Convection and Moisture Experiment

Ozonesondes are in situ balloon-borne instruments used to measure ozone concentration profiles. An ozonesonde consists of an electrochemical ozone sensor connected with a meteorological radiosonde to collect ozone, temperature, pressure, and humidity measurements as it ascends through the atmosphere. It provides ozone profile measurements at a resolution of 100 to 150 m. Ozonesondes have a typical measurement rate of 0.1 Hz and can collect profiles up to around 35 km.

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 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 Raman Lidar (RL) is a ground-based lidar system operated by the Department of Energy’s (DoE) Atmospheric Radiation Measurement (ARM) User Facility. It detects Raman backscatter in the ultraviolet range (355 nm) to provide profiles of water vapor, temperature, and aerosol and cloud optical properties. It also detects Raman backscatter from water vapor at 408 nm and molecular nitrogen at 387 nm to help derive aerosol optical properties and water vapor mixing ratios. It has a range resolution of 7.5 m, a time resolution of 10 seconds, and a pulse repetition frequency of 30 Hz. RL can deliver profile measurements from approximately 200 m up to 10 km above ground level.

The Atmospheric Emitted Radiance Interferometer (AERI) is a ground-based passive interferometer developed by the University of Wisconsin Space Science and Engineering Center (UW-SSEC) for the Department of Energy (DoE) Atmospheric Radiation Measurement (ARM) Program. It uses Fourier transform spectroscopy to measure downwelling thermal infrared emissions from the atmosphere. These measurements can be used to provide profile measurements of atmospheric temperature and water vapor and detect trace gases. AERI operates across the 3.3-19 μm spectral range and up to 25 μm for the extended range version of the instrument. It has an optimal vertical resolution of 100 meters and completes a full sky scan about every 20 seconds.

The ER-2 Doppler Radar (EDOP) is an airborne X-band radar designed to operate on the nose of the ER-2 aircraft. It measures radar reflectivity, Doppler velocity, and spectrum width to characterize precipitation systems. EDOP operates at a 9.6 GHz frequency and provides data at a rate of 2 Hz. It has a typical gate spacing of 75 m and a beamwidth of 2.9 degrees. EDOP has been replaced by the EXRAD radar.

The Multispectral Atmospheric Mapping Sounder (MAMS) is an airborne multispectral scanner developed by modifying NASA’s Thematic Mapping Sensor (TMS). MAMS captures reflected radiances in eight visible/near-infrared (VNIR) bands and thermal emissions in four infrared bands. It was built to study weather-related phenomena such as storm system structure, cloud-top temperature, and upper atmospheric water vapor. MAMS operates within the 0.42-12.56 μm spectral range over 12 channels. It has a horizontal resolution of 100 meters and a swath width of approximately 37 kilometers at a flight altitude of 20 kilometers. MAMS scans at a rate of 6.25 Hz.

The Lightning Instrument Package (LIP) is an in situ airborne system that detects electric fields. LIP uses eight electric field mills and a conductivity probe to measure the three-dimensional components of electric fields in thunderstorms around it. LIP has a sampling frequency of 0.02 seconds and an accuracy of 2.5%.

The Advanced Microwave Precipitation Radiometer (AMPR) is an airborne passive microwave radiometer. AMPR provides calibrated brightness temperatures, which can be used to determine cloud and precipitation characteristics. It operates across four microwave channels: 10.7, 19.35, 37.1, and 85.5 GHz. These frequencies are sensitive to precipitation, making AMPR well-suited for studying rain events. It has a surface footprint size ranging from 640 m (85.5 GHz) to 2.8 km (10.7 GHz).

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 Millimeter-wave Imaging Radiometer (MIR) was a passive airborne cross-track scanning radiometer developed by NASA. MIR measured brightness temperature across nine channels and was used for studying clouds, precipitation, and atmospheric water vapor. MIR operated near and around the following frequencies: 89, 150, 183, 220, and 325 GHz. It had an angular swath of 100 degrees and a sampling interval of 3 seconds. MIR usually operated on NASA ER-2 aircraft before being retired.

