The Mexican Array Radio Telescope (MEXART) is a transit instrument mainly dedicated to performing Interplanetary Scintillation (IPS) observations with a central operating frequency of 139.65 MHz. The main scientific objective is to perform studies of solar wind properties and space weather effects. MEXART initially operated with an analog beamformer (16x16 Butler matrix), which produced 16 fixed latitudinal beams. MEXART began operations and reported the first measurements of IPS sources. MEXART’s beamforming system had several problems, however. The North-South beams had poor directivity, with large side lobes, and the instrument did not achieve the expected performance. Therefore, we commissioned the design and construction of a digital back-end. The digital system solved the problems with the beamforming, increased the bandwidth, and improved significantly the instrument’s sensitivity. In this paper, we present the first light of MEXART’s digital system. We describe the new technical capabilities of the instrument, and we show some preliminary results: an estimation of the radio telescope’s sensitivity ($\Delta S_{min} = 2.28 \pm 0.23$ Jy), the transit of the Galaxy at 140 MHz with the simultaneous tracking of 62 latitudinal beams, and an example of an IPS observation and the single-station methodology to calculate the solar wind speed. The new technical capabilities of the radio telescope will provide the potential to participate in several scientific studies. These include solar wind properties, space weather forecasting, ionospheric perturbations, and astrophysical aims such as monitoring of repeating Fast Radio Bursts (FRBs), and pulsars’ observations.

We present a new spectral analysis method for the identification of periodic signals in geophysical time series. We evaluate the power spectral density with the adaptive multitaper method, a non-parametric spectral analysis technique suitable for time series characterized by colored power spectral density. Our method provides a maximum likelihood estimation of the power spectral density background according to four different models. It includes the option for the models to be fitted on four smoothed versions of the power spectral density when there is a need to reduce the influence of power enhancements due to periodic signals. We use a statistical criterion to select the best background representation among the different smoothing+model pairs. Then, we define the confidence thresholds to identify the power spectral density enhancements related to the occurrence of periodic fluctuations (γ test). We combine the results with those obtained with the multitaper harmonic F test, an additional complex-valued regression analysis from which it is possible to estimate the amplitude and phase of the signals. We demonstrate the algorithm on Monte Carlo simulations of synthetic time series and a case study of magnetospheric field fluctuations directly driven by periodic density structures in the solar wind. The method is robust and flexible. Our procedure is freely available as a stand-alone IDL code at https://zenodo.org/record/3703168. The modular structure of our methodology allows the introduction of new smoothing methods and models to cover additional types of time series. The flexibility and extensibility of the technique makes it broadly suitable to any discipline.

Between 4 and 10 September 2017, multiple solar eruptions occurred from active region AR12673. NOAA and NASA’s well-instrumented spacecraft observed the evolution of these geoeffective events from their solar origins, through the interplanetary medium, to their geospace impacts. The 6 September X9.3 flare was the largest to date for the nearly concluded solar cycle 24 and, in fact, the brightest recorded since an X17 flare in September 2005, which occurred during the declining phase of solar cycle 23. Rapid ionization of the sunlit upper atmosphere occurred, disrupting high frequency communications in the Caribbean region while emergency managers were scrambling to provide critical recovery services caused by the region’s devastating hurricanes. The 10 September west limb eruption resulted in the first solar energetic particle event since 2012 with sufficient flux and energy to yield a ground level enhancement. Spacecraft at L1, including DSCOVR, sampled the associated interplanetary coronal mass ejections minutes before their collision with Earth’s magnetosphere. Strong compression and erosion of the dayside magnetosphere occurred, placing geosynchronous satellites in the magnetosheath. Subsequent geomagnetic storms produced magnificent auroral displays and elevated hazards to power systems. Through the lens of NOAA’s space weather R-S-G storm scales, this event period increased hazards for systems susceptible to elevated “radio blackout” (R3-strong), “solar radiation storm” (S3-strong), and “geomagnetic storm” (G4-severe) conditions. The purpose of this paper is to provide an overview of the September 2017 space weather event, and a summary of its consequences, including forecaster, post event analyst and communication operator perspectives.

