Synonyms: 
P3B
P-3 Orion
NASA P-3B
NASA P-3
NASA-P3B
P-3
P-3B
P3
P3-B
WFF P3-B
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2 Channel Selected Ion Chemical Ionization Mass Spectrometer

Titration of OH in H2SO4 and measurement of H2SO4 and MSA via proton exchange with NO3-. DMSO and DMSO2 are reacted with NH4+ ions. In all cases concentrations are determined by product/reactant ion ratios. Ion ratios are measured with quadrupole mass spectrometers.

OH measurements used to understand fast photooxidation chemistry; H2SO4 used to investigate particle nucleation; H2SO4 and MSA used to understand particle growth; DMSO and DMSO2 to investigate DMS oxidation process and its relation to particle production and growth.

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Nevzorov Liquid Water Content (LWC) and Total Water Content (TWC) Probe

The Nevzorov liquid water content (LWC) and total water content (TWC) probe is a constant-temperature, hot-wire probe designed for aircraft measurements of the ice and liquid water content of clouds. The probe consists of two separate sensors for measurements of cloud liquid and total (ice plus liquid) water content. Each sensor consists of a collector and a reference winding. The reference sensors are shielded from impact with cloud particles, specifically to provide an automatic compensation for convective heat losses.

The sensitivity of the probe is estimated to be approximately 0.003– 0.005 g m23. The accuracy of LWC measurements in nonprecipitating liquid clouds is estimated as 10%–15%. Tests at the NRC high-speed icing tunnel have provided verification of the TWC measurement for small frozen droplets to an accuracy of approximately 10%–20%, but verification in snow and natural ice crystals has not yet been possible due to the absence of any accurate standards. The TWC measurement offers not only the possibility of direct measurements of ice content but also improved liquid water contents in drizzle situations. Airborne measurements have provided data on the baseline drift and sensitivity of the probe and have provided comparisons to other conventional instruments. Several cases have been documented that exhibit the unique capabilities of the instrument to separate the ice and liquid components of supercooled clouds.

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Polarimetric Ku-Band Scatterometer

PolSCAT is a Ku-band polarmetric scanning scatterometer operating at 13.95 GHz. with an approved NASA license. The transmitting polarizations of PolSCAT, alternating between Vertical and Horizontal, from pulse to pulse. Two receivers detect the V and H polarized radar echoes simultaneously allowing for measurements of VV, HH, VH, and HV radar responses. It provides scalable resolution, between 3,000 and 20,000 feet AGL.

The PolSCAT antenna assembly includes two axis gimbals for conically scanning, parabolic antenna, which is controlled from 0° (nadir) to 65 degrees. It was designed and built to investigate the benefits of active microwave for the remote sensing of high resolution snow-water-equivalent (SWE).

PolSCAT’s flexible design is compatible with many aircraft. It has flown on the NCAR C-130, NASA’s DC-8, P-3, and Twin Otter International’s, Twin Otter. Flown more than 500 hours in support of NASA’s Cold Land Process (CLPX) campaigns, PolSCAT is a very mature instrument.

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Passive Active L- and S-band Sensor

PALS is a combined polarimetric radiometer and NASA licensed radar sharing a rotating planar array antenna. The PALS instrument includes a combined L-band radiometer and scatterometer , operating at 1.413 GHz and 1.26 GHz respectively. It was designed and built to investigate the benefits of combining passive and active microwave sensors for Ocean salinity and Soil moisture remote sensing. It is the prototype for the Aquarius and SMAP missions and its flexible design is compatible with many aircraft.

The PALS radar and radiometer time share a dual pole, dual frequency planner array antenna. The antenna configuration can be fixed or rotating. It provides scalable resolution, between 3,000 and 20,000 feet AGL. It is an Aquarius and SMAP test bed.

PALS has flown on the NCAR C-130, NASA’s P-3 and Twin Otter International’s, Twin Otter. It is a very mature instrument, and has flown more than 800 hours, in support of NASA campaigns.

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Research Environment for Vehicle-Embedded Analysis on Linux

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Polarimetric Scanning Radiometer - C/X Band

Remote sensing of soil moisture using C- and X-band microwave frequencies provides less penetration of vegetation and soil probing depth than L-band, but is more amenable to implementation using airborne or spaceborne antennas of practical size. The Japanese AMSR-E imaging radiometer on board the NASA EOS Aqua satellite is one such sensor capable of retrieving soil moisture using a microwave channel at 6.9 GHz with ~75 km spatial resolution. Aqua was launched in May 2002, and will provide a global soil moisture product based on AMSR-E data. The C-band channels on the future NPOESS Conical Microwave Imager and Sounder (CMIS) will provide new operational capabilities for mapping soil moisture. Sea surface temperature is also observable under most cloud conditions using passive microwave C-band radiometry.

