Earth's Intensity Research Articles

Real-time remote sensing detection framework of the earth's surface anomalies based on a priori knowledge base

Due to the suddenness, diversity, randomness and complexity of various earth's surface anomalies caused by natural and human factors, the time-efficiency of traditional satellite remote sensing technology is seriously lagging behind the actual needs of the earth's surface anomalies early warning and emergency handling. Real-time earth's surface anomaly detection has become an important issue for achieving ecological security, human safety and health, and high-quality socioeconomic development. Therefore, this study proposed a real-time detection framework for earth's surface anomalies using a single temporal remote sensing data based on a priori knowledge base. The framework first selected an appropriate remote sensing feature system and constructed a priori knowledge base effectively reflecting the natural evolutionary law of the normal earth's surface. Then, the earth's surface anomalies were identified by comparing the real-time acquired remote sensing data to the priori knowledge base with the designed detection rules. Finally, the intensity of earth's surface anomalies was evaluated comprehensively using pixel- and patch-scale information. The preliminary analysis of several specific cases indicated that the proposed framework was reliable and could effectively identify the earth's surface anomalies with high accuracy. This proposed framework is fully applicable to the real-time detection of most earth's surface anomalies using a single temporal remote sensing data, which is not limited to a single earth's surface anomaly event. Meanwhile, the framework presents great potential for on-orbit processing of the earth's surface anomaly detection and realizing real-time remote sensing services for the early warning of the earth's surface anomalies.

A New Four‐Component L*‐Dependent Model for Radial Diffusion Based on Solar Wind and Magnetospheric Drivers of ULF Waves

AbstractWaves which couple to energetic electrons are particularly important in space weather, as they drive rapid changes in the topology and intensity of Earth's outer radiation belt during geomagnetic storms. This includes Ultra Low Frequency (ULF) waves that interact with electrons via radial diffusion which can lead to electron dropouts via outward transport and rapid electron acceleration via inward transport. In radiation belt simulations, the strength of this interaction is specified by ULF wave radial diffusion coefficients. In this paper we detail the development of new models of electric and magnetic radial diffusion coefficients derived from in‐situ observations of the azimuthal electric field and compressional magnetic field. The new models use as it accounts for adiabatic changes due to the dynamic magnetic field coupled with an optimized set of four components of solar wind and geomagnetic activity, , , , and , as independent variables (inputs). These independent variables are known drivers of ULF waves and offer the ability to calculate diffusion coefficients at a higher cadence then existing models based on Kp. We investigate the performance of the new models by characterizing the model residuals as a function of each independent variable and by comparing to existing radial diffusion models during a quiet geomagnetic period and through a geomagnetic storm. We find that the models developed here perform well under varying levels of activity and have a larger slope or steeper gradient as a function of as compared to existing models (higher diffusion at higher values).

Configuration of the Earth’s Magnetotail Current Sheet

AbstractThe spatial scale and intensity of Earth’s magnetotail current sheet determine the magnetotail configuration, which is critical to one of the most energetically powerful phenomena in the Earth’s magnetosphere, substorms. In the absence of statistical information about plasma currents, theories of the magnetotail current sheets were mostly based on the isotropic stress balance. Such models suggest that thin current sheets cannot be long and should have strong plasma pressure gradients along the magnetotail. Using Magnetospheric Multiscale and THEMIS observations and global simulations, we explore realistic configuration of the magnetotail current sheet. We find that the magnetotail current sheet is thinner than expected from theories that assume isotropic stress balance. Observed plasma pressure gradients in thin current sheets are insufficiently strong (i.e., current sheets are too long) to balance the magnetic field line tension force. Therefore, pressure anisotropy is essential in the configuration of thin current sheets where instability precedes substorm onset.

Dynamics of orbital boost maneuver of low Earth orbit satellites by electrodynamic tethers

This paper studied the dynamic characteristics of electrodynamic tethered satellite with consideration of coupled multiphysics field for orbital boost maneuver by a fully insulated electrodynamic tether (EDT). We proposed a simplified analytical nonlinear current–voltage circuit method based on the Parker–Murphy model to evaluate the real-time electric current-carrying tether. Furthermore, the performances of orbital boost maneuver by a fully insulated electrodynamic tether is investigated. This current–voltage model is influenced by the electron density, the intensity of Earth’s magnetic field and the space plasma temperature. The hollow plasma contactor located on the sub-satellite to attract the electrons from the ambient plasma. An on-board power supply is adopted to change the direction of electric current for boosting the system. The direction of electric current in tether is from main-satellite to sub-satellite. The efficiency of orbital boost maneuver is compared with different sizes of anodic contactors and the given voltage of power supply. The simulation results showed that electric current is easily affected by the fluctuation of electron density, the Earth’s magnetic field and plasma temperature. The electrodynamic tether system can stable boost its orbit altitude from 400 to 1200 km in four cases by a fully insulated electrodynamic tether.

