Deep Convective Clouds & Chemistry

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 Ultra-High Frequency (UHF) Wind Profiler is a ground-based Doppler radar. It measures electromagnetic signals to detect wind speed and direction. UHF Wind Profilers operate at the 300-1000 MHz frequency range. Due to operating at a high frequency, they allow for high-resolution wind measurements within the boundary layer.

The Mobile Integrated Profiling System (MIPS) is a ground-based mobile instrument suite operated by the University of Alabama in Huntsville (UAH). It comprises several remote sensing instruments mounted on a trailer to gather profiles and vertical structures of winds, precipitation, and clouds. These instruments include an X-band Profiling Radar (XPR), a Microwave Profiling Radiometer (MPR), a 915 MHz Wind Profiler, a ceilometer, and a Doppler Sodar. It also features multiple in situ meteorological sensors for surface measurements of temperature, pressure, relative humidity, and winds. MIPS is mainly used for studies of severe weather and the boundary layer.

The Shared Mobile Atmospheric Research and Teaching Radar (SMART-R) is a mobile Doppler radar platform program operated by the University of Oklahoma. SMART-R is a C-band radar that is mounted on a truck to collect radar measurements during precipitation events such as tornadic storms, hurricanes, and flash floods. SMART-R has a beamwidth of 1.5 degrees and a selectable bin spacing of 67 to 2000 meters. The University of Oklahoma operates two SMART-R C-band radars: SR-1 (5635 MHz) and SR-2 (5612.82 MHz).

The NOAA X-band dual-Polarimetric (NOXP) radar is a mobile ground-based radar developed by the National Severe Storms Laboratory (NSSL). It is used to measure various weather phenomena such as tornadoes, hurricanes, winter storms, and dust storms. Operating at a 3 cm wavelength, it can detect smaller particles like tiny water droplets and snowflakes. NOXP has a gate spacing of 75 m, a maximum unambiguous range of 88 km, and a volume scan time of 2-3 minutes.

The Microwave Profiling Radiometer (MPR) is a ground-based passive radiometer manufactured by Radiometrics Corporation. It measures brightness temperature across 21 K-band frequency (21-30 GHz) channels and 14 V-band frequency (51-59 GHz) channels. These measurements can be used to retrieve cloud base temperature, cloud base height, integrated liquid, and profiles of temperature, water vapor, relative humidity, and liquid water. MPR has a vertical range from the surface to 10 km and provides retrievals every 1 minute. It has a height resolution of 50 m from the surface to 0.5 km, 100 m from 0.5 to 2 km, and 250 m from 2 to 10 km.

The Mobile Integrated Sounding System (MISS) is a mobile suite of ground-based instruments operated by NCAR. It is the mobile version of NCAR’s Integrated Sounding System (ISS). MISS consists of several instruments mounted on a larger trailer to profile the atmospheric boundary layer. The MISS instrument suite includes a 915 MHz wind profiler, radiosondes, and surface meteorology sensors. It is rapidly deployable and is typically used for studying convective systems.

The Sound Detection and Ranging (SODAR) is an active ground-based acoustic sensor that measures atmospheric winds and turbulence. It sends acoustic energy into the atmosphere and detects the strength and frequency of the backscattered energy. The backscattered signal can be used to determine the horizontal wind field, assuming the scattered energy moves with the mean wind. SODARs are frequently used in boundary layer studies to measure turbulence and wind profiles.

The Mobile Alabama X-Band Radar (MAX) is a truck-mounted dual-polarization radar owned and operated by the University of Alabama in Huntsville (UAH). It is usually deployed to collect radar data on tropical storms, severe weather, and boundary layer conditions. MAX operates at 9450 MHz and has a beam width of 0.95 degrees. It has a range gate spacing of 125 meters.

Ceilometers are ground-based remote sensing sensors that measure cloud ceilings and vertical visibility. They utilize a laser or another light source to detect backscatter from clouds, precipitation, and aerosols. Ceilometers provide detailed and precise measurements under all weather conditions and are cost-effective to operate. They are commonly used in boundary layer and cloud research.

The Atmospheric Vertical Observations of CO2 in the Earth’s Troposphere (AVOCET) is an airborne in situ spectrometer built by NASA’s Langley Research Center (LaRC). AVOCET uses a differential, non-dispersive infrared spectrometer to provide high-resolution measurements of carbon dioxide (CO2). It operates at the 4.26 μm CO2 absorption band and has a measurement frequency of 5 Hz. Since the early 1990s, AVOCET has been used in multiple field studies and has taken part in over 450 science flights.

