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THz Limb Sounder (TLS) for Lower Thermospheric Wind, Oxygen Density, and TemperatureNeutral winds are one of the most critical measurements in the lower thermosphere and E region ionosphere (LTEI) for understanding complex electrodynamic processes and ion-neutral interactions. We are developing a high-sensitivity, low-power, noncryogenic 2.06 THz Schottky receiver to measure wind profiles at 100-140 km. The new technique, THz limb sounder (TLS), aims to measure LTEI winds by resolving the wind-induced Doppler shift of 2.06 THz atomic oxygen (OI) emissions. As a transition between fine structure levels in the ground electronic state, the OI emission is in local thermodynamic equilibrium(LTE) at altitudes up to 350km. This LTE property, together with day-and-night capability and small line-of-sight gradient, makes the OI limb sounding a very attractive technique for neutral wind observations. In addition to the wind measurement, TLS can also retrieve [OI] density and neutral temperature in the LTEI region. TLS leverages rapid advances in THz receiver technologies including subharmonically pumped (SHP)mixers and Schottky-diode-based power multipliers. Current SHP Schottky receivers have produced good sensitivity for THz frequencies at ambient environment temperatures (120-150 K), which are achievable through passively cooling in spaceflight. As an emerging technique, TLS can fill the critical data gaps in the LTEI neutral wind observations to enable detailed studies on the coupling and dynamo processes between charged and neutral molecules.
Document ID
20160011398
Acquisition Source
Goddard Space Flight Center
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Wu, Dong L.
(NASA Goddard Space Flight Center Greenbelt, MD United States)
Yee, Jeng-Hwa
(Johns Hopkins Univ. Laurel, MD, United States)
Schlecht, Erich
(Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Mehdi, Imran
(Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Siles, Jose
(Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Drouin, Brian J.
(Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Date Acquired
September 21, 2016
Publication Date
July 2, 2016
Publication Information
Publication: Journal of Geophysical Research: Space Physics
Publisher: Wiley
Volume: 121
Issue: 7
e-ISSN: 2169-9402
Subject Category
Earth Resources And Remote Sensing
Report/Patent Number
GSFC-E-DAA-TN35645
Distribution Limits
Public
Copyright
Other
Keywords
wind profiles
THz limb sounder
remote sensing

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