scholarly journals Steve: The Optical Signature of Intense Subauroral Ion Drifts

2019 ◽  
Vol 46 (12) ◽  
pp. 6279-6286 ◽  
Author(s):  
W. E. Archer ◽  
B. Gallardo‐Lacourt ◽  
G. W. Perry ◽  
J. P. St.‐Maurice ◽  
S. C. Buchert ◽  
...  
Keyword(s):  
Ion Drifts ◽  
Optical Signature

Steve: The optical signature of subauroral ion drifts

2020 ◽  
Author(s):  
William Archer ◽  
Bea Gallardo-Lacour ◽  
Gareth Perry ◽  
Jean-Pierre St.-Maurice ◽  
Stephan Buchert ◽  
...  
Keyword(s):  
Single Case ◽  
Scientific Publication ◽  
Single Case Study ◽  
Optical Phenomenon ◽  
Ion Drift ◽  
Ion Drifts ◽  
Optical Signature ◽  
Swarm Satellites ◽  
The Subject

<p>Little is currently known about the optical phenomenon known as Steve. The first scientific publication on the subject suggests that Steve is associated with an intense subauroral ion drift (SAID). However, additional inquiry is warranted as this suggested relationship as it is based on a single case study. Here we present eight occurrences of Steve with coincident or near‐coincident measurements from the European Space Agency's Swarm satellites and show that Steve is consistently associated with SAID. When satellite observations coincident with Steve are compared to that of typical SAID, we find the SAID associated with Steve to have above average peak ion velocities and electron temperatures, as well as extremely low plasma densities.</p>

scholarly journals A new method for measuring optical scattering properties of atmospherically relevant dusts using the Cloud and Aerosol Spectrometer with Polarization (CASPOL)

2013 ◽  
Vol 13 (3) ◽  
pp. 1345-1356 ◽  
Author(s):  
A. Glen ◽  
S. D. Brooks
Keyword(s):  
Cross Sections ◽  
Atmospheric Aerosols ◽  
Single Particle ◽  
Global Climate ◽  
Optical Scattering ◽  
Measurement Tool ◽  
Optical Signature ◽  
New Instrument ◽  
The Difference ◽  
Atmospherically Relevant

Abstract. Atmospheric aerosols have major impacts on regional and global climate through scattering and absorption of solar radiation. A new instrument, the Cloud and Aerosol Spectrometer with Polarization (CASPOL) from Droplet Measurement Technologies measures light scattered by aerosols in the forward (4° to 12°) and backward (168° to 176°) directions, with an additional polarized detector in the backward direction. Scattering by a single particle can be measured by all three detectors for aerosols in a broad range of sizes, 0.6 μm < diameter < 50 μm. The CASPOL is a unique measurement tool, since unlike most in-situ probes, it can measure optical properties on a particle-by-particle basis. In this study, single particle CASPOL measurements for thirteen atmospherically relevant dusts were obtained and their optical scattering signatures were evaluated. In addition, Scanning Electron Microscopy (SEM) was used to characterize the shape and morphology of each type of dust. The total and polarized backscatter intensities varied with particle size for all dust types. Using a new optical signature technique all but one dust type could be categorized into one of three optical scattering groups. Additionally, a composite method was used to derive the optical signature of Arizona Test Dust (ATD) by combining the signatures of its major components. The derived signature was consistent with the measured signature of ATD. Finally, calculated backscattering cross sections for representative dust from each of the three main groups were found to vary by as much as a factor of 7, the difference between the backscattering cross sections of white quartz (5.3 × 10−10 cm−2) and hematite (4.1 × 10−9 cm−2).

scholarly journals Simulation of the pre-reversal enhancement in the low latitude vertical ion drifts

2000 ◽  
Vol 27 (13) ◽  
pp. 1851-1854 ◽  
Author(s):  
C. G. Fesen ◽  
G. Crowley ◽  
R. G. Roble ◽  
A. D. Richmond ◽  
B. G. Fejer
Keyword(s):  
Low Latitude ◽  
Ion Drifts

Optical signature of topological insulators

2009 ◽  
Vol 80 (11) ◽  
Author(s):  
Ming-Che Chang ◽  
Min-Fong Yang
Keyword(s):  
Topological Insulators ◽  
Optical Signature

scholarly journals Quantum Dots: Quantum Optical Signature of Plasmonically Coupled Nanocrystal Quantum Dots (Small 38/2015)

Small ◽  
2015 ◽  
Vol 11 (38) ◽  
pp. 5176-5176 ◽  
Author(s):  
Feng Wang ◽  
Niladri S. Karan ◽  
Hue Minh Nguyen ◽  
Benjamin D. Mangum ◽  
Yagnaseni Ghosh ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Optical Signature ◽  
Nanocrystal Quantum Dots ◽  
Quantum Optical

scholarly journals Topside equatorial zonal ion velocities measured by C/NOFS during rising solar activity

2014 ◽  
Vol 32 (2) ◽  
pp. 69-75 ◽  
Author(s):  
W. R. Coley ◽  
R. A. Stoneback ◽  
R. A. Heelis ◽  
M. R. Hairston
Keyword(s):  
Solar Activity ◽  
Local Time ◽  
Geomagnetic Field ◽  
General Pattern ◽  
Magnetic Latitude ◽  
Ion Drifts ◽  
F Region ◽  
Westerly Flow ◽  
Solar Local Time ◽  
Ion Velocity

