Horizontal Component Of Geomagnetic Field Research Articles

Variation of Total Electron Content over Nepal during Geomagnetic Storms: GPS Observations

Geomagnetic storms have very profound effects on the Total Electron Content (TEC) of the ionosphere. In order to investigate the equatorial and low-latitude ionospheric response to the geomagnetic storms of varying intensities, a detailed study of vertical TEC (VTEC) variations resulting from Global Positioning System (GPS) data acquired at four GPS stations in Nepal along 80°–90° E longitude and 26°–30° N latitude sector has been carried out in the present work. The results were analyzed with other favorable inducing factors (solar wind parameters and geomagnetic indices) affecting TEC to constrain the causative factor. Positive phases are observed for all the storms studied. During the severe geomagnetic activity, the deviation was ~18 TECU, while it was recorded ~12 TECU and ~8 TECU during moderate and minor geomagnetic activity, respectively. The Detrended Cross-Correlation Analysis (DXA) illustrates that the value of the hourly average VTEC of the BESI station was found to have a strong positive correlation with other stations in all types of storm events, indicating a similar response of all stations towards the space weather events. In addition, the correlation of VTEC with solar wind parameters and geomagnetic indices illustrated that the VTEC shows a strong positive association with solar wind velocity (Vsw) in all three geomagnetic events. In contrast, the correlation of plasma density (Nsw), interplanetary magnetic field (IMF-Bz), the symmetric horizontal component of geomagnetic field (SYM-H), and Geomagnetic Auroral Electrojet (AE) index with VTEC vary with the intensity of the storm. Overall results of the study have revealed the characteristic features of TEC variation over Nepal regions during magnetic storms, which validates earlier research on ionospheric responses to geomagnetic storms and theoretical assumptions.

Disturbances in the geomagnetic field, water level and atmospheric pressure associated with Mw ≥ 6.6 earthquakes in the South Atlantic Ocean

This paper is aimed at studying disturbances in the earth’s geomagnetic field (GMF), water level (WL) and sea-level atmospheric pressure (AP) associated with Mw≥ 6.6 seismic events in the in the Scotia arch, in the South Atlantic. GMF records from observatories of the International Magnetic Observatory Network (INTERMAGNET), WL records from tide stations of the Intergovernmental Oceanographic Commission, and hourly AP records from databases of the Global Modeling and Assimilation Office of the National Aeronautics and Space Administration have been analyzed in the area under study. For the analysis of geomagnetic disturbances, the GMF horizontal component (H), which is more susceptible to variations, was considered. For the WL analysis, the discrepancy (residue) between the WL time series from tide stations and the predicted level of astronomical tides, for a 10-day period before and after the occurrence of each earthquake, was calculated. For the AP analysis, the variation of data gridded between 1 and 2 hours before and after the earthquake was calculated. The analysis of the geomagnetic data prior to the seismic event, using a high-pass filter and the wavelet method, showed: a) high energy ranges in all frequencies, even in very high ones; and b) oscillations in the filter with amplitude peaks of ± 0.2 nT, and with an anticipation and duration consistent with the wavelet method. As regards the WL residues calculated, there were oscillations in the largest amplitudes in the sensors located closest to the earthquake, thus, those large amplitudes corresponded to shorter times of arrival. The AP study showed a maximum followed by a local minimum within a range of ± 0.3 hPa around the location of the earthquake. While the GMF analysis anticipated seismic events within a range of 6-2 hours, the techniques used for WL and AP could detect Mw>7 earthquakes, associating them with the rising/falling surface of the sea. These three techniques can be used jointly to implement a prevention or early warning system for seismic events in the region under study.

Ionospheric irregularities observed during the geomagnetic storm of March 2015 and June 2015 over Ethiopia

