Magnetic Polarity Research Articles

Наземные наблюдения ОНЧ аврорального хисса в обсерваториях «Ловозеро» и «Баренцбург»

The paper presents the results of the analysis of auroral hiss bursts, measured at Lovozero and Barentsburg observatories. These points are located on close geomagnetic meridians in the auroral and circumpolar zones. The auroral hiss bursts occur first in the auroral zone at Lovozero Observatory. Then, they fade out smoothly and occur in the circumpolar zone at Barentsburg Observatory. These events are observed when geomagnetic activity and the source of phase scintillation of GPS signals move from auroral to circumpolar latitudes. Analysis of magnetic field polarization and arrival angles of the bursts has shown that the area on the Earth surface, illuminated by hiss bursts, arose at auroral latitudes near Lovozero Observatory, and then moved to higher latitudes. Since propagation of the hiss to the ground and occurrence of GPS signal scintillation requires the presence of electron density irregularities of similar scales in the ionosphere, we assume that the same irregularities could cause both phenomena. A possible cause of their occurrence is the development of current-convective and (or) drift instability in the ionosphere caused by the development of field-aligned currents. Their development is indicated by the simultaneous recording of Pi1B pulsations. The results show that the termination of hiss at auroral latitudes may be caused by a shift of the geomagnetic disturbance region to high latitudes, rather than changes of wave propagation conditions in the ionosphere.

Ground-based observations of the VLF auroral hiss at Lovozero and Barentsburg observatories

The paper presents the results of the analysis of auroral hiss bursts, measured at Lovozero and Barentsburg observatories. These points are located on close geomagnetic meridians in the auroral and circumpolar zones. The auroral hiss bursts occur first in the auroral zone at Lovozero Observatory. Then, they fade out smoothly and occur in the circumpolar zone at Barentsburg Observatory. These events are observed when geomagnetic activity and the source of phase scintillation of GPS signals move from auroral to circumpolar latitudes. Analysis of magnetic field polarization and arrival angles of the bursts has shown that the area on the Earth surface, illuminated by hiss bursts, arose at auroral latitudes near Lovozero Observatory, and then moved to higher latitudes. Since propagation of the hiss to the ground and occurrence of GPS signal scintillation requires the presence of electron density irregularities of similar scales in the ionosphere, we assume that the same irregularities could cause both phenomena. A possible cause of their occurrence is the development of current-convective and (or) drift instability in the ionosphere caused by the development of field-aligned currents. Their development is indicated by the simultaneous recording of Pi1B pulsations. The results show that the termination of hiss at auroral latitudes may be caused by a shift of the geomagnetic disturbance region to high latitudes, rather than changes of wave propagation conditions in the ionosphere.

Kerr nonlinearity in TE/TM microring resonators on cubic silicon carbide-on-insulator platforms

Kerr nonlinearity plays a pivotal role in nonlinear photonics. Recent advancement in wafer bonding techniques has led to the creation of a cubic silicon carbide-on-insulator (3C-SiCOI) platform with improved crystalline quality, offering exciting prospects for investigating the Kerr effect in 3C-SiC. In this paper, we demonstrate 3C-SiC's Kerr effects through design, fabrication, and experimental investigation. By using the cavity enhanced four-wave mixing based on microring resonator (MRRs) supporting transverse electric or magnetic (TE/TM) polarizations on the 3C-SiCOI platform, we experimentally retrieve the Kerr nonlinear index (n2) of 3C-SiC within diverse waveguide dimensions, revealing a value of 4.92 and 5.00 × 10−19 m2/W for TE and TM polarizations, respectively. We further confirm the thermal stability of the 3C-SiC in Kerr effects at elevated temperatures from 100 °C to 300 °C, showing negligible change of n2. Moreover, we demonstrated optical parametric oscillation (OPO) in the fabricated single mode MRR via a dual-pump configuration. With an input power of less than 50 mW, a distinct OPO spectrum covering the C band has been achieved. These results signify the emergence of 3C-SiCOI as a promising platform for Kerr applications.