NASA designated Reiner Gamma (RG) as the landing site for the first Payloads and Research Investigations on the Surface of the Moon (PRISM) delivery (dubbed PRISM-1a). Reiner Gamma is home to a magnetic anomaly, a region of magnetized crustal rocks. The RG magnetic anomaly is co-located with the type example of a class of irregular high-reflectance markings known as lunar swirls. RG is an ideal location to study how local magnetic fields change the interaction of an airless body with the solar wind, producing stand-off regions that are described as mini-magnetospheres. The Lunar Vertex mission, selected by NASA for PRISM-1a, has the following major goals: 1) Investigate the origin of lunar magnetic anomalies; 2) Determine the structure of the mini-magnetosphere that forms over the RG magnetic anomaly; 3) Investigate the origin of lunar swirls; and 4) Evaluate the importance of micrometeoroid bombardment vs. ion/electron exposure in the space weathering of silicate regolith. The mission goals will be accomplished by the following payload elements. The lander suite includes: The Vertex Camera Array (VCA), a set of fixed-mounted cameras. VCA images will be used to (a) survey landing site geology, and (b) perform photometric modeling to yield information on regolith characteristics. The Vector Magnetometer-Lander (VML) is a fluxgate magnetometer. VML will operate during descent and once on the surface to measure the in-situ magnetic field. Sophisticated gradiometry allows for separation of the natural field from that of the lander. The Magnetic Anomaly Plasma Spectrometer (MAPS) is a plasma analyzer that measures the energy, flux, and direction of ions and electrons. The lander will deploy a rover that conducts a traverse reaching ≥500 m distance, obtaining spatially distributed measurements at locations outside the zone disturbed by the lander rocket exhaust. The rover will carry two instruments: The Vector Magnetometer-Rover (VMR) is an array of miniature COTS magnetometers to measure the surface field. The Rover Multispectral Microscope (RMM) will collect images in the wavelength range ~0.34–1.0 um. RMM will reveal the composition, texture, and particle-size distribution of the regolith.

We investigate the solar events of late solar cycle 24 in July 2017 observed by a number of spacecraft in the inner heliosphere widely separated in heliolongitude and radial distance. These include spacecraft at L1 point, STEREO-A, near Earth satellites, and MAVEN (near Mars). The GRASP payload onboard Indian GSAT-19 satellite provides a new vantage point for Solar Energetic Particle (SEP) observations near Earth. There were two major Coronal Mass Ejections (CMEs) and a Stream Interaction Region (SIR) event in July 2017, which is a period during the deep descending phase of the historically weak solar cycle 24. The 16 July CME was Earth directed and the 24 July CME was STEREO-A and Mars directed. Earth and Mars were on the opposite sides of the solar disk, while Mars and STEREO-A were aligned with respect to the nominal Parker spiral field. The 24 July event was stronger and wider in heliolongitude. This CME-driven shock had magnetic connectivity to Earth, which produced an SEP event at Earth ~two days later. The spectral indices of the event observed directly at STEREO-A and at the remote location of ACE was found to be similar. The 16 July SIR event was observed by both MAVEN and STEREO-A. Higher particle intensities (a factor of 6 enhancement for 1 MeV protons) are observed by MAVEN (at 1.58 AU) compared to STEREO-A (at 0.96 AU). Also a spectral hardening is observed while comparing the spectral indices at these two locations, indicating proton acceleration at the SIR forward shock during the radial propagation of 0.62 AU in the interplanetary space.

We use the Space Weather Modeling Framework (SWMF) Geospace configuration to simulate a total of 122 storms from the period 2010-2019. With the focus on the storm main phase, each storm period was run for 54 hours starting from 6 hours prior to the start of the Dst depression. The simulation output of ground magnetic variations were compared with ground magnetometer station data provided by SuperMAG to statistically assess the Geospace model regional magnetic perturbation prediction performance. Our results show that the regional predictions at mid-latitudes are quite accurate, but the high-latitude regional disturbances are still difficult to predict.

Space weathering processes induce changes to the physical, chemical, and optical properties of space-exposed soil grains. For the Moon, space weathering causes reddening, darkening, and diminished contrast in reflectance spectra over visible and near-infrared wavelengths. The physical and chemical changes responsible for these optical effects occur on scales below the diffraction limit of traditional far-field spectroscopic techniques. Recently developed super-resolution spectroscopic techniques provide an opportunity to understand better the optical effects of space weathering on the sub-micrometer length scale. This paper uses synchrotron infrared nanospectroscopy to examine depth-profile samples from two mature lunar soils in the mid-infrared, 1500–700 cm-1 (6.7–14.3 μm). Our findings are broadly consistent with prior bulk observations and theoretical models of space weathered spectra of lunar materials. These results provide a direct spatial link between the physical/chemical changes in space-exposed grain surfaces and spectral changes of space-weathered bodies.