In this paper we studied the occurrence of ionospheric irregularities over Ethiopia as the consequence of the intense geomagnetic storm of March 2015 and June 2015. Total Electron Content (TEC) data obtained from six Ethiopian GPS reciever stations and those data were used to derive the ionospheric irregularities proxy indices, e.g.,rate of change of TEC (ROT) and ROT index (ROTI). These indices were used to characterize the intensity of the fluctuation of total electron content. ROTI was used as a criterion of ionospheric irregularities that took place during the storm. These indices were characterized along side with the disturbance storm time (Dst),the Interplanetary Electric Field (IEFy) and the SYM-H index (high resolution version of Dst) from ground-based magnetometers to see the effect of geomagnetic storm on horizontal component of geomagnetic field. Irregularities manifested in the form of fluctuations in TEC. Prompt penetration of electric field (PPEF) modulated the behaviour of irregularities during the initial and recovery phases of the geomagnetic storms. As a result,it was observed that the irregularities in the ionosphere of Ethiopia was in the range from weak to moderate. These irregularities generally occurred during the initial and recovery phases of the storm at all selected stations. The effect of electric field is found to depend on the local time at which the IMF Bz turned into southward. Therefore,east - west fluctuating Ey in March storm main phase is associated with suppression of irregularities in all stations and eastward Ey in the main phase of June 2015 is associated with small scale irregularity formation. The generation (inhibition) of irregularities is related to the effect of eastward (westward) storm time electric field disturbance dynamo electric fields and prompt penetration electric fields that created favourable (unfavourable) conditions for the generation of irregularities by uplifting (lowering) the F region.

Assessment of Geomagnetically Induced Currents in Low Latitude Regions with respect to Severe Geomagnetic Storm over Solar Cycle 24

Space Weather Perturbation – driven Geomagnetically Induced Currents (GIC) can cause the adverse impact to series of ground technological instruments. Power networks are the most affected technological facilities that experience malfunctions due to GIC phenomenon. High latitude regions experience more power network operation flaws due to this natural threat compared to mid latitude and low latitude regions. However different event of solar activities exhibit different space weather perturbations impacts regionally. Therefore, in this study, a thorough analysis of GIC activities during 6 severe geomagnetic storms in low latitude regions over solar cycle 24 based on Time Derivative of Horizontal Component of Geomagnetic Field (dH/dt) analysis are conducted. The results revealed that there is non-uniform latitudinal distribution of averaged dH/dt value in low latitude region and high GIC occurrences are observed during dayside. The correlation analysis between Solar Wind Parameters and GIC activities depicted that solar wind dynamic pressure (Psw) and Solar wind input energy (ε) act as Solar wind driver for the occurrences of GIC in low latitude region.

Estimating the daytime vertical E × B drift velocities in the F-region of the equatorial ionosphere using the IEEY and AMBER magnetic data in West Africa

In this paper the daytime vertical E→×B→ drift velocity in the F-region of the equatorial ionosphere was estimated from the magnetic effect of the equatorial electrojet (EEJ) in West African sector for September equinoxes in 1993 during solar cycle 22 and in 2013 during solar cycle 24. Geomagnetic data recorded during the International Equatorial Electrojet Year (IEEY) from 1993 to 1994 and the ongoing AMBER (African Meridian B-field Education and Research) program since 2008 were used. The vertical drift velocity was inferred from the EEJ contribution (ΔH) in the geomagnetic field horizontal component. The IEEY data were used to examine the seasonal variations of the daytime vertical drift velocity. The noontime seasonal averages are Vd=10.95m/s and Vd=9.46m/s respectively for March and September equinoxes, and Vd=8.75m/s and Vd=8.27m/s for December and June solstices. The daytime vertical drift velocity was found to be larger in equinoxes than in solstices. The dependence of the daytime vertical drift velocity on solar cycle was also shown by comparing the results of September equinox in 1993 and 2013. The drift velocity of 9.5 m/s in 1993 is significantly weaker than that of 24.5 m/s in 2013. This strong difference in Vd reflects the level of solar cycle between 1993 when the mean F10.7 = 109.86 sfu and 2013 when the mean F10.7 = 122.55 sfu.

Low-frequency oscillations while magnetic storms as a tool to determine the types of solar plasma flows

Comparison of wavelet spectrum (skeletons) local maxima for disturbed components of solar plasma flow parameters and geomagnetic field disturbances recorded along the meridional station chain during geomagnetic storm intervals is performed in the range of magnetohydrodynamic (MHD) waves. An algorithm for quantitative evaluation of analyzed skeletons consistency has been developed. It has been used to demonstrate the possibility of the type of solar wind plasma flow elaboration on unique spectral signs of Solar wind speed disturbances, density and interplanetary magnetic field. It is shown that the energy spectrum of oscillations for these parameters reflects the internal structure of the corresponding plasma formation. The skeletons application to the analysis of the interplanetary space main parameters made it possible to estimate the magnetosphere reaction time in geomagnetic field horizontal component oscillations at different latitudes on the disturbance. As a result, the distributed magnetosphere reaction over latitude was determined in the form of geomagnetic field oscillations on the disturbed solar flow parameters. It is shown that the dynamics of the components of the solar wind parameters disturbance spectra corresponding to plasma flows manifest themselves in the MHD spectra of high-latitude stations magnetograms and can be used as a diagnostic tool.

