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.
This editorial aims to improve awareness of the current best practices in open research, and stimulate discussion on the practical implementation of AGU's data and software policy in key areas of space weather research. We also further aim to encourage authors to take additional steps to ensure clear credit to all contributors to the work, whether that is underlying data, key software, or direct contributions to the manuscript.
Venus today is inhospitable at the surface, its average temperature of 750 K being incompatible to the existence of life as we know it. However, the potential for past surface habitability and upper atmosphere (cloud) habitability at the present day is hotly debated, as the ongoing discussion regarding a possible phosphine signature coming from the clouds shows. We review current understanding about the evolution of Venus with special attention to scenarios where the planet may have been capable of hosting microbial life. We compare the possibility of past habitability on Venus to the case of Earth by reviewing the various hypotheses put forth concerning the origin of habitable conditions and the emergence and evolution of plate tectonics on both planets. Life emerged on Earth during the Hadean when the planet was dominated by higher mantle temperatures (by about 200$^\circ$C), an uncertain tectonic regime that likely included squishy lid/plume-lid and plate tectonics, and proto continents. Despite the lack of well-preserved crust dating from the Hadean-Paleoarchean eons, we attempt to resume current understanding of the environmental conditions during this critical period based on zircon crystals and geochemical signatures from this period, as well as studies of younger, relatively well-preserved rocks from the Paleoarchean. For these early, primitive life forms, the tectonic regime was not critical but it became an important means of nutrient recycling, with possible consequences to the global environment on the long-term, that was essential to the continuation of habitability and the evolution of life. For early Venus, the question of stable surface water is closely related to tectonics. We discuss potential transitions between stagnant lid and (episodic) tectonics with crustal recycling, as well as consequences for volatile cycling between Venus’ interior and atmosphere. In particular, we review insights into Venus’ early climate and examine critical questions about early rotation speed, reflective clouds, and silicate weathering, and summarize implications for Venus’ long-term habitability. Finally, the state of knowledge of the venusian clouds and the proposed detection of phosphine is covered.
Recently, many in the space weather community have taken up the cause to advocate for an orphan among our own. It’s an important fight – for ground-based sensor networks. Although ground-based sensors are used across all disciplines of space weather, in terms of long-term support, they have no single clear home in any United States agency or department. This has resulted in an ongoing struggle throughout the community to maintain important space weather sensors and networks.The Promoting Research and Observations of Space Weather to Improve the Forecasting of Tomorrow (PROSWIFT) Act of 2020 (Public Law 116-181) attempts to clarify Federal roles and responsibilities, stating that “… ground-based observations provide crucial data necessary to understand, forecast, and prepare for space weather phenomena”, which it defines as ”radars, lidars, magnetometers, neutron monitors, radio receivers, aurora and airglow imagers, spectrometers, interferometers, and solar observatories.”The data from this list of sensors and arrays support research across the space weather domains, including magnetospheric, ionospheric, and atmospheric science. Networks are run by governmental, academic, and commercial providers, and are used to support a range of end-users, from aviation to the power sector. Given the wide range of applications, it’s not surprising that no single entity has primary custody.In separate sections of PROSWIFT, sustainment of these instruments is assigned to “The Director of the National Science Foundation, the Director of the United States Geological Survey, the Secretary of the Air Force, and, as practicable in support of the Air Force, the Secretary of the Navy” who are directed to “maintain and improve ground-based observations of the Sun, as necessary and advisable”, and also to the National Oceanic and Atmospheric Administration (NOAA), as the civil operational space weather agency that is responsible for maintaining “ground-based… assets to provide observations needed for space weather forecasting, prediction, and warnings”.While PROSWIFT’s clarification of federal responsibilities is welcome, what is highlighted is a problem of the “ownership” of the issue of long-term sustainability of such varied instruments.We can start to unravel the ownership problem by understanding its history. One complication to an easy definition is that ground-based sensor networks support both space weather science and operations. The National Science