The Polarized Imaging Nephelometer (PI-Neph) is an in situ airborne nephelometer developed at the Laboratory of Aerosols, Clouds, and Optics (LACO) at the University of Maryland Baltimore County (UMBC). PI-Neph measures the ambient scattering coefficient and phase matrix of aerosols to validate satellite aerosol observations. It simultaneously measures at 473 nm, 532 nm, and 671 nm wavelengths, with a scattering angle range of 2 to 178 degrees. PI-Neph typically records measurements every 12 or 36 seconds.

The Aerosol Mass Spectrometer (AMS) is an in situ spectrometer developed by Aerodyne Research. It employs quadrupole mass spectrometry to measure aerosol chemical composition and properties. It can detect particles ranging from 40 nm to 1 micron in size and has a time resolution of up to 10 Hz. It can be installed on aircraft, research vessels, mobile laboratories, or other ground-based platforms.

The Differential Aerosol Sizing and Hygroscopicity Spectrometer Probe (DASH-SP) is an in situ airborne spectrometer developed by Brechtel Manufacturing, Inc. It uses differential mobility analysis (DMA) combined with multiple humidification and sizing modules to measure aerosol optical size and hygroscopic growth factors. The probe can deliver faster measurement resolution compared to other hygroscopicity techniques. DASH-SP measures aerosol particles in the size range of 0.1–1.0 μm and operates at a wavelength of 532 nm. Its typical sampling rate is 1 Hz.

Condensation Particle Counters (CPCs) are in situ sensors that measure aerosol particle concentrations. CPCs determine aerosol levels by condensing fluid onto particles, causing them to grow to sizes detectable by optical scattering. Typically, CPCs can detect particles ranging from 7 nm to 3 μm, measure concentrations up to 100,000 particles per cubic centimeter, and provide readings every second. CPCs are manufactured by TSI Incorporated and can be used on airborne, shipborne, and ground-based platforms.

The Laser Aerosol Spectrometer (LAS) is an in situ airborne spectrometer manufactured by TSI, Inc. LAS measures particle size by analyzing how particles scatter light. It operates at a 633 nm wavelength and detects particles ranging from 0.09 to 7.5 μm. LAS can deliver complete particle size distributions at a rate of 10 Hz. It is commonly used as part of aerosol instrument suites, such as NASA’s Langley Aerosol Research Group Experiment (LARGE) and NOAA’s Aerosol Microphysical Properties (AMP).

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

The Proton Transfer Mass Spectrometer (PTR-MS) is an in situ spectrometer used both on aircraft and ground, developed by the University of Innsbruck in Austria. It detects volatile organic compounds (VOCs) without the need for sample preparation at very low concentrations. PTR-MS employs chemical ionization mass spectrometry, enabling quick and highly sensitive VOC detection. It has a signal integration time ranging from 0.5 to 1 second.

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

The Thermal-Dissociation Laser Induced Fluorescence (TD-LIF) is an in situ airborne sensor developed at UC Berkeley. It combines 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 a wavelength of 585 nm and typically measures at a frequency of 1 Hz.

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 Scanning Mobility Particle Sizer (SMPS) is an in situ aerosol sensor that can be operated on airborne or ground-based platforms, manufactured by TSI Incorporated. SMPS uses a differential mobility analyzer (DMA) to measure the electrical mobility diameter of aerosol particles, which helps determine the size distribution. It also counts the number of aerosol particles using a condensation particle counter (CPC). It detects particles in the size range of 10-1000 nm and typically takes about 10 seconds to complete each scan.

The Picarro gas concentration analyzer is an in situ airborne or ground-based sensor manufactured by Picarro, Inc. It uses Wavelength-Scanned Cavity Ring Spectroscopy (WS-CRDS) to measure trace gases such as carbon dioxide, carbon monoxide, methane, and water vapor. For carbon dioxide measurements, the laser within Picarro operates at 1603 nm wavelength, while 1651 nm wavelength is used for methane and water vapor measurements. Picarro has a typical sampling time of 2.5 seconds. Depending on the model, Picarro can also provide measurements of carbon isotopes for gas concentrations.

