Tropical Rain Measuring Mission-Kwajalein Experiment

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 Airborne Multichannel Microwave Radiometer (AMMR) was a remote passive, airborne microwave radiometer. It measured thermal microwave emissions in terms of brightness temperature. AMMR consisted of an array of radiometers that operated 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.

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Condensation Particle Counters (CPCs) are in situ sensors that measure aerosol particle concentration. CPCs measure aerosol concentration by condensing fluid onto the particles, allowing them to grow to more detectable sizes for optical scattering. Typically, CPCs can detect particles with a size range of 7 nm-3 μm, can measure particle concentrations up to 100,000 particles/cc, and can provide measurements at 1-second intervals. CPCs are manufactured by TSI Incorporated and can be deployed on airborne, shipborne, and ground-based platforms.

The Laser Aerosol Spectrometer (LAS) is an in situ airborne spectrometer manufactured by TSI, Inc. LAS provides measurements of particle size based on the light scattering of the sampled particles. It operates at 633 nm wavelength and has a particle size range of 0.09 to 7.5 μm. LAS can provide complete particle size distributions at a rate of 10 Hz. LAS is typically used as part of aerosol instrument suites such as NASA’s Langley Aerosol Research Group Experiment (LARGE) and NOAA’s Aerosol Microphysical Properties (AMP).

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

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

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

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 measures the light scattered by particles to determine the aerosol size distribution and concentration in the 0.1 to 3.0 μm size range. PCASP operates at the 632 nm wavelength and has a typical sampling rate of 10 Hz.

The 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.

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.

The High Volume Particle Sampler, also known as the High Volume Precipitation Spectrometer (HVPS), measures particle size distributions and obtains particle images in the size range of about 0.1 cm to 6 cm. It is an open-path instrument located on the outside of the aircraft, typically below the wing. A laser sheet throws a shadowgraph image of the hydrometeor (cloud droplets or ice crystals) in the sample volume on a photodiode array. As the hydrometeor moves through the sample volume, this optical array records the moving shape and a two-dimensional picture can be recorded. At an air speed of 100 m/s, the sample volume is 310 l/s. The recorded images can be analyzed for size distributions, number concentrations, and further cloud properties detailed below. Hydrometeors in the range of 0.3−19.2 mm can be fully recorded at a 150 μm resolution; larger particles can only be sized along the direction of flight. In order to keep the pixel resolution along the flight path constant, the system clock frequency is adjusted according to the detected True Air Speed (TAS) by the data system itself. The maximum clock frequency for the HVPS is 240 kHz. The HVPS data recorded during this project has 400 m m resolution along the flight path.

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

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

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

NOx/NOxy is an in situ chemiluminescence instrument. It provides measurements of nitrogen oxides and ozone in the atmosphere at a spatial resolution better than 100m for typical DC-8 research flight speeds. NOx/NOxy can be utilized on ground-based, airborne, and shipborne platforms allowing it to be used in various types of atmospheric chemistry and air quality studies.

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