Variation of Solar Wind Parameters Along With the Understanding of Energy Dynamics Within the Magnetospheric System During Geomagnetic Disturbances

AbstractInterplanetary solar wind parameters (velocity of solar wind particle [Vp], proton density [Nsw], and component of solar magnetic field [IMF‐Bz]) and geomagnetic indices (symmetric horizontal component of geomagnetic field [SYM‐H], auroral electrojet [AE]) divulge great deal of information about geomagnetic disturbances. To better understand the influence of solar wind invasion into the energy dynamics of magnetosphere system, we have chosen five geomagnetic disturbance events of completely different nature as the quietest days, intense storm, High Intensity Long Duration Continuous Auroral Activity, Substorm, and Supersubstorm. The statistical analysis of these five events clearly supports the case that most of the time IMF‐Bz plays major role to create magnetic reconnection leading to the geomagnetic disturbances. Our study shows that Joule heating covers the largest fraction of energy dissipation, averaging 53.6% of total deposited energy for all events. Even though, in case of Supersubstorm, the major contribution due to the ring current (47%) surpasses Joule heating (43%). The cross‐correlation analysis applied for the IMF‐Bz with SYM‐H, solar wind energy and magnetospheric sinks explain and quantify the relation between them. The positive correlation of IMF‐Bz with SYM‐H value in each event delineates that southward orientation of IMF‐Bz is responsible for the depression of SYM‐H. However, an interesting result that IMF‐Bz correlated negatively with SYM‐H value for the quiet event suggests the southward orientation of IMF‐Bz does not necessarily have to be the cause of disturbance always. In few occasion, Solar Quiet (Sq) and Lunar (L) current is found to be taking over the role of IMF‐Bz to create disturbance.

The first solar-powered Magdas-9 installation and possible geomagnetically induced currents study at Johor, Malaysia

The Magnetic Data Acquisition System (MAGDAS-9) was successfully installed at Universiti Teknologi MARA Johor, Pasir Gudang Campus, Malaysia (JOH station), under the joint collaboration between International Center for Space Weather Science and Education (ICSWSE), National Space Agency (ANGKASA) and UiTM Johor. This is the first solar-powered magnetometer under the Magnetic Data Acquisition System of Circum-pan Pacific Magnetometer Network (MAGDAS/CPMN). In this paper, construction process, installation process and analysis of first geomagnetic observations at MAGDAS JOH station are presented. In addition, analysis on time derivative of horizontal component of geomagnetic field (dH/dt) to indicate the possibility of Geomagnetically Induced Currents (GIC) occurrences is also presented in this paper. The obtained geomagnetic components: H, D, Z and Total F are approximately similar to World Magnetic Model 2015 (WMM2015) while the diurnal variation from this geomagnetic observation showing a good variation pattern. The analysis of dH/dt has indicated 2 significant events of GIC.

Classification of Solar Plasma Flows by Analyzing Out- and Intra-Magnetospheric Magnetohydrodynamic Oscillations During Magnetic Storms

Comparison of wavelet spectrum (skeletons) local maxima for disturbed components of solar plasma flow parameters and geomagnetic field disturbances recorded along the meridional station chain during geomagnetic storm intervals is performed in the range of magnetohydrodynamic (MHD) waves. An algorithm for quantitative evaluation of analyzed skeletons consistency has been developed. It has been used to demonstrate the possibility of the type of solar wind plasma flow elaboration on unique spectral signs of Solar wind speed disturbances, density and interplanetary magnetic field. It is shown that the energy spectrum of oscillations for these parameters reflects the internal structure of the corresponding plasma formation. The skeletons application to the analysis of the interplanetary space main parameters made it possible to estimate the magnetosphere reaction time in geomagnetic field horizontal component oscillations at different latitudes on the disturbance. As a result, the distributed magnetosphere reaction over latitude was determined in the form of geomagnetic field oscillations on the disturbed solar flow parameters. It is shown that the dynamics of the components of the solar wind parameters disturbance spectra corresponding to plasma flows manifest themselves in the MHD spectra of high-latitude stations magnetograms and can be used as a diagnostic tool.