The Cloud and Aerosol Particle Characterization (CAPAC) is an in situ airborne instrument package that measures cloud and aerosol particle properties. It includes three instruments: a Forward Scattering Spectrometer Probe model 300 (FSSP-300), a Two-Dimensional Optical Array Probe (2D-P), and a CAPAC video camera. It measures particle size from 0.3 micrometers to 6.4 millimeters and shape for particles between 40 micrometers and 6.4 millimeters in diameter. These measurements are used to determine particle size distribution, surface area, and water content in both ice and liquid form. CAPAC has a spatial resolution of 2 km at an aircraft speed of 200 m/sec and a temporal resolution of 0.1 Hz.

The Multicenter Airborne Coherent Atmospheric Wind Sensor (MACAWS) is an airborne lidar system developed by NASA Marshall Flight Center (MSFC), NOAA Environmental Technology Laboratory (ETL), and the Jet Propulsion Laboratory (JPL). It measures lidar backscatter to determine vertical wind profiles, two-dimensional wind fields, and aerosol backscatter in both clear and cloudy conditions. It operates at a nominal wavelength of 10.6 μm with a line-of-sight resolution of 300 meters. It has a coverage range of 10 to 30 km and can achieve a vertical resolution of up to 12.5 km.

The Lidar Atmospheric Sensing Experiment (LASE) is an airborne lidar system developed at NASA's Langley Research Center (LaRC). LASE uses the differential absorption lidar technique to provide profile measurements of water vapor and aerosols in the atmosphere. LASE operates at the 815 nm wavelength and has a measurement frequency of 5 Hz. For aerosol scattering profiles, LASE has a horizontal resolution of 200 m and a vertical resolution of 30 m. It has a horizontal resolution of 5 km and a vertical resolution of 0.2 km for water vapor measurements.

The JPL Laser Hygrometer (JLH) is an in situ airborne hygrometer developed at the Jet Propulsion Laboratory (JPL). It uses a tunable diode laser operating at 1.37 μm to measure atmospheric water vapor in the upper troposphere and lower stratosphere. JLH has a minimum spatial resolution of 25 meters and a detection range of 1 to 500 ppmv. It typically samples at 1 Hz and can provide measurements with a precision of 0.05 ppmv.

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

The Polarimetric Scanning Radiometer (PSR) is an airborne passive microwave imaging radiometer developed by Georgia Tech and NOAA. It captures polarimetric microwave emission images of Earth to analyze ocean and land surface features, precipitation, ice, and clouds. PSR operates across four microwave channels: 10.7 GHz, 18.7 GHz, 37 GHz, and 89 GHz. The PSR/A version includes an extra dual-polarimetric channel at 21.5 GHz. Operating at an altitude of 22,000 feet above sea level, PSR has a spatial resolution ranging from 0.3 to 2.2 km, depending on the frequency band and scan mode.

The Airborne Vertical Atmospheric Profiling System (AVAPS) is a system mounted on aircraft that uses dropsondes and Global Positioning System (GPS) receivers to collect in situ atmospheric profiles. It provides measurements of temperature, pressure, and humidity every 0.5 seconds, and wind data every 0.25 seconds. AVAPS features a vertical resolution of about 10 meters and can launch dropsondes every 20 seconds. Developed by the National Center for Atmospheric Research (NCAR) for the NASA Global Hawk, it can also be used on other aircraft such as the DC-8 and P-3.

The Airborne Multichannel Microwave Radiometer (AMMR) was a passive, remote airborne microwave radiometer. It measured thermal microwave emissions in terms of brightness temperature. AMMR consisted of an array of radiometers operating at the following frequencies: 10, 18.7, 21, 37, and 92 GHz. It had a typical sampling rate of 1 second and a spatial resolution of 1-2 km at the surface.

