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, enabling derivation of vegetation characteristics. It operates in the 430-870 nm 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 integration time and aircraft speed. CASI has a frame rate of 85 lines per second.

Generic Gamma-Ray Sensors (Gen-Gamma) are non-specific instruments mounted on a platform that measure gamma 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. The MMR measures radiance across 8 spectral bands spanning the infrared and visible wavelengths (0.4-12.5 μm), producing 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, such as 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 measure ice, vegetation, and soil surface properties. They operate in the C-band frequency range (4-8 GHz) and can provide measurements during both daytime and nighttime.

The Spectron Engineering-590 (SE-590) Spectroradiometer is a portable instrument manufactured by Spectron Engineering. It can be used on both airborne and ground-based platforms. The 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 instrument that measures direct solar beam transmission. The ATSP captures solar beam transmission across multiple channels spanning wavelengths 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 aboard 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 footage of various phenomena for research. 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 collect flight-level meteorological observations. Rosemount Pressure Probes include various pressure transducers, gauges, and multivariable and coplanar transmitters.

LI-COR Gas Analyzers are in situ gas analyzers manufactured by LI-COR. They can be deployed on aircraft, research vessels, vehicles, balloons, and ground-based platforms. They provide measurements of 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 that measure atmospheric state parameters. These are typically in situ sensors that measure temperature, pressure, humidity, and wind speed and 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 developed by Particle Measuring Systems, Inc. It determines particle size distribution by measuring the light intensity scattered by individual particles within a cloud. The FSSP detects particles from 0.5 to 47 μm in diameter. It operates at a wavelength of 633 nm and typically samples at 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). It measures cloud liquid water content (LWC) by detecting the heat released during droplet vaporization. It operates at a constant temperature of approximately 100°C and outputs data at 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 over a hemispherical field of view. It detects the amount of solar energy reaching the surface, capturing both direct and diffuse sunlight. Pyranometers operate across 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 that measures downward and upward longwave radiation in the 4-50 μm spectral range. It uses a thermopile sensor to detect changes in resistance or voltage, which are then used 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 instrument that measures direct solar beam transmission. The ATSP captures solar beam transmission across multiple channels spanning wavelengths 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 spanning 450 to 880 nm to 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 of 3 to 64 frames per second.

The Thematic Mapper Simulator (TMS) is an airborne imaging spectrometer that simulates 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 that simulates the Moderate-Resolution Imaging Spectrometer (MODIS) satellite instrument. MAS operates over 50 spectral channels spanning 0.55 to 14.2 μm, producing 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 aboard 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 spanning 8.2-12.2 μm. TIMS has a horizontal spatial resolution at nadir of 3 to 20 meters when flying at altitudes of 1,200 to 8,000 meters. It operates at four scan rates: 7.3, 8.7, 12, and 25 scans per second.

LI-COR Gas Analyzers are in situ gas analyzers manufactured by LI-COR. They can be deployed on aircraft, research vessels, vehicles, balloons, and ground-based platforms. They provide measurements of 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 that measure atmospheric state parameters. These are typically in situ sensors that measure temperature, pressure, humidity, and wind speed and 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 provides spatial resolution better than 100 meters at typical DC-8 research flight speeds. NOx/NOxy can be deployed on ground-based, airborne, and shipborne platforms, supporting a range of 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 chemical compounds such as trace gases, halocarbons, volatile organic compounds, nitrates, aerosols, and other chemical species. Measurements can include mixing ratios, 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 collect flight-level meteorological observations. Rosemount Pressure Probes include 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 that measure atmospheric state parameters. These are typically in situ sensors that measure temperature, pressure, humidity, and wind speed and direction. Types of atmospheric state instruments include thermometers, hygrometers, barometers, and anemometers.

LI-COR Gas Analyzers are in situ gas analyzers manufactured by LI-COR. They can be deployed on aircraft, research vessels, vehicles, balloons, and ground-based platforms. They provide measurements of 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 provides non-contact infrared (8-14 μm) temperature measurements from -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 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 to measure sea surface, ocean water, cloud, and air temperatures.

Thermo Scientific Gas Analyzers are in situ gas analyzers manufactured by ThermoFisher Scientific. They provide precise measurements of trace gases, including 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 over a hemispherical field of view. It detects the amount of solar energy reaching the surface, capturing both direct and diffuse sunlight. Pyranometers operate across 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 that simulates the Moderate-Resolution Imaging Spectrometer (MODIS) satellite instrument. MAS operates over 50 spectral channels spanning 0.55 to 14.2 μm, producing 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 that simulates 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 spanning 380 to 2510 nm. 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 is still in use.

