Geomagnetic field variations due to Solar and Lunar tides in the Brazilian Sector

2020 ◽  
Author(s):  
Vera Yesutor Tsali-Brown ◽  
Paulo Roberto Fagundes ◽  
Ana Roberta Paulino ◽  
Valdir Gil Pillat ◽  
Maurício José Alves Bolzam
Keyword(s):  
Geomagnetic Field ◽  
Maximum Amplitude ◽  
Least Square ◽  
Lunar Tide ◽  
Lunar Tides ◽  
Least Square Fit ◽  
Solar Local Time ◽  
Solar Tide ◽  
Using Data ◽  
Minimum Amplitude

<p><strong>Abstract</strong></p><p>Geomagnetic field variations in 2018 due to solar and lunar tides in the Brazilian sector were studied using data provided by magnetometers installed at São José dos Campos (23.21<sup>o</sup>S, 0345.97<sup>o</sup>W; Dip latitude 20.9<sup>o</sup>S), Eusébio, Ceará (3.89° S, 38.46° W) and São Luís, Maranhão (2.53° S, 44.30° W). Variations associated with these tides were identified using the horizontal component of the geomagnetic field, H(nT). Least square fit method was employed in determining the monthly amplitudes and phases of the diurnal, semidiurnal and ter-diurnal solar tides. The monthly amplitudes and phases of the lunar tide were then calculated using the residual measurements (obtained after subtracting the solar tidal components from each day), converting the solar local time to lunar time and subjecting the residuals to harmonic analysis. The maximum solar tide amplitude recorded was 23.96nT(diurnal) in March, at Eusébio whereas the minimum amplitude was 0.45nT(terdiurnal) recorded in December at São José dos Campos. The lunar tide recorded a maximum amplitude of 4.33nT(semidiurnal) in February, at São Luís and a minimum amplitude of 0.13nT(diurnal) in August, at Eusébio.</p><p> </p><p> </p><p><strong>Keywords</strong>: Solar tides, Lunar tides, Geomagnetic field, Magnetometer.</p><p> </p>

scholarly journals On the variability of the semidiurnal solar and lunar tides of the equatorial electrojet during sudden stratospheric warmings

2018 ◽  
Author(s):  
Tarique A. Siddiqui ◽  
Astrid Maute ◽  
Nick Pedatella ◽  
Yosuke Yamazaki ◽  
Hermann Lühr ◽  
...  
Keyword(s):  
Zonal Wind ◽  
Equatorial Electrojet ◽  
Stratospheric Warming ◽  
Tidal Amplitude ◽  
Lunar Tide ◽  
Sudden Stratospheric Warming ◽  
Lunar Tides ◽  
Neutral Temperature ◽  
Tidal Changes ◽  
Solar Tide

Abstract. The variabilities of the semidiurnal solar and lunar tide of the equatorial electrojet (EEJ) are investigated during the 2003, 2006, 2009 and 2013 major sudden stratospheric warming (SSW) events in this study. For this purpose, the ground-magnetometer recordings at the equatorial observatories in Huancayo and Fuquene are utilized. Results show a major enhancement in the amplitude of the EEJ semidiurnal lunar tide in each of the four warming events. The EEJ semidiurnal solar tidal amplitude shows an amplification prior to the onset of warmings, a reduction during the deceleration of the zonal mean zonal wind at 60° N and 10 hPa and a second enhancement a few days after the peak reversal of the zonal mean zonal wind during all the four SSWs. Results also reveal that the amplitude of the EEJ semidiurnal lunar tide becomes comparable or even greater than the amplitude of the EEJ semidiurnal solar tide during all these warming events. The present study also compares the EEJ semidiurnal solar and lunar tidal changes with numerical simulations of the variability of the migrating semidiurnal solar (SW2) and lunar (M2) tide in neutral temperature at ~ 120 km altitude. A better agreement between the enhancements of the EEJ semidiurnal lunar tide and the M2 tide in neutral temperature is observed in comparison with the enhancements of the EEJ semidiurnal solar tide and the SW2 tide in neutral temperature.