Vein width measurement of groundwater on Earth's surface using Semiconductor Laser Light and Proton Precession Magnetometer

Near-surface geophysical methods such as Semiconductor LASER Light Box (SCLLB) and Proton Precession Magnetometer (PPM) coupled with Vertical Electrical Soundings (VES) and water dowsing approach are used to measure the vein width of Groundwater (GW) on the Earth's surface at fifteen locations in the Deccan Trap flood basalt area in Pune region, Maharashtra, India. The main objective is to validate old simple water dowsing way of GW detection in hard rock using the established modern science and technology namely VES, PPM and SCLLB techniques. On the basis of deflection of the L-shaped copper rods, the presence of GW with clues on the edges of GW vein is detected using the old traditional dowsing method. The efficacy of dowsing is verified by VES. It is found that apparent resistivity in the range from 48Ωm to 117Ωm over the GW location delineated by the dowser is relatively low, thus confirming the presence of GW in the study area. Variation in the intensity of Earth's Magnetic Field (EMF) measured by PPM is found in the range from 37,788nT to 43,242nT over GW locations. High magnetic intensity values indicated high GW potential in weathered vesicular-amygdaloidal basalt and magnetic field gradient changes enabled to calculate GW vein width. It is suggested that water dowsers might get a dowsing reaction as a result of entering into magnetic field gradient changes caused by GW. Digital barometer records the atmospheric pressure (P) and temperature (T) showing that both P and T are higher than the non-GW location which alters refractive index (RI) of medium over GW locations in the study area. A small change in RI alters the intensity of the semiconductor laser beam (≈234 μA to 1204 μA) indicating the edges of GW vein, thus giving the width of the vein. The results obtained by PPM and SCLLB match with dowsing responses. It is found that GW sources and width of GW vein (≈1 m to 6 m) in Deccan basaltic terrain can be measured quickly and with ease by using SCLLB in comparison to VES and PPM. It is concluded that the application of proposed modern instrumental measurement survey by PPM and SCLLB coupled with the old simple technology of water dowsing demonstrated the potential to generate a subsurface water resource database at the national level, especially in hard rock.

Evidence for Fe-Si-O liquid immiscibility at deep Earth pressures

Seismic observations suggest that the uppermost region of Earth's liquid outer core is buoyant, with slower velocities than the bulk outer core. One possible mechanism for the formation of a stably stratified layer is immiscibility in molten iron alloy systems, which has yet to be demonstrated at core pressures. We find immiscibility between liquid Fe-Si and Fe-Si-O persisting to at least 140 GPa through a combination of laser-heated diamond-anvil cell experiments and first-principles molecular dynamics simulations. High-pressure immiscibility in the Fe-Si-O system may explain a stratified layer atop the outer core, complicate differentiation and evolution of the deep Earth, and affect the structure and intensity of Earth's magnetic field. Our results support silicon and oxygen as coexisting light elements in the core and suggest that [Formula: see text] does not crystallize out of molten Fe-Si-O at the core-mantle boundary.

Advancing Precambrian palaeomagnetism with the PALEOMAGIA and PINT(QPI) databases

State-of-the-art measurements of the direction and intensity of Earth’s ancient magnetic field have made important contributions to our understanding of the geology and palaeogeography of Precambrian Earth. The PALEOMAGIA and PINT(QPI) databases provide thorough public collections of important palaeomagnetic data of this kind. They comprise more than 4,100 observations in total and have been essential in supporting our international collaborative efforts to understand Earth's magnetic history on a timescale far longer than that of the present Phanerozoic Eon. Here, we provide an overview of the technical structure and applications of both databases, paying particular attention to recent improvements and discoveries.