The Airborne Rain Mapping Radar (ARMAR) is an airborne Ku-band Doppler radar developed by the Jet Propulsion Laboratory (JPL). It was designed to simulate the Tropical Rainfall Measuring Mission (TRMM) satellite mission for algorithm development and calibration. ARMAR operates at 13.8 GHz to measure the return power of microwave energy, which is used to determine velocity and reflectivity. It can also serve as a radiometer to measure brightness temperature. ARMAR typically scans across the track at 20-degree angles but can operate at a fixed angle. It has a horizontal resolution of 800 m and a swath width of 9 km at a flight altitude of 12 km.

The JPL Surface Acoustic Wave (SAW) Hygrometer is an in situ airborne microhygrometer developed by the Jet Propulsion Laboratory (JPL). It uses a SAW device to detect condensation for dewpoint or frostpoint temperature measurements. The JPL SAW hygrometer is two orders of magnitude more sensitive to condensation compared to chilled-mirror hygrometers, allowing for a faster response to humidity changes. JPL SAW Hygrometer has a temporal resolution of up to 0.1 seconds.

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.

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 ER-2 Doppler Radar (EDOP) is an airborne X-band radar designed to operate on the nose of the ER-2 aircraft. It measures radar reflectivity, Doppler velocity, and spectrum width to characterize precipitation systems. EDOP operates at a 9.6 GHz frequency and provides data at a rate of 2 Hz. It has a typical gate spacing of 75 m and a beamwidth of 2.9 degrees. EDOP has been replaced by the EXRAD radar.

The NPOESS Aircraft Sounder Testbed - Microwave (NAST-M) is an airborne microwave radiometer operated by the Massachusetts Institute of Technology (MIT). It measures brightness temperature, which can be used to retrieve water vapor profiles in the atmosphere. It consists of two radiometers: one operating across eight channels between 50-57 GHz and the other across nine at 118 GHz. In 2003, NAST-M was upgraded with two additional radiometers at 183 and 425 GHz to enhance water vapor retrievals and detect small hydrometeors. NAST-M has a spatial resolution of 2.6 km and a cross-track swath width of 100 km at a flight altitude of 20 km. Its typical integration time is 100 ms.

The Multispectral Atmospheric Mapping Sounder (MAMS) is an airborne multispectral scanner developed by modifying NASA’s Thematic Mapping Sensor (TMS). MAMS captures reflected radiances in eight visible/near-infrared (VNIR) bands and thermal emissions in four infrared bands. It was built to study weather-related phenomena such as storm system structure, cloud-top temperature, and upper atmospheric water vapor. MAMS operates within the 0.42-12.56 μm spectral range over 12 channels. It has a horizontal resolution of 100 meters and a swath width of approximately 37 kilometers at a flight altitude of 20 kilometers. MAMS scans at a rate of 6.25 Hz.

The Lightning Instrument Package (LIP) is an in situ airborne system that detects electric fields. LIP uses eight electric field mills and a conductivity probe to measure the three-dimensional components of electric fields in thunderstorms around it. LIP has a sampling frequency of 0.02 seconds and an accuracy of 2.5%.

The NPOESS Aircraft Sounder Testbed - Interferometer (NAST-I) is an airborne infrared interferometer operated and maintained by NASA Langley Research Center (LaRC). It uses Fourier transform spectroscopy to measure brightness temperature and radiance. NAST-I operates within the spectral range of 3.7-16.1 µm and has a spectral resolution of 0.25 cm-1. It features a spatial resolution of 2.6 km and a cross-track swath width of 46 km at a flight altitude of 20 km. A complete scan cycle for NAST-I takes approximately 12.2 seconds.

The Advanced Microwave Precipitation Radiometer (AMPR) is an airborne passive microwave radiometer. AMPR provides calibrated brightness temperatures, which can be used to determine cloud and precipitation characteristics. It operates across four microwave channels: 10.7, 19.35, 37.1, and 85.5 GHz. These frequencies are sensitive to precipitation, making AMPR well-suited for studying rain events. It has a surface footprint size ranging from 640 m (85.5 GHz) to 2.8 km (10.7 GHz).

