Boreal Ecosystem-Atmosphere Study

The Compact Airborne Spectrographic Imager (CASI) is an airborne push-broom imaging spectrometer developed by Itres Research Ltd. CASI measures reflectance in the visible/near-infrared (VNIR) spectral region, which can be used to derive vegetation characteristics. It operates in the 430-870 nm spectral range and has a 35-degree field of view (FOV). CASI has a cross-track ground resolution of 1.23 meters at 1 km altitude above ground level (AGL). The along-track resolution depends on the integration time and the aircraft speed. CASI has a frame rate of 85 lines per second.

Generic-Gamma Ray Sensors (Gen-Gamma) refer to non-specific instruments on a platform used to measure gamma-ray radiation. They are typically passive sensors that detect the energy of emitted gamma radiation. Gamma-ray measurements are used to identify radioactive isotopes for environmental monitoring and geological studies.

The CCRS-SAR was an airborne synthetic aperture radar (SAR) operated by the Canada Center for Remote Sensing (CCRS) from the mid-1980s until 1996. It featured two radars operating in the C-band (5.3 GHz) and X-band (9.25 GHz). Both radars had dual-channel receivers and dual-polarized antennas, collecting radar images of land, sea ice, and ocean surfaces. The C-band radar had a 3 dB range resolution of 5.7 m in high-resolution mode, while the X-band radar had a range resolution of 4.8 m. CCRS-SAR had a slant range swath width of 16.4 km and an azimuth resolution of 6 m in high-resolution mode.

The Modular Multiband Radiometer (MMR) is an airborne multispectral radiometer manufactured by Barnes Engineering Company. MMR measures radiance across 8 spectral bands in the infrared and visible wavelengths (0.4-12.5 μm) to produce images of vegetation and other surface features. At an altitude of 300 meters, the MMR has an instantaneous field of view (IFOV) of about 79 meters and a 15-degree field of view (FOV). It is typically deployed on small aircraft like helicopters but can also be used on ground-based platforms.

C-band scatterometers are active non-imaging scatterometers that measure microwave backscatter. They are typically used to measure ocean surface winds but can also be used to measure ice, vegetation, and soil surface properties. They operate in the C-band frequency range (4-8 GHz) and can provide measurements during the day and night.

The Spectron Engineering-590 (SE-590) Spectroradiometer is a portable spectroradiometer manufactured by Spectron Engineering. It can be used on both airborne and ground-based platforms. SE-590 uses a charge-coupled device (CCD) area array detector to measure reflectance. It operates across the visible to short-wave infrared spectral range (350-2500 nm). The SE-590 has a ground resolution of 4.5 meters when flown at an altitude of 300 meters.

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

The POLarization and Directionality of the Earth’s Reflectances (POLDER) is a spaceborne passive radiometer onboard the Japan Aerospace Exploration Agency’s Advanced Earth Observing Satellite. POLDER has also been used in several airborne investigations to calibrate instruments and measure surface reflectance and solar radiation. POLDER has a ground spatial resolution of 7 km by 6 km at nadir and operates across eight discrete spectral bands (443 nm - 910 nm).

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.

Rosemount Pressure Probes are in situ airborne pressure sensors manufactured by Rosemount, Inc. They provide high-precision atmospheric pressure measurements and are typically used to gather flight-level meteorological observations. Rosemount Pressure Probes consist of various pressure transducers, gauges, and multivariable and coplanar transmitters.

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.

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 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.

Rosemount Temperature Probes are in situ airborne temperature sensors manufactured by Rosemount, Inc. They provide atmospheric temperature measurements and are typically used to collect flight-level meteorological observations. Rosemount Temperature Probes consist of temperature transmitters, thermocouple sensors, resistance temperature detectors, and other temperature sensors.

The King Probe is an in situ airborne cloud instrument developed by Warren King (Commonwealth Scientific and Industrial Research Organisation) and manufactured by Particle Measuring Systems (PMS) and Droplet Measurement Technologies (DMT). The King Probe measures cloud liquid water content (LWC) by detecting the heat released when water droplets vaporize. It operates at a constant temperature of approximately 100°C and has a data output rate of 1 to 10 Hz. The probe is commonly used in studies of cloud microphysics and aircraft icing.