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

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

The Particle Analysis by Laser Mass Spectrometry (PALMS) is a laser ionization mass spectrometer operated by NOAA. PALMS provides in situ measurements of aerosol particles and their chemical composition by using a UV laser pulse (193 nm) to generate ions. These ions are then analyzed with a time-of-flight mass spectrometer to produce the mass spectrum of each particle, which can be used to classify individual aerosol particles. PALMS has an aerosol size range of 0.2 to 3 microns and typically collects data at about 1 to 10 Hz. It can be used for either airborne or laboratory aerosol measurements.

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 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.

Broadband Radiometers (BBR) are modified versions of the Kipp & Zonen CM-22 pyranometers and CG-4 pyrgeometers. They have been adapted for use on 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 measures solar spectral irradiance in the troposphere. SSFR works within the 300-2150 nm wavelength range and offers a spectral resolution of 8-12 nm. It typically collects data at 1 Hz and has a radiometric accuracy of 3%.

The Differential Absorption Lidar (DIAL) - High Spectral Resolution Lidar (HSRL) is an airborne lidar that combines both DIAL and HSRL techniques to measure ozone and aerosols at the same time. DIAL typically operates at wavelengths of 289 nm and 300 nm to profile ozone. The HSRL modification adds a three-wavelength (355 nm, 532 nm, 1064 nm) narrowband laser to the DIAL system, enabling measurements of aerosol backscatter, extinction, depolarization, and other aerosol properties. For ozone measurements, DIAL-HSRL generally has a vertical resolution of 330 m and a temporal resolution of 90 seconds. For aerosol measurements, it features a vertical resolution of 30 m and a temporal resolution of 10 seconds.

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 Difference Frequency Generation Absorption Spectrometer (DFGAS) is an in situ airborne spectrometer developed by the National Center for Atmospheric Research (NCAR). It employs 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 gathers measurements in 1-second intervals for approximately 60 to 120 seconds, depending on measurement requirements. 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 an in situ optical sensor produced by Droplet Measurement Technologies. It detects cloud condensation nuclei (CCN) by supersaturating the sampled air, allowing CCN particles to become detectable. The particles are then measured with an optical particle counter (OPC). CNC can detect particles from 0.75 to 10 μm in diameter and operates at a sampling rate of 1 Hz. It is suitable for both airborne and ground-based operations.

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

The In Situ Airborne Formaldehyde (ISAF) is an airborne optical sensor developed by NASA's Goddard Space Flight Center (GSFC). ISAF uses laser-induced fluorescence (LIF) to measure formaldehyde throughout the troposphere and lower stratosphere. It operates at a wavelength of 353 nm and has a sampling frequency of 1 Hz. ISAF can detect formaldehyde concentrations from 10 pptv to hundreds of ppbv with an accuracy of 10%.

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.

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.

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

The 2D-Stereo Particle Probe (2D-S) is an in situ airborne optical imaging device developed by SPEC Inc. It uses two diode laser beams to create stereo images of cloud particles via linear array shadowing. These images allow for the determination of cloud particle size distribution, particle number concentration, and ice or liquid water content. 2D-S has a resolution of 10 µm and can measure hydrometeors ranging from 25 to 1280 µm.

The Aerosol Optical Properties (AOP) is an in situ airborne suite consisting of a Cavity Ringdown Spectrometer (CRDS), a Photoacoustic Absorption Spectrometer (PAS), and an Ultra-High Sensitivity Aerosol Size Spectrometer (UHSAS). It provides multi-wavelength measurements of aerosol extinction, absorption, and other properties. CRDS measures aerosol extinction at 405, 532, and 662 nm wavelengths and has an accuracy of less than 2%. PAS measures absorption at 405, 532, and 660 nm wavelengths and has a sampling rate of 1 Hz. UHSAS measures the size distribution of aerosol particles within the size range of 0.008 to 1 μm. The measurements from the combined AOP instrument package allow for the calculation of radiative forcing and atmospheric heating rates.

The Charged-couple device (CCD) Actinic Flux Spectroradiometer (CAFS) is an in situ airborne spectroradiometer developed by the Atmospheric Radiation Investigations and Measurements (ARIM) laboratory at NCAR. CAFS measures spectrally resolved ultraviolet and visible actinic flux between 280-650 nm. These measurements can be used to derive the photolysis frequencies for several chemical compounds such as ozone, nitrogen dioxide, formaldehyde, and nitrate. CAFS has a temporal resolution of 1 Hz and a wavelength resolution of about 1.8 nm at 297 nm.