Using five independent substorm onset lists, we show that substorms occur more frequently when the Interplanetary Magnetic Field (IMF) By component and the dipole tilt angle Ψ have different signs as opposed to when they have the same sign. These results confirm that for Ψ ≠ 0 the magnetosphere exhibits an explicit dependence on the polarity of By, as other recent studies have suggested, and imply variation in the dayside reconnection rate and/or the magnetotail response. On the other hand, we find no clear relationship between substorm intensity and this explicit By effect. We additionally observe more frequent onsets for positive By in an onset list based on identifying negative bays in the auroral electrojet, regardless of season. Taking into account all five onset lists, we conclude that this phenomenon is not real, but is rather a consequence of the particular substorm identification method, which is affected by local ionospheric conditions that depend on By and Ψ.

We present a methodology that allows researchers to simulate in real time the spatiotemporal dynamics of the ground electric field (GEF) in a given 3-D conductivity model of the Earth based on continuously augmented data on the spatiotemporal evolution of the inducing source. The formalism relies on the factorization of the source by spatial modes and time series of respective expansion coefficients and exploits precomputed frequency-domain GEF generated by corresponding spatial modes. To validate the formalism, we invoke a high-resolution 3-D conductivity model of Fennoscandia and consider a realistic source built using the Spherical Elementary Current Systems (SECS) method as applied to magnetic field data from the IMAGE network of observations. The factorization of the SECS-recovered source is then performed using the principal component analysis. Eventually, we show that the GEF computation at a given time instant on a 512 x 512 grid requires less than 0.025 seconds provided that frequency-domain GEF due to pre-selected spatial modes are computed in advance. Taking the 7-8 September 2017 geomagnetic storm as a space weather event, we show that real-time high-resolution 3-D modeling of the GEF is feasible. This opens a practical opportunity for GEF (and eventually geomagnetically induced currents) nowcasting and forecasting.

Geomagnetic indices are routinely used to characterize space weather event intensity. The DST index is well resolved, but only available over 5 solar cycles. The aa index extends over 14 cycles but is highly discretized with poorly resolved extremes. We parameterize extreme aa activity by the annual averaged top few % of observed values, show these are exponentially distributed and they track annual DST index minima. This gives a 14 cycle average ~4% chance of at least one great (DST<-500nT) storm and ~28% chance of at least one severe (DST<-250nT) storm per year. At least one DST=-809[-663,-955]nT event in a given year would be a 1:151 year event. Carrington event estimate DST~-850nT is within the same distribution as other extreme activity seen in aa since 1868 so that its likelihood can be deduced from that of more moderate events. Events with DST<-1000nT are in a distinct class, requiring special conditions.

We perform a geomagnetic event simulation using a newly developed magnetohydrodynamic with adaptively embedded particle-in-cell (MHD-AEPIC) model. We have developed effective criteria to identify reconnection sites in the magnetotail and cover them with the PIC model. The MHD-AEPIC simulation results are compared with Hall MHD and ideal MHD simulations to study the impacts of kinetic reconnection at multiple physical scales. At the global scale, the three models produce very similar SYM-H and SuperMag Electrojet (SME) indexes, which indicates that the global magnetic field configurations from the three models are very close to each other. We also compare the ionospheric solver results and all three models generate similar polar cap potentials and field aligned currents. At the mesoscale we compare the simulations with in situ Geotail observations in the tail. All three models produce reasonable agreement with the Geotail observations. At the kinetic scales, the MHD-AEPIC simulation can produce a crescent shape distribution of the electron velocity space at the electron diffusion region which agrees very well with MMS observations near a tail reconnection site. These electron scale kinetic features are not available in either the Hall MHD or ideal MHD models. Overall, the MHD-AEPIC model compares well with observations at all scales, it works robustly, and the computational cost is acceptable due to the adaptive adjustment of the PIC domain. It remains to be determined whether kinetic physics can play a more significant role in other types of events, including but not limited to substorms.