A pyranometer is a ground-based or airborne radiation sensor that measures solar irradiance across a hemispherical field of view. It detects the amount of solar energy reaching the surface, capturing both direct and diffuse sunlight. Pyranometers operate within a spectral range of 280-3000 nm. They are most commonly used for solar monitoring, climate research, weather forecasting, agriculture, and energy management.

A pyrgeometer is a ground-based or airborne passive radiation sensor. It measures downward and upward longwave radiation in the 4-50 μm spectral range. Pyrgeometers measure changes in resistance/voltage using a thermopile sensor to determine longwave radiation. These measurements can be used to calculate the infrared radiation flux. Pyrgeometers are typically used for climatological, meteorological, and agricultural applications.

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

The Advanced Solid-state Array Spectroradiometer (ASAS) is an airborne, passive multi-angle spectrometer operated by NASA Goddard Space Flight Center (GSFC). ASAS measures reflectance across 30 spectral channels within the 450 to 880 nm wavelength range to help characterize the directional variability of various land surface cover types. At typical flight altitudes of 4,500 to 5,000 meters, ASAS has a spatial resolution of 3 to 4 meters at nadir. It has a frame rate ranging from 3 to 64 frames per second.

The Thematic Mapper Simulator (TMS) is an airborne imaging spectrometer designed to simulate the Landsat Thematic Mapper. It captures radiance measurements and imagery for mapping vegetation and land cover. TMS operates across ten spectral channels in the visible and near-infrared spectrum (0.42-2.35 μm) and two in the thermal infrared range (8.5-14 μm). It has a horizontal spatial resolution of 25 m and a swath width of 15.6 km at an altitude of 19.8 km. TMS has a scan rate of 12.5 scans per second and a total field of view of 42.5 degrees.

The MODIS Airborne Simulator (MAS) is an airborne multispectral spectrometer designed to simulate the satellite instrument Moderate-Resolution Imaging Spectrometer (MODIS). MAS operates over 50 spectral channels in the 0.55 to 14.2 μm range, providing high-resolution images of clouds and surface features. It has a horizontal spatial resolution of 50 meters and a swath width of about 36 kilometers at an altitude of 20 km at nadir. Its scan rate is 6.25 Hz, with each scan line containing 716 pixels.

The POLarization and Directionality of the Earth’s Reflectances (POLDER) is a spaceborne passive radiometer onboard the Japan Aerospace Exploration Agency’s Advanced Earth Observing Satellite. POLDER has also been used in several airborne investigations to calibrate instruments and measure surface reflectance and solar radiation. POLDER has a ground spatial resolution of 7 km by 6 km at nadir and operates across eight discrete spectral bands (443 nm - 910 nm).

The Thermal Infrared Multispectral Scanner (TIMS) is an airborne thermal infrared spectrometer used for geologic mapping. It captures multispectral thermal images across six channels within the 8.2-12.2 μm wavelength range. TIMS has a horizontal spatial resolution at nadir of 3 to 20 meters when flying at altitudes between 1,200 and 8,000 meters. It operates at four distinct scan rates: 7.3, 8.7, 12, and 25 scans per second.

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.

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

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

Rosemount Pressure Probes are in situ airborne pressure sensors manufactured by Rosemount, Inc. They provide high-precision atmospheric pressure measurements and are typically used to gather flight-level meteorological observations. Rosemount Pressure Probes consist of various pressure transducers, gauges, and multivariable and coplanar transmitters.

Rosemount Temperature Probes are in situ airborne temperature sensors manufactured by Rosemount, Inc. They provide atmospheric temperature measurements and are typically used to collect flight-level meteorological observations. Rosemount Temperature Probes consist of temperature transmitters, thermocouple sensors, resistance temperature detectors, and other temperature sensors.

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.

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 Precision Radiation Thermometer (PRT-5) is an in situ infrared temperature sensor. It makes non-contact infrared (8-14 μm) temperature measurements between -50 to 150 degrees Celsius with an accuracy of 0.5 degrees Celsius. It has a typical field of view of 2 degrees and a response time of either 0.3 Hz, 3 Hz, or 30 Hz. PRT-5 can be deployed on aircraft, vehicles, research vessels, and other ground-based platforms. It can be used for sea surface, ocean water, cloud, and air temperature measurements.

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.

A pyranometer is a ground-based or airborne radiation sensor that measures solar irradiance across a hemispherical field of view. It detects the amount of solar energy reaching the surface, capturing both direct and diffuse sunlight. Pyranometers operate within a spectral range of 280-3000 nm. They are most commonly used for solar monitoring, climate research, weather forecasting, agriculture, and energy management.