Abstract. The Ion Velocity Meter (IVM), a part of the Coupled Ion Neutral Dynamic Investigation (CINDI) instrument package on the Communication/Navigation Outage Forecast System (C/NOFS) spacecraft, has made over 5 yr of in situ measurements of plasma temperatures, composition, densities, and velocities in the 400–850 km altitude range of the equatorial ionosphere. These measured ion velocities are then transformed into a coordinate system with components parallel and perpendicular to the geomagnetic field allowing us to examine the zonal (horizontal and perpendicular to the geomagnetic field) component of plasma motion over the 2009–2012 interval. The general pattern of local time variation of the equatorial zonal ion velocity is well established as westward during the day and eastward during the night, with the larger nighttime velocities leading to a net ionospheric superrotation. Since the C/NOFS launch in April 2008, F10.7 cm radio fluxes have gradually increased from around 70 sfu to levels in the 130–150 sfu range. The comprehensive coverage of C/NOFS over the low-latitude ionosphere allows us to examine variations of the topside zonal ion velocity over a wide level of solar activity as well as the dependence of the zonal velocity on apex altitude (magnetic latitude), longitude, and solar local time. It was found that the zonal ion drifts show longitude dependence with the largest net eastward values in the American sector. The pre-midnight zonal drifts show definite solar activity (F10.7) dependence. The daytime drifts have a lower dependence on F10.7. The apex altitude (magnetic latitude) variations indicate a more westerly flow at higher altitudes. There is often a net topside subrotation at low F10.7 levels, perhaps indicative of a suppressed F region dynamo due to low field line-integrated conductivity and a low F region altitude at solar minimum.

scholarly journals Improvement of Atmospheric Correction of Satellite Sentinel-3/OLCI Data for Oceanic Waters in Presence of Sargassum

2022 ◽  
Vol 14 (2) ◽  
pp. 386
Author(s):  
Léa Schamberger ◽  
Audrey Minghelli ◽  
Malik Chami ◽  
François Steinmetz
Keyword(s):  
Near Infrared ◽  
Ocean Color ◽  
Atmospheric Correction ◽  
Correction Algorithm ◽  
Infrared Band ◽  
Economic Issues ◽  
Optical Signature ◽  
Color Data ◽  
The Caribbean ◽  
Satellite Ocean Color

The invasive species of brown algae Sargassum gathers in large aggregations in the Caribbean Sea, and has done so especially over the last decade. These aggregations wash up on shores and decompose, leading to many socio-economic issues for the population and the coastal ecosystem. Satellite ocean color data sensors such as Sentinel-3/OLCI can be used to detect the presence of Sargassum and estimate its fractional coverage and biomass. The derivation of Sargassum presence and abundance from satellite ocean color data first requires atmospheric correction; however, the atmospheric correction procedure that is commonly used for oceanic waters needs to be adapted when dealing with the occurrence of Sargassum because the non-zero water reflectance in the near infrared band induced by Sargassum optical signature could lead to Sargassum being wrongly identified as aerosols. In this study, this difficulty is overcome by interpolating aerosol and sunglint reflectance between nearby Sargassum-free pixels. The proposed method relies on the local homogeneity of the aerosol reflectance between Sargassum and Sargassum-free areas. The performance of the adapted atmospheric correction algorithm over Sargassum areas is evaluated. The proposed method is demonstrated to result in more plausible aerosol and sunglint reflectances. A reduction of between 75% and 88% of pixels showing a negative water reflectance above 600 nm were noticed after the correction of the several images.

scholarly journals Two-Code Keying and Code Conversion for Optical Buffer Design in Optical Packet Switching Networks

Electronics ◽  
2019 ◽  
Vol 8 (10) ◽  
pp. 1117 ◽  
Author(s):  
Chen ◽  
Chen ◽  
Wu
Keyword(s):  
Packet Switching ◽  
Hamming Distance ◽  
Optical Packet Switching ◽  
Spectral Amplitude ◽  
Optical Signature ◽  
Optical Buffering ◽  
Buffer Design ◽  
Optical Packet Switching Networks ◽  
Spectral Amplitude Coding ◽  
Code Division Multiple

Buffering management is a crucial function in current optical packet switching (OPS) networks. To avoid packet blocking due to competition for the same switched path, optical buffering is required to queue packets after a router makes the forwarding decision. In this paper, the author proposed a buffering scheme based on optical code-division multiple access (OCDMA), where each packet is encoded with an optical signature code. An optical coding technique combining spectral-amplitude coding (SAC) and two-code keying (TCK) is introduced to advance the buffering performance regarding packet loss probability. In TCK, the payload bits “1” and “0” of a stored packet are respectively converted to a SAC signal and its complementarity. As the Hamming distance between the coding signals of bits “1” and “0” is extended, the existing drawback that the OCDMA-based buffer capacity is limited by the decoder noise increased with the number of queued SAC packets is resolved. Moreover, an encoder consisting of a fiber Bragg grating (FBG) array is applied for simplifying the system design. A SAC signal and its complementary counterpart can be generated simultaneously without the need of an extra encoder.

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