Effect of Cu Additive on the Microstructure and Magnetic Properties of Fe-6.5wt%Si High Silicon Steel by Induction Melting Method

Fe-6.5wt%Si high silicon steel alloy was prepared using the vacuum induction melting method. Ordered phase formation in Fe-6.5wt%Si alloy was inhibited by adding trace Cu and induction cycle heating purification treatment. The microstructure and magnetic properties of high silicon steel were investigated. The results show that with the increase of Cu content, the alloy microstructure first changed from coarse grain to fine isoaxial crystal, followed by strip dendrite, with ordered cracking. The saturated polarization strength of the alloy decreased from 25.1 emu of the sample without adding Cu and heating once to 21.5 emu for seven cycles, the residual magnetic polarization increased from 0.0255 emu to 0.048 emu, the slope of the magnetization curve slowed down, and the coercive force increased from 2.4 Oe to 4.0 Oe. With the increase of cyclic heating times, the microstructure of the alloy without added Cu refined and transitioned from columnar to equiaxial crystals, from isoaxial dendrite to strip with the addition of 0.03 wt%Cu, and from strip to isoaxial structure with the addition of 0.05 wt%Cu. With the increase of cycle heating times, the saturation magnetization strength of the alloy without Cu and with 0.03 wt%Cu alloy increased, while the recalcitrant force reduced. Conversely, the saturation polarization strength decreased for the alloy with 0.05 wt% Cu, and the coercive force was also reduced.

Cataglyphis ants have a polarity-sensitive magnetic compass.

Spatial orientation based on the geomagnetic field (GMF) is a widespread phenomenon in the animal kingdom, predominantly observed in long-distance migrating birds,1 sea turtles,2 lobsters,3 and Lepidoptera.4,5 Although magnetoreception has been studied intensively, the mechanism remains elusive. A crucial question for a mechanistic understanding of magnetoreception is whether animals rely on inclination or polarity-based magnetic information. Inclination-based magnetic orientation utilizes the angle between the magnetic field lines and gravity, indicating poleward and equatorward. In contrast, polarity-based magnetic orientation allows animals to detect the polarity of the GMF, the north and south direction of the field vector. Cataglyphis desert ants are excellent experimental models for testing whether magnetic inclination or polarity of the magnetic field is used for navigation. Desert ants are solitary foragers with exceptional navigational skills.6 When the ants leave their underground nest for the first time to become foragers, they perform learning walks for up to threedays to learn the visual panorama and calibrate their compass systems.7,8 The ants repeatedly stop their forward movement during learning walks for performing turns (pirouettes), interrupted by stopping phases. Gaze directions during the longest stopping phases are directed toward the nest entrance.9 We experimentally manipulated look-back behavior systematically by altering polarity or inclination of the GMF. We demonstrate that Cataglyphis ants, contrary to most other insects studied,10 possess a polarity-sensitive magnetic compass, making them ideal experimental models for narrowing down the evidence for particle-based mechanisms underlying magnetosensation in this insect.

Establishing room-temperature multiferroic behaviour in bismuth-based perovskites

In the search of single-phase multiferroic materials at room temperature, a ceramic system with composition 0.5(0.94Bi0.5Na0.5TiO3-0.06BaTiO3)-0.5BiFe0.8Mn0.2O3 (BNT-6BT-5BFO2M) was fabricated via the solid-state reaction route, and its crystal structure, dielectric, ferroelectric, and magnetic properties were studied. The results indicate that the ceramic can be considered a single-phase perovskite system with ferroelectric and ferromagnetic characteristics at room temperature. The ferroelectricity is evidenced by the switching of ferroelectric domains, as imaged by piezoresponse force microscopy (PFM). The presence of a weak ferromagnetism is manifested by a non-negligible remnant magnetization in the magnetization-magnetic field loops. The spontaneous net magnetization is mediated by the presence of Mn4+ ions, which may introduce ferromagnetic Fe3+-O-Mn4+ double-exchange interactions in the system. The PFM images taken during the application of a magnetic field of 2000 Oe revealed that the ferroelectric domain structure at room temperature can be significantly influenced by the magnetic field, reflecting the presence of a magnetoelectric effect that allows the occurrence of magnetic field-induced polarization reorientation.

Spin-Selective Charge Transfer-SERS Driven Label-Free Enantioselective Discrimination of Chiral Molecules on Ag Nanoparticle-Decorated Ni Nanorod Arrays.

