Altair: an incoherent scatter radar for equatorial spread <i>F</i> studies

Tsunoda, R. T.; Baron, M. J.; Owen, J.; Towle, D. M.

doi:10.1029/rs014i006p01111

Cited by 83 publications

(13 citation statements)

References 29 publications

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“…The evidence that supports this upwelling paradigm is substantial [see Tsunoda, 2015]. Breakthrough descriptions of upwellings and the EPB development process were provided by measurements made with Advanced Research Project Agency (ARPA) Long-range Tracking and Identification Radar (ALTAIR), a fully steerable incoherent scatter radar [Tsunoda et al, 1979]; those results can be found in a series of papers [e.g., Tsunoda and White, 1981;Tsunoda, 1981Tsunoda, , 1983Tsunoda, , 2005Tsunoda et al, 1982;Tsunoda, 2005Tsunoda, , 2015.…”

Section: Need For Two-dimensional Descriptionmentioning

confidence: 99%

Off‐great‐circle paths in transequatorial propagation: 1. Discrete and diffuse types

et al. 2016

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There is mounting evidence that plasma structure in nighttime equatorial F layer evolves from large‐scale wave structure (LSWS) in the bottomside F layer. This process cannot be ignored because equatorial plasma bubbles (EPBs) arise from large‐amplitude LSWS; and, because intense radiowave scintillations are associated with EPBs, understanding the LSWS‐to‐EPB process is a crucial step toward reliable Space Weather Forecasting. In this regard, the transequatorial propagation (TEP) experiment appears to be the most useful among available research instruments. After a lapse of 30 years, the TEP experiment has been resurrected; a goal of this research is to understand TEP measurements well enough so that they can be used to diagnose the LSWS‐to‐EPB process. Toward this end, new results are presented in two companion papers. Herein (P1), off‐great‐circle (OGC) propagation paths are shown to consist of two types, discrete and diffuse. The new findings include the following: (1) a generalized multireflection model that can explain most of the observed properties; (2) the discrete type is supported by multireflections from an unstructured upwelling, (3) the diffuse type is supported by reflections from plasma structure in EPBs; and (4) the observed east‐west (EW) asymmetry can be explained in terms of a distorted upwelling or plasma structure along the west wall of an upwelling. In Paper 2 (P2), a second form of observed EW asymmetry is explained in terms of plasma structure, which is not aligned with the geomagnetic field. The findings strongly confirm a close relationship between upwellings, ESF patches, and OGC paths.

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Section: Need For Two-dimensional Descriptionmentioning

confidence: 99%

Off‐great‐circle paths in transequatorial propagation: 1. Discrete and diffuse types

et al. 2016

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“…It provides tracking precision metrics, radar cross section (RCS) signature, and range-Doppler imaging for deep-space operations, satellite observations, strategic reentry missions, and multiple-intercept engagement tracking. Situated at 4.3°N magnetic dip latitude, the radar is also well suited for investigations of incoherent and coherent backscatter from the equatorial ionosphere [e.g., Caton et al, 2009;Hysell et al, 2006;Tsunoda et al, 1979]. The fully steerable parabolic dish antenna (46 m diameter) operates in dualfrequency mode transmitting signals at 158 MHz (VHF) and 422 MHz (UHF).…”

Section: Observations From the Altair Radarmentioning

confidence: 99%

Multiple phase screen modeling of ionospheric scintillation along radio occultation raypaths

et al. 2011

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We present the Radio Occultation Scintillation Simulator (ROSS), which uses the multiple phase screen method (MPS) to simulate the forward scatter of radio waves by irregularities in the equatorial ionosphere during radio occultation experiments. ROSS simulates propagation through equatorial plasma bubbles which are modeled as homogeneous electron density fluctuations modulated by a Chapman profile in altitude and a Gaussian window in the magnetic east‐west direction. We adjust the parameters of the density model using electron density profiles derived from the ALTAIR incoherent scatter radar (9.4°N, 167.5°E, 4.3° north dip), and space‐to‐ground observations of scintillation using VHF and GPS receivers that are colocated with the radar. We compare the simulated occultation scintillation to observations of scintillation from the CORISS instrument onboard the C/NOFS satellite during a radio occultation occurring near ALTAIR on 21 April 2009. The ratio of MPS predicted S4 to CORISS observed S4 throughout the F region altitudes of 240–350 km ranged between 0.86 and 1.14.

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“…Further work is needed to determine the optimal regularization approach to be used with data having a large dynamic range. Figure 8 shows the comparison of SSULI measurements made during an overflight of the ALTAIR [Tsunoda et al, 1979] incoherent scatter radar on Roi Namur (9°23 0 46″N, 167°28 0 33″E) in the Marshall Islands. The radar was scanning along the orbit plane of the DMSP F-19 satellite on 19 August 2014 at~0713 UT (18.4 LT).…”

Section: Resultsmentioning

confidence: 99%

Ionospheric‐thermospheric UV tomography: 1. Image space reconstruction algorithms

2017

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We present the Volume Emission Rate Tomography (VERT) technique for inverting satellite-based, multisensor limb and nadir measurements of atmospheric ultraviolet emission to create whole-orbit reconstructions of atmospheric volume emission rate. The VERT approach is more general than previous ionospheric tomography methods because it can reconstruct the volume emission rate field irrespective of the particular excitation mechanisms (e.g., radiative recombination, photoelectron impact excitation, and energetic particle precipitation in auroras); physical models are then applied to interpret the airglow. The technique was developed and tested using data from the Special Sensor Ultraviolet Limb Imager and Special Sensor Ultraviolet Spectrographic Imager instruments aboard the Defense Meteorological Satellite Program F-18 spacecraft and planned for use with upcoming remote sensing missions. The technique incorporates several features to optimize the tomographic solutions, such as the use of a nonnegative algorithm (Richardson-Lucy, RL) that explicitly accounts for the Poisson statistics inherent in optical measurements, capability to include extinction effects due to resonant scattering and absorption of the photons from the lines of sight, a pseudodiffusion-based regularization scheme implemented between iterations of the RL code to produce smoother solutions, and the capability to estimate error bars on the solutions. Tests using simulated atmospheric emissions verify that the technique performs well in a variety of situations, including daytime, nighttime, and even in the challenging terminator regions. Lastly, we consider ionospheric nightglow and validate reconstructions of the nighttime electron density against Advanced Research Project Agency (ARPA) Long-range Tracking and Identification Radar (ALTAIR) incoherent scatter radar data.

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Altair: an incoherent scatter radar for equatorial spread F studies

Cited by 83 publications

References 29 publications

Off‐great‐circle paths in transequatorial propagation: 1. Discrete and diffuse types

Off‐great‐circle paths in transequatorial propagation: 1. Discrete and diffuse types

Multiple phase screen modeling of ionospheric scintillation along radio occultation raypaths

Ionospheric‐thermospheric UV tomography: 1. Image space reconstruction algorithms

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