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Nakagawa H, Tsukada S, Katagiri T, Kasaba Y, Murata I, Hirahara Y, Matsuura Y, Yamazaki A. Mid-infrared laser heterodyne spectrometer by hollow optical fiber and its newly designed coupler. APPLIED OPTICS 2023; 62:A31-A36. [PMID: 36821297 DOI: 10.1364/ao.475426] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2022] [Accepted: 11/21/2022] [Indexed: 06/18/2023]
Abstract
We demonstrate a newly designed, to the best of our knowledge, hollow optical fiber coupler for a mid-infrared (IR) laser heterodyne spectrometer that mixes a targeted light source with local oscillator (LO) light. The hollow fiber achieves a high transmission efficiency ∼80-90%/m, not only for a coherent laser source but also for an incoherent blackbody source. The branching characteristics of the hollow optical fiber coupler are found to be strongly dependent on the curvature and length of the input port fiber, indicating that the branching ratio could be designed independently for each input port. Our laboratory measurements demonstrate that the branching ratio and transmittance of the coupler can be varied by coupling a flexible fiber to the input side owing to the excitation of higher-order modes. Using the hollow optical fiber coupler, a high-resolution emission spectrum of the quantum cascade laser at 10.3 µm for our C O 2 laser-based heterodyne spectrometer is successfully achieved. Using a C O 2 laser with a hollow fiber and a blackbody as a direct input signal in free space, we obtain the sensitivity performance of IR laser heterodyne spectrometer as 2000-3000 K of the system noise temperature. This suggests that the transmission of a coherent LO laser through a hollow optical fiber has almost the same sensitivity for the IR heterodyne detection as that without a fiber.
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Stallard TS, Melin H, Miller S, Moore L, O'Donoghue J, Connerney JEP, Satoh T, West RA, Thayer JP, Hsu VW, Johnson RE. The Great Cold Spot in Jupiter's upper atmosphere. GEOPHYSICAL RESEARCH LETTERS 2017; 44:3000-3008. [PMID: 28603321 PMCID: PMC5439487 DOI: 10.1002/2016gl071956] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2016] [Revised: 01/18/2017] [Accepted: 02/28/2017] [Indexed: 05/29/2023]
Abstract
Past observations and modeling of Jupiter's thermosphere have, due to their limited resolution, suggested that heat generated by the aurora near the poles results in a smooth thermal gradient away from these aurorae, indicating a quiescent and diffuse flow of energy within the subauroral thermosphere. Here we discuss Very Large Telescope-Cryogenic High-Resolution IR Echelle Spectrometer observations that reveal a small-scale localized cooling of ~200 K within the nonauroral thermosphere. Using Infrared Telescope Facility NSFCam images, this feature is revealed to be quasi-stable over at least a 15 year period, fixed in magnetic latitude and longitude. The size and shape of this "Great Cold Spot" vary significantly with time, strongly suggesting that it is produced by an aurorally generated weather system: the first direct evidence of a long-term thermospheric vortex in the solar system. We discuss the implications of this spot, comparing it with short-term temperature and density variations at Earth.
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Affiliation(s)
- Tom S. Stallard
- Department of Physics and AstronomyUniversity of LeicesterLeicesterUK
| | - Henrik Melin
- Department of Physics and AstronomyUniversity of LeicesterLeicesterUK
| | - Steve Miller
- Department of Physics and AstronomyUniversity College LondonLondonUK
| | - Luke Moore
- Center for Space PhysicsBoston UniversityBostonMassachusettsUSA
| | | | | | - Takehiko Satoh
- Institute of Space and Astronautical ScienceJAXASagamiharaJapan
| | - Robert A. West
- Jet Propulsion LaboratoryCalifornia Institute of TechnologyPasadenaCaliforniaUSA
| | - Jeffrey P. Thayer
- Aerospace Engineering SciencesUniversity of Colorado BoulderBoulderColoradoUSA
| | - Vicki W. Hsu
- Aerospace Engineering SciencesUniversity of Colorado BoulderBoulderColoradoUSA
| | - Rosie E. Johnson
- Department of Physics and AstronomyUniversity of LeicesterLeicesterUK
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Zhang X, West RA, Irwin PGJ, Nixon CA, Yung YL. Aerosol influence on energy balance of the middle atmosphere of Jupiter. Nat Commun 2015; 6:10231. [PMID: 26694318 PMCID: PMC4703888 DOI: 10.1038/ncomms10231] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2015] [Accepted: 11/18/2015] [Indexed: 11/09/2022] Open
Abstract
Aerosols are ubiquitous in planetary atmospheres in the Solar System. However, radiative forcing on Jupiter has traditionally been attributed to solar heating and infrared cooling of gaseous constituents only, while the significance of aerosol radiative effects has been a long-standing controversy. Here we show, based on observations from the NASA spacecraft Voyager and Cassini, that gases alone cannot maintain the global energy balance in the middle atmosphere of Jupiter. Instead, a thick aerosol layer consisting of fluffy, fractal aggregate particles produced by photochemistry and auroral chemistry dominates the stratospheric radiative heating at middle and high latitudes, exceeding the local gas heating rate by a factor of 5-10. On a global average, aerosol heating is comparable to the gas contribution and aerosol cooling is more important than previously thought. We argue that fractal aggregate particles may also have a significant role in controlling the atmospheric radiative energy balance on other planets, as on Jupiter.