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 Millimeter-wave Imaging Radiometer (MIR) was a passive airborne cross-track scanning radiometer developed by NASA. MIR measured brightness temperature across nine channels and was used for studying clouds, precipitation, and atmospheric water vapor. MIR operated near and around the following frequencies: 89, 150, 183, 220, and 325 GHz. It had an angular swath of 100 degrees and a sampling interval of 3 seconds. MIR usually operated on NASA ER-2 aircraft before being retired.

The Atmospheric Emitted Radiance Interferometer (AERI) is a ground-based passive interferometer developed by the University of Wisconsin Space Science and Engineering Center (UW-SSEC) for the Department of Energy (DoE) Atmospheric Radiation Measurement (ARM) Program. It uses Fourier transform spectroscopy to measure downwelling thermal infrared emissions from the atmosphere. These measurements can be used to provide profile measurements of atmospheric temperature and water vapor and detect trace gases. AERI operates across the 3.3-19 μm spectral range and up to 25 μm for the extended range version of the instrument. It has an optimal vertical resolution of 100 meters and completes a full sky scan about every 20 seconds.

The Raman Lidar (RL) is a ground-based lidar system operated by the Department of Energy’s (DoE) Atmospheric Radiation Measurement (ARM) User Facility. It detects Raman backscatter in the ultraviolet range (355 nm) to provide profiles of water vapor, temperature, and aerosol and cloud optical properties. It also detects Raman backscatter from water vapor at 408 nm and molecular nitrogen at 387 nm to help derive aerosol optical properties and water vapor mixing ratios. It has a range resolution of 7.5 m, a time resolution of 10 seconds, and a pulse repetition frequency of 30 Hz. RL can deliver profile measurements from approximately 200 m up to 10 km above ground level.

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.

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

The Stepped Frequency Microwave Radiometer (SFMR) is a passive airborne C-band radiometer developed by ProSensing Inc. It measures brightness temperature across six frequency bands from 4.6 to 7.2 GHz. These measurements can be used to estimate rain rates and surface winds. SFMR is primarily employed for research missions involving hurricanes and tropical storms, notably by NOAA’s Hurricane Research Division (HRD). It has a spatial resolution of approximately 1.5 km and a temporal resolution of roughly 4 seconds.

The High Volume Precipitation Spectrometer (HVPS) is an in situ airborne particle imager manufactured by SPEC Inc. It uses a 128-photodiode array to capture images of precipitation particles. These images can be used to determine the particles' shape, size, and concentration. HVPS-3 has a pixel resolution of 150 μm and a maximum field of view of 1.92 cm.

The Airborne eXpendable BathyThermograph (AXBT) is an in situ sensor that measures ocean temperature and conductivity. It is deployed from an aircraft using a small parachute and floats to the ocean surface after impact. The floating portion of the instrument then releases a probe into the ocean that collects profile measurements to a depth of about 1000 meters. AXBT has a vertical descent of about 1.5 meters per second.

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.

X-band radars are ground-based radars that operate in the 8-12 GHz frequency range. They provide measurements of radar reflectivity, Doppler velocity, and other radar parameters to characterize precipitation and clouds. Due to operating on a smaller wavelength, the X-band radars are more sensitive and can detect smaller particles, making them useful for studying light precipitation and cloud development.

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

The ER-2 Doppler Radar (EDOP) is an airborne X-band radar designed to operate on the nose of the ER-2 aircraft. It measures radar reflectivity, Doppler velocity, and spectrum width to characterize precipitation systems. EDOP operates at a 9.6 GHz frequency and provides data at a rate of 2 Hz. It has a typical gate spacing of 75 m and a beamwidth of 2.9 degrees. EDOP has been replaced by the EXRAD radar.