scholarly journals On the variability of the semidiurnal solar and lunar tides of the equatorial electrojet during sudden stratospheric warmings

2018 ◽  
Vol 36 (6) ◽  
pp. 1545-1562 ◽  
Author(s):  
Tarique A. Siddiqui ◽  
Astrid Maute ◽  
Nick Pedatella ◽  
Yosuke Yamazaki ◽  
Hermann Lühr ◽  
...  
Keyword(s):  
Zonal Wind ◽  
Equatorial Electrojet ◽  
Tidal Amplitude ◽  
Lunar Tide ◽  
Sudden Stratospheric Warming ◽  
Lunar Tides ◽  
Neutral Temperature ◽  
Tidal Changes ◽  
Solar Tide ◽  
E Region

Abstract. The variabilities of the semidiurnal solar and lunar tides of the equatorial electrojet (EEJ) are investigated during the 2003, 2006, 2009 and 2013 major sudden stratospheric warming (SSW) events in this study. For this purpose, ground-magnetometer recordings at the equatorial observatories in Huancayo and Fúquene are utilized. Results show a major enhancement in the amplitude of the EEJ semidiurnal lunar tide in each of the four warming events. The EEJ semidiurnal solar tidal amplitude shows an amplification prior to the onset of warmings, a reduction during the deceleration of the zonal mean zonal wind at 60∘ N and 10 hPa, and a second enhancement a few days after the peak reversal of the zonal mean zonal wind during all four SSWs. Results also reveal that the amplitude of the EEJ semidiurnal lunar tide becomes comparable or even greater than the amplitude of the EEJ semidiurnal solar tide during all these warming events. The present study also compares the EEJ semidiurnal solar and lunar tidal changes with the variability of the migrating semidiurnal solar (SW2) and lunar (M2) tides in neutral temperature and zonal wind obtained from numerical simulations at E-region heights. A better agreement between the enhancements of the EEJ semidiurnal lunar tide and the M2 tide is found in comparison with the enhancements of the EEJ semidiurnal solar tide and the SW2 tide in both the neutral temperature and zonal wind at the E-region altitudes.

Least-square refinement of structure parameters from CBED integrated intensities: application to determination of temperature factors in Y BA2CU3O7

1992 ◽  
Vol 50 (2) ◽  
pp. 1456-1457
Author(s):  
Kjersti Gjønnes ◽  
Jon Gjønnes
Keyword(s):  
Least Square ◽  
Measured Intensity ◽  
Structure Information ◽  
Accurate Temperature ◽  
Least Square Fit ◽  
Case Application ◽  
Integrated Intensities ◽  
Temperature Factors ◽  
Narrow Bands

Electron diffraction intensities can be obtained at large scattering angles (sinθ/λ ≥ 2.0), and thus structure information can be collected in regions of reciprocal space that are not accessable with other diffraction methods. LACBED intensities in this range can be utilized for determination of accurate temperature factors or for refinement of coordinates. Such high index reflections can usually be treated kinematically or as a pertubed two-beam case. Application to Y Ba2Cu3O7 shows that a least square refinememt based on integrated intensities can determine temperature factors or coordinates.LACBED patterns taken in the (00l) systematic row show an easily recognisable pattern of narrow bands from reflections in the range 15 < l < 40 (figure 1). Integrated intensities obtained from measured intensity profiles after subtraction of inelastic background (figure 2) were used in the least square fit for determination of temperature factors and refinement of z-coordinates for the Ba- and Cu-atoms.