Enantioselective discrimination is critical in several fields, particularly in pharmaceutics and clinical drug research. Chiral molecules possess unique charge transfer properties, showing an enantioselective preference for electron spin orientation when interacting with the magnetic surface. Here, we developed spin-selective charge transfer (SSCT)-based label-free surface-enhanced Raman scattering (SERS) achiral magnetic substrates for the enantioselective discrimination of chiral molecules without creating asymmetric chiral adsorption sites. The e-beam-based glancing angle deposition (GLAD) technique was utilized to construct achiral magnetic surface-enhanced Raman scattering (SERS) substrates by decorating Ag nanoparticles over Ni nanorods. SERS spectroscopy was carried out on significant enantiomers, including cystine, alanine, and DOPA (l-3-(3,4-dihydroxyphenyl) alanine). An external electromagnet was used to manipulate the magnetic substrate's spin polarization by altering the magnetic field's direction. Subsequently, SERS spectra were acquired. Based on the magnetic field's direction, there is a complementary variation in the intensities of SERS spectra of the enantiomers. The SSCT process between molecule-metal complexes synergized with the magnetic field direction to control the electron spin, leading to SERS-based enantioselective discrimination. This label-free, easy, yet practical approach offers a characteristic paradigm shift from the recent complex approaches for chiral detection and separation.

Simulation of Thermal Nonequilibrium Cycles in the Solar Wind

Thermal nonequilibrium (TNE) is a condition of the plasma in the solar corona in which the local rate of energy loss due to radiation increases to the point that it cannot be sustained by the various heating terms acting on the plasma, precluding the existence of a steady state. The limit cycles of precipitation and evaporation that result from TNE have been simulated in 1D models of coronal loops, as well as 2D and 3D models of the solar chromosphere and lower corona. However, a careful study of TNE in the solar wind has not been performed until now. Here, we demonstrate that for suitable combinations of local and global heating rates, it is possible for the plasma to exhibit a TNE condition, even in the context of a transonic solar wind with appreciable mass and energy fluxes. This implies limits on the amount of footpoint heating that can be withstood under steady-state conditions in the solar wind, and may help to explain the variability of solar wind streams that emanate from regions of highly concentrated magnetic flux on the solar surface. The implications of this finding pertain to various sources of high-density solar wind, including plumes that form above regions of mixed magnetic polarity in polar coronal holes and the slow solar wind that emanates from coronal hole boundaries.

Bias voltage driven tunneling magnetoresistance polarity reversal in 2D stripy antiferromagnet CrOCl

Atomically thin materials with coupled magnetic and electric polarization are critical for developing energy-efficient and high-density spintronic devices, yet they remain scarce due to often conflicting requirements of stabilizing both magnetic and electric orders. The recent discovery of the magnetoelectric effect in the 2D stripy antiferromagnet CrOCl highlights this semiconductor as a promising platform to explore electric field effects on magnetoresistance. In this study, we systematically investigate the magnetoresistance in tunneling junctions of bilayer and monolayer CrOCl. We observe that the transition from antiferromagnetic to ferrimagnetic phases in both cases induces a positive magnetoresistance at low bias voltages, which reverses to a negative value at higher bias voltages. This polarity reversal is attributed to the additional electric dipoles present in the antiferromagnetic state, as supported by our theoretical calculations. These findings suggest a pathway for the electric control of spintronic devices and underscore the potential of 2D magnets like CrOCl in advancing energy-efficient spintronic applications.

Polarization-independent topological corner states based on all-dielectric valley photonic crystals

Recently, topological edge states and corner states have provided new ways to manipulate light transmission and localization. Up to now, most works have focused on either transverse magnetic or transverse electric polarization. In contrast, dual-polarization photonic topological states have attracted extensive attention because of their potential applications in polarization-independent photonic devices. Previous study realizes the polarization-independent topological corner states by independently tuning the out-of-plane permittivity and the in-plane permittivity of the anisotropic elliptic metamaterial, which is difficult to realize in the optical regime. In this work, we achieve polarization-independent topological edge states and corner states based on all-dielectric fishnet photonic crystals made of isotropic material. Note that the frequencies of the topological edge states and corner states depend on the structure’s effective refractive index, which is related to the filling ratio of the dielectric material. By selecting a suitable filling ratio of the dielectric material, polarization-independent edge states and corner states are realized. In addition, we further construct a topological waveguide-cavity coupling system and demonstrate the function of a polarization-independent optical notch filter. Our work paves the way for the implementation of polarization-independent topological photonic devices.