Spectral characteristic of geomagnetically induced current during geomagnetic storms by wavelet techniques

An EMF (electromagnetic field) is induced over an incremental area when magnetized plasma from sun interacts with the Earth's magnetic field. This phenomenon delivers a Geomagnetically Induced Current (GIC) or induces geo-electric field at the Earth's surface and in the ground. GIC and horizontal component of geomagnetic field have been studied with respect to various geomagnetic events. Particularly, we have studied four events. The first one is geomagnetically quiet period (5 October 2003), the second one is weak storm (21 October 2003), the third one is moderate storm (14 October 2003) and the last one is an intense storm (30 October 2003). By comparing the development of GIC during geomagnetic storms, we found that intense geomagnetic storms show higher development on GIC magnitude. The GIC during storm events is several times greater than that during the quiet day. AE index shows more activity in the event of 30th October than other events and GIC is also more in this event. This can be accounted to the greater geomagnetic disturbance in this case. The power ranges of higher intensity are seen at various time scales on different events. We have analysed GIC signal associated with four geomagnetic storms and found distinct periodicities at the time when H component highly perturbed. The characteristic of GIC signal demonstrates high variability with time without presence of continuous periodicities. Discrete wavelet transform (DWT) analysis reveals that whenever the geomagnetic field is perturbed, there will be high possibility of detecting GIC. The singularities present in GIC signal are due to the peak value of electrical currents system in the ionosphere and magnetosphere, and corresponding high fluctuations in H component. In this work, we explore the remarkable ability of wavelets to highlight the singularities associated with discontinuities present in the GIC.

Ground-Based Observations of Powerful Solar Flares Precursors

AbstractThe opportunity of development the short-term forecasting technique of geoeffective solar flares is presented in this study. This technique is based on the effect of growth the fluctuations of horizontal component of geomagnetic field before the solar proton flares, that is considered as a prognostic parameter of solar proton flares.

Solar and lunar tidal variabilities in GPS‐TEC and geomagnetic field variations: Seasonal as well as during the sudden stratospheric warming of 2010

AbstractThe Global Positioning System (GPS) deduced total electron content (TEC) data at 15°N (geomagnetic), which is the northern crest region of equatorial ionization anomaly, are used to study solar and lunar tidal variabilities during the years 2008 and 2009 and also during the 2009–2010 winter, when a major sudden stratospheric warming (SSW) event has occurred. The diurnal and semidiurnal tidal amplitudes show semiannual variation with maximum amplitudes during February–March and September–November, whereas terdiurnal tide is larger during April–September. They show significant longitudinal variability with larger (smaller) amplitudes over 250°E–150°E (200°E–250°E). Lunar semidiurnal tidal amplitudes show sporadic enhancements during northern winter months and negligible amplitudes during northern summer months. They also show notable longitudinal variabilities. The solar migrating tides DW1 and SW2 show semiannual variation with larger amplitudes during spring equinox months, whereas TW3 maximizes during northern summer. DW2 shows larger amplitudes during summer months. During the SSW, except TW3, the migrating tides DW1 and SW2 show considerable enhancements. Among solar nonmigrating tides, SW1, TW2, and DS0 show larger enhancements. Solar tides in TEC and equatorial electrojet strength over Tirunelveli vary with the time scale of 60 days during October 2009–March 2010 similar to ozone mass mixing ratio at 10 hPa, and this confirms the vital role of ozone in tidal variabilities in ionospheric parameters. Lunar tidal amplitudes in changes in horizontal component of geomagnetic field (ΔH) are larger over Tirunelveli, a station near dip equator. Solar semidiurnal tides in ΔH have larger amplitudes than lunar tides over polar stations, Mawson and Godhavn.

Influence of geomagnetic activity and atmospheric pressure in hypertensive adults.