The MODIS Airborne Simulator (MAS) is an airborne multispectral spectrometer designed to simulate the satellite instrument Moderate-Resolution Imaging Spectrometer (MODIS). MAS operates over 50 spectral channels in the 0.55 to 14.2 μm range, providing high-resolution images of clouds and surface features. It has a horizontal spatial resolution of 50 meters and a swath width of about 36 kilometers at an altitude of 20 km at nadir. Its scan rate is 6.25 Hz, with each scan line containing 716 pixels.

The Thematic Mapper Simulator (TMS) is an airborne imaging spectrometer designed to simulate the Landsat Thematic Mapper. It captures radiance measurements and imagery for mapping vegetation and land cover. TMS operates across ten spectral channels in the visible and near-infrared spectrum (0.42-2.35 μm) and two in the thermal infrared range (8.5-14 μm). It has a horizontal spatial resolution of 25 m and a swath width of 15.6 km at an altitude of 19.8 km. TMS has a scan rate of 12.5 scans per second and a total field of view of 42.5 degrees.

The Airborne Visible/Infrared Imaging Spectrometer - Classic (AVIRIS-C) is a passive imaging spectrometer developed at the Jet Propulsion Laboratory (JPL). It collects visible and infrared images across 224 spectral channels in the 380 to 2510 nm range. It has a horizontal resolution of 20 m and a swath width of 12 km at an altitude of 20 km. It operates at a scan rate of 12 Hz. AVIRIS-C has been replaced by AVIRIS-Next Generation (AVIRIS-NG), but it still remains in use.

The Airborne Ocean Color Imager (AOCI) was an airborne multispectral imaging spectrometer developed by Daedalus Enterprises. It was designed to measure visible and infrared radiance over water to evaluate chlorophyll levels and turbidity. It operated within the 0.436-12.279 μm wavelength range, featuring eight spectral channels in the visible and near-infrared, and two channels in the thermal infrared. AOCI had a spatial resolution of 49.5 meters at nadir at an altitude of 19,800 meters. Its scan rate ranged from 10 to 100 scans per second.

Radiosondes are a balloon-borne instrument package used to collect profile measurements of pressure, temperature, humidity, and winds. These sensors are connected to a radio transmitter that sends the measurements to a ground receiver typically operating in the 400-406 MHz range. They typically provide measurements at 1-6 seconds, depending on the type and manufacturer of the radiosonde. Radiosondes are used for weather forecasting, ground truth satellite data, atmospheric research, and input for weather prediction models.

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.

Eddy Covariance Flux Towers are in situ micrometeorological surface towers. They are equipped with gas sensors to continuously measure the trace gas fluxes between the land surface and the atmosphere. Eddy Covariance Towers are typically used to measure fluxes for carbon dioxide (CO2), methane (CH4), and water vapor (H2O). These towers are also equipped with various meteorological sensors to measure air temperature, precipitation, winds, radiation, and soil temperature.

Rain gauges are ground-based instruments that measure liquid precipitation amounts directly over a specified period. Different rain gauges, such as tipping buckets and weighing gauges, collect and record data in various ways. Because of their small size and easy setup, rain gauges can be placed in different locations and are often used alongside other precipitation instruments like disdrometers to gather more details, such as precipitation rate and 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.

Soil temperature sensors are in situ ground-based sensors used to measure and monitor soil temperature. They measure soil temperature by using thermistors or thermocouples to detect changes in resistance to calculate the temperature. Soil temperature sensors are used for agricultural purposes, environmental monitoring, and ecological research.

A pyrgeometer is a ground-based or airborne passive radiation sensor. It measures downward and upward longwave radiation in the 4-50 μm spectral range. Pyrgeometers measure changes in resistance/voltage using a thermopile sensor to determine longwave radiation. These measurements can be used to calculate the infrared radiation flux. Pyrgeometers are typically used for climatological, meteorological, and agricultural applications.

A snow measuring rod is a ground-based instrument used to measure snow depth. It is designed to be pushed into the snow until the underlying surface is reached to determine the snow depth. Snow measuring rods can be manual or automated, with the automated rod able to measure the depth and position simultaneously.