To provide airborne mapping capabilities for measuring both soil moisture and sea surface temperature a second operational PSR scanhead was built incorporating fully polarimetric C- and X-band radiometers inside a standard PSR scanhead drum. The C-band radiometer in PSR/CX provides vertically and horizontally polarized measurements within four adjacent subbands at 5.80-6.20, 6.30-6.70, 6.75-7.10, and 7.15-7.50 GHz. In addition, the radiometer provides fully polarimetric measurements at 6.75-7.10 GHz. The use of four subbands and polarimetric capability has provided a unique means of demonstrating and optimizing algorithms for RFI mitigation.

PSR/CX was originally implemented using only a C-band radiometer (as PSR/C) in preparation for SGP99. In preparation for SMEX02 an X-band radiometer was added to provide vertically and horizontally polarized measurements within four bands at 10.60-10.68, 10.68-10.70, 10.70-10.80, and 10.60-10.80 GHz. Fully polarimetric measurements are provided within 10.60-10.80 GHz. The combined dual-band system provides additional information on soil moisture, along with the capability to measure precipitation and the near-surface wind vector over water backgrounds. The X-band channels also provide additional RFI mitigation capability.

Applications of PSR/CX include ocean surface emissivity studies, soil moisture mapping, sea ice mapping, and imaging of heavy precipitation.

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Polarimetric Scanning Radiometer - Original Scanhead

The PSR/A scanhead provides either full-Stokes vector or tri-polarimetric sensitivity at the radiometric bands of 10.7, 18.7, and 37 GHz, and thus is well suited for the NPOESS Integrated Program Office’s internal government (IG) studies of ocean surface wind vector measurements. PSR data has been used to demonstrate the first-ever retrieval of ocean surface wind fields using conically-scanned polarimetric radiometer data. The results have suggested that the NPOESS specification for wind vector accuracy will be achievable with a polarimetric two-look system.

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Polarimetric Scanning Radiometer

The Polarimetric Scanning Radiometer (PSR) is a versatile airborne microwave imaging radiometer developed by the Georgia Institute of Technology and the NOAA Environmental Technology Laboratory (now NOAA/ESRL PSD) for the purpose of obtaining polarimetric microwave emission imagery of the Earth's oceans, land, ice, clouds, and precipitation. The PSR is the first airborne scanned polarimetric imaging radiometer suitable for post-launch satellite calibration and validation of a variety of future spaceborne passive microwave sensors. The capabilities of the PSR for airborne simulation are continuously being expanded through the development of new mission-specific scanheads to provide airborne post-launch simulation of a variety of existing and future U.S. sensors, including CMIS, ATMS, AMSU, SSMIS, WindSat, TMI, RAMEX, and GEM.

The basic concept of the PSR is a set of polarimetrc radiometers housed within a gimbal-mounted scanhead drum. The scanhead drum is rotatable by the gimbal positioner so that the radiometers (Figure 2.) can view any angle within ~70° elevation of nadir at any azimuthal angle (a total of 1.32 pi sr solid angle), as well as external hot and ambient calibration targets. The configuration thus supports conical, cross-track, along-track, fixed-angle stare, and spotlight scan modes. The PSR was designed to provide several specific and unique observational capabilities from various aircraft platforms. The original design was based upon several observational objectives:

1. To provide fully polarimetric (four Stokes' parameters: Tv, Th, TU, and TV) imagery of upwelling thermal emissions at several of the most important microwave sensing frequencies (10.7, 18.7, 37.0, and 89.0 GHz), thus providing measurements from X to W band;
2. To provide the above measurements with absolute accuracy for all four Stokes' parameters of better than 1 K for Tv and Th, and 0.1 K for TU and TV;
3. To provide radiometric imaging with both fore and aft look capability (rather than single swath observations);
4. To provide conical, cross-track, along-track, and spotlight mode scanning capabilities; and
5. To provide imaging resolutions appropriate for high resolution studies of precipitating and non-precipitating clouds, mesoscale ocean surface features, and satellite calibration/validation at Nyquist spatial sampling.

The original system has been extended - as discussed below - to greatly exceed the original design objectives by providing additional radiometric channels and expanded platform capabilities.

The PSR scanhead was designed for in-flight operation without the need for a radome (i.e., in direct contact with the aircraft slipstream), thus allowing precise calibration and imaging with no superimposed radome emission signatures. Moreover, the conical scan mode allows the entire modified Stokes' vector to be observed without polarization mixing.

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Radar Synthetic Aperture Thinned Array Radiometer - Active

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Quadropole Mass Spectrometer

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