The influence of shield wires on Geomagnetically Induced Currents (GICs) in power systems is considered. For the most simple power network, with one single transmission line and one shield wire connecting two substations, we derive the expressions for the voltage source and the resistance of the Thévenin equivalent circuits that, in parallel with the substations grounding resistances, produce the same effects on GICs as the full circuit. Our model extends results from previous studies that considered the effect of shield wires resistances by also including the induced geoelectric field.

Using fully kinetic Particle-In-Cell (PIC) modelling we investigate how magnetic reconnection responds to a varying guide field in one of the inflow regions. We find that the reconnection rate varies significantly when the orientation of the magnetic field changes between being strictly antiparallel and having a guide field. These variations are fairly consistent with the scaling relation for asymmetric reconnection developed by Cassak and Shay (2007). However, the rate is also found to be non-linearly modulated by changes in the ion inflow velocity. The spatio-temporal change in the inflow velocity arises as the magnetic forces reconfigure to regions of different magnetic field strengths. The variations in the inflow magnetic field configuration allow for different gradients in the magnetic field, leading to asymmetries in the magnetic tension force. By momentum conservation, this facilitates asymmetries in the inflow velocity, which in turn affects the flux transport into the reconnection site. The outflow is found to be less laminar when the inflow varies, and various signatures of the inflow variations are identified in the outflow.

Measurements in the heliosphere and high-resolution fluid simulations give clear indications for the anisotropy of plasma turbulence in the presence of magnetic fields. How this anisotropy affects transport processes like diffusion and dispersion remains an open question. The first efforts to characterize Lagrangian single-particle diffusion and two-particle dispersion in incompressible magnetohydrodynamic (MHD) turbulence were performed a decade ago. We revisit those pioneering results through updated simulations performed at higher Reynolds number. We present new investigations that use the dispersion of many Lagrangian tracer particles to examine the extremes of dispersion and the anisotropy in direct numerical simulations. We then point out directions in which Lagrangian statistics need to be developed to address the fundamental problem of anisotropic MHD turbulence and transport in solar and stellar winds.

Jupiter possesses the strongest magnetic field of all planets in the solar system. Unique information about the dynamo process acting at Jupiter can be inferred by modelling and interpreting its field. Using the fluxgate magnetometer measurements acquired during the four years of the Juno mission, we derive an internal and secular magnetic field model in spherical harmonics. The static part is derived to degree 16 with a secular time variation to degree 8. We use properties of the power spectrum of the static field to infer the upper boundary of the dynamo convective region at 0.830±0.022 Jupiter radius. This confirms the role of the transition layer in the field generation inside Jupiter. The secular variation timescales indicate that advective effects dominate the dynamo and the secular variation structures estimated at the dynamo radius suggest that the complex flow involves non-zonal features.

On June 7th, 2021 the Juno spacecraft visited Ganymede and provided the first in situ observations since Galileo’s last flyby in 2000. The measurements obtained along a one-dimensional trajectory can be brought into global context with the help of three-dimensional magnetospheric models. Here we apply the magnetohydrodynamic model of Duling et al. (2014) to conditions during the Juno flyby. In addition to the global distribution of plasma variables we provide mapping of Juno’s position along magnetic field lines, Juno’s distance from closed field lines and detailed information about the magnetic field’s topology. We find that Juno did not enter the closed field line region and that the boundary between open and closed field lines on the surface matches the poleward edges of the observed auroral ovals. To estimate the sensitivity of the model results, we carry out a parameter study with different upstream plasma conditions and other model parameters.

Recent measurements collected by the Mars Curiosity Rover at the Gale Crater revealed an unexpectedly large seasonal cycle of molecular oxygen (O2). We use a 1-D photochemical model, including inorganic and organic chemistry, and its adjoint model to quantify the sensitivity of changes in O2 to changes in inorganic and organic compounds. We show that O2 changes are most sensitive to changes in organic compounds from the oxidation of methane. We find that an accelerated loss of atmospheric methane, achieved either by increasing the atmospheric loss or by imposing an additional surface loss, does not reconcile model and observed values of O2 but it helps to explain the O2 seasonal variation. The resulting changes in atmospheric composition are below the detection limits of orbiting instruments.