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

A pyranometer is a ground-based or airborne radiation sensor that measures solar irradiance across a hemispherical field of view. It detects the amount of solar energy reaching the surface, capturing both direct and diffuse sunlight. Pyranometers operate within a spectral range of 280-3000 nm. They are most commonly used for solar monitoring, climate research, weather forecasting, agriculture, and energy management.

C-band radars operate within the 4-8 GHz frequency range. They provide measurements of radar reflectivity, Doppler velocity, and other parameters to characterize precipitation and clouds. C-band radars are usually used for short-range weather observations because they are more prone to attenuation.

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.

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

The LI-COR Plant Canopy Analyzer is an in situ analyzer manufactured by LI-COR for leaf area index (LAI) measurements. It measures diffuse sky radiation that passes through the canopy across five zenith angels to determine LAI and other canopy characteristics. It can be used for most sky conditions and canopy types, such as row crops, grasslands, isolated trees, and forests. The optical sensor within the Plant Canopy Analyzer has a wavelength range of 320-490 nm. It has a field of view of 148 degrees and an operating temperature range of -20 to 50 degrees Celsius.

Digital cameras are used to provide imagery for research applications. Cameras are used on aircraft to collect aerial imagery for mapping and surveying, environmental monitoring, cloud observations, agriculture, geological studies, and other Earth science applications. They are also used at field sites to capture visual observations to monitor changes in land cover, vegetation, clouds, air quality, glaciers, and other phenomena.

The LI-COR Quantum Sensor is a ground-based, in situ radiation sensor manufactured by LI-COR. It collects precise photosynthetically active radiation (PAR) measurements beneath vegetation or under artificial light sources. The sensor detects radiation within the same light spectrum (400 - 700 nm) that plants use for photosynthesis. While primarily used for ground-based measurements, the LI-COR Quantum Sensor can also be mounted on aircraft. It is suitable for long-term deployments and remains durable in high temperatures and humidity conditions.

The Spectron Engineering-590 (SE-590) Spectroradiometer is a portable spectroradiometer manufactured by Spectron Engineering. It can be used on both airborne and ground-based platforms. SE-590 uses a charge-coupled device (CCD) area array detector to measure reflectance. It operates across the visible to short-wave infrared spectral range (350-2500 nm). The SE-590 has a ground resolution of 4.5 meters when flown at an altitude of 300 meters.

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.

Spectrophotometers are passive photometers that measure the light intensity of the sample solution as a function of the wavelength of the electromagnetic radiation. Spectrophotometers are typically used for ground-based or shipborne observations. They can operate either in the ultraviolet to visible (185-700 nm) spectral range or the infrared (700-15000 nm) range. They are typically used in vegetation studies, air pollution monitoring, and water and soil quality analysis.

The Lyman-alpha Hygrometer is an in situ hygrometer designed for deployment on airborne or ground-based platforms. It measures water vapor absorption at the Lyman-alpha wavelength (121.6 nm) of atomic hydrogen to determine the total water content in the atmosphere. It has a detection limit of 0.1 ppmv and a typical data acquisition rate of 1 second. The Lyman-alpha hygrometer provides water vapor measurements with an accuracy of 6% and a precision of 5%.

The Analytical Spectral Device Full Range (ASD-FR) is a ground-based passive spectroradiometer made by Malvern PANalytical. It measures reflectance, transmittance, radiance, and irradiance spectra of vegetation, soils, rocks, and bodies of water. It operates across the entire solar irradiance spectrum (350-2500 nm). It has a spectral resolution of 3 nm in the visible and near-infrared (VNIR) region and 8 nm in the shortwave infrared (SWIR). ASD-FR is used for collecting ground truth data, geology research, plant physiology, ecology studies, and other atmospheric remote sensing applications.

A Tunable Diode Laser Absorption Spectrometer (TDLAS) is an in situ optical spectrometer used either on aircraft or on the ground. TDLAS detects the wavelength-dependent absorption of light to measure the concentrations of various trace gases. It can also identify the gas species' temperature, pressure, velocity, and mass flux when applicable. TDLAS typically has a time resolution of 1 second.

A Snow Water Equivalent (SWE) Sampler is a ground-based device used in the field to measure SWE. A core sample of snow is collected using a snow tube sampler or snow corer. The tube is inserted vertically into the snowpack until it reaches the ground surface, and a ruler on the tube measures the snow depth. The sample is then removed and weighed on a calibrated scale to determine the snow density. The SWE within the sample is calculated by multiplying the snow density by the snow depth.