The CalTech Chemical Ionization Mass Spectrometer (CIT-CIMS) is an in situ airborne single-mass spectrometer. CIT-CIMS uses CF3O-ion chemistry and compact time-of-flight and triple quadrupole spectrometers to measure specific atmospheric trace gases such as nitric acid, hydrogen peroxide, and sulfur dioxide. It was designed with rapid scan capabilities, enabling it to operate at a high temporal resolution (10 Hz) and detect a wide range of masses. CIT-CIMS is typically used for airborne observations but can also be employed for ground-based measurements.

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

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

The Three-View Particle Imager (3V-CPI) is an in-situ airborne spectrometer and particle imager made by SPEC, Inc. The 3V-CPI combines a Cloud Particle Imager (CPI) and a 2D-Stereo Particle Probe (2D-S). Its primary function is capturing high-resolution images used to determine the size, shape, and concentration of hydrometeors. The 3V-CPI offers a resolution of 10 μm and can detect hydrometeors up to 1280 μm.

The Aero-Laser VUV Resonance Fluorescence Carbon Monoxide Analyzer (Aero-Laser VUV) is an in situ, airborne instrument made by Aero-Laser. It detects carbon monoxide (CO) concentrations using resonance fluorescence. The Aero-Laser VUV operates around a wavelength of 150 nm and typically provides a temporal resolution of 1 second. It has a detection range from 2 ppbv to 10 ppmv and an accuracy of approximately 3%.

Video cameras capture video recordings of various phenomena for research purposes. They are used on aircraft to provide continuous views of weather and terrain below the flight path. Video cameras are also employed to verify the aircraft's flight track. Additionally, they are deployed at field sites to monitor changes in vegetation, land cover, clouds, air quality, glaciers, and other Earth science phenomena.

The Cloud Droplet Probe (CDP) is an in situ cloud probe manufactured by Droplet Measurement Technologies. It measures the particle size distribution and concentration for cloud particles in the 2-50 μm size range. CDP detects pulses of light scattered from a laser (658 nm) to count and size individual cloud droplets. CDP has a typical measurement rate of 1 Hz and can detect concentrations of up to 2000 particles per cubic centimeter.

Condensation Particle Counters (CPCs) are in situ sensors that measure aerosol particle concentrations. CPCs determine aerosol levels by condensing fluid onto particles, causing them to grow to sizes detectable by optical scattering. Typically, CPCs can detect particles ranging from 7 nm to 3 μm, measure concentrations up to 100,000 particles per cubic centimeter, and provide readings every second. CPCs are manufactured by TSI Incorporated and can be used on airborne, shipborne, and ground-based platforms.

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

The HIAPER Airborne Radiation Package (HARP) is an in situ airborne radiometer developed by NCAR, the University of Colorado, the Leibniz-Institute for Tropospheric Research, Metcon, Inc., and enviscope GmbH. The instrument measures actinic flux and spectral irradiance. HARP operates in the 280-680 nm wavelength range for actinic flux and in the 260-2400 nm range for irradiance. It typically samples data at a frequency of 1 Hz.

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

The Scanning Mobility Particle Sizer (SMPS) is an in situ aerosol sensor that can be operated on airborne or ground-based platforms, manufactured by TSI Incorporated. SMPS uses a differential mobility analyzer (DMA) to measure the electrical mobility diameter of aerosol particles, which helps determine the size distribution. It also counts the number of aerosol particles using a condensation particle counter (CPC). It detects particles in the size range of 10-1000 nm and typically takes about 10 seconds to complete each scan.

The Peroxide Chemical Ionization Mass Spectrometer (P-CIMS) is an in situ airborne spectrometer made by THS Instruments LLC. It is a modified CIMS instrument that operates in negative ion mode to measure gas-phase peroxide species like hydrogen peroxide (H2O2) and acetic acid (CH3COOH). It has detection limits of 11 ppt for H2O2 and 10 ppt for CH3COOH. P-CIMS provides measurements at a rate of 10 Hz.

The Picarro gas concentration analyzer is an in situ airborne or ground-based sensor manufactured by Picarro, Inc. It uses Wavelength-Scanned Cavity Ring Spectroscopy (WS-CRDS) to measure trace gases such as carbon dioxide, carbon monoxide, methane, and water vapor. For carbon dioxide measurements, the laser within Picarro operates at 1603 nm wavelength, while 1651 nm wavelength is used for methane and water vapor measurements. Picarro has a typical sampling time of 2.5 seconds. Depending on the model, Picarro can also provide measurements of carbon isotopes for gas concentrations.