The Angstrom-Prescott (A-P) model is widely suggested for estimating solar radiation (Rs) in areas without measured or deficiency of data. The coefficients of this model must be locally calibrated, to calculate evapotranspiration (ET) correctly. The aim of this research was calibration and validation of the coefficients of the A-P model at six meteorological stations across arid and semi-arid regions of Iran. This model was improved by adding the air temperature and relative humidity terms. Besides, the coefficients (’a’ and ‘b’) of the A-P model and improved models was calibrated using some optimization algorithms including Harmony Search (HS) and Shuffled Complex Evolution (SCE). Performance indices, i.e., Root Mean Square Error (RMSE), Mean Bias Error (MBE), and coefficient of determination (R2) were used to analyze the models ability in estimating Rs. The results indicated that the performance of the A-P model had more precision and less error than improved models in all the stations. In addition, the best results were obtained for the A-P model with the SCE algorithm. The RMSE varies between 0.82 and 2.67 MJ m-2 day-1 for the A-P model with the SCE algorithm in the calibration phase. In the SCE algorithm, the values of RMSE had decreased about 4% and 7% for Mashhad and Kerman stations in the calibration phase compared to the HS algorithm, respectively. In other words, the highest decrease of RMSE is related to Kerman station.

Reconstructions for global temperature development show an upward oscillation for the period of the 1880s through 1980s. This oscillation is being associated with natural variability and the temperature rise between the 1910s and 1940s with increased solar activity. The temperature impact of the 11-year solar cycle [Schwabe cycle] and the physical mechanism involved are insufficiently understood. Here, for the 22-year magnetic solar cycle [Hale cycle] a seawater surface temperature [SST] impact is described of 0,215 °C (0,238 ± 0,05 °C per W/m2); the derived impact for the 11-year cycle is 0,122 °C (0,135 ± 0,03 °C per W/m2). Also, a parallel development is described for seawater surface temperature [HadSST3 dataset] and the minima of total solar irradiance [LISIRD dataset] after a correction based on the 22-year solar cycle polarity change. With the correction, the combination of the positive and negative minima shows for the period 1890-1985 a high SST solar sensitivity: 1,143 ± 0,23 °C per W/m2 (with 90,5% declared variance). This implies that the Sun has caused a warming of 1,07 °C between Maunder minimum (late 17th century) and the most recent solar minimum year 2017 - which is well over half of the intermediate temperature rise of approximately 1,5 °C. The results demonstrate that the 22-year cycle forms a crucial factor required for better understanding the Sun-temperature relation. Ignoring the 22-year cycle leads to significant underestimation of the Sun’s influence in climate change combined with an overestimation of the impact of anthropogenic factors and greenhouse gases such as CO2.

Plasma beta is an important parameter characterizing dynamics of various systems such as the solar wind, planetary magnetospheres, and accretion disks. Dependence of some plasma properties such as spectral break, relative proton-electron heating, and intermittency has been studied using observations as well as simulations [1,2,3]. In this study, we use particle-in-cell (PIC) simulations of turbulence to study various, yet unexplored, aspects of this beta variation. We analyze kinetic range electric fields, the variation of scale-to-scale energy transfer, and higher order statistics with respect to plasma beta. Systematic trends in the behavior of various quantities are discussed, and their implications for kinetic plasma dissipation are examined. Finally, we extend this approach to laminar reconnection, which shows turbulence like properties of magnetic spectrum and energy cascade [4,5]. References: Chen, et. al., Geophy. Res. Lett. 41.22 (2014); (https://doi.org/10.1002/2014GL062009) Franci, et. al., ApJ 833 91 (2016); (https://doi.org/10.3847/1538-4357/833/1/91) Parashar, et. al., ApJ Lett. 864 L21 (2018);(https://doi.org/10.3847/2041-8213/aadb8b ) Adhikari, et. al., Phys. of Plasmas 27,042305 (2020); (https://doi.org/10.1063/1.5128376) Adhikari, et. al.(2021); (arXiv:2104.12013)

Santolík, O., Kolmašová, I., Pickett, J. S., & Gurnett, D. A. (2021). Multi-point Observation of Hiss Emerging from Lightning Whistlers. Journal of Geophysical Research: Space Physics, 126, e2021JA029524. https://doi.org/10.1029/2021JA029524

