Arctic Research of the Composition of the Troposphere from Aircraft and Satellites

The Research Scanning Polarimeter (RSP) is an airborne, passive polarimeter developed by SpecTIR Corporation. It measures total radiance and linear polarization across 9 spectral bands in the visible and infrared wavelengths (410-2250 nm). These measurements can be used to derive aerosol and cloud properties. RSP has a time resolution of 0.8 seconds, a field of view of 14 mrad, and a horizontal resolution of about 100 m at an altitude of 5 km.

The High Spectral Resolution Lidar (HSRL) is an airborne lidar system developed at NASA Langley Research Center (LaRC). It utilizes 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 have a typical 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 about 6 km. HSRL is typically flown on investigations to validate observations from the CALIPSO spaceborne lidar.

This description will be added in future versions

The Airborne Tunable Laser Absorption Spectrometer (ATLAS) is an in situ airborne spectrometer developed by NASA. ATLAS utilizes second-harmonic absorption spectrometry to measure trace gases in the lower stratosphere such as nitrous oxide, methane, carbon monoxide, and ozone. The laser within ATLAS is tuned to the infrared absorption band of the target gas and is frequency modulated at 2 kHz with the second-harmonic detection occurring at 4 kHz. ATLAS provides measurements at a time resolution of 1 s and has a spatial resolution of about 200 m when deployed on the ER-2 aircraft.

Spectrometers are instruments used to separate and measure the spectral components of a substance. They are typically used to 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 of spectrometers are optical, nuclear magnetic resonance, and mass spectrometers. They can be deployed on aircraft, research vessels, vehicles, and other ground-based platforms

Condensation Particle Counters (CPCs) are in situ sensors that measure aerosol particle concentration. CPCs measure aerosol concentration by condensing fluid onto the particles, allowing them to grow to more detectable sizes for optical scattering. Typically, CPCs can detect particles with a size range of 7 nm-3 μm, can measure particle concentrations up to 100,000 particles/cc, and can provide measurements at 1-second intervals. CPCs are manufactured by TSI Incorporated and can be deployed on airborne, shipborne, and ground-based platforms.

The Carbon monOxide by Attenuated Laser Transmission (COBALT) is an in situ airborne spectrometer manufactured by Los Gatos Research. It uses off-axis integrated cavity output spectroscopy (OA-ICOS) to measure carbon monoxide in the troposphere and tropopause. COBALT operates at 4.60 μm wavelength and has a typical sampling frequency of 1 Hz. COBALT provides measurements at a precision of 0.2 ppbv and does not require regular calibration.

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 Aerosol Mass Spectrometer (AMS) is a spectrometer that measures the chemical composition and properties of sub-micron aerosol particles. AMS has a maximum data collection of 100 Hz and can detect particles with a size range of 40 nm to 1 micron. It operates by switching between mass spectrum (MS) mode and particle time-of-flight (PToF) mode to determine the chemical makeup of aerosol samples. The AMS can be deployed on aircraft, ships, mobile laboratories, or placed directly at a field site.

The Optical Particle Counter is an instrument based on the principle of light scattering from particles. It is a real time instrument that is typically used to measure particles above 0.05 μm in diameter.

Aethalometer is an in situ aerosol instrument manufactured by Magee Scientific that can be deployed on either airborne or ground-based platforms. It samples aerosols through a filter tape and measures the attenuation of transmitted light to determine the concentration of black carbon particles. The Aethalometer operates across seven optical wavelengths (370, 470, 520, 590, 660, 880, and 950 nm) and can provide data at a rate of 1 Hz. It has a measurement range of 0-500 μg per cubic meter and a resolution of 0.1 μg per cubic meter.

The Cloud Absorption Radiometer (CAR) is an airborne multi-wavelength scanning radiometer developed by Goddard Space Flight Center (GSFC). CAR provides measurements of scattered radiance and bidirectional reflectance of the surface across 14 spectral bands in the visible and near-infrared wavelengths (0.34-2.30 µm). It also acquires imagery of cloud and Earth surface features. CAR has a scan rate of 1.67 Hz (100 rpm) and has a spatial resolution of 4m at nadir for an altitude of 200m above ground level.