Explaining Why Some Paleomagnetic Results Fail

Reordering of mineral crystal lattice structures during laboratory heating may explain the frequent need to reject results of experiments that estimate the intensity of Earth's past magnetic fields.

Geomagnetic Navigation and Magnetic Maps in Sea Turtles

: Sea turtles can extract two types of navigational information from Earth's magnetic field: (1) directional or compass information; and, (2) positional or map information useful in assessing geographic location. Within the latter category, turtles perceive at least two geomagnetic elements: the intensity of Earth's field and its inclination. Both vary across the globe so that different oceanic regions are typically marked by different magnetic fields. For hatchling loggerhead turtles undertaking their first transoceanic migration, regional magnetic fields function as open-sea navigational markers, eliciting changes in swimming direction at crucial points in the migratory route. Older sea turtles use magnetic information in a classical navigational map, allowing them to assess position relative to specific geographic destinations. Although the magnetic maps of sea turtles lack the high resolution of human global positioning systems, they may provide an interesting conceptual design for low-resolution positioning systems that can function independently of GPS.

Chronology errors and their effects on the recovery of characteristic time scales of the geodynamo from relative paleointensity

The intensity of Earth’s magnetic field has been modeled as a continuing sequence of growths and decays due to a rotating parametric instability (RPI) of the fluid core. Taking paleomagnetic intensity as a proxy for the turbulent fluid velocity field, timescales of motion in the fluid core and geodynamo can be inferred from estimates of growth and decay. While such inferences may be in error from several possible sources, this work examines the effect of age errors on relative paleointensity data from cores of marine sediments. True temporal variations in paleomagnetic intensity are distorted by stretching and compressing the observations in time and displacement in age of paleomagnetic features due to errors in the ages of paleomagnetic samples. For the interval 0–75 ka, growths and decays previously found in three single-site records are seen in one composite stack but not in a second composite stack over the same age interval. The coherence spectra for all pairs of individual records that make up the stack illustrate the apparent smoothing of relative paleointensity records that are stacked over a common age interval. We further demonstrate that the events seen in both the stack and the single core records are predictable from the same method of pairwise coherence. Thus single-site and composite stacks can both be used to estimate growth and decay rates of the paleomagnetic field, provided constraints from coherence of pairs making up the stack are respected. It is also concluded that temporal properties of a growth and decay process are best obtained from individual records and then stacked by event, even though these events may appear at different times as a result of discrepancies in age models. The main contribution of this work is therefore to confirm the previous analysis of growth and decay in sequences of relative paleointensity using a newly developed analytical model.

The Cretaceous superchron geodynamo: observations near the tangent cylinder.

If relationships exist between the frequency of geomagnetic reversals and the morphology, secular variation, and intensity of Earth's magnetic field, they should be best expressed during superchrons, intervals tens of millions of years long lacking reversals. Here we report paleomagnetic and paleointensity data from lavas of the Cretaceous Normal Polarity Superchron that formed at high latitudes near the tangent cylinder that surrounds the solid inner core. The time-averaged field recorded by these lavas is remarkably strong and stable. When combined with global results available from lower latitudes, these data define a time-averaged field that is overwhelmingly dominated by the axial dipole (octupole components are insignificant). These observations suggest that the basic features of the geomagnetic field are intrinsically related. Superchrons may reflect times when the nature of core-mantle boundary heat flux allows the geodynamo to operate at peak efficiency.

Orbital influence on Earth's magnetic field: 100,000-year periodicity in inclination.

A continuous record of the inclination and intensity of Earth's magnetic field, during the past 2.25 million years, was obtained from a marine sediment core of 42 meters in length. This record reveals the presence of 100,000-year periodicity in inclination and intensity, which suggests that the magnetic field is modulated by orbital eccentricity. The correlation between inclination and intensity shifted from antiphase to in-phase, corresponding to a magnetic polarity change from reversed to normal. To explain the observation, we propose a model in which the strength of the geocentric axial dipole field varies with 100,000-year periodicity, whereas persistent nondipole components do not.

Excursions in geomagnetism

The intensity of Earth's magnetic field varies on timescales varying from seconds to tens of millions of years. Only with palaeomagnetic records going back deep into the past can putative causes for the variations be tested. A new composite analysis of 33 records covers the past 800,000 years: one conclusion to be drawn for it is that it seems unlikely that field intensity has been influenced by variations in Earth's orbit.