Application of linear regularization methods to Arecibo vector velocities

Sulzer, M. P.; Aponte, N.; González, S. A.

doi:10.1029/2005ja011042

Cited by 27 publications

(30 citation statements)

References 4 publications

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“…Similar data are available for the Gregorian feed system. Combining both data streams and using an inversion procedure similar to that of Sulzer et al [2005], we have estimated the zonal and meridional F ‐region drifts continuously throughout the observations. The results (not shown) argue that the F ‐region drifts and associated background electric fields were small between 1930–2030 LT.…”

Section: Observationsmentioning

confidence: 99%

Dynamic instability in the lower thermosphere inferred from irregular sporadic E layers

et al. 2012

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[1] Simultaneous observations of an irregular sporadic E layer from the Arecibo incoherent scatter radar and a coherent scatter radar located on St. Croix are presented. The layers exhibit periodic structuring which is attributed to shear instability in the neutral flow. Estimates of the time-varying vector neutral wind profiles in which the layer was embedded are analyzed and shown to be shear unstable in the Richardson number sense. In addition to the calculation of the Richardson number values, we present an eigenvalue analysis of the model of Miles (1961) and Howard (1961) for the observed wind profiles. The calculated eigenmodes have dominant Kelvin-Helmholtz modes for the estimated flow that are propagating to the southwest with phase speeds near 50 m/s and horizontal wavelengths between 10-15 km. The growth times for the waves would have been as little as about 1 min. These features are in reasonable agreement with the observed of E s -layer structure. The Miles-Howard model has been analyzed extensively in the past using both analytic and numerical techniques, but calculations of eigenmodes for the equations in a case with background winds that have turning and speed shear have not been carried out previously, as far as we know. The difficulties associated with the calculation are related to identifying the fastest growing modes among the large number of modes that satisfy the equations. The technique and the relationship of the solutions to the observed sporadic E layer wave structure are described.

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Section: Observationsmentioning

confidence: 99%

Dynamic instability in the lower thermosphere inferred from irregular sporadic E layers

et al. 2012

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“…A linear regularization method developed by Sulzer et al . [] has been adopted to convert the LOS ion drifts to the vector ion drifts. Derivations of diffusion velocities and meridional winds are found in Gong and Zhou [].…”

Section: Introductionmentioning

confidence: 99%

The F region and topside ionosphere response to a strong geomagnetic storm at Arecibo

et al. 2013

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[1] We analyze the data derived from the Arecibo incoherent scatter radar measurements to investigate the response of the F region and topside ionosphere to a strong geomagnetic storm that occurred during the period of 5-6 August 2011. The meridional wind was extremely enhanced at the early stage of the storm. The peak velocity reached approximately 300 m/s at an altitude of 340 km, which is seldom seen at the Arecibo latitude. During the storm, the vertical ion drift caused by the meridional wind was positively correlated with that caused by the electric field, which is opposite to the quiet time relationship. The disturbed vertical ion drifts resulted in large ionospheric perturbations in the F and topside regions. Several collapses were observed in h m F 2 during the storm night. N m F 2 rapidly increased after the storm and then decreased around midnight. At an altitude of 610 km, the concentration of H + and O + , and the ratio of H + over electron density all exhibited large variations. The ratio of H + over electron density changed from less than 10% to more than 80% in a matter of 2 hours in the morning of 6 August. One explanation for such a behavior is that vertical transport dominates over charge exchange late at night due to the lower concentration of O + .

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“…In view of the slow slew rate of the Arecibo beam system, this assumption may not be difficult to violate. Sulzer et al [2005] introduced a novel refinement, incorporating statistical inverse theory in the estimation of F region plasma drifts from data taken when the beam was continuously swinging. In this paper, we generalize the result and apply a related technique to the entire horizontal wind estimation problem.…”

Section: Introductionmentioning

confidence: 99%

High time and height resolution neutral wind profile measurements across the mesosphere/lower thermosphere region using the Arecibo incoherent scatter radar

2014

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Citation:Hysell, D. L., M. F. Larsen, and M. P. Sulzer (2014), High time and height resolution neutral wind profile measurements across the mesosphere/lower thermosphere region using the Arecibo incoherent scatter radar, J. Geophys. Res. Space Physics, 119, 2345-2358, doi:10.1002 Abstract A method for estimating the vector neutral wind profiles in the mesosphere and lower thermosphere (MALT) region of the upper atmosphere from Arecibo dual-beam incoherent scatter radar data is presented. The method yields continuous estimates of both the altitude-averaged F region plasma drifts and all three components of the altitude-resolved neutral wind profiles in the MALT using data taken while the Arecibo feed system swings in azimuth. The problem is mixed determined, and its solution is not inherently unique. Second-order Tikhonov regularization is used to find solutions consistent with the available data while being minimally structured, additional structure being unsupported by the data. The solution is found using the method of conjugate gradient least squares and sparse matrix mathematics. Example data acquired during an interval of midlatitude spread F are used to illustrate the method. The estimated wind profiles exhibit characteristics broadly consistent with gravity waves but are impulsive, with features that generally persist for less than one and a half wave periods.

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Application of linear regularization methods to Arecibo vector velocities

Cited by 27 publications

References 4 publications

Dynamic instability in the lower thermosphere inferred from irregular sporadic E layers

Dynamic instability in the lower thermosphere inferred from irregular sporadic E layers

The F region and topside ionosphere response to a strong geomagnetic storm at Arecibo

High time and height resolution neutral wind profile measurements across the mesosphere/lower thermosphere region using the Arecibo incoherent scatter radar

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