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

Radiosondes are balloon-borne instrument packages that collect profiles of pressure, temperature, humidity, and wind. 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 every 1-6 seconds, depending on the radiosonde type and manufacturer. Radiosondes are used for weather forecasting, ground-truthing satellite data, atmospheric research, and as input for weather prediction models.

Ozonesondes are in situ balloon-borne instruments that measure ozone concentration profiles. An ozonesonde consists of an electrochemical ozone sensor connected to a meteorological radiosonde, which collects 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 typically operate at a 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 trace gas fluxes between the land surface and the atmosphere. Eddy Covariance Towers are typically used to measure fluxes of carbon dioxide (CO2), methane (CH4), and water vapor (H2O). These towers are also equipped with various meteorological sensors to measure air temperature, precipitation, wind, radiation, and soil temperature.

Rain gauges are ground-based instruments that directly measure the amount of liquid precipitation over a specified period. Different types of 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, such as disdrometers, to gather additional details, such as precipitation rate and size distribution.

Generic-Atmospheric State (Gen-AtmsState) refers to non-specific instruments on a platform that measure atmospheric state parameters. These are typically in situ sensors that measure temperature, pressure, humidity, and wind speed and 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 use thermistors or thermocouples to detect changes in resistance and calculate temperature. Soil temperature sensors are used for agricultural purposes, environmental monitoring, and ecological research.

A snow measuring rod is a ground-based instrument used to measure snow depth. It is pushed into the snow until the underlying surface is reached, thereby determining the depth. Snow measuring rods can be manual or automated, with automated rods able to measure 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, not sunlight scattered by aerosols. These measurements can be used to determine aerosol optical depth by applying Beer’s Law. Sunphotometers have been deployed on aircraft, research vessels, and field sites for aerosol research and monitoring.

A pyrgeometer is a ground-based or airborne passive radiation sensor that measures downward and upward longwave radiation in the 4-50 μm spectral range. It uses a thermopile sensor to detect changes in resistance or voltage, which are then used 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 pyranometer is a ground-based or airborne radiation sensor that measures solar irradiance over a hemispherical field of view. It detects the amount of solar energy reaching the surface, capturing both direct and diffuse sunlight. Pyranometers operate across 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 in 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 typically used for short-range weather observations because they are more prone to attenuation.

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

LI-COR Gas Analyzers are in situ gas analyzers manufactured by LI-COR. They can be deployed on aircraft, research vessels, vehicles, balloons, and ground-based platforms. They provide measurements of 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 that measure atmospheric state parameters. These are typically in situ sensors that measure temperature, pressure, humidity, and wind speed and 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 chemical compounds such as trace gases, halocarbons, volatile organic compounds, nitrates, aerosols, and other chemical species. Measurements can include mixing ratios, composition, particle size, optical properties, and particle size distribution.

The LI-COR Plant Canopy Analyzer is an in situ instrument manufactured by LI-COR for leaf area index (LAI) measurements. It measures diffuse sky radiation passing through the canopy at five zenith angles to determine LAI and other canopy characteristics. It can be used under most sky conditions and across canopy types, including 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.

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.

Digital cameras provide imagery for research applications. Cameras are mounted 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 deployed at field sites to capture visual observations that 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 measurements of photosynthetically active radiation (PAR) 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.

The Spectron Engineering-590 (SE-590) Spectroradiometer is a portable instrument manufactured by Spectron Engineering. It can be used on both airborne and ground-based platforms. The 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.

Spectrophotometers are passive photometers that measure the intensity of light transmitted through a sample solution as a function of the wavelength of electromagnetic radiation. They are typically used for ground-based or shipborne observations. They can operate in the ultraviolet-to-visible (185-700 nm) or infrared (700-15000 nm) spectral ranges. They are commonly 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 6% accuracy and 5% precision.

A Snow Water Equivalent (SWE) Sampler is a ground-based device used in the field to measure SWE. A snow core 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 that measure photosynthetically active radiation (PAR) in plant canopies. They make PAR measurements both above and below the canopy to calculate the leaf area index (LAI). Ceptometers are used in vegetation and agricultural research on plant growth, canopy structure, light interception, and other canopy characteristics.

NOx/NOxy is an in situ chemiluminescence instrument that measures nitrogen oxides and ozone in the atmosphere. It provides spatial resolution better than 100 meters at typical DC-8 research flight speeds. NOx/NOxy can be deployed on ground-based, airborne, and shipborne platforms, supporting a range of atmospheric chemistry and air quality studies.