Do the calendar anomalies still exist? Evidence from Indian currency market

2016 ◽  
Vol 42 (2) ◽  
pp. 136-150 ◽  
Author(s):  
Satish Kumar ◽  
Rajesh Pathak
Keyword(s):  
Least Square ◽  
January Effect ◽  
Currency Markets ◽  
Content Type ◽  
Currency Market ◽  
Before And After ◽  
Calendar Anomalies ◽  
Ordinary Least Square Regression ◽  
The 2008 Financial Crisis ◽  
Using Data

Purpose – The purpose of this paper is to examine the presence of the day-of-the-week (DOW) and January effect in the Indian currency market for selected currency pairs; USD-(Indian rupee) INR, EUR-INR, GBP-INR and JPY-INR, from January, 1999 to December, 2014. Design/methodology/approach – Ordinary least square regression analysis is used to examine the presence of DOW and January effect to test the efficiency of the Indian currency market. The sample period is later divided into two sub-periods, that is, pre- and post-2008 to capture the behavior of returns before and after the 2008 financial crisis. Further, the authors also use the non-parametric technique, the Kruskal-Wallis test, to provide robustness check for the results. Findings – The results indicate that the returns during Monday to Wednesday are positive and higher than the returns on Thursday and Friday which show negative returns. The returns during January are found to be higher than the returns during rest of the year. Further, all currencies exhibit significant DOW and January effects in pre-crisis period, however, post-crisis; these effects disappear for all currencies indicating that the markets have become more efficient in the later time. The findings can be further attributed to the increased intervention in the forex markets by the Reserve Bank of India after the crisis. Practical implications – The results have important implications for both traders and investors. The findings suggest that the investors might not be able to earn excess profits by timing their positions in some particular currencies taking the advantage of DOW or January effect which in turn indicates that the currency markets have become more efficient with time. The results are in conformity with those reported for the developed markets. The results might be appealing to the practitioners as well in a way that they can consider the state of financial market for financial decision making. Originality/value – The authors provide the first study to examine the calendar anomalies (DOW and January effect) across a range of emerging currencies using 16 years of data from January, 1999 to December, 2014. To the best of the authors’ knowledge, no study has yet examined these calendar anomalies in the currency markets using data which covers two important periods, pre-2008 and post-2008.

Array design

1968 ◽  
Vol 58 (3) ◽  
pp. 977-991
Author(s):  
Richard A. Haubrich
Keyword(s):  
High Resolution ◽  
Data Processing ◽  
Least Square ◽  
Wave Number ◽  
Array Design ◽  
Least Square Fit ◽  
The Difference ◽  
Set Of Points ◽  
Array Output

abstract Arrays of detectors placed at discrete points are often used in problems requiring high resolution in wave number for a limited number of detectors. The resolution performance of an array depends on the positions of detectors as well as the data processing of the array output. The performance can be expressed in terms of the “spectrum window”. Spectrum windows may be designed by a general least-square fit procedure. An alternate approach is to design the array to obtain the largest uniformly spaced coarray, the set of points which includes all the difference spacings of the array. Some designs obtained from the two methods are given and compared.

THE INVESTIGATION OF THE PG PULSATIONS WITH USING DATA OF ARASE, GOES SATELLITES AND GROUND-BASED STATIONS

2021 ◽  
Vol 44 ◽  
pp. 63-66
Author(s):  
V.B. Belakhovsky ◽  
◽  
V.A. Pilipenko ◽  
K. Shiokawa ◽  
Y. Miyoshi ◽  
...  
Keyword(s):  
Geomagnetic Field ◽  
Conjugate Point ◽  
Physical Nature ◽  
Recovery Phase ◽  
Radial Component ◽  
Field Lines ◽  
Using Data ◽  
Giant Pulsations ◽  
Favorable Conditions ◽  
Phase Relationships

The physical nature of Pg (pulsation giant) pulsations, which were observed in the magnetosphere by the Japanese satellite Arase, geostationary satellites GOES, and ground stations of the THEMIS and CARISMA networks, was investigated in this work. Pg pulsations belong to the Pc4 frequency range and are characterized by a very monochromatic shape. For the event on 5 June, 2018, according to the data from the Arase satellite, the Pg pulsation wave packet was recorded in the dawn sector during 3 hours. The pulsations are most pronounced in the radial component of the geomagnetic field, their frequency was about 11 mHz. Pg pulsations observed in the magnetosphere were accompanied by pulsations with the same period according to data from a number of ground-based magnetic stations located near the conjugate point. According to the data of ground stations, the pulsations were most strongly expressed in the Y-component of the geomagnetic field. Pg pulsations were accompanied by pulsations in electron and proton fluxes according to the Arase, GOES satellite observations. There are no clear phase relationships between geomagnetic pulsations and pulsations in charge particle fluxes. Pg pulsations were excited under quiet geomagnetic conditions (SYM-H = -10 nT, AE = 100-400 nT) on the recovery phase of the small geomagnetic storm. It is assumed that the expansion of the plasmasphere at low geomagnetic activity leads to an increase in the plasma density in the region of the geostationary orbit, which creates favorable conditions for the excitation of Pg pulsations due to the drift-bounce resonance of protons with the geomagnetic field lines oscillations in the magnetosphere.

