Southern African Regional Science Initiative

The AErosol RObotic NETwork (AERONET) is a federated network of ground-based remote sensing aerosol sensors established by NASA and the PHOtométrie pour le Traitement Opérationnel de Normalisation Satellitaire (PHOTONS) in 1993. Each AERONET site includes a CIMEL Electronique sunphotometer that measures sun irradiance and sky radiances. These measurements are used to determine aerosol properties such as aerosol optical depth and extinction. The sunphotometers operate at nine wavelengths (340, 380, 440, 500, 675, 870, 937, 1020, and 1640 nm) and provide aerosol data approximately every 15 minutes. AERONET sites are distributed worldwide, enabling mapping of about 90% of the Earth’s surface.

The Fourier Transformation Spectrometer (FTS) is a high-resolution spectrometer used both in airborne and ground-based applications. FTS measures the solar radiance reflected from the surface, which can be used to estimate levels of carbon monoxide (CO), carbon dioxide (CO2), and methane (CH4) in the atmosphere. It offers a spatial resolution of approximately 100m by 1000m and operates at a measurement frequency of 1 Hz during typical research flights.

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.

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.

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 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.

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.

Infrared Thermometers (IRTs) are ground-based pyrometers that measure the brightness temperature of a scene within their field of view. They determine brightness temperature by detecting electromagnetic radiation emitted by Earth’s surface. These measurements are used to find either the surface skin temperature or the sea surface temperature, depending on whether the platform is on land or water. IRTs typically operate within the 8- to 14-μm wavelength range.

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.

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.

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.

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.

The Fourier Transformation Spectrometer (FTS) is a high-resolution spectrometer used both in airborne and ground-based applications. FTS measures the solar radiance reflected from the surface, which can be used to estimate levels of carbon monoxide (CO), carbon dioxide (CO2), and methane (CH4) in the atmosphere. It offers a spatial resolution of approximately 100m by 1000m and operates at a measurement frequency of 1 Hz during typical research flights.

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.

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 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.

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.

Infrared Thermometers (IRTs) are ground-based pyrometers that measure the brightness temperature of a scene within their field of view. They determine brightness temperature by detecting electromagnetic radiation emitted by Earth’s surface. These measurements are used to find either the surface skin temperature or the sea surface temperature, depending on whether the platform is on land or water. IRTs typically operate within the 8- to 14-μm wavelength range.

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.

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.

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

The Airborne Multi-angle Imaging SpectroRadiometer (AirMISR) is a passive remote sensor with a pushbroom design, developed by the Jet Propulsion Laboratory (JPL). AirMISR captures visible and infrared images similar to those from the MISR instrument on the Terra satellite. It gathers data using a single camera at nine viewing angles and operates in four spectral bands: 443 nm, 555 nm, 670 nm, and 865 nm. AirMISR has approximately an 11 km swath width and an instantaneous field of view of 7 m x 6 m at nadir. It is usually flown on the NASA ER-2 aircraft due to its high operating altitude of 20 km.

The Measurement of Pollution in the Troposphere - Aircraft (MOPITT-A) is an airborne radiometer developed at the University of Toronto. It is a scaled-down version of the MOPITT instrument on the Terra satellite and is used for validation measurements. It detects thermal and solar radiation to deliver column measurements of carbon monoxide (CO) and methane (CH4). MOPITT-A operates across four channels at wavelengths of 4.617 μm, 2.334 μm, and 2.258 μm. Its footprint covers 2.52 km, with an accuracy of 10% for CO and 1% for CH4.

The RC-10 Mapping Camera was an airborne imaging system built by Wild Heerburg. It was a metric mapping camera with a shutter intervalometer designed to capture stereo imagery. It functioned across the 510 to 900 nm spectral range and had a typical resolution of 1.5 to 4 meters. The camera featured a 9x9 image format and was mounted in the Q-bay, nose pod, and both left and right wing pods of NASA’s ER-2 aircraft.

The Cloud Physics Lidar (CPL) is an airborne lidar system designed specifically to provide multi-wavelength measurements of cirrus clouds, sub-visual cirrus clouds, and aerosols. It measures lidar backscatter at three wavelengths: 355 nm, 532 nm, and 1064 nm. These measurements can be used to determine cloud optical depth, particle size distribution, extinction profiles, aerosol layers, and other properties. CPL has a vertical resolution of 30 m and a typical horizontal resolution of 200 m. It has a measurement sampling rate of 1 Hz.