Foundation (NSF) has a long history of supporting novel instrument development, small arrays of sensors placed for scientific research (fundamental research is the foundation of NSF’s mandate), and mid- and larger-scale facilities. But the needs of science do not necessarily intersect the needs of operations, and neither do their requirements in terms of engineering and support. Operational sensors, in many cases, are entirely different than scientific sensors.Like scientific arrays, operational sensors must provide the “right” data - accurate and relevant – but the delivery of those data must also be timely, consistent, and reliable. In other words, the data must be usable for space weather predictions, forecasts, and alerts. The United States Geological Survey (USGS) is one example of a federal provider of operational ground-based data. The commercial sector, by mandate of PROSWIFT, is another.Whether scientific or operational, ground-based networks need to be supported and maintained long-term to fulfill their missions. It is more expensive to shut down and rebuild an array than to keep it operating, and strategic planning is required to prioritize and balance needs across the space weather enterprise.Those taking up the initiative to support ground-based sensors span the space weather enterprise, reflecting the interdisciplinary and cross-sector need for these data. In addition to a myriad of white papers submitted to the Heliophysics Decadal Survey (e.g., Hartinger et al., and Bhatt et al.) and publications (see Engebretson and Zesta, 2017, and Bain et al., 2023), advisory groups such as the Space Weather Advisory Group (SWAG) and the National Academies Space Weather Roundtable, both put into place by the PROSWIFT Act itself, have taken up the cause. The SWAG, in a public meeting on March 20, 2023 (https://www.weather.gov/swag), called for a “paradigm shift”, agreeing upon a recommendation that there is a need “Provide long-term support for operational ground-based and airborne sensors and networks”.It’s clear that these data are crucial for space weather – both space weather research and operations. With the approach of solar maximum, and the associated rise in space weather hazard, what’s less clear is whether this problem will be solved in time. The community efforts have been effective in raising awareness about the dire situation facing many ground-based sensor networks. What is needed now is a mechanism to maintain these networks long-term, and advocacy for new Federal appropriations to support the organizations that take on the responsibility.
Extreme solar particle events (ESPEs) are rare and the most potent known processes of solar eruptive activity. During ESPEs, a vast amount of cosmogenic isotopes (CIs) 10Be, 36Cl and 14C can be produced in the Earth’s atmosphere. Accordingly, CI measurements in natural archives allow us to evaluate particle fluxes during ESPEs. In this work, we present a new method of ESPE fluence (integral flux) reconstruction based on state-of-the-art modeling advances, allowing to fit together different CI data within one model. We represent the ESPE fluence as an ensemble of scaled fluence reconstructions for ground-level enhancement (GLE) events registered by the neutron monitor network since 1956 coupled with satellite and ionospheric measurements data. Reconstructed ESPE fluences appear softer in its spectral shape than earlier estimates, leading to significantly higher estimates of the low-energy (E<100 MeV) fluence. This makes ESPEs even more dangerous for modern technological systems than previously believed. Reconstructed ESPE fluences are fitted with a modified Band function, which eases the use of obtained results in different applications.
The polar cap can become teardrop shaped through the poleward expansion of the dusk and dawn sectors of the auroral oval, to form what is called horse collar aurora (HCA). The formation of HCA has been linked to dual-lobe reconnection (DLR) where magnetic flux is closed at the dayside magnetopause. A prolonged period of northward IMF is required for the formation of HCA. HCA have previously been identified in UV images captured by the Special Sensor Ultraviolet Spectrographic Imager (SSUSI) instrument on-board the Defense Meteorological Satellite Program (DMSP) spacecraft F16, F17 and F18. Events that have concurrent 630.0 nm all-sky camera (ASC) data from the Redline Geospace Observatory (REGO) Resolute Bay site are now studied in more detail, making use of the higher cadence of the ASC images compared to DMSP/SSUSI. 11 HCA events are studied and classified based on the IMF conditions at the end of the event. Five of the events were found to end via a southward turning of the IMF, two end with positive By dominated IMF and four with negative By dominance. Under positive (negative) By the arcs move duskward (dawnward) in the northern hemisphere with the opposite true in the southern hemisphere. Under a southward turning the arcs move equatorward. One event is of particular interest as it occurred while there was a transpolar arc (TPA) also present. Understanding the evolution of HCA will allow DLR to be studied in more detail.
