Deep Convective Clouds & Chemistry

The Shared Mobile Atmospheric Research and Teaching Radar (SMART-R) consist of two mobile C-band Doppler weather radars (SR-1 and SR-2). SR-1 operates at a frequency of 5635 MHz, and SR-2 operates at 5612.82. The SMART-R radars have been deployed to take radar measurements during tornadic storms, hurricanes, flash flooding events, and other precipitation events. It is owned and operated by the University of Oklahoma.

The NCAR Mobile Integrated Sounding System (MISS) is the mobile version of the Integrated Sounding System. It is a suite of multiple instrument sensors on a larger trailer towed by a truck. The sensors include a 915 MHz wind profiler radar, radiosondes, and surface meteorology measurements. The MISS provides atmospheric profiles of winds, temperature, humidity, and pressure. It is designed to be rapidly deployable and is typically used during convective storms.

Ceilometers are ground-based, remote-sensing sensors that provide measurements of cloud ceilings and vertical visibility. They use either a laser beam or another light source to detect backscatter of clouds, precipitation, and aerosols. Ceilometers can provide detailed and accurate measurements in all types of weather conditions and have low operating costs. Ceilometers are typically used in boundary layer and cloud research applications.

The Mobile Alabama X-Band radar (MAX) is a truck-mounted radar owned and operated by the University of Alabama in Huntsville (UAH). MAX is often used during severe weather deployments. In addition to its mobility, MAX also has a quick set up time. MAX is a joint effort between UAH and Baron.

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The NOAA X-band dual-Polarimetric (NOXP) radar is a ground-based mobile radar developed by the National Severe Storms Laboratory (NSSL). It has been used to provide radar measurements of various weather phenomena such as tornadoes, hurricanes, winter storms, and dust storms. It operates at a 3 cm wavelength allowing it to detect smaller particles such as 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.

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If instrument model information is not available, can use this instrument entry for temperature, pressues, wind speed, wind direction, humidity

The Mobile Integration Profiling System (MIPS) is an instrument suite operated by the University of Alabama in Huntsville. MIPS is made up of multiple instruments used to study the atmosphere. It has a set up time of around five minutes, making it very useful during severe weather deployments.

The UHF Wind Profile is a Doppler radar that uses electromagnetic signals to remotely detect wind speed and direction. It operates at a frequency of 915 MHz and has a radar range of 75-300m. At this frequency, it provides continuous wind profile measurements up to the boundary layer.

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.

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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.

The Aero-Laser VUV Resonance Fluorescence Carbon Monoxide Analyzer (Aero-Laser VUV) is an in situ, airborne instrument manufactured by Aero-Laser. It measures carbon monoxide (CO) concentrations by using the principle of resonance fluorescence. The Aero-Laser VUV analyzer operates around 150 nm wavelength and has a typical time resolution of 1 s. It has a detection range of 2 ppbv to 10 ppmv and has an accuracy of around 3%.

The SR instrument is a 2 or 4 channel chemiluminescence-based NO-analyzer for all applications involving the measurement of extremely low concentrations. Optimized for airborne and ground use, typically in stratospheric research programs.

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 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 Passive-Cavity Aerosol Spectrometer Probe (PCASP) is an in situ airborne optical spectrometer manufactured by Droplet Measurement Technologies. It measures the light scattered by particles to determine the aerosol size distribution and concentration in the 0.1 to 3.0 μm size range. PCASP operates at the 632 nm wavelength and has a typical sampling 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 and 1651 nm wavelength 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.

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.

The Chemical Ionization – Ion Trap Mass Spectrometer (CI-ITMS) is a type of CIMS instrument. Ion Trap Mass Spectrometers are highly sensitive instruments, making them useful for studying atmospheric chemistry. CI-ITMS takes measurements of nitric acid and sulfur dioxide specifically.

The Forward Scattering Spectrometer Probe (FSSP) is an in situ airborne optical particle counter originally designed by Particle Measuring Systems, Inc. It provides particle size distribution by measuring the intensity of the light scattered by individual particles within the cloud. FSSP can detect particles within a diameter range of 0.5 to 47 μm. It operates at a wavelength of 633 nm and has a typical sampling frequency of 1 Hz.

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The Aerosol Optical Properties (AOP) is a suite consisting of three instruments: a cavity ringdown (CRD) aerosol extinction spectrometer, a photoacoustic absorption spectrometer (PAS), and an ultra-high sensitivity aerosol size spectrometer (UHSAS). This suite measures aerosol absorption and extinction, and can also characterize black carbon optics. AOP was designed to provide quick and accurate measurements of aerosols with stability while aboard an aircraft.

The Atmospheric Vertical Observations of CO2 in the Earth’s Troposphere (AVOCET) is an airborne in situ spectrometer developed 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. AVOCET has been deployed in several field investigations since the early 1990s and has participated in over 450 science flights.

The Polarized Imaging Nephelometer is an in situ instrument designed and built at the Laboratory for Aerosols, Clouds and Optics (LACO) at the University of Maryland Baltimore County for the measurement of components of the aerosol phase matrix in high angular resolution between 2 to 178 deg scattering angles. The measured phase matrix provides extensive characterization of the scattering properties of the studied aerosols allowing for a very comprehensive set of aerosol scattering parameters. These measurements are essential for the validation of the new generation of aerosol remote sensors like the APS polarimeter in the Glory satellite, and for the construction of accurate models of real aerosol particles, specially the non-spherical ones.

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) with multiple humidification and sizing modules to measure aerosol optical size and hygroscopic growth factors. The probe can provide faster time resolution measurements compared to other hygroscopicity techniques. DASH-SP can measure aerosol particles in the size range of 0.1–1.0 μm and operates at the 532 nm wavelength.