The Single Particle Soot Photometer (SP2) is a laser-induced photometer manufactured by Droplet Measurement Technologies. SP2 provides measurements of the black carbon (BC) mass content of individual aerosol particles as well as the optical and physical properties of the particles containing BC. SP2 can be utilized on airborne or ground-based platforms and can be deployed with a paired Humidified-Dual SP2 (HD-SP2). It can detect aerosol particles with a diameter size of 200-400 nm and can measure 25,000 particles/second.

Broadband Radiometers (BBR) are modified versions of the Kipp & Zonen CM-22 pyranometers and CG-4 pyrgeometers. They have been modified to be more suitable for airborne platforms through different instrument housing and signal amplification. BBR measures solar irradiance in the 0.2-3.6 μm wavelength range and infrared (IR) irradiance in the 4.5-42 μm range. These measurements can be used to derive net irradiance, radiative forcing, absorption, and albedo. It has a typical sampling rate of 1 Hz and a hemispheric field-of-view.

The Solar Spectral Flux Radiometer (SSFR) is an airborne radiometer developed by the Ames Atmospheric Radiation Group. It provides remotely sensed measurements of solar spectral irradiance in the troposphere. SSFR operates across the 300-2150 nm wavelength range and has a spectral resolution of 8-12 nm. It has a typical data collection rate of 1 Hz and has a radiometric accuracy of 3%.

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 optical method for counting atmospheric aerosol particles.

The Airborne Tracking Sun Photometer (ATSP) is an airborne instrument that measures direct solar beam transmission. The ATSP measures solar beam transmission through multiple channels with wavelengths ranging between 354 and 2139 nm. These measurements can be used to derive aerosol optical depth and other aerosol properties. There are multiple versions of this instrument, including one developed by the NASA Ames Research Center.

The Particle Soot Absorption Photometer (PSAP) is an in situ airborne photometer manufactured by Radiance Research. It uses Beer's Law to measure the change in light transmission of aerosol particles. These measurements can be used to derive aerosol absorption and extinction. PSAP operates across three wavelengths (467, 530, and 660 nm) and has a temporal resolution of 1 second. It is typically deployed on aircraft, but it can be deployed on other platforms such as ships and vehicles.

The Tandem Differential Mobility Analyzer (TDMA) is an in situ airborne and ground-based analyzer that measures the physical properties of aerosol particles such as size distribution and concentration. It can measure particles in the size range of 0.013 to 0.75 mm at a size resolution of 0.013 mm at 0.2 mm. The TDMA is sometimes combined with an Aerodynamic Particle Sizer (APS) to allow measurements of particles in the submicron range. A typical measurement sequence of TDMA can take approximately 45 minutes to complete.

Nephelometers are in situ airborne or ground-based optical sensors. They measure the total scattering and backscattering of aerosol particles in the atmosphere. Nephelometers operate across three wavelengths: 450 nm, 550 nm, and 700 nm, and have a typical time resolution of 1 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.

The Measurements of Atmospheric Carbon Dioxide Over Northwestern North America (MACDON-NA) is an in situ airborne gas analyzer. It is a modified LI-COR model 6252 infrared gas analyzer instrument that measures atmospheric carbon dioxide (CO2). The CO2 measurement is based on the difference in the absorption of infrared radiation passing through two gas sampling cells. MACDON-NA operates at the 4.26 μm wavelength and a constant pressure of 250 torr. It has a typical time response of 0.1 seconds.

Spectrometers are instruments used to separate and measure the spectral components of a substance. They are typically used to 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 of spectrometers are optical, nuclear magnetic resonance, and mass spectrometers. They can be deployed on aircraft, research vessels, vehicles, and other ground-based platforms

The Particle Into Liquid Sampler (PILS) is an in situ aerosol sampler manufactured by Brechtel Manufacturing Inc. PILS can be utilized by both ground-based and airborne platforms to collect continuous measurements of ambient aerosol bulk composition. The particles sampled by PILS are mixed with saturated water vapor to produce droplets that are analyzed by either an ion chromatograph (IC) or a total organic carbon detector (TOC). PILS can measure aerosol particles with a size range of 70 nm to 2.5 μm and has a time resolution of 3 min for airborne measurements and 15 min for ground-based.

