Evidence for short spatial correlation lengths of the noontime equatorial electrojet inferred from a comparison of satellite and ground magnetic data

Solar quiet current (S_q) and Equatorial Electrojet (EEJ) are two current systems which are produced by electric current in the ionosphere. The enhancement of the horizontal magnetic field is the EEJ. This research is needed for monitoring equatorial geomagnetic current which causes atmospheric instabilities and affects high frequency and satellite communication. This study presents the longitudinal and latitudinal variation of equatorial electrojet signature at stations within the 96°mm and 210°mm African and Asian sectors respectively during quiet condition. Data from eleven observatories were used for this study. The objectives was to determine the longitudinal and latitudinal geomagnetic field variations during solar quiet conditions, Investigate monthly variation and diurnal transient seasonal variation; Measure the strength of the EEJ at stations within the same longitudinal sectors and find out the factors responsible for the longitudinal and latitudinal variation of EEJ. Horizontal (H) component of geomagnetic field for the year 2008 from Magnetic Data Acquisition System (MAGDAS) network were used for the study. The International Quiet Days (IQDs) were used to identify quiet days. Daily baseline values for each of the geomagnetic element H were obtained. The monthly average of the diurnal variation was found. The seasonal variation of dH was found. Results showed that: The longitudinal and latitudinal variation in the dH differs in magnitude from one station to another within the same longitude due to the difference in the influence of the EEJ on them.

Download Full-text

Performance of Two Different Flight Configurations for Drone-Borne Magnetic Data

Sensors ◽

10.3390/s21175736 ◽

2021 ◽

Vol 21 (17) ◽

pp. 5736

Author(s):

Filippo Accomando ◽

Andrea Vitale ◽

Antonello Bonfante ◽

Maurizio Buonanno ◽

Giovanni Florio

Keyword(s):

Electromagnetic Interference ◽

Source Parameters ◽

Spectral Characteristics ◽

Magnetic Data ◽

Prototype System ◽

Control Dataset ◽

Periodic Data ◽

Ground Magnetic ◽

The Stability ◽

Careful Processing

The compensation of magnetic and electromagnetic interference generated by drones is one of the main problems related to drone-borne magnetometry. The simplest solution is to suspend the magnetometer at a certain distance from the drone. However, this choice may compromise the flight stability or introduce periodic data variations generated by the oscillations of the magnetometer. We studied this problem by conducting two drone-borne magnetic surveys using a prototype system based on a cesium-vapor magnetometer with a 1000 Hz sampling frequency. First, the magnetometer was fixed to the drone landing-sled (at 0.5 m from the rotors), and then it was suspended 3 m below the drone. These two configurations illustrate endmembers of the possible solutions, favoring the stability of the system during flight or the minimization of the mobile platform noise. Drone-generated noise was filtered according to a CWT analysis, and both the spectral characteristics and the modelled source parameters resulted analogously to that of a ground magnetic dataset in the same area, which were here taken as a control dataset. This study demonstrates that careful processing can return high quality drone-borne data using both flight configurations. The optimal flight solution can be chosen depending on the survey target and flight conditions.

Download Full-text

A model for estimating the relation between the Hall to Pedersen conductance ratio and ground magnetic data derived from CHAMP satellite statistics

Annales Geophysicae ◽

10.5194/angeo-25-721-2007 ◽

2007 ◽

Vol 25 (3) ◽

pp. 721-736 ◽

Cited By ~ 17

Author(s):

L. Juusola ◽

O. Amm ◽

K. Kauristie ◽

A. Viljanen

Keyword(s):