Ceptometers are ground-based radiation sensors used to measure photosynthetically active radiation (PAR) in plant canopies. Ceptometers make PAR measurements above and below the canopy to calculate the leaf area index (LAI). Ceptometers are used for vegetation and agriculture research into plant growth, canopy structure, light interception, and other canopy characteristics.

Soil moisture probes are in situ ground-based sensors that measure soil water content. The most common type of soil moisture probes used for scientific research use dielectric permittivity techniques, such as capacitance or time-domain reflectometry sensors. These types of probes measure the charge-storage capacity of the soil to determine the soil moisture content. They typically operate at frequencies around 50 MHz and above to reduce sensitivity to salinity. Soil moisture probes provide continuous measurements and are relatively easy to deploy.

Rain gauges are ground-based instruments that measure liquid precipitation amounts directly over a specified period. Different rain gauges, such as tipping buckets and weighing gauges, collect and record data in various ways. Because of their small size and easy setup, rain gauges can be placed in different locations and are often used alongside other precipitation instruments like disdrometers to gather more details, such as precipitation rate and size distribution.

The Multiband Vegetation Image (MVI) is a ground-based imager operated by the University of Wisconsin. It uses a combination of a charge-coupled device (CCD) camera and a two-band filter exchange mechanism to capture imagery in the visible (400-620 nm) and near-infrared (720-950 nm) spectral bands. This imagery is used to determine canopy and leaf characteristics such as leaf area index (LAI), canopy gap fraction, canopy gap-size distribution, and leaf angle distribution. Each image is 512 x 1024 pixels, with each pixel representing 1 cm at a distance of 10 m from the camera. MVI has a field of view (FOV) of 15 x 30 degrees.

The High-Performance Liquid Chromatograph (HPLC) is an in situ ground-based analyzer used to separate and identify components in a sample of air or a mixture. It works by injecting a liquid into the sample, causing different flow rates for each component as they pass through the column. As each component exits the column, their concentrations are measured at a high resolution. In Earth science research, HPLC is commonly used to detect various trace species in the atmosphere, such as formaldehyde, hydrogen peroxide, and volatile organic compounds (VOCs). Although primarily used for laboratory analysis and ground-based measurements, it can also be employed for airborne measurements.

The NOAA/ETL Scanning Ka-band Cloud Radar (NOAA/K) is a ground-based millimeter wave radar. It operates at a 34.66 GHz frequency to measure radar reflectivity and Doppler velocity. These measurements are used to characterize cloud microphysical properties such as cloud droplet size and concentration. NOAA/K has a beam width ranging from 0.3 to 0.5 degrees, a pulse length of 0.25 microseconds, and a resolution of 37.5 meters. It is deployed on a flatbed trailer, making it easily transportable.

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 Radio Acoustic Sounding System (RASS) is an active ground-based acoustic sounder that provides profiles of virtual temperature. It uses radar techniques to measure acoustic disturbances and derive the virtual temperature. RASS is typically used alongside radar wind profilers (RWPs) and operates at frequencies of 915 MHz and 1290 MHz. It has a sampling rate of approximately 5 to 15 minutes, a vertical resolution of 150 m, and a horizontal resolution of 60 m.

Stream gauges are ground-based sensors that measure the water level or stage of rivers and streams at specific locations. The flow or discharge of a river can then be calculated from these stage measurements. These gauges can provide continuous data, making them useful for monitoring flood risk and water supply. The United States Geological Survey (USGS) operates a network of over 10,000 stream gauges across the United States to assist with flood prediction and water resource management.

The Portable Apparatus for Rapid Acquisition of Bidirectional Observations of the Land and Atmosphere (PARABOLA) is a passive ground-based sphere scanning radiometer. It measures surface reflectance across eight spectral channels. The first four channels (444, 551, 650, and 860 nm) coincide with spectral bands from the Multi-angle Imaging SpectroRadiometer (MISR) on the Terra satellite for validation purposes. The last four channels are used for the characterization of water vapor (944 nm), aerosol optical depth at longer wavelengths (1028 and 1650 nm), and measurements of photosynthetically active radiation (400-700 nm). The measurements from PARABOLA can be used to derive the surface bidirectional reflectance factor and sky and surface radiances. A complete scan of both sky and ground hemispheres takes approximately 3 minutes.