The Difference Frequency Generation Absorption Spectrometer is an instrument designed to measure formaldehyde in the atmosphere. It measures the gas using an infrared laser. The instrument uses two lasers that operate at 1562nm and 1083nm. The instrument was used in multiple campaigns, and has since been replaced by the Compact Atmospheric Multispecies Spectrometer (CAMS).

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.

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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 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 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.

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 and 1651 nm wavelength 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.

If instrument mode or detailed specification information is not available, can use this entry for spectrometers of various types. A spectrometer is an instrument that measures a range of a characteristic for a given substance or wavelength. There are many different types of spectrometers. Some examples are mass spectrometers, spectrophotometers, and magnetic radiation spectrometers.

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.

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

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 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 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 Differential Absorption Lidar (DIAL) - High Spectral Resolution Lidar (HSRL) is an airborne lidar that implements both the DIAL and HSRL lidar techniques to measure ozone and aerosols simultaneously. DIAL operates typically at the 289 nm and 300 nm wavelengths to measure ozone profiles. The HSRL modification adds a 3-wavelength (355 nm, 532 nm, 1064 nm) narrowband laser to the DIAL system allowing for the measurements of aerosol backscatter, aerosol extinction, depolarization, and other aerosol properties. For ozone measurements, DIAL-HSRL has a typical vertical resolution of 330 m with a temporal resolution of 90 seconds. For aerosol measurements, it has a typical vertical resolution of 30 m with a temporal resolution of 10 seconds.

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

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.

The 2D-Stereo Particle Probe (2D-S) is an in situ airborne optical imaging probe developed by SPEC Inc. The 2D-S uses two diode laser beams to produce stereo cloud particle images through linear array shadowing. Through the imagery, cloud particle size distribution, particle number concentration, and ice/liquid water content can be determined. It has a resolution of 10 µm and can measure hydrometeors in the 25-1280 µm range.

The Meteorological Measurement System (MMS) is an in situ airborne instrument used for measuring atmospheric state parameters. MMS provides high-resolution and accurate measurements of atmospheric pressure, temperature, and wind direction/speed immediately around the plane. Additional parameters can be derived such as potential temperature, true airspeed, turbulence dissipation rate, and Reynolds number. Measurements of all parameters are typically collected at a rate of 20 Hz.

The Three-View Particle Imager (3V-CPI) is a spectrometer that measures the size, shape, and concentration of hydrometeors. The 3V-CPI was designed by Stratton Park Engineering Company and is a combination of two of their instruments: the 2D-S and the CPI. The 2D-S probes have a 9mm resolution while the CPI probe produces images with a pixel size that's roughly 2.3 micrometers. This enables the 3V-CPI to produce high resolution images of crystals and other hydrometeors such as: rain, drizzle and large cloud droplets. The 3V-CPI is currently housed at the Department of Energy’s Atmospheric Radiation Measurement (ARM) facility.

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a miniature, lightweight, low-power cloud particle spectrometer that measures droplets in the range of 2-50 µm in concentrations as high as 2000 particles/cm3

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 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.

The HIAPER Airborne Radiation Package (HARP) is an in situ airborne radiometer that was developed by NCAR, the University of Colorado, the Leibniz-Institute for Tropospheric Research, Metcon, Inc., and enviscope GmbH. The instrument provides measurements of actinic flux and spectral irradiance. HARP operates in the 280-680 nm wavelength range for actinic flux and the 260-2400 nm range for irradiance. HARP has a typical sampling 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.

The PCIMS instrument is a slightly modified CIMS instrument manufactured by THS Instruments LLC. Mechanically it consists of a differentially pumped quadrupole mass spectrometer. The instrument operates in negative ion mode and currently I- and O2- reagent ions are used to measure hydrogen peroxide and methylhydroperoxide, respectively, by the formation of cluster ions at masses 80 and 161. The reagent ions are produced by flowing a N2/CH3I/O2 mixture past a 210Po foil.

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 and 1651 nm wavelength 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 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 VCSEL hygrometer is an open-path, laser-based hygrometer that measures absolute concentration of water vapor (molecules per cm-3) at a rate of 25 Hz. The instrument is designed for operation throughout the troposphere and lower stratosphere. Two water vapor absorption lines are used: a “weak” line at 1853.37 nm for lower tropospheric mixing ratios and a “strong” line at 1854.03 nm for middle and upper tropospheric concentrations. VCSELs have a wide current tuning capability and can probe each line by changing the laser injection current with only slight adjustments to the laser temperature. Switching between the absorption lines generally occurs near a fractional absorption of 10-3, though a hysteresis is built in to prevent rapid switching near this transition (generally a factor of four in each direction). The thresholds for line switching changes slightly with temperature and pressure, but it generally is in the -15 to -25 C frost point range.

The Closed-path Laser Hygrometer (CLH) is a tunable diode laser hygrometer that was developed by the University of Colorado along with the Jet Propulsion Laboratory (JPL). The CLH measures water vapor via second-harmonic absorption spectroscopy. It provides measurements approximately every 1.5 seconds and operates at the 1.37 μm wavelength.

The 2D-C/P Hydrometeor Imaging Probe (2D-C/P) is an in situ, airborne instrument that captures imagery of hydrometeors. It collects these images by recording the status (illuminated or shadowed) of the photodiode array as the shadow of the hydrometeors passes over. 2D-C/P also provides 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.

This data will be added in future versions.

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 utilizes difference-frequency generation (DFG) to produce the mid-IR light by mixing two near-IR (1562 and 1083 nm) laser sources. CAMS provides high-precision measurements at a sampling frequency of 1 Hz.

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.