl nitrate (PAN), and carbon monoxide. PANTHER has a sampling frequency of 60 to 120 seconds and an accuracy of around 2% for most species, except for PAN (10%). The development of PANTHER was funded through NASA’s Instrument Incubator Program and NOAA’s Climate and Global Change Program.

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 Nucleation-mode Aerosol Size Spectrometer (NMASS) is an airborne, in situ spectrometer used to measure particle size distribution and cloud condensation nuclei (CCN). NMASS includes five parallel condensation nucleus counters (CNCs) that sample particles within the 3 to 60 nm diameter range. It can be mounted on various types of aircraft and is ideal for sampling cirrus clouds in the upper atmosphere. NMASS delivers rapid measurements with a temporal resolution of 10 Hz.

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.

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.

The Airborne Tracking Sun Photometer (ATSP) is an airborne device that measures direct solar beam transmission. The ATSP captures solar beam transmission through multiple channels with wavelengths spanning from 354 to 2139 nm. These measurements can be used to determine aerosol optical depth and other aerosol characteristics. Several versions of this instrument exist, including one developed by the NASA Ames Research Center.

The High Spectral Resolution Lidar (HSRL) is an airborne lidar system developed at NASA Langley Research Center (LaRC). It uses the HSRL technique at 532 nm and the standard backscatter technique at 1064 nm to provide profile measurements of aerosol backscatter, extinction, and depolarization. The profiles of aerosol backscatter and depolarization typically have a vertical resolution of 30 m and a horizontal resolution of about 1 km. For the extinction profiles, the vertical resolution is 300 m with a horizontal resolution of approximately 6 km. HSRL is usually flown during investigations to validate observations from the CALIPSO spaceborne lidar.

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 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 Fourier Transformation Spectrometer (FTS) is a high-resolution spectrometer used both in airborne and ground-based applications. FTS measures the solar radiance reflected from the surface, which can be used to estimate levels of carbon monoxide (CO), carbon dioxide (CO2), and methane (CH4) in the atmosphere. It offers a spatial resolution of approximately 100m by 1000m and operates at a measurement frequency of 1 Hz during typical research flights.

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 Optical Particle Counter (OPC) is an optical device used to measure aerosol particle size and concentration. It determines particle size and concentration by detecting the intensity of scattered light. Most OPCs operate within the visible to near-infrared wavelengths (500-1100 nm) and have a time resolution of 1 second. They are typically used to measure particles larger than 0.5 μm in diameter. OPCs can be used for both airborne and ground-based applications.

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 NOAA Frost Point Hygrometer (FPH) is a balloon-borne sensor that collects profile measurements of atmospheric water vapor. It employs the chilled-mirror principle to determine the frost or dew point temperature up to 28 km in the atmosphere. FPH takes measurements with a vertical resolution of 5-10 m and a temporal resolution of 1-2 seconds.

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.

The Fourier Transformation Spectrometer (FTS) is a high-resolution spectrometer used both in airborne and ground-based applications. FTS measures the solar radiance reflected from the surface, which can be used to estimate levels of carbon monoxide (CO), carbon dioxide (CO2), and methane (CH4) in the atmosphere. It offers a spatial resolution of approximately 100m by 1000m and operates at a measurement frequency of 1 Hz during typical research flights.

The Raman Lidar (RL) is a ground-based lidar system operated by the Department of Energy’s (DoE) Atmospheric Radiation Measurement (ARM) User Facility. It detects Raman backscatter in the ultraviolet range (355 nm) to provide profiles of water vapor, temperature, and aerosol and cloud optical properties. It also detects Raman backscatter from water vapor at 408 nm and molecular nitrogen at 387 nm to help derive aerosol optical properties and water vapor mixing ratios. It has a range resolution of 7.5 m, a time resolution of 10 seconds, and a pulse repetition frequency of 30 Hz. RL can deliver profile measurements from approximately 200 m up to 10 km above ground level.

Differential Optical Absorption Spectroscopy (DOAS) is a passive spectrometer technique used to measure trace gas concentrations. It detects trace gases by measuring specific, narrow-band absorptions in the ultraviolet and visible light spectrum. DOAS is typically used to detect ozone (O3), nitrogen dioxide (NO2), formaldehyde (CH2O), and sulfur dioxide (SO2). It is suitable for both airborne and ground-based applications.

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

Generic-Radiometers refer to non-specific radiometers on a platform. These are typically passive microwave radiometers that measure brightness temperature. Radiometers can be used to retrieve temperature and water vapor profiles, soil moisture content, ocean salinity, precipitation and cloud properties, and vegetation.

Sunphotometers are passive optical sensors that measure the amount of sunlight. They are pointed directly at the sun to measure direct sunlight and not sunlight scatter from aerosols. These measurements can be used to determine the aerosol optical depth by following Beer’s Law. Sunphotometers have been deployed on aircraft, research vessels, and field sites for aerosol research and monitoring.

The Alfred Wegener Institute (AWI) Differential Absorption Lidar (DIAL) is a ground-based lidar system located in Ny-Alesund, Spitsbergen, within the Network for the Detection of Stratospheric Change (NDSC). It is a multi-wavelength lidar that measures backscatter to retrieve aerosol and ozone profiles. It uses the DIAL technique to measure ozone at 308 and 353 nm. It detects aerosols at 353 nm, 532 nm, and 1064 nm wavelengths. It also detects Raman scattering light at the 607 nm wavelength. Its resolution ranges from 600 meters to 6 km, depending on the altitude.

Rocketsondes or sounding rockets are sondes released from a rocket instead of a balloon. They can reach altitudes higher than a typical balloon-borne radiosonde. Rocketsondes provide vertical profiles of atmospheric winds, temperature, pressure, density, and moisture upon descent after being ejected from the rocket at or near apogee. NASA’s Wallops Flight Facility (WFF) launches sounding rockets at Wallops and other locations through its Sounding Rocket Program.