Current Density ◽

Geomagnetic Latitude ◽

Magnetic Data ◽

Equivalent Current ◽

Champ Satellite ◽

Long Time ◽

Conductance Ratio ◽

Ground Magnetic ◽

Eiscat Radar ◽

Magnetic Satellite

Abstract. The goal of this study is to find a way to statistically estimate the Hall to Pedersen conductance ratio α from ground magnetic data. We use vector magnetic data from the CHAMP satellite to derive this relation. α is attained from magnetic satellite data using the 1-D Spherical Elementary Current Systems (SECS). The ionospheric equivalent current density can either be computed from ground or satellite magnetic data. Under the required 1-D assumption, these two approaches are shown to be equal, which leads to the advantage that the statistics are not restricted to areas covered by ground data. Unlike other methods, using magnetic satellite measurements to determine α ensures reliable data over long time sequences. The statistical study, comprising over 6000 passes between 55° and 76.5° northern geomagnetic latitude during 2001 and 2002, is carried out employing data from the CHAMP satellite. The data are binned according to activity and season. In agreement with earlier studies, values between 1 and 3 are typically found for α. Good compatibility is found, when α attained from CHAMP data is compared with EISCAT radar measurements. The results make it possible to estimate α from the east-west equivalent current density Jφ; [A/km]: α=2.07/(36.54/|Jφ|+1) for Jφ<0 (westward) and α=1.73/(14.79/|Jφ+1) for Jφ0 (eastward). Using the same data, statistics of ionospheric and field-aligned current densities as a function of geomagnetic latitude and MLT are included. These are binned with respect to activity, season and IMF BZ and BY. For the first time, all three current density components are simultaneously studied this way on a comparable spatial scale. With increasing activity, the enhancement and the equatorward expansion of the electrojets and the R1 and R2 currents is observed, and in the nightside, possible indications of a Cowling channel appear. During southward IMF BZ, the electrojets and the R1 and R2 currents are stronger and clearer than during northward BZ. IMF BY affects the orientation of the pattern.

Download Full-text

Determination of vortex current structure in the high-latitude ionosphere with associated GIC bursts from ground magnetic data

Journal of Atmospheric and Solar-Terrestrial Physics ◽

10.1016/j.jastp.2020.105514 ◽

2021 ◽

Vol 212 ◽

pp. 105514

Author(s):

V.E. Chinkin ◽

A.A. Soloviev ◽

V.A. Pilipenko ◽

M.J. Engebretson ◽

YaA. Sakharov

Keyword(s):

High Latitude ◽

Magnetic Data ◽

Current Structure ◽

High Latitude Ionosphere ◽

Ground Magnetic

Download Full-text

Reconstruction of the magnetic connection from Mercury to the solar corona

10.5194/egusphere-egu2020-7086 ◽

2020 ◽

Author(s):

Alessandro Ippolito ◽

Christina Plainaki ◽

Gaetano Zimbardo ◽

Stefano Massetti ◽

Anna Milillo

Keyword(s):

Magnetic Field ◽

Solar Corona ◽

Magnetic Data ◽

Monte Carlo Code ◽

Correlation Lengths ◽

Magnetic Fluctuation ◽

Magnetic Field Model ◽

Field Lines ◽

Field Correlation ◽

Accelerated Particles

<p>The magnetic foot point of Mercury on the solar disk has been reconstructed for selected case studies, in order to better understand the interaction between the solar corona and the planet. The transport of the magnetic field lines in the heliosphere is here evaluated with a Monte Carlo code that gives a random displacement at each step of the integration along the Parker magnetic field model. Such displacement is proportional to a &#8220;local&#8221; diffusion coefficient, which is a function of the fluctuation level and magnetic field correlation lengths. The simulation is tailored to specific events by using the observed values of solar wind velocity and magnetic fluctuation levels. Magnetic data from MAG/MESSENGER have been considered to compute the magnetic fluctuation level, while, concerning proton fluxes, FIPS/MESSENGER data has been taken into account. A number of SEP events observed on Mercury during 2011 and 2012 have been analysed, studying, for each event, the magnetic connection from Mercury to the solar corona, and the position of the active region possibly source of the accelerated particles observed.</p>

Download Full-text

Spatial correlation length of normalized cone data in sand: case study in the north of Denmark

Canadian Geotechnical Journal ◽

10.1139/cgj-2013-0294 ◽

2014 ◽

Vol 51 (8) ◽

pp. 844-857 ◽

Cited By ~ 25

Author(s):

S. Firouzianbandpey ◽

D.V. Griffiths ◽

L.B. Ibsen ◽

L.V. Andersen

Keyword(s):

Spatial Correlation ◽

Correlation Length ◽

Vertical Direction ◽

Cone Penetration ◽

Correlation Lengths ◽

Cone Penetration Testing ◽

The North ◽

Site Investigations ◽

Depositional Process ◽

Spatial Correlation Length

The main topic of this study is to assess the anisotropic spatial correlation lengths of a sand layer deposit based on cone penetration testing with pore pressure measurement (CPTu) data. Spatial correlation length can be an important factor in reliability analysis of geotechnical systems, yet it is rarely estimated during routine site investigations. Results from two different sites in the north of Denmark are reported in this paper, indicating quite strong anisotropy due to the depositional process, with significantly shorter spatial correlation lengths in the vertical direction. It is observed that the normalized cone resistance is a better estimator of spatial trends than the normalized friction ratio.

Download Full-text