The interaction of Io with the co-rotating magnetosphere of Jupiter is known to produce Alfven wings that couple the moon to Jupiter's ionosphere. We present first results from a new numerical model to describe the propagation of these Alfven waves in this system. The model is cast in magnetic dipole coordinates and includes a dense plasma torus that is centered around the centrifugal equator. Results are presented for two density models, showing the dependence of the interaction on the magnetospheric density. Model results are presented for the case when Io is near the centrifugal and magnetic equators as well as when Io is at its northernmost magnetic latitude. The effect of the conductance of Jupiter's ionosphere is considered, showing that a long auroral footprint tail is favored by high Pedersen conductance in the ionosphere. The current patterns in these cases show a U-shaped footprint due to the generation of field-aligned current on the Jupiter-facing and Jupiter-opposed sides of Io, which may be related to the structure in the auroral footprint seen in the infrared by Juno. A model for the development of parallel electric fields is introduced, indicating that the main auroral footprints of Io can generate parallel potentials of up to 100 kV.
The propagating muons deposit their energies in the volume-of-interest (VOI) within the tomographic configurations, and this energy loss directly indicates that there is a difference in terms of the kinetic energy between the incoming muons and the the outgoing muons. In this study, by using the GEANT4 simulations, we first elaborate this energy difference over the nuclear waste barrels that contain cobalt, strontium, caesium, uranium, and plutonium. We show that the deposited energy through these VOIs is not negligible for the initial energy bins. Then, we suggest a correction factor for the image reconstruction codes where the initial kinetic energy of the entering muons is coarsely predicted in accordance with the deflection angle through the hodoscope sections, thereby renormalizing the deflection angle in the bottom hodoscope depending on the intrinsic properties of the corresponding VOIs. This correction factor encompasses useful information about the target volume traversed by the muons since it is related to the intrinsic features of the VOI. Therefore, it might be utilized in order to complement the scattering information as an input to the image reconstruction.
Space weather phenomena occur from the Sun to the Earth with damaging impacts on ground-based and space-borne technological infrastructure. The geomagnetic auroral electrojet indices, AU, AL, and AE, have been widely used for monitoring space weather and geomagnetic activities during space storms and substorms. The time series data of solar wind monitored by upstream satellite and ground-based auroral electrojet indices form the input-output system characterizing the dynamic coupling among solar wind, Earth’s magnetosphere, and ionosphere. The data-driven predictions of auroral electrojet indices during geomagnetic storms and substorms face the challenges of capturing the variations of ionospheric electrojet current driven by multiple solar wind variables and are modeled as a coupled complex system with finite and variable memory. The recurrent neural network (RNN) based Long Short-Term Memory (LSTM) machine learning algorithm is well suited to classify, process, and make predictions of the coupled solar wind-magnetosphere-ionosphere system by preserving important information from earlier parts of the coupled time series and carrying it forward. In this study, an RNN-based LSTM model has been built to predict the time series of AE/AL indices with multi-variate solar wind inputs. Both 5-minute and hourly long-term time series data from the NASA OMNI database were used to drive the LSTM model. The coupled time series data are divided into training and testing datasets. The Root-Mean-Square-Error (RMSE) between the predicted and actual AE/AL indices of the testing sets was used to evaluate the roles of the number of layers in the LSTM, memory length of the coupled system, prediction time, and different combinations of solar wind input parameters (magnetic field, velocity, and density). The performance of the LSTM model in predicting AL/AE indices during major geomagnetic storm and substorm events is analyzed. The differences and challenges of applying LSTM to predict 5-min and hourly AE/AL indices are also discussed.
