P-3 Orion - WFF

The Marshall Airborne Polarimetric Imaging Radiometer (MAPIR) is a dual beam, dual angle polarimetric, scanning L band passive microwave radiometer system developed by the Observing Microwave Emissions for Geophysical Applications (OMEGA) team at MSFC. MAPIR observes naturally-emitted radiation from the ground primarily for remote sensing of land surface brightness temperature from which we can retrieve soil moisture and possibly surface or water temperature and ocean salinity.

MAPIR consists of an electronically steered phased array antenna comprised of 81 receiving patch elements and associated electronics to provide the required beam steering capability. The antenna produces two independent beams that can be individually scanned to any user-defined scan angle. The antenna is connected to four microwave radiometers and a microwave spectrum analyzer. Two radiometers operate over a narrow band (science band) between 1400-1427 MHz. Two other radiometers operate over a wider bandwidth (1350-1450 MHz) and are used for Radio Frequency interference (RFI) surveillance. The outputs of the four radiometers are routed to the digital back end module that digitizes and filters the signal into 16 well isolated spectral sub-bands and computes the first four statistical moments in each sub-band from which the radio brightness temperature and kurtosis (a statistical measure, indicative of RFI) can be computed in post-processing.

MAPIR can operate in two user-selectable modes: Single-Beam Dual (simultaneous) Polarization and Dual (simultaneous) Beam Single Polarization. In the first mode, both beams of the antenna are directed to scan to the same angle, but the radiometers are observing orthogonal polarizations (horizontal and vertical) at the same time. In the second mode, the two antenna beams can be directed to different azimuth and/or angles and the radiometers observe the same polarization at the same time. The instrument is capable of electronic beam steering to one-degree of resolution from 0-40 degrees in elevation and 0-360 degrees azimuth in both beams. MAPIR precision is 0.01K and brightness temperature accuracy is 5 degrees K accuracy over a 10 ms integration interval, but is capable of achieving 0.5K sensitivity over a 1 second integration interval. Near-term improvements to MAPIR will bring that accuracy to 3 K over a 10 ms integration period.

NASA’s Land, Vegetation and Ice Sensor (LVIS) is a wide-swath, high-altitude, full-waveform airborne laser altimeter and camera sensor suite designed to provide elevation and surface structure measurements over hundreds of thousands of square kilometers. LVIS is an efficient and cost-effective capability for mapping land, water, and ice surface topography, vegetation height and vertical structure, and surface dynamics. The LVIS Facility is comprised of two high-altitude scanning lidar systems plus cameras that have been integrated on numerous NASA, NSF, and commercial aircraft platforms providing a diverse and flexible capability to meet a broad range of science needs. The newest Facility lidar (LVIS-F) began operations in 2017 using a 4,000 Hz laser, and an earlier 1,000 Hz sensor built in 2010 has undergone various upgrades (LVIS-Classic). High-resolution, commercial off-the-shelf cameras are co-mounted with LVIS lidars providing geotagged image coverage across the LVIS swath. LVIS sensors have flown extensively for a wide range of science applications and have been installed on over a dozen different aircraft, most recently on NASA’s high-altitude Gulfstream-V jet based at Johnson Space Center

The LVIS lidars are full-waveform laser altimeters, meaning that the systems digitally record both the outgoing and reflected laser pulse shapes providing a true 3-dimensional record of the surface and centimeter-level range precision. Multiple science data products are available for each footprint, including the geolocated waveform vector, sub-canopy topography, canopy or structure height, surface complexity, and others. LVIS lidars map a ±6 degree wide data swath centered on nadir (e.g., at an operating altitude of 10 km, the data swath is 2 km wide). They are designed to fly at higher altitudes than what is typical for commercial lidars in order to map a wider swath with low incidence angles, avoid the need for terrain following, while operating at much higher speeds that maximize the range of the aircraft. Recent data campaigns include deployments to Antarctica, Greenland, Canada, Alaska, the conterminous US, Central America, French Guiana, and Gabon.

LISA co-observes with existing passive microwave sensors to identify sources of damaging radio frequency interference (RFI)

· 1200-1700 MHz using broadbeam spiral antenna
· Spectrum analyzer for full bandwidth monitoring of power spectral density
· 14 MHz (8+8 bit @ 20 MSPS) coherent sampling capability for waveform capture and analysis
· Flexible script command language for system control & experiment automation

1) Time of Flight Aerosol Mass Spectrometer (ToF-AMS)

Total and single particle characterization of volatile aerosol ionic and organic components (50-700nm). Uncertainty depends on species and concentration.

2) Single Particle Soot Photometer (SP2)

Single particle measure of BC (soot) mass in particles and determination of mixed particle size and non-BC coating using laser scattering and incandescence. 70-700nm. Single particle counting up to 10,000 per sec.

