Learjet
SPEC Inc. Learjet 25

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 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 Fast Cloud Droplet Probe (FCDP) is an in-situ airborne cloud probe manufactured by SPEC Inc. FCDP measures the concentration and size of cloud droplets by detecting the amount of light scattered by the particles. It measures particles within the diameter size range of 1.5-50 microns and has a typical measurement frequency of 1 Hz.

The Nezorov Probe is an in situ airborne hot-wire probe that measures the liquid water content (LWC) and total water content (TWC) of clouds. It determines LWC and WC by detecting heat loss of its two sensors by evaporation of cloud water and by convective heat losses. 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 at 1-second intervals with an accuracy of 10%.

The Nucleation-mode Aerosol Size Spectrometer (NMASS) is an airborne, in situ spectrometer used to measure particle size distribution and cloud condensation nuclei (CCN). NMASS consists of 5 parallel condensation nucleus counters (CNCs) that are used to sample particles within the 3 to 60 nm diameter range. It can be equipped on multiple types of aircraft and is ideal for sampling cirrus clouds in the upper atmosphere. NMASS provides fast time response measurements at a temporal resolution of 10 Hz.

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 AIMMS - 20 delivers precise real-time meteorological data at rates up to 20Hz. Formed by a combination of four modules: an Inertial Measurement Unit module (IMU) that delivers six degree-of-freedom rate data at 40Hz; a GPS Phase Module that processes satellite navigation signals from two antennas; an Air-Data-Probe (ADP) that measures temperature, humidity, barometric pressure and the aircraft-relative flow vector; and, a Central Processing Module (CPM) to process GPS data, inertial signals and air-data information that yield accurate wind data when combined.

The Rosemount Icing Detector (RICE) is an in situ airborne probe manufactured by Rosemount Inc. It is a magnetostrictive oscillation probe that detects changes in the frequency of oscillation due to ice buildup on the sensing cylinder. These changes in frequency can be related to the rate of ice accretion, which can be used to derive liquid water content. RICE has a typical sampling rate of 1 second.

The 2D-Stereo Particle Probe (2D-S) is an in situ airborne optical imaging probe developed by SPEC Inc. The 2D-S uses two diode laser beams to produce stereo cloud particle images through linear array shadowing. Through the imagery, cloud particle size distribution, particle number concentration, and ice/liquid water content can be determined. It has a resolution of 10 µm and can measure hydrometeors in the 25-1280 µm range.

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.

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.