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

The Lyman-alpha Hygrometer is an in situ hygrometer designed for deployment on airborne or ground-based platforms. It measures water vapor absorption at the Lyman-alpha wavelength (121.6 nm) of atomic hydrogen to determine the total water content in the atmosphere. It has a detection limit of 0.1 ppmv and a typical data acquisition rate of 1 second. The Lyman-alpha hygrometer provides water vapor measurements with an accuracy of 6% and a precision of 5%.

Rosemount Pressure Probes are in situ airborne pressure sensors manufactured by Rosemount, Inc. They provide high-precision atmospheric pressure measurements and are typically used to gather flight-level meteorological observations. Rosemount Pressure Probes consist of various pressure transducers, gauges, and multivariable and coplanar transmitters.

Rosemount Temperature Probes are in situ airborne temperature sensors manufactured by Rosemount, Inc. They provide atmospheric temperature measurements and are typically used to collect flight-level meteorological observations. Rosemount Temperature Probes consist of temperature transmitters, thermocouple sensors, resistance temperature detectors, and other temperature sensors.

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 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 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 King Probe is an in situ airborne cloud instrument developed by Warren King (Commonwealth Scientific and Industrial Research Organisation) and manufactured by Particle Measuring Systems (PMS) and Droplet Measurement Technologies (DMT). The King Probe measures cloud liquid water content (LWC) by detecting the heat released when water droplets vaporize. It operates at a constant temperature of approximately 100°C and has a data output rate of 1 to 10 Hz. The probe is commonly used in studies of cloud microphysics and aircraft icing.

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

The Precision Radiation Thermometer (PRT-5) is an in situ infrared temperature sensor. It makes non-contact infrared (8-14 μm) temperature measurements between -50 to 150 degrees Celsius with an accuracy of 0.5 degrees Celsius. It has a typical field of view of 2 degrees and a response time of either 0.3 Hz, 3 Hz, or 30 Hz. PRT-5 can be deployed on aircraft, vehicles, research vessels, and other ground-based platforms. It can be used for sea surface, ocean water, cloud, and air temperature measurements.

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.

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 Aethalometer is an in situ aerosol measuring device made by Magee Scientific. It can be used on both airborne and ground-based platforms. It collects aerosols through a filter tape and gauges the attenuation of transmitted light to assess black carbon particle levels. The Aethalometer works across seven optical wavelengths (370, 470, 520, 590, 660, 880, and 950 nm) and delivers 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.

A pyranometer is a ground-based or airborne radiation sensor that measures solar irradiance across a hemispherical field of view. It detects the amount of solar energy reaching the surface, capturing both direct and diffuse sunlight. Pyranometers operate within a spectral range of 280-3000 nm. They are most commonly used for solar monitoring, climate research, weather forecasting, agriculture, and energy management.

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.

A pyrometer is a remote-sensing infrared thermometer that measures the temperature of distant objects. It determines an object's temperature by detecting its thermal radiation. It can be mounted on aircraft, ground vehicles, or water-based platforms for surface and sea surface temperature observations. For atmospheric studies, the pyrometer usually operates in the 9.6 to 11.5 µm spectral range and has a temperature range of -25 to 200 degrees Celsius. Pyrometers typically have a response time between 5 milliseconds and 600 seconds.

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

Generic-Chemistry Related Sensors (Gen-Chemistry) refers to non-specific instruments on a platform used for atmospheric chemistry measurements. These are typically in situ analyzers that measure various chemical compounds such as trace gases, halocarbons, volatile organic compounds, nitrates, aerosols, and other chemical species. Measurements can include mixing ratio, composition, particle size, optical properties, and particle size distribution.

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

The Advanced Solid-state Array Spectroradiometer (ASAS) is an airborne, passive multi-angle spectrometer operated by NASA Goddard Space Flight Center (GSFC). ASAS measures reflectance across 30 spectral channels within the 450 to 880 nm wavelength range to help characterize the directional variability of various land surface cover types. At typical flight altitudes of 4,500 to 5,000 meters, ASAS has a spatial resolution of 3 to 4 meters at nadir. It has a frame rate ranging from 3 to 64 frames per second.