The HR-AMS is an upgraded version of Aerodyne’s AMS instrument. HR-AMS has a high spatial resolution and a time-of-flight measurement technique. HR-AMS is a mass spectrometer that measures aerosols in the troposphere.

The GC-MS instrument is a combination of two instruments: a gas chromatograph and a mass spectrometer. It is used on airborne platforms to study atmospheric chemistry, specifically non-methane halocarbons and volatile organic compounds.

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 Georgia Institute of Technology Chemical Ionization Mass Spectrometer (GT-CIMS) is an in situ airborne spectrometer. It uses a lower-pressure flow tube reactor to measure reactive nitrogen species such as nitric acid and peroxyacetyl nitrate (PAN) in the lower atmosphere. GT-CIMS has a typical temporal resolution of 1 second and a detection limit of 10 pptv.

This description will be added in a future version.

The Thermal-Dissociation Laser Induced Fluorescence (TD-LIF) is an in situ airborne sensor developed at UC Berkeley. It uses a combination of the TD and LIF techniques to measure nitrogen dioxide (NO2), peroxynitrates, nitric acid (HNO3), and other stable organic nitrates in the atmosphere. TD-LIF operates at the 585 nm wavelength and has a typical measurement frequency of 1 Hz.

The Scanning Mobility Particle Sizer (SMPS) is an in situ airborne or ground-based aerosol sensor manufactured by TSI Incorporated. SMPS uses a differential mobility analyzer (DMA) to measure the electrical mobility diameter of aerosol particles to determine the size distribution. It also measures the number of aerosol particles by using a condensation particle counter (CNC). It can detect particles within the size range of 10-1000 nm and can provide measurements typically around 10 seconds per scan.

The Trace Organic Gas Analyzer (TOGA) is an in situ airborne analyzer that measures volatile organic compounds (VOCs) in the atmosphere. It uses a combination of fast gas chromatography and mass spectroscopy to provide atmospheric mixing ratios of VOCs. It can detect a wide range of VOCs with high precision (<3%) and accuracy (20% or better) at a time resolution of 40 seconds for a 2-minute cycle.

This description will be added in a future version.

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 Proton Transfer Mass Spectrometer (PTR-MS) is an in situ airborne and ground-based spectrometer designed by the University of Innsbruck in Austria. It measures volatile organic compounds (VOCs) without sample preparation at very low concentrations. PTR-MS uses chemical ionization mass spectroscopy allowing for fast and highly sensitive detection of VOCs. It has a 0.5 to 1 s signal integration time.

Aethalometer is an in situ aerosol instrument manufactured by Magee Scientific that can be deployed on either airborne or ground-based platforms. It samples aerosols through a filter tape and measures the attenuation of transmitted light to determine the concentration of black carbon particles. The Aethalometer operates across seven optical wavelengths (370, 470, 520, 590, 660, 880, and 950 nm) and can provide data at a rate of 1 Hz. It has a measurement range of 0-500 μg per cubic meter and a resolution of 0.1 μg per cubic meter.

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 one instrument. CAPS measures the size distribution of aerosol, cloud, and liquid droplets for particles between the sizes of 50-1600 μm at a time resolution of 1 Hz. It can also record images of cloud particles and provide measurements of temperature, pressure, and LWC.

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.

A Tunable Diode Laser Absorption Spectrometer (TDLAS) is an airborne or ground-based in situ optical spectrometer. TDLAS measures the wavelength-dependent absorption of light to determine the concentration of various trace gases. It can also determine the gas species' temperature, pressure, velocity, and mass flux when possible. TDLAS has a typical time resolution of 1 second.

The Ultra-High Sensitivity Aerosol Spectrometer (UHSAS) is an in situ spectrometer manufactured by Droplet Measurement Technologies. It can be utilized on both airborne and ground-based platforms to measure aerosol size distribution and concentration. UHSAS determines the particle size by detecting the peak light signals of the aerosol particles which are illuminated by a 1054 nm laser. UHSAS can sample particles within the 60 - 1000 nm size range and has a sampling frequency of 10 Hz.

