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Temperature and ozone volume mixing ratio profiles obtained from the Halogen Occultation Experiment (HALOE) aboard the Upper Atmospheric Research Satellite (UARS) over India and over the open ocean to the south during the period 1991-2001…

大气与海洋物理 · 物理学 2009-05-29 S. Fadnavis , Devendraa Siingh , G. Beig , R. P. Singh

Coherent detection can provide enhanced receiver sensitivity and spectral efficiency in free-space optical (FSO) communications. However, turbulence can cause modal power coupling effects on a Gaussian data beam and significantly degrade…

Adaptive Optics (AO) is an innovative technique that substantially improves the optical performance of ground-based telescopes. The SOAR Adaptive Module (SAM) is a laser-assisted AO instrument, designed to compensate ground-layer…

天体物理仪器与方法 · 物理学 2018-08-28 D. M. Faes , A. Tokovinin , T. Vieira , A. Mello , M. Domingues , D. Andrade , B. C. Quint , J. B. Santos

Solar wind is probably the best laboratory to study turbulence in astrophysical plasmas. In addition to the presence of magnetic field, the differences with neutral fluid isotropic turbulence are: weakness of collisional dissipation and…

太阳与恒星天体物理 · 物理学 2015-06-16 Olga Alexandrova , Christopher H. K. Chen , Luca Sorriso-Valvo , Timothy S. Horbury , Stuart D. Bale

When structured light is propagated through the atmosphere, turbulence results in modal scattering and distortions. An extensively studied example is that of light carrying orbital angular momentum (OAM), where the atmosphere is treated as…

光学 · 物理学 2021-09-22 Asher Klug , Isaac Nape , Andrew Forbes

We studied Faraday rotation measure (RM) in turbulent media with the rms Mach number of unity, using isothermal, magnetohydrodynamic turbulence simulations. Four cases with different values of initial plasma beta were considered. Our main…

星系天体物理 · 物理学 2014-11-20 Qingwen Wu , Jongsoo Kim , Dongsu Ryu , Jungyeon Cho , Paul Alexander

Over the past decade, optical orbital angular momentum (OAM) modes were shown to offer advantages in optical information acquisition. Here, we introduce a new scheme for optical ranging in which depth is estimated through the angular…

One important frontier for astronomical adaptive optics (AO) involves methods such as Multi-Object AO and Multi-Conjugate AO that have the potential to give a significantly larger field of view than conventional AO techniques. A second key…

天体物理仪器与方法 · 物理学 2015-05-13 S. Mark Ammons , Luke Johnson , Edward A. Laag , Renate Kupke , Donald T. Gavel , Brian J. Bauman , Claire E. Max

This paper proposes a unified statistical channel model to characterize the atmospheric turbulence induced distortions faced by orbital angular momentum (OAM) in free space optical (FSO) communication systems. In this channel model, the…

信号处理 · 电气工程与系统科学 2019-10-24 El-Mehdi Amhoud , Boon S. Ooi , Mohamed-Slim Alouini

In this paper we show that Sun-viewing images obtained by the Mars Science Laboratory (MSL) Navigation Cameras (Navcam) can be used for retrieving the dust optical depth and constrain the aerosol physical properties at Gale Crater by…

地球与行星天体物理 · 物理学 2020-09-02 H. Chen-Chen , S. Perez-Hoyos , A. Sanchez-Lavega

With Rytov approximation theory, we derive the analytic expression of detection probability of Airy vortex beam carrying orbital angular momentum (OAM) through an anisotropic weak oceanic turbulence. We investigate the influences of…

经典物理 · 物理学 2018-10-17 Xinguang Wang , Zhen Yang , Shengmei Zhao

The InSight mission, featuring continuous high-frequency high-sensitivity pressure measurements, is in ideal position to study the active atmospheric turbulence of Mars. Data acquired during 1.25 Martian year allows us to study the seasonal…

地球与行星天体物理 · 物理学 2021-11-02 Audrey Chatain , Aymeric Spiga , Don Banfield , Francois Forget , Naomi Murdoch

Strong turbulence conditions create amplitude aberrations through the effects of near-field diffraction. When integrated over long optical path lengths, amplitude aberrations (seen as scintillation) can nullify local areas in the recorded…

天体物理仪器与方法 · 物理学 2020-12-30 Justin R. Crepp , Stanimir O. Letchev , Sam J. Potier , Joshua H. Follansbee , Nicholas T. Tusay

Detecting the presence of circumstellar dust around nearby solar-type main sequence stars is an important pre-requisite for the design of future life-finding space missions such as ESA's Darwin or NASA's Terrestrial Planet Finder (TPF). The…

天体物理学 · 物理学 2009-11-13 O. Absil , V. Coude du Foresto , M. Barillot , M. R. Swain

We analyze a suite of thin sheet magnetohydrodynamical simulations based on the formulation of Basu, Ciolek, Dapp & Wurster. These simulations allow us to examine the observational consequences to a star-forming region of varying the input…

太阳与恒星天体物理 · 物理学 2009-07-22 Helen Kirk , Doug Johnstone , Shantanu Basu

Light beams can be characterized by their complex spatial profiles in both intensity and phase. Analogous to time signals, which can be decomposed into multiple orthogonal frequency functions, a light beam can also be decomposed into a set…

Turbulent properties of the quiet Sun represent the basic state of surface conditions, and a background for various processes of solar activity. Therefore understanding of properties and dynamics of this `basic' state is important for…

太阳与恒星天体物理 · 物理学 2012-06-27 I. N. Kitiashvili , V. I. Abramenko , P. R. Goode , A. G. Kosovichev , S. K. Lele , N. N. Mansour , A. A. Wray , V. B. Yurchyshyn

Studies of solar wind turbulence traditionally employ high-resolution magnetic field data, but high-resolution measurements of ion and electron moments have been possible only recently. We report the first turbulence studies of ion and…

We test a new technique of studying magnetohydrodynamic (MHD) turbulence suggested by Lazarian \& Pogosyan, using synthetic synchrotron polarization observations. This paper focuses on a one-point statistics, which is termed the…

高能天体物理现象 · 物理学 2016-07-20 Jian-Fu Zhang , Alex Lazarian , Hyeseung Lee , Jungyeon Cho

Using the novel Magnetospheric Multiscale (MMS) mission data accumulated during the 2019 MMS Solar Wind Turbulence Campaign, we calculate the Taylor microscale $(\lambda_{\mathrm{T}})$ of the turbulent magnetic field in the solar wind. The…