The High Altitude Monolithic Microwave integrated Circuit (MMIC) Sounding Radiometer (HAMSR) is an airborne microwave sounder developed by the Jet Propulsion Laboratory through the NASA Instrument Incubator Program. HAMSR measures brightness temperature, which can be used to derive three-dimensional profiles of temperature, water vapor, and cloud liquid water in the atmosphere. It operates across 25 spectral channels in three microwave bands (50-60 GHz, 118 GHz, 183 GHz) and has a sampling frequency of 5 seconds. HAMSR has a horizontal spatial resolution of 2 km at nadir and a field of view of approximately 40 km at an altitude of 20 km.

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.

Dropsondes, also known as dropwindsondes, are in situ instruments designed to be released from aircraft. They are equipped with Global Positioning System (GPS) receivers and sensors to collect profile measurements of pressure, temperature, humidity, wind speed, and wind direction. Dropsondes are important during field investigations because they enable researchers to collect vertical profiles in remote locations and during severe weather conditions. Typically, dropsondes have a vertical resolution of 5 meters and provide wind speed and direction measurements every 0.25 seconds, while temperature, pressure, and humidity are recorded every 0.5 seconds.

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

The Lightning Instrument Package (LIP) is an in situ airborne system that detects electric fields. LIP uses eight electric field mills and a conductivity probe to measure the three-dimensional components of electric fields in thunderstorms around it. LIP has a sampling frequency of 0.02 seconds and an accuracy of 2.5%.

The Microwave Temperature Profiler (MTP) is an airborne microwave radiometer developed by the Jet Propulsion Laboratory and later modified by NCAR. It measures brightness temperature from oxygen molecules at 56.363 GHz, 57.612 GHz, and 58.363 GHz. These measurements are converted into air temperature through a statistical retrieval process. It samples across 10 viewing angles and has a vertical resolution of 150 m near the aircraft. MTP provides profiles every 17 seconds with about 4 km of horizontal spacing.

The Advanced Microwave Precipitation Radiometer (AMPR) is an airborne passive microwave radiometer. AMPR provides calibrated brightness temperatures, which can be used to determine cloud and precipitation characteristics. It operates across four microwave channels: 10.7, 19.35, 37.1, and 85.5 GHz. These frequencies are sensitive to precipitation, making AMPR well-suited for studying rain events. It has a surface footprint size ranging from 640 m (85.5 GHz) to 2.8 km (10.7 GHz).

The NOAA Dual-Beam UV-Absorption Ozone Photometer (NOAA-O3) is an in situ optical balloon-borne and airborne instrument that measures ozone concentrations in the troposphere and lower stratosphere. It operates at a wavelength of 254 nm, enabling it to calculate ozone number density due to the precise ozone absorption cross section at that wavelength. It has a sampling rate of 2 Hz and a horizontal resolution of 100 to 200 meters during typical research flights.

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

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

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

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

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

An Electric Field Mill (EFM) is a ground-based and airborne electric sensor developed at NASA Marshall Space Flight Center (MSFC). It measures the full vector components of the atmospheric electric field and provides information about the electrical structure within and around storms. EFMs can detect both intracloud and cloud-to-ground lightning and can operate in large thunderstorm fields (thousands of volts per meter). An EFM typically has a response time of about 10 Hz.

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

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

Generic-Atmospheric State (Gen-AtmsState) refers to non-specific instruments on a platform used for measurements of atmospheric state parameters. These are typically in situ sensors that measure temperature, pressure, humidity, and wind speed/direction. Types of atmospheric state instruments include thermometers, hygrometers, barometers, and anemometers.

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

Generic-Atmospheric State (Gen-AtmsState) refers to non-specific instruments on a platform used for measurements of atmospheric state parameters. These are typically in situ sensors that measure temperature, pressure, humidity, and wind speed/direction. Types of atmospheric state instruments include thermometers, hygrometers, barometers, and anemometers.

The Lower Fuselage (LF) Radar is an airborne radar system that operates on the lower fuselage of the NOAA P-3 aircraft used by the Hurricane Research Division. It measures radar reflectivity, Doppler velocity, and other radar parameters to characterize tropical storms and precipitation. It operates at the 5370 MHz frequency and has a horizontal beamwidth of 1.1 degrees. The LF Radar has a maximum ambiguous range of 750 km and a pulse repetition frequency of 200 Hz.