The Single Particle Soot Photometer (SP2) is a laser-induced photometer manufactured by Droplet Measurement Technologies. SP2 provides measurements of the black carbon (BC) mass content of individual aerosol particles as well as the optical and physical properties of the particles containing BC. SP2 can be utilized on airborne or ground-based platforms and can be deployed with a paired Humidified-Dual SP2 (HD-SP2). It can detect aerosol particles with a diameter size of 200-400 nm and can measure 25,000 particles/second.

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 CalTech Chemical Ionization Mass Spectrometer (CIT-CIMS) is an in situ airborne single mass spectrometer. CIT-CIMS utilizes 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, allowing it to operate at a high temporal resolution (10 Hz) and detect a wide mass range. CIT-CIMS is typically used for airborne observations, but it can be used for ground-based observations as well.

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.

The Difference Frequency Generation Absorption Spectrometer (DFGAS) is an in situ airborne spectrometer developed by the National Center for Atmospheric Research (NCAR). It uses difference-frequency generation (DFG) at 3.5 μm by combining two infrared laser sources operating at 1562 and 1083 nm to measure formaldehyde in the atmosphere. DFGAS acquires measurements in 1-second increments for a period of about 60 to 120 seconds, depending on the measurement needs. DFGAS has since been replaced by the Compact Atmospheric Multispecies Spectrometer (CAMS).

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 optical method for counting atmospheric aerosol particles.

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 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 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.

Nephelometers are in situ airborne or ground-based optical sensors. They measure the total scattering and backscattering of aerosol particles in the atmosphere. Nephelometers operate across three wavelengths: 450 nm, 550 nm, and 700 nm, and have a typical time resolution of 1 Hz.

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 Multi-Axis Differential Optical Absorption Spectrometer (MAX-DOAS) is a ground-based passive spectrometer. It measures the scattered solar light at different elevations to determine trace gases in the troposphere. MAX-DOAS is designed to have low residual error in the ultraviolet and visible spectrums, allowing detection in both pristine and polluted environments. Typical MAX-DOAS instruments operate in the 300-700 nm spectral range with a spectral resolution of 0.4-1.5 nm depending on the target species.

The UAF Cloud Polarization Lidar (CPL) is a ground-based lidar located at the Arctic Facility for Atmospheric Remote Sensing (AFARS) at the University of Alaska Fairbanks (UAF). It measures lidar backscatter and depolarization ratio using a ruby laser transmitter at 0.694 μm. UAF CPL has a range resolution of 7.5 m and a time resolution of 10 seconds. It provides lidar depolarization ratio measurements with an accuracy of 0.02.

This data will be added in future versions

The Measurements of Atmospheric Carbon Dioxide Over Northwestern North America (MACDON-NA) is an in situ airborne gas analyzer. It is a modified LI-COR model 6252 infrared gas analyzer instrument that measures atmospheric carbon dioxide (CO2). The CO2 measurement is based on the difference in the absorption of infrared radiation passing through two gas sampling cells. MACDON-NA operates at the 4.26 μm wavelength and a constant pressure of 250 torr. It has a typical time response of 0.1 seconds.

Spectrometers are instruments used to separate and measure the spectral components of a substance. They are typically used to 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 of spectrometers are optical, nuclear magnetic resonance, and mass spectrometers. They can be deployed on aircraft, research vessels, vehicles, and other ground-based platforms

The Particle Into Liquid Sampler (PILS) is an in situ aerosol sampler manufactured by Brechtel Manufacturing Inc. PILS can be utilized by both ground-based and airborne platforms to collect continuous measurements of ambient aerosol bulk composition. The particles sampled by PILS are mixed with saturated water vapor to produce droplets that are analyzed by either an ion chromatograph (IC) or a total organic carbon detector (TOC). PILS can measure aerosol particles with a size range of 70 nm to 2.5 μm and has a time resolution of 3 min for airborne measurements and 15 min for ground-based.