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

The Closed-path Laser Hygrometer (CLH) is an in situ airborne tunable diode laser hygrometer developed by the University of Colorado and the Jet Propulsion Laboratory (JPL). It uses second-harmonic absorption spectroscopy to measure atmospheric water vapor. It operates at the 1.37 μm wavelength and has a measurement frequency of 0.8 Hz.

The 2D-C/P Hydrometeor Imaging Probe (2D-C/P) is an in situ, airborne instrument that captures images of hydrometeors. It records these images by detecting the illuminated or shadowed states of the photodiode array as the shadow of the hydrometeors passes over. 2D-C/P also offers measurements of particle size distribution, cloud droplet concentration, and hydrometeor shape. Typically, 2D-C/P probes have an image resolution of 25 micrometers and can image hydrometeors with diameters up to 1600 micrometers.

The Compact Atmospheric Multispecies Spectrometer (CAMS) is an in situ airborne spectrometer developed by the University of Colorado. CAMS uses mid-IR (3.53 μm) absorption spectroscopy to measure formaldehyde and ethane in the atmosphere. It employs difference-frequency generation (DFG) to produce mid-IR light by mixing two near-IR (1562 and 1083 nm) laser sources. CAMS provides high-precision measurements at a sampling rate of 1 Hz.

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.

TSI Particle Probes are in situ particle counters and detectors manufactured by TSI Incorporated. They are used to detect aerosol particles and determine concentration and particle counts. TSI Particle Probes are typically combined with particle sizers, which can measure size distribution. TSI Particle Probes can be deployed on aircraft, research vessels, and ground-based platforms.

The Vertical Cavity Surface Emitting Laser (VCSEL) Hygrometer is an airborne hygrometer that measures water vapor concentration in the troposphere and lower stratosphere. It is an open-path, laser-based hygrometer that operates near the 1854 nm wavelength. The VCSEL hygrometer provides real-time water vapor concentration measurements at a sampling rate of 25 Hz. At this rate, the hygrometer has a spatial resolution of approximately 10 meters when the Gulfstream-V aircraft is at maximum speed.

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 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 Picarro gas concentration analyzer is an in situ airborne or ground-based sensor manufactured by Picarro, Inc. It uses Wavelength-Scanned Cavity Ring Spectroscopy (WS-CRDS) to measure trace gases such as carbon dioxide, carbon monoxide, methane, and water vapor. For carbon dioxide measurements, the laser within Picarro operates at 1603 nm wavelength, while 1651 nm wavelength is used for methane and water vapor measurements. Picarro has a typical sampling time of 2.5 seconds. Depending on the model, Picarro can also provide measurements of carbon isotopes for gas concentrations.

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.

The Chemical Ionization - Ion Trap Mass Spectrometer (CI-ITMS) is an airborne in situ spectrometer developed by the German Aerospace Center (DLR). It uses ion trap mass spectrometry to measure peroxyacetyl nitrate (PAN), peroxypropionyl nitrate (PPN), nitric acid (HNO3), and sulfur dioxide (SO2) in the troposphere and lower stratosphere. It has a time resolution of 2 seconds, a detection limit of 25 picomoles per mole, and an accuracy of better than 10% for PAN measurements. It is typically flown on the DLR Falcon research aircraft.

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

Condensation Particle Counters (CPCs) are in situ sensors that measure aerosol particle concentrations. CPCs determine aerosol levels by condensing fluid onto particles, causing them to grow to sizes detectable by optical scattering. Typically, CPCs can detect particles ranging from 7 nm to 3 μm, measure concentrations up to 100,000 particles per cubic centimeter, and provide readings every second. CPCs are manufactured by TSI Incorporated and can be used on airborne, shipborne, and ground-based platforms.

The Aero-Laser VUV Resonance Fluorescence Carbon Monoxide Analyzer (Aero-Laser VUV) is an in situ, airborne instrument made by Aero-Laser. It detects carbon monoxide (CO) concentrations using resonance fluorescence. The Aero-Laser VUV operates around a wavelength of 150 nm and typically provides a temporal resolution of 1 second. It has a detection range from 2 ppbv to 10 ppmv and an accuracy of approximately 3%.

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 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 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).

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.

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-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.