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

Soil moisture probes are in situ, ground-based sensors that measure soil water content. The most common type of soil moisture probe used in scientific research employs dielectric permittivity techniques, such as capacitance or time-domain reflectometry. These probes measure the soil's charge-storage capacity to determine 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 directly measure the amount of liquid precipitation over a specified period. Different types of 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, such as disdrometers, to gather additional 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 combines a charge-coupled device (CCD) camera with 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, including 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 that separates and identifies 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, its concentration is measured at 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 34.66 GHz to measure radar reflectivity and Doppler velocity. These measurements are used to characterize cloud microphysical properties, including droplet size and concentration. NOAA/K has a beam width of 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.

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 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 support 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, spherical-scanning radiometer. It measures surface reflectance across eight spectral channels. The first four channels (444, 551, 650, and 860 nm) align with spectral bands from the Multi-angle Imaging SpectroRadiometer (MISR) on the Terra satellite for validation. The remaining four channels characterize water vapor (944 nm), aerosol optical depth at longer wavelengths (1028 and 1650 nm), and photosynthetically active radiation (400-700 nm). PARABOLA measurements can be used to derive the surface bidirectional reflectance factor and sky and surface radiances. A complete scan of both the sky and ground hemispheres takes approximately 3 minutes.

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

The Analytical Spectral Device Full Range (ASD-FR) is a ground-based passive spectroradiometer manufactured 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). The ASD-FR is used to collect ground truth data, support geological research, study plant physiology and ecology, and support other atmospheric remote sensing applications.

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 collect flight-level meteorological observations. Rosemount Pressure Probes include 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.

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

LI-COR Gas Analyzers are in situ gas analyzers manufactured by LI-COR. They can be deployed on aircraft, research vessels, vehicles, balloons, and ground-based platforms. They provide measurements of 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 that measure atmospheric state parameters. These are typically in situ sensors that measure temperature, pressure, humidity, and wind speed and 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 Passive-Cavity Aerosol Spectrometer Probe (PCASP) is an in situ airborne optical spectrometer manufactured by Droplet Measurement Technologies. It measures light scattered by particles to determine aerosol size distribution and concentration across 0.1 to 3.0 μm. PCASP operates at 632 nm and typically samples at 10 Hz.

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 6% accuracy and 5% precision.

NOx/NOxy is an in situ chemiluminescence instrument that measures nitrogen oxides and ozone in the atmosphere. It provides spatial resolution better than 100 meters at typical DC-8 research flight speeds. NOx/NOxy can be deployed on ground-based, airborne, and shipborne platforms, supporting a range of atmospheric chemistry and air quality studies.

A pyrometer is a remote-sensing infrared thermometer that measures the temperature of distant objects by detecting their 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.

The Condensation Nuclei Counter (CNC) is an in situ optical sensor produced by Droplet Measurement Technologies and TSI, Inc. It detects cloud condensation nuclei (CCN) by supersaturating the sampled air, making CCN particles detectable. The particles are then measured by an optical particle counter (OPC). The CNC detects 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 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 profiles 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 Forward Scattering Spectrometer Probe (FSSP) is an in situ airborne optical particle counter developed by Particle Measuring Systems, Inc. It determines particle size distribution by measuring the light intensity scattered by individual particles within a cloud. The FSSP detects particles from 0.5 to 47 μm in diameter. It operates at a wavelength of 633 nm and typically samples at 1 Hz.

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). It measures cloud liquid water content (LWC) by detecting the heat released during droplet vaporization. It operates at a constant temperature of approximately 100°C and outputs data at 1 to 10 Hz. The probe is commonly used in studies of cloud microphysics and aircraft icing.

The Precision Radiation Thermometer (PRT-5) is an in situ infrared temperature sensor. It provides non-contact infrared (8-14 μm) temperature measurements from -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 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 to measure sea surface, ocean water, cloud, and air temperatures.

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

Thermo Scientific Gas Analyzers are in situ gas analyzers manufactured by ThermoFisher Scientific. They provide precise measurements of trace gases, including ozone, carbon dioxide, carbon monoxide, and sulfur dioxide. Thermo Scientific Gas Analyzers can be deployed on aircraft, research vessels, and ground-based platforms.

The Aethalometer is an in situ aerosol measurement device made by Magee Scientific. It can be used on both airborne and ground-based platforms. It collects aerosols on a filter tape and measures the attenuation of transmitted light to assess black carbon concentrations. The Aethalometer operates across seven optical wavelengths (370, 470, 520, 590, 660, 880, and 950 nm) and provides data at 1 Hz. It has a measurement range of 0-500 μg per cubic meter and a resolution of 0.1 μg per cubic meter.

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 chemical compounds such as trace gases, halocarbons, volatile organic compounds, nitrates, aerosols, and other chemical species. Measurements can include mixing ratios, composition, particle size, optical properties, and particle size distribution.