The HR-AMS is an upgraded version of Aerodyne’s AMS instrument. HR-AMS has a high spatial resolution and a time-of-flight measurement technique. HR-AMS is a mass spectrometer that measures aerosols in the troposphere.

The GC-MS instrument is a combination of two instruments: a gas chromatograph and a mass spectrometer. It is used on airborne platforms to study atmospheric chemistry, specifically non-methane halocarbons and volatile organic compounds.

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 Georgia Institute of Technology Chemical Ionization Mass Spectrometer (GT-CIMS) is an in situ airborne spectrometer. It uses a lower-pressure flow tube reactor to measure reactive nitrogen species such as nitric acid and peroxyacetyl nitrate (PAN) in the lower atmosphere. GT-CIMS has a typical temporal resolution of 1 second and a detection limit of 10 pptv.

This description will be added in a future version.

The Thermal-Dissociation Laser Induced Fluorescence (TD-LIF) is an in situ airborne sensor developed at UC Berkeley. It uses a combination of the TD and LIF techniques to measure nitrogen dioxide (NO2), peroxynitrates, nitric acid (HNO3), and other stable organic nitrates in the atmosphere. TD-LIF operates at the 585 nm wavelength and has a typical measurement frequency of 1 Hz.

The Scanning Mobility Particle Sizer (SMPS) is an in situ airborne or ground-based aerosol sensor manufactured by TSI Incorporated. SMPS uses a differential mobility analyzer (DMA) to measure the electrical mobility diameter of aerosol particles to determine the size distribution. It also measures the number of aerosol particles by using a condensation particle counter (CNC). It can detect particles within the size range of 10-1000 nm and can provide measurements typically around 10 seconds per scan.

The Trace Organic Gas Analyzer (TOGA) is an in situ airborne analyzer that measures volatile organic compounds (VOCs) in the atmosphere. It uses a combination of fast gas chromatography and mass spectroscopy to provide atmospheric mixing ratios of VOCs. It can detect a wide range of VOCs with high precision (<3%) and accuracy (20% or better) at a time resolution of 40 seconds for a 2-minute cycle.

This description will be added in a future version.

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 Proton Transfer Mass Spectrometer (PTR-MS) is an in situ airborne and ground-based spectrometer designed by the University of Innsbruck in Austria. It measures volatile organic compounds (VOCs) without sample preparation at very low concentrations. PTR-MS uses chemical ionization mass spectroscopy allowing for fast and highly sensitive detection of VOCs. It has a 0.5 to 1 s signal integration time.

Aethalometer is an in situ aerosol instrument manufactured by Magee Scientific that can be deployed on either airborne or ground-based platforms. It samples aerosols through a filter tape and measures the attenuation of transmitted light to determine the concentration of black carbon particles. The Aethalometer operates across seven optical wavelengths (370, 470, 520, 590, 660, 880, and 950 nm) and can provide data at a rate of 1 Hz. It has a measurement range of 0-500 μg per cubic meter and a resolution of 0.1 μg per cubic meter.

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 one instrument. CAPS measures the size distribution of aerosol, cloud, and liquid droplets for particles between the sizes of 50-1600 μm at a time resolution of 1 Hz. It can also record images of cloud particles and provide measurements of temperature, pressure, and LWC.

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.

A Tunable Diode Laser Absorption Spectrometer (TDLAS) is an airborne or ground-based in situ optical spectrometer. TDLAS measures the wavelength-dependent absorption of light to determine the concentration of various trace gases. It can also determine the gas species' temperature, pressure, velocity, and mass flux when possible. TDLAS has a typical time resolution of 1 second.

The Ultra-High Sensitivity Aerosol Spectrometer (UHSAS) is an in situ spectrometer manufactured by Droplet Measurement Technologies. It can be utilized on both airborne and ground-based platforms to measure aerosol size distribution and concentration. UHSAS determines the particle size by detecting the peak light signals of the aerosol particles which are illuminated by a 1054 nm laser. UHSAS can sample particles within the 60 - 1000 nm size range and has a sampling frequency of 10 Hz.