The Thematic Mapper Simulator (TMS) is an airborne imaging spectrometer designed to simulate the Landsat Thematic Mapper. It captures radiance measurements and imagery for mapping vegetation and land cover. TMS operates across ten spectral channels in the visible and near-infrared spectrum (0.42-2.35 μm) and two in the thermal infrared range (8.5-14 μm). It has a horizontal spatial resolution of 25 m and a swath width of 15.6 km at an altitude of 19.8 km. TMS has a scan rate of 12.5 scans per second and a total field of view of 42.5 degrees.

The MODIS Airborne Simulator (MAS) is an airborne multispectral spectrometer designed to simulate the satellite instrument Moderate-Resolution Imaging Spectrometer (MODIS). MAS operates over 50 spectral channels in the 0.55 to 14.2 μm range, providing high-resolution images of clouds and surface features. It has a horizontal spatial resolution of 50 meters and a swath width of about 36 kilometers at an altitude of 20 km at nadir. Its scan rate is 6.25 Hz, with each scan line containing 716 pixels.

The POLarization and Directionality of the Earth’s Reflectances (POLDER) is a spaceborne passive radiometer onboard the Japan Aerospace Exploration Agency’s Advanced Earth Observing Satellite. POLDER has also been used in several airborne investigations to calibrate instruments and measure surface reflectance and solar radiation. POLDER has a ground spatial resolution of 7 km by 6 km at nadir and operates across eight discrete spectral bands (443 nm - 910 nm).

The Scanning Lidar Imager of Canopies by Echo Recovery (SLICER) is an airborne and ground-based lidar system. SLICER provides measurements of various canopy characteristics such as canopy height, vertical structure, and ground elevation. It has a horizontal resolution of 10 meters and a vertical resolution of 1 meter and operates at 1.06 microns. SLICER can deliver high-resolution measurements beneath dense canopies and vegetated areas.

The MODIS Airborne Simulator (MAS) is an airborne multispectral spectrometer designed to simulate the satellite instrument Moderate-Resolution Imaging Spectrometer (MODIS). MAS operates over 50 spectral channels in the 0.55 to 14.2 μm range, providing high-resolution images of clouds and surface features. It has a horizontal spatial resolution of 50 meters and a swath width of about 36 kilometers at an altitude of 20 km at nadir. Its scan rate is 6.25 Hz, with each scan line containing 716 pixels.

The Airborne Visible/Infrared Imaging Spectrometer - Classic (AVIRIS-C) is a passive imaging spectrometer developed at the Jet Propulsion Laboratory (JPL). It collects visible and infrared images across 224 spectral channels in the 380 to 2510 nm range. It has a horizontal resolution of 20 m and a swath width of 12 km at an altitude of 20 km. It operates at a scan rate of 12 Hz. AVIRIS-C has been replaced by AVIRIS-Next Generation (AVIRIS-NG), but it still remains in use.

Soil temperature sensors are in situ ground-based sensors used to measure and monitor soil temperature. They measure soil temperature by using thermistors or thermocouples to detect changes in resistance to calculate the temperature. Soil temperature sensors are used for agricultural purposes, environmental monitoring, and ecological research.

A pyrgeometer is a ground-based or airborne passive radiation sensor. It measures downward and upward longwave radiation in the 4-50 μm spectral range. Pyrgeometers measure changes in resistance/voltage using a thermopile sensor to determine longwave radiation. These measurements can be used to calculate the infrared radiation flux. Pyrgeometers are typically used for climatological, meteorological, and agricultural applications.

A snow measuring rod is a ground-based instrument used to measure snow depth. It is designed to be pushed into the snow until the underlying surface is reached to determine the snow depth. Snow measuring rods can be manual or automated, with the automated rod able to measure the depth and position simultaneously.

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

A pyranometer is a ground-based or airborne radiation sensor that measures solar irradiance across a hemispherical field of view. It detects the amount of solar energy reaching the surface, capturing both direct and diffuse sunlight. Pyranometers operate within a spectral range of 280-3000 nm. They are most commonly used for solar monitoring, climate research, weather forecasting, agriculture, and energy management.

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.

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

The LI-COR Plant Canopy Analyzer is an in situ analyzer manufactured by LI-COR for leaf area index (LAI) measurements. It measures diffuse sky radiation that passes through the canopy across five zenith angels to determine LAI and other canopy characteristics. It can be used for most sky conditions and canopy types, such as row crops, grasslands, isolated trees, and forests. The optical sensor within the Plant Canopy Analyzer has a wavelength range of 320-490 nm. It has a field of view of 148 degrees and an operating temperature range of -20 to 50 degrees Celsius.