Morphologic transformation of ferrofluid during micropump driving under field control.

The superiority of ferrofluid pumps in the fields of biomedical, life science, energy, and power research has been experimentally demonstrated. However, the mechanisms underlying the morphological transformations of ferrofluid fusion and separation during pump driving are not completely understood. To bridge the gap between the theory and practical applications of ferrofluid pumps, we employed optical methods to record the dynamic morphological transformation of rotating and fixed ferrofluids under different magnetic field polarities, magnetic field distributions, and ferrofluid mass fractions. The magnetic field polarity causes dynamic differences in the fusion-separation process of the ferrofluid but does not affect the volume segmentation of the ferrofluid, which depends on the ratio of the magnetic field intensities. When this ratio deviates from one, the morphology of ferrofluid changes, reducing the pumping efficiency. Compared to external environmental factors, the mass fraction does not change the morphology of the ferrofluid. However, high mass fractions lead to wall-clinging of the ferrofluid, and low mass fractions induce bubbles, both of which detrimentally affect the pumping performance. This study reveals the properties of ferrofluid and the effects of external environmental conditions on the morphological transformation of ferrofluid, providing references for optimizing ferrofluid pumps.

Facile synthesis of novel nitrogen-doped diamond with excellent microwave absorption and thermal conductive performance

Herein, nitrogen doped polycrystalline diamond was prepared using the microwave plasma chemical vapor deposition (MPCVD) method with H2–CH4–N2 gas sources to achieve excellent electromagnetic (EM) wave absorption and thermal management properties. The effect of the nitrogen content (0 to 50 ppm) on its performance was studied. The 25-ppm nitrogen doped diamond demonstrated excellent EM wave absorption performance, achieving a minimum reflection loss (RLmin) of −44.8 dB at 6.7 GHz and a maximum effective absorption band (EAB) of 5.4 GHz (3.7–9.1 GHz). The superior absorption performance could be attributed to synergistic attenuation mechanisms including dipole and interface polarization, conduction loss, eddy current loss, and magnetic polarization, intensified by nitrogen vacancy centers. This multifunctional material, combining high thermal conductivity with effective low-frequency EM wave absorption, showed promise for applications in 5G communications and electronic devices.

Magnetoelectric Coupling in a Mn4Na-Organic Complex under Pulsed Magnetic Fields up to 73 T.

Research on the magnetoelectric (ME) effect (or spin-electric coupling) in molecule-based magnetic materials is a relatively nascent but promising topic. Molecule-based magnetic materials have diverse magnetic functionalities that can be coupled to electrical properties. Here we investigate a realization of ME coupling that is fundamental but not heavily studied─the coupling of magnetic spin level crossings to changes in electric polarization. A mixed-valence Mn4Na complex with a total ground-state spin S = 5/2 under zero magnetic field and S = 17/2 under high magnetic field undergoes a cascade of ground-state level crossings of the Sz states with increasing magnetic field. Magnetization and electrical polarization measurements under pulsed magnetic fields up to 73 T show that each spin level crossing is accompanied by a significant change in electric polarization that is an even function of the applied magnetic field. A molecular Hamiltonian describing antiferromagnetic exchange in a distorted tetrahedron of three MnIII and one MnII ions matches the data well. We conclude that the ME coupling is caused by magnetostriction within the polar molecule as it distorts to lower its magnetic exchange energy.

Interplay of surface plasmon and Fabry-Perot resonances in metallic hole arrays on dielectric layers

This study investigates the resonant behavior of a nanostructured absorber consisting of a metal hole array (MHA) on a dielectric layer (BCB) forming a cavity on a metal ground plane (MGP). By varying the thickness of the BCB layer, the resonance spectra were analyzed under different conditions. Our simulations reveal the intricate interplay between surface plasmon and Fabry-Perot resonances within the MHA-BCB-MGP structure. We observe that as the dielectric thickness changes, the resonance peaks shift, exhibiting phenomena such as Rabi splitting and bifurcation. These features are particularly pronounced under transverse magnetic polarization, indicating the complex interaction between different resonance modes and polarization states. In addition, changes in MHA diameter affected the dominance of either surface plasmon or Fabry-Perot resonances, illustrating the complex relationship between structure and resonance behavior. Reflection spectra under different polarizations and angles of incidence showed agreement between simulation and experiment, validating the proposed model.