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 CalTech Chemical Ionization Mass Spectrometer (CIT-CIMS) is an in situ airborne single mass spectrometer. CIT-CIMS utilizes 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, allowing it to operate at a high temporal resolution (10 Hz) and detect a wide mass range. CIT-CIMS is typically used for airborne observations, but it can be used for ground-based observations as well.

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.

The Difference Frequency Generation Absorption Spectrometer (DFGAS) is an in situ airborne spectrometer developed by the National Center for Atmospheric Research (NCAR). It uses difference-frequency generation (DFG) at 3.5 μm by combining two infrared laser sources operating at 1562 and 1083 nm to measure formaldehyde in the atmosphere. DFGAS acquires measurements in 1-second increments for a period of about 60 to 120 seconds, depending on the measurement needs. DFGAS has since been replaced by the Compact Atmospheric Multispecies Spectrometer (CAMS).

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 optical method for counting atmospheric aerosol particles.

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 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 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.

Nephelometers are in situ airborne or ground-based optical sensors. They measure the total scattering and backscattering of aerosol particles in the atmosphere. Nephelometers operate across three wavelengths: 450 nm, 550 nm, and 700 nm, and have a typical time resolution of 1 Hz.

The Measurements of Atmospheric Carbon Dioxide Over Northwestern North America (MACDON-NA) is an in situ airborne gas analyzer. It is a modified LI-COR model 6252 infrared gas analyzer instrument that measures atmospheric carbon dioxide (CO2). The CO2 measurement is based on the difference in the absorption of infrared radiation passing through two gas sampling cells. MACDON-NA operates at the 4.26 μm wavelength and a constant pressure of 250 torr. It has a typical time response of 0.1 seconds.

Spectrometers are instruments used to separate and measure the spectral components of a substance. They are typically used to 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 of spectrometers are optical, nuclear magnetic resonance, and mass spectrometers. They can be deployed on aircraft, research vessels, vehicles, and other ground-based platforms

The Particle Into Liquid Sampler (PILS) is an in situ aerosol sampler manufactured by Brechtel Manufacturing Inc. PILS can be utilized by both ground-based and airborne platforms to collect continuous measurements of ambient aerosol bulk composition. The particles sampled by PILS are mixed with saturated water vapor to produce droplets that are analyzed by either an ion chromatograph (IC) or a total organic carbon detector (TOC). PILS can measure aerosol particles with a size range of 70 nm to 2.5 μm and has a time resolution of 3 min for airborne measurements and 15 min for ground-based.

The HR-AMS is an upgraded version of Aerodyne’s AMS instrument. HR-AMS has a high spatial resolution and a time-of-flight measurement technique. HR-AMS is a mass spectrometer that measures aerosols in the troposphere.

The GC-MS instrument is a combination of two instruments: a gas chromatograph and a mass spectrometer. It is used on airborne platforms to study atmospheric chemistry, specifically non-methane halocarbons and volatile organic compounds.

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 Georgia Institute of Technology Chemical Ionization Mass Spectrometer (GT-CIMS) is an in situ airborne spectrometer. It uses a lower-pressure flow tube reactor to measure reactive nitrogen species such as nitric acid and peroxyacetyl nitrate (PAN) in the lower atmosphere. GT-CIMS has a typical temporal resolution of 1 second and a detection limit of 10 pptv.

This description will be added in a future version.

The Thermal-Dissociation Laser Induced Fluorescence (TD-LIF) is an in situ airborne sensor developed at UC Berkeley. It uses a combination of the TD and LIF techniques to measure nitrogen dioxide (NO2), peroxynitrates, nitric acid (HNO3), and other stable organic nitrates in the atmosphere. TD-LIF operates at the 585 nm wavelength and has a typical measurement frequency of 1 Hz.

The Scanning Mobility Particle Sizer (SMPS) is an in situ airborne or ground-based aerosol sensor manufactured by TSI Incorporated. SMPS uses a differential mobility analyzer (DMA) to measure the electrical mobility diameter of aerosol particles to determine the size distribution. It also measures the number of aerosol particles by using a condensation particle counter (CNC). It can detect particles within the size range of 10-1000 nm and can provide measurements typically around 10 seconds per scan.