An Electric Field Mill (EFM) is a ground-based and airborne electric sensor developed at NASA Marshall Space Flight Center (MSFC). It measures the full vector components of the atmospheric electric field and provides information about the electrical structure within and around storms. EFMs can detect both intracloud and cloud-to-ground lightning and can operate in large thunderstorm fields (thousands of volts per meter). An EFM typically has a response time of about 10 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). The King Probe measures cloud liquid water content (LWC) by detecting the heat released when water droplets vaporize. It operates at a constant temperature of approximately 100°C and has a data output rate of 1 to 10 Hz. The probe is commonly used in studies of cloud microphysics and aircraft icing.

The Rosemount Icing Detector (RICE) is an in-situ airborne probe developed by Rosemount Inc. It uses magnetostrictive oscillation to detect shifts in frequency caused by ice accumulation on the sensing cylinder. These frequency changes correlate with the rate of ice buildup, which helps determine liquid water content. RICE typically samples every second.

The Tail Doppler Radar (TDR) is an airborne vertically scanning, pulse Dopper X-band radar operated by NOAA. It is installed on the tail of the research aircraft and is typically equipped on NOAA’s P-3 aircraft for hurricane and precipitation research missions. TDR measures radar reflectivity and Doppler wind velocities at the 9315 MHz frequency band. It has a horizontal beam width of 1.35 degrees and a range gate spacing of 150 or 300 meters.

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.

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

The 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.

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 X-Band Polarimetric Doppler Weather Radar (XPOL) is a ground-based, transportable polarimetric radar manufactured by ProSensing. XPOL measures reflectivity, Doppler velocity, and polarimetric radar parameters to characterize precipitation and clouds. XPOL operates at a 9.41 GHz frequency and has a typical beam width of 1.4 degrees. It has a selectable range resolution of 15-150 meters.

The Tropical Ocean/Global Atmosphere (TOGA) C-band Radar is a ground-based radar that was developed for the TOGA COARE campaign. It is a C-band (5600-5650 MHz) Doppler radar that measures reflectivity, Doppler velocity, spectrum width, and other radar parameters to characterize precipitation. It is currently located at Wallops Flight Facility (WFF) and can be deployed for land or sea-based operations. The TOGA radar has a beam width of 1.55 degrees and a typical bin spacing of 150 meters.

The NASA S-band Dual Polarimetric Radar (NPOL) is a portable, ground-based scanning dual-polarimetric Doppler radar. As an active remote sensor, NPOL detects reflected electromagnetic waves to determine radar reflectivity, Doppler velocity, rainfall rate, particle size distribution, water content, and precipitation type. Normally, NPOL has a beamwidth of 0.95°, a gate spacing of 0.15 km, and a maximum range of 150 km. It is operationally comparable to Doppler radars used by the U.S. National Weather Service’s Next Generation Weather Radar (NEXRAD) network, but NPOL has the benefit of being fully deployable.

The Lidar Atmospheric Sensing Experiment (LASE) is an airborne lidar system developed at NASA's Langley Research Center (LaRC). LASE uses the differential absorption lidar technique to provide profile measurements of water vapor and aerosols in the atmosphere. LASE operates at the 815 nm wavelength and has a measurement frequency of 5 Hz. For aerosol scattering profiles, LASE has a horizontal resolution of 200 m and a vertical resolution of 30 m. It has a horizontal resolution of 5 km and a vertical resolution of 0.2 km for water vapor measurements.

The Microwave Temperature Profiler (MTP) is an airborne microwave radiometer developed by the Jet Propulsion Laboratory and later modified by NCAR. It measures brightness temperature from oxygen molecules at 56.363 GHz, 57.612 GHz, and 58.363 GHz. These measurements are converted into air temperature through a statistical retrieval process. It samples across 10 viewing angles and has a vertical resolution of 150 m near the aircraft. MTP provides profiles every 17 seconds with about 4 km of horizontal spacing.

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

The 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.

