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CAMEX-4
CAMEX4
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High Altitude Monolithic Microwave integrated Circuit (MMIC) Sounding Radiometer

The High Altitude Monolithic Microwave integrated Circuit (MMIC) Sounding Radiometer (HAMSR) is a microwave atmospheric sounder developed by JPL under the NASA Instrument Incubator Program. Operating with 25 spectral channels in 3 bands (50-60 Ghz, 118 Ghz, 183 Ghz), it provides measurements that can be used to infer the 3-D distribution of temperature, water vapor, and cloud liquid water in the atmosphere, even in the presence of clouds. The new UAV-HAMSR with 183GHz LNA receiver reduces noise to less than a 0.1K level improving observations of small-scale water vapor. HAMSR is mounted in payload zone 3 near the nose of the Global Hawk.

HAMSR was designed and built at the Jet Propulsion Laboratory under the NASA Instrument Incubator Program and uses advanced technology to achieve excellent performance in a small package. It was first deployed in the field in the 2001 Fourth Convection and Moisture Experiment (CAMEX-4) - a hurricane field campaign organized jointly by NASA and the Hurricane Research Division (HRD) of NOAA in Florida. HAMSR also participated in the Tropical Cloud Systems and Processes (TCSP) hurricane field campaign in Costa Rica in 2005. In both campaigns HAMSR flew as a payload on the NASA high-altitude ER-2 aircraft. It was also one of the payloads in the 2006 NASA African Monsoon Multidisciplinary Activities (NAMMA) field campaign in Cape Verde - this time using the NASA DC-8. HAMSR provides observations similar to those obtained with microwave sounders currently operating on NASA, NOAA and ESA spacecraft, and this offers an opportunity for valuable comparative analyses.

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Cloud Particle Imager

The CPI records high-resolution (2.3 micron pixel size) digital images of particles that pass through the sample volume at speeds up to 200 m/s. In older models, CCD camera flashes up to 75 frames per second (fps), potentially imaging more than 25 particles per frame. More recent camera upgrades capable of bringing frame rate to nearly 500 fps. Real time image processing crops particle images from the full frame, eliminating blank space and compressing data by >1000:1. CPI is designed for ummanned use, with AI parameters to optimize performance without supervision.

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Counterflow Virtual Impactor

The NCAR counterflow virtual impactor (CVI) (Noone et al., 1988; Twohy et al., 1997) is an airborne instrument that can be used for studies of aerosol/cloud interactions, cloud physics, and climate. At the CVI inlet tip, cloud droplets or ice crystals larger than about 8 µm aerodynamic diameter are separated from the interstitial aerosol and impacted into dry nitrogen gas. This separation is possible via a counterflow stream of nitrogen out the CVI tip, which assures that only larger particles (cloud droplets or ice crystals) are sampled. Because droplets or crystals in a sampling volume of about 200 l/min are impacted into a sample stream of approximately 10 l/min, concentrations within the CVI are significantly enhanced. The water vapor and non-volatile residual nuclei remaining after droplet evaporation are sampled downstream of the inlet with selected instruments. These may include a Lyman-alpha or similar hygrometer, a condensation nucleus counter, an optical particle counter, filters for chemical analyses, or user instruments.

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ER-2 Doppler Radar

EDOP is an X-band (9.6 GHz) Doppler radar nose-mounted in the ER-2. The instrument has two antennas: one nadir-pointing with pitch stabilization, and the other forward pointing. The general objectives of EDOP are the measurement of the vertical structure of precipitation and air motions in mesoscale precipitation systems and the development of spaceborne radar algorithms for precipitation estimation.

EDOP measures high-resolution time-height sections of reflectivity and vertical hydrometeor velocity (and vertical air motion when the hydrometeor fall speed and aircraft motions are removed). An additional capability on the forward beam permits measurement of the linear depolarization ratio (LDR) which provides useful information on orientation of the hydrometeors (i.e., the canting angle), hydrometeor phase, size, etc. The dual beam geometry has advantages over a single beam. For example, along-track horizontal air motions can be calculated by using the displacement of the ER-2 to provide dual Doppler velocities (i.e., forward and nadir beams) at a particular altitude.

EDOP is designed as a turn-key system with real-time processing on-board the aircraft. The RF system consists of a coherent frequency synthesizer which generates the transmitted and local oscillator frequencies used in the system, a pulse modulated (0.5 to 2.0 micro-second pulse) high gain 20 kW Traveling Wave Tube Amplifier which is coupled through the duplexer to the antenna, and the receiver which is comprised of a low-noise (~1dB) GaAs preamplifier followed by a mixer for each of the receive channels. The composite system generates a nadir oriented beam with a co-polarized receiver and a 350 forward directed beam with co- and cross- polarized receivers. The antenna design consists of two separate offset-fed parabolic antennas, with high polarization isolation feed horns, mounted in the nose radome of the ER-2. The antennas are 0.76 m diameter resulting in a 30 beamwidth and a spot size of about 1.2 km at the surface (assuming a 20 km aircraft altitude). The two beams operate simultaneously from a single transmitter.

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Conically-Scanning Two-look Airborne Radiometer

C-STAR measures precipitation, surface water and near ocean surface wind speed and direction.

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Advanced Microwave Precipitation Radiometer

The AMPR is a total power passive microwave radiometer producing calibrated brightness temperatures (TB) at 10.7, 19.35, 37.1, and 85.5 GHz. These frequencies are sensitive to the emission and scattering of precipitation-size ice, liquid water, and water vapor. The AMPR performs a 90º cross-track data scan perpendicular to the direction of aircraft motion. It processes a linear polarization feed with full vertical polarization at -45º and full horizontal polarization at +45º, with the polarization across the scan mixed as a function of sin2, giving an equal V-H mixture at 0º (aircraft nadir). A full calibration is made every fifth scan using hot and cold blackbodies. From a typical ER-2 flight altitude of ~20 km, surface footprint sizes range from 640 m (85.5 GHz) to 2.8 km (10.7 GHz). All four channels share a common measurement grid with collocated footprint centers, resulting in over-sampling of the low frequency channels with respect to 85.5 GHz.

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Airborne Coherent Lidar for Advanced In-flight Measurements

ACLAIM is a 2-micron lidar operating at 100 pulses per second using an 8 cm diameter expanded beam. It was developed for advanced turbulence detection with applications to supersonic inlet control, mitigation of aircraft gust response and aircrew / passenger warning for improved seatbelt utilization.

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