The Trace Organic Gas Analyzer (TOGA) is an in situ airborne analyzer that measures volatile organic compounds (VOCs) in the atmosphere. It uses a combination of fast gas chromatography and mass spectroscopy to provide atmospheric mixing ratios of VOCs. It can detect a wide range of VOCs with high precision (<3%) and accuracy (20% or better) at a time resolution of 40 seconds for a 2-minute cycle.

This description will be added in a future version.

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 Proton Transfer Mass Spectrometer (PTR-MS) is an in situ airborne and ground-based spectrometer designed by the University of Innsbruck in Austria. It measures volatile organic compounds (VOCs) without sample preparation at very low concentrations. PTR-MS uses chemical ionization mass spectroscopy allowing for fast and highly sensitive detection of VOCs. It has a 0.5 to 1 s signal integration time.

Aethalometer is an in situ aerosol instrument manufactured by Magee Scientific that can be deployed on either airborne or ground-based platforms. It samples aerosols through a filter tape and measures the attenuation of transmitted light to determine the concentration of black carbon particles. The Aethalometer operates across seven optical wavelengths (370, 470, 520, 590, 660, 880, and 950 nm) and can provide data at a rate of 1 Hz. It has a measurement range of 0-500 μg per cubic meter and a resolution of 0.1 μg per cubic meter.

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 one instrument. CAPS measures the size distribution of aerosol, cloud, and liquid droplets for particles between the sizes of 50-1600 μm at a time resolution of 1 Hz. It can also record images of cloud particles and provide measurements of temperature, pressure, and LWC.

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.

A Tunable Diode Laser Absorption Spectrometer (TDLAS) is an airborne or ground-based in situ optical spectrometer. TDLAS measures the wavelength-dependent absorption of light to determine the concentration of various trace gases. It can also determine the gas species' temperature, pressure, velocity, and mass flux when possible. TDLAS has a typical time resolution of 1 second.

The Ultra-High Sensitivity Aerosol Spectrometer (UHSAS) is an in situ spectrometer manufactured by Droplet Measurement Technologies. It can be utilized on both airborne and ground-based platforms to measure aerosol size distribution and concentration. UHSAS determines the particle size by detecting the peak light signals of the aerosol particles which are illuminated by a 1054 nm laser. UHSAS can sample particles within the 60 - 1000 nm size range and has a sampling frequency of 10 Hz.

The Single Particle Soot Photometer (SP2) is a laser-induced photometer manufactured by Droplet Measurement Technologies. SP2 provides measurements of the black carbon (BC) mass content of individual aerosol particles as well as the optical and physical properties of the particles containing BC. SP2 can be utilized on airborne or ground-based platforms and can be deployed with a paired Humidified-Dual SP2 (HD-SP2). It can detect aerosol particles with a diameter size of 200-400 nm and can measure 25,000 particles/second.

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 CalTech Chemical Ionization Mass Spectrometer (CIT-CIMS) is an in situ airborne single mass spectrometer. CIT-CIMS utilizes 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, allowing it to operate at a high temporal resolution (10 Hz) and detect a wide mass range. CIT-CIMS is typically used for airborne observations, but it can be used for ground-based observations as well.

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.

The Difference Frequency Generation Absorption Spectrometer (DFGAS) is an in situ airborne spectrometer developed by the National Center for Atmospheric Research (NCAR). It uses difference-frequency generation (DFG) at 3.5 μm by combining two infrared laser sources operating at 1562 and 1083 nm to measure formaldehyde in the atmosphere. DFGAS acquires measurements in 1-second increments for a period of about 60 to 120 seconds, depending on the measurement needs. DFGAS has since been replaced by the Compact Atmospheric Multispecies Spectrometer (CAMS).

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 optical method for counting atmospheric aerosol particles.

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 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 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.

Nephelometers are in situ airborne or ground-based optical sensors. They measure the total scattering and backscattering of aerosol particles in the atmosphere. Nephelometers operate across three wavelengths: 450 nm, 550 nm, and 700 nm, and have a typical time resolution of 1 Hz.