We performed a study of the systolic and diastolic arterial blood pressure behavior under natural variables such as the atmospheric pressure and the horizontal geomagnetic field component. We worked with a group of eight adult hypertensive volunteers, four men and four women, with ages between 18 and 27years in Mexico City during a geomagnetic storm in 2014. The data was divided by gender, age, and day/night cycle. We studied the time series using three methods: correlations, bivariate analysis, and superposed epoch (within a window of 2days around the day of occurrence of a geomagnetic storm) analysis, between the systolic and diastolic blood pressure and the natural variables. The correlation analysis indicated a correlation between the systolic and diastolic blood pressure and the atmospheric pressure and the horizontal geomagnetic field component, being the largest during the night. Furthermore, the correlation and bivariate analyses showed that the largest correlations are between the systolic and diastolic blood pressure and the horizontal geomagnetic field component. Finally, the superposed epoch analysis showed that the largest number of significant changes in the blood pressure under the influence of geomagnetic field occurred in the systolic blood pressure for men.

Quiet Time Correlation Between Geomagnetic Field Variations and the Dynamics of the East African Equatorial Ionosphere

The equatorial ionosphere is highly dynamic and consequently poses serious threats to communication and navigation systems. As a result, proper understanding of ionospheric dynamics is important. The present paper presents the results of an investigation of the correlation between quiet time vertical total electron content (VTEC) and solar quiet variation in the horizontal component of geomagnetic field (Sq(H)) from low solar activity year (2009) to the high solar activity year (2014) within the equatorial East African sector using statistical analysis method. Values of Sq(H) were observed to increase steadily from around 0700LT attaining maximum values around 1100-1200LT, then descending towards zero level and beyond. The magnitudes of (VTEC) increase uniformly from around 0600-1000LT, then gradually, attaining maximum values around 1300-1500LT. The time instants of occurrence of these peaks are mainly controlled by drifts and photo-ionization. The correlation coefficients (ccs) between (VTEC) and Sq(H) were found to be strongest during the ascending phase (0600-1200LT), ranging from 0.69 to 0.98 at Addis Ababa and 0.61 to 0.97 at Nairobi. During the descending phase (1300-1800LT), ccs range from -0.28 to 0.89 at Addis Ababa and-0.06 to 0.76 at Nairobi. A high level of significance (99.98%) of ccs was obtained. The good linear relationship is attributed to the independent increase of the eastward electric field and photo-ionization on (VTEC) while poor relationship is possibly due to domination of photo-ionization over equatorial ionization anomaly (EIA) development. The annual ccs between (VTEC) and Sq(H) exhibit a general dependence on solar activity at Addis Ababa, closer to the dip equator, rather than at Nairobi during the ascending phase of the daytime. This observation suggests that the EEJ changes linearly with change in solar activity, thus streamlining the variations in TEC, through drifts, and Sq(H) by intensifying the eastward equatorial electric field.

The First Documented Space Weather Event That Perturbed the Communication Networks in Iberia

AbstractIn this work, we review the first space weather event that affected significantly a number of communication networks in the Iberian Peninsula (Southwest of Europe). The event took place on 31 October 1903, during the ascending phase of solar cycle 14 (the lowest since the Dalton Minimum). We describe the widespread problems that occurred in the telegraph communication network in two midlatitude countries (Portugal and Spain), that was practically interrupted from 09 h30 to 21 h00 UT. Different impacts on the telegraphic communication are described and shown to be dependent on the large‐scale orientation of the wires. In order to put these results into a wider context we provide measurements of the concurrent geomagnetic field that are available from the observatories of Coimbra (Portugal) and San Fernando (Spain). The measurements confirm the simultaneous occurrence of large geomagnetic disturbances. In particular, the magnetograms recorded in Coimbra show a clear and large amplitude storm sudden commencement around 05 h30. The main phase, with a H (horizontal component of geomagnetic field) maximum range of ~500 nT, started approximately 1 h later and lasted for almost 10 h, suggesting that the interplanetary magnetic field was strongly southward for long time.