Fe-loaded two-dimensional nitrogen-doped carbon for electromagnetic wave absorption

Abstract Electromagnetic wave absorbing materials are particularly important in modern electronics, especially in the fields of stealth and communications. Carbon-based materials show great promise in the production and application of efficient wave-absorbing materials due to their rich structure, ultra-light weight, good corrosion resistance, and low cost. Among them, nitrogen-doped carbon-based two-dimensional materials have a stronger depletion effect on electromagnetic waves due to their higher specific surface area and abundant polarization states. In this article, nitrogen-doped carbon 2D flakes (NC) were successfully synthesized by a hydrothermal method. Furthermore, Fe single atoms were successfully loaded onto their surfaces, creating Fe@NC. The wave-absorbing properties of Fe@NC samples were significantly enhanced, with the minimum reflection loss (RLmin) reaching -69.22 dB at 11.48 GHz and the effective absorption bandwidth (EAB) extending to 5.79 GHz. The enhancement of electromagnetic wave absorption is attributed to the synergistic effects of magnetic loss, relaxation processes, dipole polarization, and electrical conduction loss. The successful preparation of Fe@NC offers new possibilities for the development of atomically dispersed wave-absorbing materials.

Design of Magnetic Fluid-Enhanced Optical Fiber Polarization Filter.

In this paper, we demonstrated a method of filling the air holes of a photonic crystal fiber (PCF), coated with gold film, with magnetic fluid (MF) to enhance the Surface Plasmon Resonance (SPR). The simulation results show that at the wavelength of 1260-1675 nm, the minimum loss coefficient of the y-polarization mode is 4.7 times that before filling with MF, and the x-polarization mode is 0.45 times greater. Then, based on this method, we designed a polarizing filter with a core diameter of 9 µm. The numerical simulation results indicate that it not only maintains the same core diameter as the single-mode fiber, but also has a larger bandwidth and a higher extinction ratio (ER). Additionally, we can optimize its ER at a specific wavelength by adjusting the magnetic field.

Nested active regions anchor the heliospheric current sheet and stall the reversal of the coronal magnetic field

During the solar cycle, the Sun's magnetic field polarity reverses due to the emergence, cancellation, and advection of magnetic flux towards the rotational poles. Flux emergence events occasionally cluster together, although it is unclear if this is due to the underlying solar dynamo or simply by chance. Regardless of the cause, we aim to characterise how the reversal of the Sun's magnetic field and the structure of the solar corona are influenced by nested flux emergence. From the spherical harmonic decomposition of the Sun's photospheric magnetic field, we identified times when the reversal of the dipole component stalls for several solar rotations. Using observations from sunspot cycle 23 to present, we located the nested active regions responsible for each stalling and explored their impact on the coronal magnetic field using potential field source surface extrapolations. Nested flux emergence has a more significant impact on the topology of the coronal magnetic field than isolated emergences as it produces a coherent (low spherical harmonic order) contribution to the photospheric magnetic field. The heliospheric current sheet, which separates oppositely directed coronal magnetic fields, can become anchored above nested active regions due to the formation of strong opposing magnetic fluxes. Further flux emergence, cancellation, differential rotation, and diffusion, then effectively advects the heliospheric current sheet and shifts the dipole axis. Nested flux emergence can restrict the evolution of the heliospheric current sheet and impede the reversal of the coronal magnetic field. The sources of the solar wind can be more consistently identified around nested active regions because the magnetic field topology remains self-similar for multiple solar rotations. This highlights the importance of identifying and tracking nested active regions to guide the remote-sensing observations of modern heliophysics missions.

Multiferroic properties in poly(vinylidene-fluoride)-based magnetostrictive/piezoelectric laminate composites