The Nezorov Probe is an in situ airborne hot-wire probe that measures clouds' liquid water content (LWC) and total water content (TWC). It determines LWC and TWC by detecting heat loss from its two sensors caused by evaporation of cloud water and convective heat losses. Operating at a constant temperature of 90 degrees Celsius, it can measure LWC and TWC in the range of 0.005-3 grams per cubic meter. The Nevzorov Probe provides measurements every second with an accuracy of 10%.

The Lightning Instrument Package (LIP) is an in situ airborne system that detects electric fields. LIP uses eight electric field mills and a conductivity probe to measure the three-dimensional components of electric fields in thunderstorms around it. LIP has a sampling frequency of 0.02 seconds and an accuracy of 2.5%.

The Cloud Particle Imager (CPI) is an airborne imager developed by SPEC Inc. CPI captures high-resolution (2.3 μm pixel size) images of cloud particles that pass through its sampling volume. It uses a charge-coupled device (CCD) camera operating at 810 nm to record images and can capture up to 74 frames per second with a refresh rate of 40 Hz. The images from CPI can be used to determine microphysical properties such as particle size and shape.

The Airborne Coherent Lidar for Advanced In-Flight Measurements (ACLAIM) is an active lidar system developed by Coherent Technologies, Inc. It is designed to detect and alert pilots to clear air turbulence, improving aviation safety. ACLAIM measures lidar backscatter at a wavelength of 2 microns and operates at 100 pulses per second. It was developed as part of NASA’s Aviation Safety Program.

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

The Airborne Second Generation Precipitation Radar (APR-2) is a dual-frequency, cross-track scanning radar used for measuring precipitation from aircraft. It detects radar backscatter from rain to determine reflectivity, Doppler velocity, and linear depolarization ratio (LDR). APR-2 operates at 13.4 GHz and 35.6 GHz and has a pulse repetition frequency (PRF) of 5000 Hz. At an altitude of 11,000 feet, it offers a horizontal resolution of 730 meters at 13.4 GHz and 920 meters at 35.6 GHz. The radar has a vertical resolution of 60 meters and a ground swath width of 10 km.

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

The 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 JPL Laser Hygrometer (JLH) is an in situ airborne hygrometer developed at the Jet Propulsion Laboratory (JPL). It uses a tunable diode laser operating at 1.37 μm to measure atmospheric water vapor in the upper troposphere and lower stratosphere. JLH has a minimum spatial resolution of 25 meters and a detection range of 1 to 500 ppmv. It typically samples at 1 Hz and can provide measurements with a precision of 0.05 ppmv.

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

The Conically-Scanning Two-look Airborne Radiometer (C-STAR) is an airborne passive microwave radiometer developed at NASA's Marshall Space Flight Center (MSFC). It is a Ka-band (37 GHz) radiometer that measures ocean brightness temperature to determine precipitation rate and surface water and near-ocean-surface winds. It has a footprint size at nadir of 2 km x 3.5 km at a flight altitude of 10 km. C-STAR has an integration time of 100 ms and a scan rate of 6 revolutions per minute. It has a half-power beamwidth of 7.5 degrees and a field of view of 45 degrees.

Dropsondes, also known as dropwindsondes, are in situ instruments designed to be released from aircraft. They are equipped with Global Positioning System (GPS) receivers and sensors to collect profile measurements of pressure, temperature, humidity, wind speed, and wind direction. Dropsondes are important during field investigations because they enable researchers to collect vertical profiles in remote locations and during severe weather conditions. Typically, dropsondes have a vertical resolution of 5 meters and provide wind speed and direction measurements every 0.25 seconds, while temperature, pressure, and humidity are recorded every 0.5 seconds.

The High Volume Precipitation Spectrometer (HVPS) is an in situ airborne particle imager manufactured by SPEC Inc. It uses a 128-photodiode array to capture images of precipitation particles. These images can be used to determine the particles' shape, size, and concentration. HVPS-3 has a pixel resolution of 150 μm and a maximum field of view of 1.92 cm.