scholarly journals Multiscale variation model and activity level estimation algorithm of the Earth's magnetic field based on wavelet packets

2018 ◽  
Vol 36 (5) ◽  
pp. 1207-1225 ◽  
Author(s):  
Oksana V. Mandrikova ◽  
Igor S. Solovyev ◽  
Sergey Y. Khomutov ◽  
Vladimir V. Geppener ◽  
Dmitry M. Klionskiy ◽  
...  
Keyword(s):  
Geomagnetic Field ◽  
Numerical Algorithms ◽  
Estimation Algorithm ◽  
Solar Wind Plasma ◽  
Activity Level ◽  
High Temporal Resolution ◽  
Suggested Approach ◽  
Characteristic Variation ◽  
Using Data ◽  
Multiscale Mathematical Model

Abstract. We suggest a wavelet-based multiscale mathematical model of geomagnetic field variations. The model is particularly capable of reflecting the characteristic variation and local perturbations in the geomagnetic field during the periods of increased geomagnetic activity. Based on the model, we have designed numerical algorithms to identify the characteristic variation component as well as other components that represent different geomagnetic field activity. The substantial advantage of the designed algorithms is their fully automatic performance without any manual control. The algorithms are also suited for estimating and monitoring the activity level of the geomagnetic field at different magnetic observatories without any specific adjustment to their particular locations. The suggested approach has high temporal resolution reaching 1 min. This allows us to study the dynamics and spatiotemporal distribution of geomagnetic perturbations using data from ground-based observatories. Moreover, the suggested approach is particularly capable of discovering weak perturbations in the geomagnetic field, likely linked to the nonstationary impact of the solar wind plasma on the magnetosphere. The algorithms have been validated using the experimental data collected at the IKIR FEB RAS observatory network. Keywords. Magnetospheric physics (storms and substorms)

scholarly journals Topside equatorial zonal ion velocities measured by C/NOFS during rising solar activity

2014 ◽  
Vol 32 (2) ◽  
pp. 69-75 ◽  
Author(s):  
W. R. Coley ◽  
R. A. Stoneback ◽  
R. A. Heelis ◽  
M. R. Hairston
Keyword(s):  
Solar Activity ◽  
Local Time ◽  
Geomagnetic Field ◽  
General Pattern ◽  
Magnetic Latitude ◽  
Ion Drifts ◽  
F Region ◽  
Westerly Flow ◽  
Solar Local Time ◽  
Ion Velocity

Abstract. The Ion Velocity Meter (IVM), a part of the Coupled Ion Neutral Dynamic Investigation (CINDI) instrument package on the Communication/Navigation Outage Forecast System (C/NOFS) spacecraft, has made over 5 yr of in situ measurements of plasma temperatures, composition, densities, and velocities in the 400–850 km altitude range of the equatorial ionosphere. These measured ion velocities are then transformed into a coordinate system with components parallel and perpendicular to the geomagnetic field allowing us to examine the zonal (horizontal and perpendicular to the geomagnetic field) component of plasma motion over the 2009–2012 interval. The general pattern of local time variation of the equatorial zonal ion velocity is well established as westward during the day and eastward during the night, with the larger nighttime velocities leading to a net ionospheric superrotation. Since the C/NOFS launch in April 2008, F10.7 cm radio fluxes have gradually increased from around 70 sfu to levels in the 130–150 sfu range. The comprehensive coverage of C/NOFS over the low-latitude ionosphere allows us to examine variations of the topside zonal ion velocity over a wide level of solar activity as well as the dependence of the zonal velocity on apex altitude (magnetic latitude), longitude, and solar local time. It was found that the zonal ion drifts show longitude dependence with the largest net eastward values in the American sector. The pre-midnight zonal drifts show definite solar activity (F10.7) dependence. The daytime drifts have a lower dependence on F10.7. The apex altitude (magnetic latitude) variations indicate a more westerly flow at higher altitudes. There is often a net topside subrotation at low F10.7 levels, perhaps indicative of a suppressed F region dynamo due to low field line-integrated conductivity and a low F region altitude at solar minimum.