Multiferroic materials (MFM) have drawn considerable attention for developing smart multifunctional devices. Herein, poly(vinylidene-fluoride)-based (PVDF) MFM composite films of Ba0.85Ca0.15Zr0.1Ti0.9O3-PVDF/CoFe2O4-PVDF/Ba0.85Ca0.15Zr0.1Ti0.9O3-PVDF with sandwich-laminated structure are developed and investigated for its dielectric, magnetic, ferroelectric and magnetodielectric (MD) properties. An improved polar β–phase is formed with the particles of CoFe2O4 and Ba0.85Ca0.15Zr0.1Ti0.9O3 embedded in PVDF matrix. Both magnetic (M–H) and ferroelectric polarization (P–E) hysteresis loops indicate the multiferroic nature at room temperature, i.e., the coexistence of ferroelectric and ferromagnetic ordering in composite films. An enhanced ferroelectricity is obtained for the maximum polarization (Pmax∼1.57 μC/cm2 at 750 kV/cm) and the higher dielectric constant (εr∼16.84) as well as a lower dielectric loss tanδ < 0.04, compared to the pristine PVDF matrix (Pmax∼0.88 μC/cm2, εr∼10.26). A recyclable energy density of Wrec∼0.84 J/cm3 at 750 kV/cm is observed, together with a high efficiency (η∼87.82 %). The ferromagnetic behavior is confirmed by the M-H hysteresis loop, which exhibits significant magnetic properties, i.e., saturation magnetization (MS∼0.58 emu/g) and coercivity (HC∼1.72 kOe). Additionally, a robust magnetodielectric effect with a large negative coefficient (∼8.23 %) is achieved at a low magnetic field H∼3 kOe. The laminate composite film exhibits room temperature multiferroic with a large MD response, making it a promising candidate for utilization in intelligent multifunctional devices.

Enhancing supercapacitor performance through rapid charge transport induced by magnetic field-driven spin polarization

Magnetic supercapacitors have garnered significant attention, with notable progress in recent years. However, the underlying mechanisms remain unclear and require further investigation for future energy storage applications. In this study, we designed and fabricated Mn-Fe2O3/reduced graphene oxide (Mn-Fe2O3/rGO) nanostructures by employing heteroatom doping and interface engineering. Theoretical calculations showed that incorporating Mn2+ into Fe2O3 modulates electron localization around Fe atoms, leading to spin polarization in Fe 3d orbital electrons. Our experiments demonstrated that the optimized Mn-Fe2O3/rGO nanostructure processes ferromagnetic properties with a negative magnetoresistance effect at room temperature, suggesting that substantial spin-polarized charges rapidly participate in surface charge–discharge reactions under an applied magnetic field. This phenomenon resulted in a remarkable specific capacitance of 2956.4 F g−1 at 1 A g−1, along with superior cyclic stability. Additionally, the asymmetric supercapacitor device achieved an energy density of 220.19 W h kg−1 at a power density of 3.93 kW kg−1, with excellent capacitance retention of 98.5 % after 5000 cycles. This work paves the way for improving the performance of magnetic supercapacitors based on metal oxide electrode materials.

Improved chronostratigraphy and fine-tuned timing for Late Triassic palaeoenvironmental changes in SW Britain using coupled magnetic polarity and carbon isotope stratigraphy

Understanding the synchronicity of global climatic, environmental, and biotic events around the Norian-Rhaetian boundary (NRB) is problematic because of major international differences in biochronology. We instead use magnetostratigraphic and global carbon isotopic changes to produce more precise global correlation. This work focusses on the base and top of the Rhaetian, with principal age control from a new late Norian to latest Rhaetian magnetostratigraphy from Lavernock (southern Wales) which can be directly correlated to the proposed NRB sections at Pignola Abriola (Italy) and Steinbergkogel (Austria). A disconformity exists in the Lavernock section in its late Norian part (Branscombe Mudstone Formation), but the NRB interval is largely complete. The magnetostratigraphy and a composite δ13Corg stratigraphy from three British sections, demonstrate synchronous changes in both terrestrial and marine records. This analysis indicates the older proposed definition of the NRB from Steinbergkogel is in the upper few metres of the Branscombe Mudstone Formation, while the younger NRB definition from Pignola Abriola is in the upper parts of the Blue Anchor Formation. The latest Rhaetian magnetostratigraphy from Lavernock records reverse magnetochrons UT26r and UT28r which closely pre-date and post-date the widely recognised Marshi and Spelae carbon isotope excursions, respectively. Magnetochrons UT28r and UT27r were previously recognised at St Audrie's Bay (SW England), with relationships to the Newark Supergroup which tightly constrain the first phase of CAMP eruptions to overlap the Spelae excursion. The carbon isotope excursions present in the Blue Anchor Formation lacustrine successions, demonstrate the likely atmospheric, and global spread of these perturbations.