Claims of paleodata periodicity are many and controversial, so that, for example, superimposing Phanerozoic (0–541 My) mass-extinction periods renders life on Earth impossible. This period hunt coincided with the modernization of geochronology, which now ties geological timescales to orbital frequencies. Such tuneup simplifies energy-band (variance-) stratification of information contents, enabling the separation of astronomical signals from harmonics, e.g., using variance-based spectral analysis. I thus show on diverse data (geomagnetic polarity, cratering, extinction episodes) as a proxy of planetary paleodynamics that many-body subharmonic entrainment induces a resonant response of the Earth to astronomical forcing so that the 2π-phase-shifted axial precession p=26 ky, and its Pi=2πp/i; i=1,…,n harmonics, get resonantly responsible for virtually all paleodata periods. This resonantly quasiperiodic nature of strata is co-triggered by a p'/4-lockstep to the p'=41-ky obliquity (also 2π-phase-shifted, to P'=3.5-My superperiod). For verification, residuals analysis after suppressing 2πp (and thus Pi, too) in the current polarity-reversals GPTS-95 timescale’s calibration extending to end-Campanian (0–83 My) successfully detected weak signals of Earth-Mars planetary resonances, reported previously from older epochs. The significant intrinsic residual signal is 26.5-My Rampino period — the carrier wave of crushing deflections co-responsible for transformative polarity reversals. While the (2πp, Pi) resonant response of the Earth to orbital forcing is the long-sought energy transfer mechanism of the Milankovitch theory, fundamental system properties — 2π-phase-shift, ¼ lockstep to a forcer, and the discrete time translation symmetry (multiplied or halved periods) — previously thought confined to (quantum) time crystal, here appear macroscopic, rendering the concept of time crystal unremarkable. In turn, such a surprising cross-scale outcome has confirmed the main result: that of planetary precession being a cataclysmic geodynamic phenomenon as claimed in the past, e.g., as the mechanism for Earth expansion; then a time crystal in quantum dynamics could be due to particle entrainment, such as the collisions resulting in Feshbach resonances.

The explosive eruption of the Hunga-Tonga volcano in the southwest Pacific at 0415UT on 15 January 2022 triggered gigantic atmospheric disturbances with surface air pressure wave propagating around the globe in Lamb mode. In space, concentric traveling ionosphere disturbances (CTIDs) are also observed as a manifestation of air pressure acoustic waves in New Zealand ~0500UT and Australia ~0630UT. As soon as the wave reached central Australia ~0800UT, CTIDs appeared simultaneously in the northern hemispheres through magnetic field line conjugate effect, which is much earlier than the arrival of the air pressure wave to Japan after 1100UT. Combining observations over Australia and Japan between 0800-1000UT, CTIDs with characteristics of phase velocities of 320-390 m/s are observed, matching with the dispersion relation of Lamb mode. The arrival of atmospheric Lamb wave to Japan later created in situ CTIDs showing the same Lamb mode characteristics as the earlier arriving CTIDs.

Shock waves are common in the heliosphere and beyond. The collisionless nature of most astrophysical plasmas allows for the energy processed by shocks to be partitioned amongst particle sub-populations and electromagnetic fields via physical mechanisms that are not well understood. The electrostatic potential across such shocks is frame dependent. In a frame where the incident bulk velocity is parallel to the magnetic field, the deHoffmann-Teller frame, the potential is linked directly to the ambipolar electric field established by the electron pressure gradient. Thus measuring and understanding this potential solves the electron partition problem, and gives insight into other competing shock processes. Integrating measured electric fields is space is problematic since the measurements can have offsets that change with plasma conditions. The offsets, once integrated, can be as large or larger than the shock potential. Here we exploit the high-quality field and plasma measurements from NASA's Magnetospheric Multiscale mission to attempt this calculation. We investigate recent adaptations of the deHoffmann-Teller frame transformation to include time variability, and conclude that in practise these face difficulties inherent in the 3D time-dependent nature of real shocks by comparison to 1D simulations. Potential estimates based on electron fluid and kinetic analyses provide the most robust measures of the deHoffmann-Teller potential, but with some care direct integration of the electric fields can be made to agree. These results suggest that it will be difficult to independently assess the role of other processes, such as scattering by shock turbulence, in accounting for the electron heating.