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Affiliation(s)
- Xi Zhang
- Department of Earth and Planetary Sciences, University of California Santa Cruz, Santa Cruz, California 95064, USA
| | - Robert A West
- Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, California 91109, USA
| | - Patrick G J Irwin
- Atmospheric, Oceanic and Planetary Physics, University of Oxford, Clarendon Laboratory, Parks Road, Oxford OX1 3PU, UK
| | - Conor A Nixon
- NASA Goddard Space Flight Center, Greenbelt, Maryland 20771, USA
| | - Yuk L Yung
- Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, California 91125, USA
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Gladstone GR, Waite JH, Grodent D, Lewis WS, Crary FJ, Elsner RF, Weisskopf MC, Majeed T, Jahn JM, Bhardwaj A, Clarke JT, Young DT, Dougherty MK, Espinosa SA, Cravens TE. A pulsating auroral X-ray hot spot on Jupiter. Nature 2002; 415:1000-3. [PMID: 11875561 DOI: 10.1038/4151000a] [Citation(s) in RCA: 158] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Jupiter's X-ray aurora has been thought to be excited by energetic sulphur and oxygen ions precipitating from the inner magnetosphere into the planet's polar regions. Here we report high-spatial-resolution observations that demonstrate that most of Jupiter's northern auroral X-rays come from a 'hot spot' located significantly poleward of the latitudes connected to the inner magnetosphere. The hot spot seems to be fixed in magnetic latitude and longitude and occurs in a region where anomalous infrared and ultraviolet emissions have also been observed. We infer from the data that the particles that excite the aurora originate in the outer magnetosphere. The hot spot X-rays pulsate with an approximately 45-min period, a period similar to that reported for high-latitude radio and energetic electron bursts observed by near-Jupiter spacecraft. These results invalidate the idea that jovian auroral X-ray emissions are mainly excited by steady precipitation of energetic heavy ions from the inner magnetosphere. Instead, the X-rays seem to result from currently unexplained processes in the outer magnetosphere that produce highly localized and highly variable emissions over an extremely wide range of wavelengths.
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Affiliation(s)
- G R Gladstone
- Southwest Research Institute, San Antonio, Texas 78228, USA.
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Grodent D, Waite JH, Gérard JC. A self-consistent model of the Jovian auroral thermal structure. ACTA ACUST UNITED AC 2001. [DOI: 10.1029/2000ja900129] [Citation(s) in RCA: 143] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Perry JJ, Kim YH, Fox JL, Porter HS. Chemistry of the Jovian auroral ionosphere. ACTA ACUST UNITED AC 1999. [DOI: 10.1029/1999je900022] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Sada PV, Bjoraker GL, Jennings DE, McCabe GH, Romani PN. Observations of CH4, C2H6, and C2H2 in the stratosphere of Jupiter. ICARUS 1998; 136:192-201. [PMID: 11878354 DOI: 10.1006/icar.1998.6021] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
We have performed high-resolution spectral observations at mid-infrared wavelengths of CH4 (8.14 micrometers), C2H6 (12.16 micrometers), and C2H2 (13.45 micrometers) on Jupiter. These emission features probe the stratosphere of the planet and provide information on the carbon-based photochemical processes taking place in that region of the atmosphere. The observations were performed using our cryogenic echelle spectrometer CELESTE, in conjunction with the McMath-Pierce 1.5-m solar telescope between November 1994 and February 1995. We used the methane observations to derive the temperature profile of the jovian atmosphere in the 1-10 mbar region of the stratosphere. This profile was then used in conjunction with height-dependent mixing ratios of each hydrocarbon to determine global abundances for ethane and acetylene. The resulting mixing ratios are 3.9(+1.9)(-1.3) x 10(-6) for C2H6 (5 mbar pressure level), and 2.3 +/- 0.5 x 10(-8) for C2H2 (8 mbar pressure level), where the quoted uncertainties are derived from model variations in the temperature profile which match the methane observation uncertainties.
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Affiliation(s)
- P V Sada
- Planetary Systems Branch, NASA Goddard Space Flight Center, Greenbelt, Maryland 20771, USA.
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Orton G, A'Hearn M, Baines K, Deming D, Dowling T, Goguen J, Griffith C, Hammel H, Hoffmann W, Hunten D. Collision of comet Shoemaker-Levy 9 with Jupiter observed by the NASA infrared telescope facility. Science 1995; 267:1277-82. [PMID: 7871423 DOI: 10.1126/science.7871423] [Citation(s) in RCA: 52] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The National Aeronautics and Space Administration (NASA) Infrared Telescope Facility was used to investigate the collision of comet Shoemaker-Levy 9 with Jupiter from 12 July to 7 August 1994. Strong thermal infrared emission lasting several minutes was observed after the impacts of fragments C, G, and R. All impacts warmed the stratosphere and some the troposphere up to several degrees. The abundance of stratospheric ammonia increased by more than 50 times. Impact-related particles extended up to a level where the atmospheric pressure measured several millibars. The north polar near-infrared aurora brightened by nearly a factor of 5 a week after the impacts.
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Affiliation(s)
- G Orton
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena 91109
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Drossart P, Bézard B, Atreya SK, Bishop J, Waite JH, Boice D. Thermal profiles in the auroral regions of Jupiter. ACTA ACUST UNITED AC 1993. [DOI: 10.1029/93je01801] [Citation(s) in RCA: 56] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Kostiuk T, Romani P, Espenak F, Livengood TA, Goldstein JJ. Temperature and abundances in the Jovian auroral stratosphere: 2. Ethylene as a probe of the microbar region. ACTA ACUST UNITED AC 1993. [DOI: 10.1029/93je01332] [Citation(s) in RCA: 84] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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