The Airborne Tracking Sun Photometer (ATSP) is an airborne instrument that measures direct solar beam transmission. The ATSP captures solar beam transmission across multiple channels spanning wavelengths 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 spanning 450 to 880 nm to 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 of 3 to 64 frames per second.

The Thematic Mapper Simulator (TMS) is an airborne imaging spectrometer that simulates 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 that simulates the Moderate-Resolution Imaging Spectrometer (MODIS) satellite instrument. MAS operates over 50 spectral channels spanning 0.55 to 14.2 μm, producing 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 aboard 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 canopy characteristics, including canopy height, vertical structure, and ground elevation. It has a horizontal resolution of 10 meters and a vertical resolution of 1 meter, and it operates at 1.06 microns. SLICER can deliver high-resolution measurements beneath dense canopies and in vegetated areas.

The MODIS Airborne Simulator (MAS) is an airborne multispectral spectrometer that simulates the Moderate-Resolution Imaging Spectrometer (MODIS) satellite instrument. MAS operates over 50 spectral channels spanning 0.55 to 14.2 μm, producing 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 spanning 380 to 2510 nm. 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 is still in use.

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

A snow measuring rod is a ground-based instrument used to measure snow depth. It is pushed into the snow until the underlying surface is reached, thereby determining the depth. Snow measuring rods can be manual or automated, with automated rods able to measure 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, not sunlight scattered by aerosols. These measurements can be used to determine aerosol optical depth by applying Beer’s Law. Sunphotometers have been deployed on aircraft, research vessels, and field sites for aerosol research and monitoring.

A pyrgeometer is a ground-based or airborne passive radiation sensor that measures downward and upward longwave radiation in the 4-50 μm spectral range. It uses a thermopile sensor to detect changes in resistance or voltage, which are then used 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 pyranometer is a ground-based or airborne radiation sensor that measures solar irradiance over a hemispherical field of view. It detects the amount of solar energy reaching the surface, capturing both direct and diffuse sunlight. Pyranometers operate across a spectral range of 280-3000 nm. They are most commonly used for solar monitoring, climate research, weather forecasting, agriculture, and energy management.

LI-COR Gas Analyzers are in situ gas analyzers manufactured by LI-COR. They can be deployed on aircraft, research vessels, vehicles, balloons, and ground-based platforms. They provide measurements of 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 that measure atmospheric state parameters. These are typically in situ sensors that measure temperature, pressure, humidity, and wind speed and 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 chemical compounds such as trace gases, halocarbons, volatile organic compounds, nitrates, aerosols, and other chemical species. Measurements can include mixing ratios, composition, particle size, optical properties, and particle size distribution.

The LI-COR Plant Canopy Analyzer is an in situ instrument manufactured by LI-COR for leaf area index (LAI) measurements. It measures diffuse sky radiation passing through the canopy at five zenith angles to determine LAI and other canopy characteristics. It can be used under most sky conditions and across canopy types, including 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.

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 Quantum Sensor is a ground-based, in situ radiation sensor manufactured by LI-COR. It collects precise measurements of photosynthetically active radiation (PAR) 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.

The Spectron Engineering-590 (SE-590) Spectroradiometer is a portable instrument manufactured by Spectron Engineering. It can be used on both airborne and ground-based platforms. The 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.

A Snow Water Equivalent (SWE) Sampler is a ground-based device used in the field to measure SWE. A snow core 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 probe used in scientific research employs dielectric permittivity techniques, such as capacitance or time-domain reflectometry. These probes measure the soil's charge-storage capacity to determine 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 directly measure the amount of liquid precipitation over a specified period. Different types of 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, such as disdrometers, to gather additional 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 combines a charge-coupled device (CCD) camera with 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, including 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 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 support 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, spherical-scanning radiometer. It measures surface reflectance across eight spectral channels. The first four channels (444, 551, 650, and 860 nm) align with spectral bands from the Multi-angle Imaging SpectroRadiometer (MISR) on the Terra satellite for validation. The remaining four channels characterize water vapor (944 nm), aerosol optical depth at longer wavelengths (1028 and 1650 nm), and photosynthetically active radiation (400-700 nm). PARABOLA measurements can be used to derive the surface bidirectional reflectance factor and sky and surface radiances. A complete scan of both the sky and ground hemispheres takes approximately 3 minutes.

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

Radiosondes are balloon-borne instrument packages that collect profiles of pressure, temperature, humidity, and wind. 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 every 1-6 seconds, depending on the radiosonde type and manufacturer. Radiosondes are used for weather forecasting, ground-truthing satellite data, atmospheric research, and as input for weather prediction models.