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 Scanning High-resolution Interferometer Sounder (S-HIS) is an airborne cross-track scanning interferometer developed by the Space Science and Engineering Center at the University of Wisconsin-Madison. It measures emitted thermal radiation between 3.3 and 18 microns with high spectral resolution. These measurements help derive atmospheric profiles of temperature and water vapor in clear-sky conditions. S-HIS has a spatial resolution of 2 km and a swath width of 40 km at an altitude of 20 km at nadir. It operates at a sampling frequency of 0.5 seconds and has an absolute radiance accuracy of 0.2 K.

The Solar Spectral Flux Radiometer (SSFR) is an airborne radiometer developed by the Ames Atmospheric Radiation Group. It measures solar spectral irradiance in the troposphere. SSFR works within the 300-2150 nm wavelength range and offers a spectral resolution of 8-12 nm. It typically collects data at 1 Hz and has a radiometric accuracy of 3%.

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 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.

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 Counterflow Virtual Impactor (CVI) is an in situ airborne instrument that samples cloud droplets. It samples cloud droplets by removing them from the surrounding air through inertial impaction. CVI is typically deployed with additional sensors to provide measurements of cloud particle concentration, cloud liquid water, and water vapor of the sample droplets. CVI can detect cloud droplets as small as 7 microns in diameter and has a typical time response of 1 second.

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

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 Shortwave Spectroradiometer (SWS) is a radiometer that measures absolute visible and near-infrared spectral radiance. It includes two Zeiss spectroradiometers to measure spectral radiance, which are used to determine cloud optical depth, particle size, and water path. One spectroradiometer operates in the 300-1100 nm wavelength range at a spectral resolution of 8 nm, while the other operates in the 900-2200 nm range at a resolution of 12 nm. SWS has a sampling frequency of 1 Hz. The Department of Energy’s Atmospheric Radiation Measurement (ARM) User Facility operated a ground-based SWS, and the Facility for Airborne Atmospheric Measurements (FAAM) operated an airborne version as part of the airborne laboratory.

The Small Ice Detector 3 (SID-3) is an in situ airborne particle imager built by the University of Hertfordshire. It measures high-resolution angular scattering patterns of individual cloud particles to determine particle size distribution and number concentration. It operates at 532 nm and has a 5 to 50 μm detection range. SID-3 provides number concentration measurements typically every 1 second and particle size distribution measurements every 10 seconds.

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.

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

The Microwave Airborne Radiometer Scanning System (MARSS) is a passive, along-track scanning microwave radiometer developed by the United Kingdom Met Office and Laboratoire de Me´te´orologie Dynamique du Centre Nationale de Recherche Scientifique (LMD CNRS). It measures brightness temperature across five channels, two at 89 and 157 GHz and three channels centered at the water vapor absorption line at 183 GHz. It is typically used for the calibration and validation of satellite observations. MARSS has a 3-second scan time and an accuracy of better than 1 K.

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 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.

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

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.

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 Fourier Transformation Spectrometer (FTS) is a high-resolution spectrometer used both in airborne and ground-based applications. FTS measures the solar radiance reflected from the surface, which can be used to estimate levels of carbon monoxide (CO), carbon dioxide (CO2), and methane (CH4) in the atmosphere. It offers a spatial resolution of approximately 100m by 1000m and operates at a measurement frequency of 1 Hz during typical research flights.

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.

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.

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.

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.

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.

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.

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.

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.

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.

Infrared Thermometers (IRTs) are ground-based pyrometers that measure the brightness temperature of a scene within their field of view. They determine brightness temperature by detecting electromagnetic radiation emitted by Earth’s surface. These measurements are used to find either the surface skin temperature or the sea surface temperature, depending on whether the platform is on land or water. IRTs typically operate within the 8- to 14-μm wavelength range.

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 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.

The Surface-sensing Measurements for Atmospheric Radiative Transfer (SMART) is a ground-based remote instrument suite operated by NASA Goddard Space Flight Center (GSFC). It consists of several remote sensing instruments, such as a micro-pulse lidar, sun photometer, and broadband radiometers housed in a twenty-foot trailer. SMART provides measurements of solar spectral radiance, surface spectral bi-directional reflectance, albedo, and shortwave and longwave irradiance at a spectral resolution of 1 nm. It operates across the ultraviolet to microwave spectral range. SMART is part of the SMARTLabs mobile facilities.