The LI-COR Quantum Sensor is a ground-based, in situ radiation sensor manufactured by LI-COR. It collects precise photosynthetically active radiation (PAR) measurements beneath vegetation or under artificial light sources. The sensor detects radiation within the same light spectrum (400 - 700 nm) that plants use for photosynthesis. While primarily used for ground-based measurements, the LI-COR Quantum Sensor can also be mounted on aircraft. It is suitable for long-term deployments and remains durable in high temperatures and humidity conditions.

The Spectron Engineering-590 (SE-590) Spectroradiometer is a portable spectroradiometer manufactured by Spectron Engineering. It can be used on both airborne and ground-based platforms. SE-590 uses a charge-coupled device (CCD) area array detector to measure reflectance. It operates across the visible to short-wave infrared spectral range (350-2500 nm). The SE-590 has a ground resolution of 4.5 meters when flown at an altitude of 300 meters.

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.

A Snow Water Equivalent (SWE) Sampler is a ground-based device used in the field to measure SWE. A core sample of snow is collected using a snow tube sampler or snow corer. The tube is inserted vertically into the snowpack until it reaches the ground surface, and a ruler on the tube measures the snow depth. The sample is then removed and weighed on a calibrated scale to determine the snow density. The SWE within the sample is calculated by multiplying the snow density by the snow depth.

Soil moisture probes are in situ ground-based sensors that measure soil water content. The most common type of soil moisture probes used for scientific research use dielectric permittivity techniques, such as capacitance or time-domain reflectometry sensors. These types of probes measure the charge-storage capacity of the soil to determine the soil moisture content. They typically operate at frequencies around 50 MHz and above to reduce sensitivity to salinity. Soil moisture probes provide continuous measurements and are relatively easy to deploy.

Rain gauges are ground-based instruments that measure liquid precipitation amounts directly over a specified period. Different rain gauges, such as tipping buckets and weighing gauges, collect and record data in various ways. Because of their small size and easy setup, rain gauges can be placed in different locations and are often used alongside other precipitation instruments like disdrometers to gather more details, such as precipitation rate and size distribution.

The Multiband Vegetation Image (MVI) is a ground-based imager operated by the University of Wisconsin. It uses a combination of a charge-coupled device (CCD) camera and a two-band filter exchange mechanism to capture imagery in the visible (400-620 nm) and near-infrared (720-950 nm) spectral bands. This imagery is used to determine canopy and leaf characteristics such as leaf area index (LAI), canopy gap fraction, canopy gap-size distribution, and leaf angle distribution. Each image is 512 x 1024 pixels, with each pixel representing 1 cm at a distance of 10 m from the camera. MVI has a field of view (FOV) of 15 x 30 degrees.

Stream gauges are ground-based sensors that measure the water level or stage of rivers and streams at specific locations. The flow or discharge of a river can then be calculated from these stage measurements. These gauges can provide continuous data, making them useful for monitoring flood risk and water supply. The United States Geological Survey (USGS) operates a network of over 10,000 stream gauges across the United States to assist with flood prediction and water resource management.

The Portable Apparatus for Rapid Acquisition of Bidirectional Observations of the Land and Atmosphere (PARABOLA) is a passive ground-based sphere scanning radiometer. It measures surface reflectance across eight spectral channels. The first four channels (444, 551, 650, and 860 nm) coincide with spectral bands from the Multi-angle Imaging SpectroRadiometer (MISR) on the Terra satellite for validation purposes. The last four channels are used for the characterization of water vapor (944 nm), aerosol optical depth at longer wavelengths (1028 and 1650 nm), and measurements of photosynthetically active radiation (400-700 nm). The measurements from PARABOLA can be used to derive the surface bidirectional reflectance factor and sky and surface radiances. A complete scan of both sky and ground hemispheres takes approximately 3 minutes.

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.

Radiosondes are a balloon-borne instrument package used to collect profile measurements of pressure, temperature, humidity, and winds. These sensors are connected to a radio transmitter that sends the measurements to a ground receiver typically operating in the 400-406 MHz range. They typically provide measurements at 1-6 seconds, depending on the type and manufacturer of the radiosonde. Radiosondes are used for weather forecasting, ground truth satellite data, atmospheric research, and input for weather prediction models.