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Microbiome of the upper troposphere: Species composition and prevalence, effects of tropical storms, and atmospheric implications

DeLeon-Rodriguez, N., et al. (2013), Microbiome of the upper troposphere: Species composition and prevalence, effects of tropical storms, and atmospheric implications, Proc. Natl. Acad. Sci., doi:10.1073/pnas.1212089110.

Hurricane Imaging Radiometer

HIRAD is a multi-frequency, hurricane imaging, interferometric single-pol passive C-band radiometer, operating from 4 GHz to 7 GHz, with both cross-track and along-track resolution that measures strong ocean surface winds through heavy rain from an aircraft or space-based platform. A one-dimensional thinned synthetic aperture array antenna is used to obtain wide-swath measurements with multiple simultaneous beams in a push-broom configuration. HIRAD features software beam forming with no moving parts, internal hot, cold, and noise diode based calibration, and continuous, gap-free imaging. Its swath width is approximately 60 degrees in either direction. There are two products: rain rate and wind speed.

The basis of the HIRAD design is the Stepped Frequency Microwave Radiometer (SFMR) that has successfully measured surface wind speed and rain rate in hurricanes from the NOAA Hurricane Research Division’s (HRD) P-3 aircraft. Unlike the SFMR that views only at nadir, the HIRAD provides wide-swath measurements between ± 40 degrees in incidence angle with a spot-beam spatial resolution of approximately 1-3 km. HIRAD would be able to provide high resolution hurricane imaging when used on an operational hurricane surveillance aircraft such as the NOAA HRD’s Gulfstream-IV.

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High Altitude Imaging Wind and Rain Airborne Profiler

HIWRAP (High-Altitude Imaging Wind and Rain Airborne Profiler) is a dual-frequency radar (Ka- and Ku-band), dual-beam (300 and 400 incidence angle), conical scan, solid-state transmitter-based system, designed for operation on the high-altitude (20 km) Global Hawk UAV. HIWRAP characteristics: Conically scanning; Simultaneous Ku/Ka-band & two beams @30 and 40 deg; Winds using precipitation & clouds as tracers; Ocean vector wind scatterometry; Map the 3-dimensional winds and precipitation within hurricanes and other severe weather events; Map ocean surface winds in clear to light rain regions using scatterometry.

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Airborne Second Generation Precipitation Radar

The APR-2 is a dual-frequency (13 GHz & 35 GHz), Doppler, dual-polarization radar system. It has a downward looking antenna that performs cross track scans, covering a swath that is +/- 25 to each side of the aircraft path. Additional features include: simultaneous dual-frequency, matched beam operation at 13.4 and 35.6 GHz (same as GPM Dual-Frequency Precipitation Radar), simultaneous measurement of both like- and cross-polarized signals at both frequencies, Doppler operation, and real-time pulse compression (calibrated reflectivity data can be produced for large areas in the field during flight, if necessary).

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Doppler Aerosol WiNd Lidar

The NASA Langley Research Center DAWN (Doppler Aerosol WiNd) lidar system employs a pulsed, solid-state laser operating at 2053 nm wavelength. It pulses at 10 Hz with up to 100 mJ/pulse which are 180 ns long. Using a wedge scanner, several different azimuth angles can be measured below the aircraft, all at a 30 degree off-nadir angle. Multiple azimuth angles enable horizontal wind calculation, mitigate cloud obscurations, and measure atmospheric variability. DAWN can provide vertical profiles of the zonal (u) and meridional (v) components of the horizontal wind below the aircraft, typically at ~60 meter resolution. Various vertical and horizontal resolutions are possible in post processing. DAWN can also provide vertical profiles of line of sight (LOS) wind speed at each azimuth angle. It can also be operated to stare persistently at any particular azimuth angle to simulate what a satellite such as European Space Agency Atmospheric Dynamics Mission (ADM) Aeolus would observe. DAWN signal returns also permit retrieval of vertical profiles of relative aerosol backscatter and wind turbulence.

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