scholarly journals Results of wind velocity measurements at middle and high latitudes by the meteor radar method.

1979 ◽  
Vol 31 (3) ◽  
pp. 411-418 ◽  
Author(s):  
I. A. LYSENKO ◽  
A. D. ORLYANSKY ◽  
Yu. I. PORTNYAGIN
Keyword(s):  
Wind Velocity ◽  
High Latitudes ◽  
Meteor Radar ◽  
Velocity Measurements ◽  
Radar Method

A discussion on D and E region winds over Europe - A study of the wind régime at an altitude of about 100 km by the meteor-radar method

1972 ◽  
Vol 271 (1217) ◽  
pp. 601-611 ◽  
Keyword(s):  
Meteor Radar ◽  
Wind Regime ◽  
Radar Method ◽  
E Region

Wind results obtained by the meteor-radar method at Heiss Island, Obninsk and Molodezhnaya during 1964-8 are described in terms of periodic and prevailing components.

Solar Orbiter observations of solar wind current sheets and their deHoffman-Teller frames

2021 ◽  
Author(s):  
Konrad Steinvall ◽  
Yuri Khotyaintsev ◽  
Giulia Cozzani ◽  
Andris Vaivads ◽  
Christopher Owen ◽  
...  
Keyword(s):  
Solar Wind ◽  
Electric Field ◽  
Wind Velocity ◽  
Solar Wind Velocity ◽  
Field Measurements ◽  
Velocity Measurements ◽  
Current Sheets ◽  
Spacecraft Orbit ◽  
Electric Field Measurements ◽  
Good Agreement

<p>Solar wind current sheets have been extensively studied at 1 AU. The recent advent of Parker Solar Probe and Solar Orbiter (SolO) has enabled us to study these structures at a range of heliocentric distances.</p><p>We present SolO observations of current sheets in the solar wind at heliocentric distances between 0.55 and 0.85 AU, some of which show signatures of ongoing magnetic reconnection. We develop a method to find the deHoffman-Teller frame which minimizes the Y-component (the component tangential to the spacecraft orbit) of the electric field. Using the electric field measurements from RPW and magnetic field measurements from MAG, we use our method to determine the deHoffman-Teller frame of solar wind current sheets. The same method can also be used on the Alfvénic turbulence and structures found in the solar wind to obtain a measure of the solar wind velocity.</p><p>Our preliminary results show a good agreement between our modified deHoffmann-Teller analysis based on the single component E-field, and the conventional deHoffman-Teller analysis based on 3D plasma velocity measurements from PAS. This opens up the possibility to use the RPW and MAG data to obtain an estimate of the solar wind velocity when particle data is unavailable.</p>

scholarly journals Climatology of the mesopause density using a global distribution of meteor radars

2018 ◽  
Author(s):  
Wen Yi ◽  
Xianghui Xue ◽  
Iain M. Reid ◽  
Damian J. Murphy ◽  
Chris M. Hall ◽  
...  
Keyword(s):  
Northern Hemisphere ◽  
High Latitudes ◽  
Meteor Radar ◽  
Low Latitude ◽  
Wave Forcing ◽  
Spring Equinox ◽  
Spatial Coverage ◽  
Low Latitudes ◽  
Variation Characteristics ◽  
Temporal And Spatial