A pyrheliometer is a ground-based passive radiation sensor. It is used to measure direct beam solar irradiance. Pyrheliometers use a thermopile that converts heat from sunlight to an electrical signal to determine solar radiation. Pyrheliometers measure solar radiation in the 200-4000 nm wavelength range.

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.

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 Solar Spectral Flux Radiometer (SSFR) is an airborne radiometer developed by the Ames Atmospheric Radiation Group. It measures solar spectral irradiance in the troposphere. SSFR works within the 300-2150 nm wavelength range and offers a spectral resolution of 8-12 nm. It typically collects data at 1 Hz and has a radiometric accuracy of 3%.

The Fourier Transformation Spectrometer (FTS) is a high-resolution spectrometer used both in airborne and ground-based applications. FTS measures the solar radiance reflected from the surface, which can be used to estimate levels of carbon monoxide (CO), carbon dioxide (CO2), and methane (CH4) in the atmosphere. It offers a spatial resolution of approximately 100m by 1000m and operates at a measurement frequency of 1 Hz during typical research flights.

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 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.

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.

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 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.

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 Aerodynamic Particle Sizer (APS) is an in situ spectrometer manufactured by TSI Instruments. APS measures aerodynamic particles in the 0.5-20 μm size range. It also measures the light-scattering intensity of the particles in the 0.37-20 μm optical size range. APS provides particle size distributions for 52 channels at a typical sampling time of 1 second. It uses a laser diode operating at 655 nm and has a size resolution of 0.02 μm at 1 μm. APS can be deployed on aircraft, ships, or ground-based platforms.

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

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

The Johnson-Williams Cloud Water Meter (CWM) is an airborne hot wire probe designed by Johnson-Williams, Inc. The CWM measures the liquid water content (LWC) of clouds using an electrical circuit that detects resistivity changes caused by cloud droplets evaporating from an exposed heated wire. It can measure LWC levels from 0 to 6 grams per cubic meter and operates at airspeeds between 50 and 150 meters per second. The device runs on a constant current and usually records data at 2 Hz.

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

The Particule Volume Matter (PVM-100A) is an in situ airborne cloud probe manufactured by Gerber Scientific. It measures liquid water content and the effective radius of cloud droplets by measuring the scattering intensity proportional to the droplets' density and particle surface area density. PVM-100A operates at 780 nm and has a measurement rate of up to 5000 Hz. It can measure droplets in the size range of 3-50 μm diameter. The ground-based model of this instrument is PVM-100.

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.

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.

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

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 AErosol RObotic NETwork (AERONET) is a federated network of ground-based remote sensing aerosol sensors established by NASA and the PHOtométrie pour le Traitement Opérationnel de Normalisation Satellitaire (PHOTONS) in 1993. Each AERONET site includes a CIMEL Electronique sunphotometer that measures sun irradiance and sky radiances. These measurements are used to determine aerosol properties such as aerosol optical depth and extinction. The sunphotometers operate at nine wavelengths (340, 380, 440, 500, 675, 870, 937, 1020, and 1640 nm) and provide aerosol data approximately every 15 minutes. AERONET sites are distributed worldwide, enabling mapping of about 90% of the Earth’s surface.

The NASA Micro-Pulse Lidar Network (MPLNET) is a worldwide ground-based network of Micro-Pulse Lidar (MPL) systems that has been operational since 1999. MPLNET offers continuous observations of aerosol and cloud vertical structures as well as boundary layer height from the surface up to 30 km. The MPL systems operate at a wavelength range of 523-532 nm and have a vertically-resolved spatial resolution of 30 to 75 meters, depending on the station. Many MPLNET sites are co-located with locations in the NASA Aerosol Robotic Network (AERONET) to help minimize retrieval errors.

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.

The Southern Hemisphere ADditional OZonesondes (SHADOZ) is a NASA-sponsored network of ozonesonde stations distributed across tropical, subtropical, and remote regions of the Southern Hemisphere. Electrochemical concentration cell (ECC) ozonesondes are launched from each station to gather profile measurements of ozone, temperature, pressure, and relative humidity. The measurements are taken at a sampling rate of 1 Hz with a vertical resolution of 100 to 150 meters. SHADOZ was created to coordinate launches among the stations and to provide a central data archive for ozone vertical profiles used in climatological and trend analyses.