Influence of geomagnetic activity and atmospheric pressure on human arterial pressure during the solar cycle 24

We performed a study of the systolic (SBP) and diastolic (DBP) arterial blood pressure behavior under natural variables such as the atmospheric pressure (AtmP) and the horizontal geomagnetic field component (H). We worked with a sample of 304 healthy normotense volunteers, 152 men and 152 women, with ages between 18 and 84years in Mexico City during the period 2008–2014, corresponding to the minimum, ascending and maximum phases of the solar cycle 24. The data was divided by gender, age and day/night cycle. We studied the time series using three methods: Correlations, bivariate and superposed epochs (within a window of three days around the day of occurrence of a geomagnetic storm) analysis, between the SBP and DBP and the natural variables (AtmP and H). The correlation analysis indicated correlation between the SBP and DBP and AtmP and H, being the largest during the night. Furthermore, the correlation and bivariate analysis showed that the largest correlations are between the SBP and DBP and the AtmP. The superposed epoch analysis found that the largest number of significant SBP and DBP changes occurred for women. Finally, the blood pressure changes are larger during the solar minimum and ascending solar cycle phases than during the solar maximum; the storms of the minimum were more intense than those of the maximum and this could be the reason of behavior of the blood pressure changes along the solar cycle.

Influence of magnetic field on the spatial orientation in zebrafish (Danio rerio) (Cyprinidae) and Roach (Rutilus rutilus) (Cyprinidae)

Preferred direction of motion under influence of geomagnetic field and its modifications was registered in zebrafish (Danio rerio) raised in laboratory culture and in roach (Rutilus rutilus) from the Rybinsk Reservoir. In the geomagnetic field, specimens of zebrafish prefer two opposite directions oriented towards the north and south, while they prefer towards east and west at 90° turning of the horizontal component of geomagnetic field. The specimens of roach in the geomagnetic field prefer only the direction oriented towards east–northeast. This direction coincides with the direction along the canal where roach was sampled to the main river channel part of the Rybinsk Reservoir. At 90° rotation of the horizontal component of geomagnetic field, the direction turns to the south–southeast. The reasons for selection of certain directions in the geomagnetic field are discussed.

Influence of magnetic field on zebrafish activity and orientation in a plus maze

We describe an impact of the geomagnetic field (GMF) and its modification on zebrafish's orientation and locomotor activity in a plus maze with four arms oriented to the north, east, south and west. Zebrafish's directional preferences were bimodal in GMF: they visited two arms oriented in opposed directions (east–west) most frequently. This bimodal preference remained stable for same individuals across experiments divided by several days. When the horizontal GMF component was turned 90° clockwise, the preference accordingly shifted by 90° to arms oriented to the north and south. Other modifications of GMF (reversal of both vertical and horizontal GMF components; reversal of vertical component only; and reversal of horizontal component only) did not exert any discernible effect on the orientation of zebrafish. The 90° turn of horizontal component also resulted in a significant increase of fish's locomotor activity in comparison with the natural GMF. This increase became even more pronounced when the horizontal component was repeatedly turned by 90° and back with 1min interval between turns. Our results show that GMF and its variations should be taken into account when interpreting zebrafish's directional preferences and locomotor activity in mazes and other experimental devices.

The Theory and Realization Method for Weak-Magnetic Environment Simulation

The horizontal component of geomagnetic field is so weak in high latitude area that the magnetic navigation equipment available can not work, a method is introduced to simulate this weak-magnetic environment to by using artificial controllable magnetic field to neutralize geomagnetic horizontal component .Theoretical and simulation analysis is involved; using circular Helmholtz coils, an experimental device is made for the experimental research for weak-magnetic environment simulation. The experimental results show that this method has a certain feasibility

Complexity signatures in the geomagnetic <i>H</i> component recorded by the Tromsø magnetometer (70° N, 19° E) over the last quarter of a century

Abstract. Solar disturbances, depending on the orientation of the interplanetary magnetic field, typically result in perturbations of the geomagnetic field as observed by magnetometers on the ground. Here, the geomagnetic field's horizontal component, as measured by the ground-based observatory-standard magnetometer at Tromsø (70° N, 19° E), is examined for signatures of complexity. Twenty-five year-long 10 s resolution data sets are analysed for fluctuations with timescales of less than 1 day. Quantile–quantile plots are employed first, revealing that the fluctuations are better represented by Cauchy rather than Gaussian distributions. Thereafter, both spectral density and detrended fluctuation analysis methods are used to estimate values of the generalized Hurst exponent, α. The results are then compared with independent findings. Inspection and comparison of the spectral and detrended fluctuation analyses reveal that timescales between 1 h and 1 day are characterized by fractional Brownian motion with a generalized Hurst exponent of ~1.4, whereas including timescales as short as 1 min suggests fractional Brownian motion with a generalized Hurst exponent of ~1.6.