scholarly journals Semi-Analytic Evaluation of 1, 2 and 3-Electron Coulomb Integrals with Gaussian Expansion of Distance Operators W= RC1-nRD1-M, RC1-Nr12-M, R12-Nr13-M

2019 ◽  
Author(s):  
Sandor Kristyan
Keyword(s):  
Gaussian Function ◽  
Approximate Solutions ◽  
Equation System ◽  
Least Square ◽  
Position Vector ◽  
Least Square Fit ◽  
Analytic Expressions ◽  
The One ◽  
Analytical Expressions ◽  
Coulomb Integrals

The equations derived help to evaluate semi-analytically (mostly for k=1,2 or 3) the important Coulomb integrals Int rho(r1)…rho(rk) W(r1,…,rk) dr1…drk, where the one-electron density, rho(r1), is a linear combination (LC) of Gaussian functions of position vector variable r1. It is capable to describe the electron clouds in molecules, solids or any media/ensemble of materials, weight W is the distance operator indicated in the title. R stands for nucleus-electron and r for electron-electron distances. The n=m=0 case is trivial, the (n,m)=(1,0) and (0,1) cases, for which analytical expressions are well known, are widely used in the practice of computation chemistry (CC) or physics, and analytical expressions are also known for the cases n,m=0,1,2. The rest of the cases – mainly with any real (integer, non-integer, positive or negative) n and m - needs evaluation. We base this on the Gaussian expansion of |r|^-u, of which only the u=1 is the physical Coulomb potential, but the u≠1 cases are useful for (certain series based) correction for (the different) approximate solutions of Schrödinger equation, for example, in its wave-function corrections or correlation calculations. Solving the related linear equation system (LES), the expansion |r|^-u about equal SUM(k=0toL)SUM(i=1toM) Cik r^2k exp(-Aik r^2) is analyzed for |r| = r12 or RC1 with least square fit (LSF) and modified Taylor expansion. These evaluated analytic expressions for Coulomb integrals (up to Gaussian function integrand and the Gaussian expansion of |r|^-u) are useful for the manipulation with higher moments of inter-electronic distances via W, even for approximating Hamiltonian.

scholarly journals The Parameter Estimation of Double Exponential Pulse Based on a Least Infinity Norm Fitting Method

2021 ◽  
Vol 2083 (4) ◽  
pp. 042002
Author(s):  
Yuewu Shi ◽  
Wei Wang ◽  
Zhizhen Zhu ◽  
Xin Nie
Keyword(s):  
Estimation Error ◽  
Estimation Method ◽  
Maximum Amplitude ◽  
Least Square Method ◽  
Least Square ◽  
Physical Parameters ◽  
Infinity Norm ◽  
Fitting Method ◽  
Double Exponential ◽  
Exponential Pulse

Abstract This paper presents an estimation method of double exponential pulse (DEP) between the physical parameters rise time (t r), full width at half maximum amplitude (t FWHM) and the mathematical parameters α, β. A newly fitting method based on the least infinity norm criterion is proposed to deal with the estimation problem of DEP. The calculation process and equation of parameters of this method is proposed based on an m-th-order polynomial fitting model. This estimation method is compared with the least square method by the same data and fitting function. The results show that the maximum estimation error of parameters of double exponential pulse obtained by the least infinity norm method is 1.5 %.

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