Abstract. The existing distribution of meteor radars located from high- to low-latitude regions provides a favourable temporal and spatial coverage for investigating the climatology of the global mesopause density. In this study, we report the climatology of the mesopause density estimated using multiyear observations from nine meteor radars, namely, the Davis Station (68.6° S, 77.9° E), Svalbard (78.3° N, 16° E) and Tromsø (69.6° N, 19.2° E) meteor radars located at high latitudes, the Mohe (53.5° N, 122.3° E), Beijing (40.3° N, 116.2° E), Mengcheng (33.4° N, 116.6° E) and Wuhan (30.5° N, 114.6° E) meteor radars located in the mid-latitudes, and the Kunming (25.6° N, 103.8° E) and Darwin (12.3° S, 130.8° E) meteor radars located at low latitudes. The daily mean density was estimated using ambipolar diffusion coefficients derived from the meteor radars and temperatures from the Microwave Limb Sounder (MLS) on board the Aura satellite. The seasonal variations in the Davis Station meteor radar densities in the southern polar mesopause are mainly dominated by an annual oscillation (AO). The mesopause densities observed by the Svalbard and Tromsø meteor radars at high latitudes and the Mohe and Beijing meteor radars at high mid-latitudes in the Northern Hemisphere show mainly an AO and a relatively weak semiannual oscillation (SAO). The mesopause densities observed by the Mengcheng and Wuhan meteor radars at lower mid-latitudes and the Kunming and Darwin meteor radars at low latitudes show mainly an AO. The SAO is evident in the Northern Hemisphere, especially at high latitudes, and its largest amplitude, which is detected at the Tromsø meteor radar, is comparable to the AO amplitudes. These observations indicate that the mesopause densities over the southern and northern high latitudes exhibit a clear seasonal asymmetry. The maxima of the yearly variations in the mesopause densities display a clear temporal variation across the spring equinox as the latitude decreases; these latitudinal variation characteristics may be related to latitudinal changes influenced by gravity wave forcing. In addition to an AO, the mesopause densities over low latitudes also clearly show a variation with a periodicity of 30–60 days related to the Madden-Julian oscillation in the subtropical troposphere.

scholarly journals Four-dimensional mesospheric and lower thermospheric wind fields using Gaussian process regression on multistatic specular meteor radar observations

2021 ◽  
Author(s):  
Ryan Volz ◽  
Jorge L. Chau ◽  
Philip J. Erickson ◽  
Juha P. Vierinen ◽  
J. Miguel Urco ◽  
...  
Keyword(s):  
Gaussian Process ◽  
Wind Velocity ◽  
Wind Field ◽  
Gaussian Process Regression ◽  
Small Scale ◽  
Model Parameters ◽  
Meteor Radar ◽  
Wind Fields ◽  
Data Set ◽  
Uncertainty Estimates

Abstract. Mesoscale dynamics in the mesosphere and lower thermosphere (MLT) region have been difficult to study from either ground- or satellite-based observations. For understanding of atmospheric coupling processes, important spatial scales at these altitudes range between tens to hundreds of kilometers in the horizontal plane. To date, this scale size is challenging observationally, and so structures are usually parameterized in global circulation models. The advent of multistatic specular meteor radar networks allows exploration of MLT mesocale dynamics on these scales using an increased number of detections and a diversity of viewing angles inherent to multistatic networks. In this work, we introduce a four dimensional wind field inversion method that makes use of Gaussian process regression (GPR), a non-parametric and Bayesian approach. The method takes measured projected wind velocities and prior distributions of the wind velocity as a function of space and time, specified by the user or estimated from the data, and produces posterior distributions for the wind velocity. Computation of the predictive posterior distribution is performed on sampled points of interest and is not necessarily regularly sampled. The main benefits of the GPR method include this non-gridded sampling, the built-in statistical uncertainty estimates, and the ability to horizontally-resolve winds on relatively small scales. The performance of the GPR implementation has been evaluated on Monte Carlo simulations with known distributions using the same spatial and temporal sampling as one day of real meteor measurements. Based on the simulation results we find that the GPR implementation is robust, providing wind fields that are statistically unbiased and with statistical variances that depend on the geometry and are proportional to the prior velocity variances. A conservative and fast approach can be straightforwardly implemented by employing overestimated prior variances and distances, while a more robust but computationally intensive approach can be implemented by employing training and fitting of model parameters. The latter GPR approach has been applied to a 24-hour data set and shown to compare well to previously used homogeneous and gradient methods. Small scale features have reasonably low statistical uncertainties, implying geophysical wind field horizontal structures as low as 20–50 km. We suggest that this GPR approach forms a suitable method for MLT regional and weather studies.

Wind velocity measurements with acoustic daylight.

2010 ◽  
Vol 127 (3) ◽  
pp. 2037-2037
Author(s):  
Oleg A. Godin ◽  
Vladimir G. Irisov ◽  
Mikhail I. Charnotskii
Keyword(s):  
Wind Velocity ◽  
Velocity Measurements
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