3) A size-resolved thermo-optic aerosol discriminator (30 s avg.):

Aerosol size distribution from 0.12 up to 7.0 μm, often where most aerosol mass, surface area and optical effects are dominant. Uses a modified Laser Optical Particle Counter (OPC) and computer controlled thermal conditioning system is used upstream (airstream dilution dried). Characterizes aerosol components volatile at 150, 300 and 400C and refractory aerosol at 400C (sea salt, dust and soot/flyash). (Clarke, 1991, Clarke et al., 2004). Uncertianty about 15%

4) Condensation Nuclei - heated and unheated (available at 1Hz)

Two butanol based condensation nuclei (CN) counter (TSI 3010) count all particles between 0.01-3.0 um. Total CN, refractory CN (those remaining at 300C after sulfate is removed) and volatile CN (by difference) are obtained as a continuous readout as a fundamental air mass indicator (Clarke et al. 1996). Uncertainty ~ 5%.

5) Aerodynamic Particle Sizer – (APS-TSI3320) – (<5min/scan)

To further characterize larger “dry” particles, including dust, an APS is operated which sizes particles aerodynamically from 0.8 to 20 μm into 50 channels. Uncertainty~10%.

6) Differential Mobility Analyzer with thermal conditioning – (<3 min/scan)

Volatility tandem thermal differential mobility analyzer (VTTDMA) with thermal analysis that provides size information (mass, surface area, number distributions) and their state of mixing over the 0.01 to 0.3μm size range (Clarke et al., 1998, 2007) for sampling times of about 1-3 minutes. Uncertainty ~10%

7) Nephelometer (10-7 m-1 detection for 60s avg., recorded every 1 sec.)

A 3 wavelength nephelometer (450, 550, 700nm) is used for total scattering and submicrometer scattering values using a Radiance Research single wavelength nephelometer (and thereby coarse dust scattering by difference).

8) Two Particle Soot Absorption Photometers (PSAP-Radiance Research; detection <0.1μg m-3 for 5 min. avg. )

The PSAP is used to quantify the spectral light absorption coefficient of the total and submicron aerosol (eg. soot, BC) at three wavelengths (450, 550, 660nm).

9) Humidity Dependent Light-Scattering (10-6 m-1 detection for 60s avg.; recorded every 1 s)

Two additional Radiance Research single-wavelength nephelometers are operated at two humidities (high/low) to establish the humidity dependence of light scattering, f(RH).

The NASA-Langley GPS remote sensing (GPSRS) instrument simultaneously correlates the unique satellite pseudo-random noise (PRN) code in a given satellite signal with an instrument-generated copy of the code. For each surface measurement, the reflected signal is correlated at 14 successive delay times (or delay bins) relative to the arrival of the signal from the specular point. The correlation results are squared as part of instrument signal processing and recorded for later analysis.

Two GPS-derived classification features are merged with visible image data to create terrain-moisture (TM) classes, or visibly identifiable terrain or landcover classes containing a surface/soil moisture component. As compared to using surface imagery alone, classification accuracy is significantly improved for a number of visible classes when adding the GPS-based signal features. Since the strength of the reflected GPS signal is proportional to the amount of moisture in the surface, use of these GPS features provides information about the surface that is not obtainable using visible wavelengths alone. Application areas include hydrology, precision agriculture, and wetlands mapping.

GISMO is a concept for a spaceborne radar system designed to measure the surface and basal topography of terrestrial ice sheets and to determine the physical properties of the glacier bed. Our primary objective is to develop this new technology for obtaining spaceborne estimates of the mass of the polar ice sheets with an ultimate goal of providing essential information to modelers estimating the mass balance of the polar ice sheets and estimating the response of ice sheets to changing climate. Our technology concept employs VHF and P-band interferometric radars using a novel clutter rejection technique for measuring the surface and bottom topographies of polar ice sheets. Our approach will enable us to reduce signal contamination from surface clutter, measure the topography of the glacier bed, and paint a picture of variations in bed characteristics. The technology will also have applications for planetary exploration including studies of the Martian ice caps and the icy moons of the outer solar system. We have recently shown that it is possible to image a small portion of the base of the polar ice sheets using a SAR approach. Through the concept developed here, we believe that, for the first time, we can image the base and map the 3-dimensional basal topography beneath an ice sheet at up to 5 km depth.

GISMO is a NASA Instrument Incubator Project.

The GIFS instrument, a tunable triple-etalon Fabry-Perot Imaging Spectrometer, is designed to measure the O2 absorption lines in solar radiation reflected off the Earth’s surface. This optical technique can provide data to characterize cloud properties in 2 dimensions. The instrument also potentially provides measurements with spatial resolution, spatial coverage, revisit time, and precision/accuracy that would be difficult to obtain with existing methods.

The instrument enables measurements of cloud top temperature, pressure and altitude on a global scale, when deployed in geostationary orbit. Introduction of these data points into weather forecasting models will lead to significant improvements in the forecasting of weather events, including hurricane motion and intensity. The GIFS instrument successfully flew and operated on-board a NASA P-3 Orion in multiple flights throughout January and February 2008.