Electron temperature anisotropy-driven instabilities such as the electron firehose instability (EFI) are especially significant in space collisionless plasmas, where collisions are so scarce that wave-particle interactions are the leading mechanisms in the isotropization of the distribution function and energy transfer. Observational statistical studies provided convincing evidence in favor of the EFI constraining the electron distribution function and limiting the electron temperature anisotropy. Magnetic reconnection is characterized by regions of enhanced temperature anisotropy that could drive instabilities – including the electron firehose instability – affecting the particle dynamics and the energy conversion. However, in situ observations of the fluctuations generated by the EFI are still lacking and the interplay between magnetic reconnection and EFI is still largely unknown. In this study, we use high-resolution in situ measurements by the Magnetospheric Multiscale (MMS) spacecraft to identify and investigate EFI fluctuations in the magnetic reconnection exhaust in the Earth’s magnetotail. We find that the wave properties of the observed fluctuations largely agree with theoretical predictions of the non-propagating EF mode. These findings are further supported by comparison with the linear kinetic dispersion relation. Our results demonstrate that the magnetic reconnection outflow can be the seedbed of EFI and provide the first direct in situ observations of EFI-generated fluctuations.
As a rule, the phase velocity of unstable Farley-Buneman waves is found not to exceed the ion-acoustic speed, cs. However, there are known exceptions: under strong electric field conditions, much faster Doppler shifts than expected cs values are sometimes observed with coherent radars at high latitudes. These Doppler shifts are associated with narrow spectral width situations. To find out how much faster than cs these Doppler shifts might be, we developed a proper cs model as a function of altitude and electric field strength based on ion frictional heating and on a recently developed empirical model of the electron temperature under strong electric field conditions. Motivated by the ‘narrow fast’ observations, we then explored how ion drifts in the upper part of the unstable region could add to the Doppler shift observed with coherent radars. While there can be no ion drift contribution for the most unstable modes, and therefore no difference with cs for such modes, under strong electric field conditions, a large ion drift contribution of either sign needs to be added to the Doppler shift of more weakly unstable modes, turning them into ‘fast-‘ or ‘slow-’ narrow spectra. Particularly between 110 and 115 km, the ion drift can alter the Doppler shift of the more weakly unstable modes by several 100 m/s, to the point that their largest phase velocities could approach the ambient E x B drift itself.
Models of the high-latitude ionospheric electric field are commonly used to specify the magnetospheric forcing in thermosphere or whole atmosphere models. The use of decades-old models based on spacecraft data is still widespread. Currently the Heelis and Weimer climatology models are most commonly used but it is possible a more recent electric field model could improve forecasting functionality. Modern electric field models, derived from radar data, have been developed to incorporate advances in data availability. It is expected that climatologies based on this larger and up-to-date dataset will better represent the high latitude ionosphere and improve forecasting abilities. An example of two such models, which have been developed using line-of-sight velocity measurements from the Super Dual Auroral Radar Network (SuperDARN) are the Thomas and Shepherd model (TS18), and the Time-Variable Ionospheric Electric Field model (TiVIE). Here we compare the outputs of these electric field models during the September 2017 storm, covering a range of solar wind and interplanetary magnetic field (IMF) conditions. We explore the relationships between the IMF conditions and the model output parameters such as transpolar voltage, the polar cap size and the lower latitude boundary of convection. We find that the electric potential and field parameters from the spacecraft-based models have a significantly higher magnitude than the SuperDARN-based models. We discuss the similarities and differences in topology and magnitude for each model.
We built an integrated nonlinear analysis software -INA- designed to study space plasma turbulence and intermittency. The MATLAB programming environment was used for the algorithmic development and implementation of methods for spectral analysis, multiscale fluctuations and multifractal analysis. The performance of INA is demonstrated using magnetic field measurements from the Cluster 3 spacecraft during an inbound pass through the Earth’s magnetosheath region. We show how specific features of the power spectral density (PSD) can be mapped to localised time-frequency regions in the spectrogram representation, and identify multiple intermittent events using the wavelet-based local intermittency measure (LIM). Multiscale probability density functions (PDFs) showed clear departures from Gaussianity, signifying the presence of intermittency. Structure functions (SFs) and rank-ordered multifractal analysis (ROMA) revealed the multifractal nature of the analysed signal. INA is freely distributed as a standalone executable file to any interested user, and provides an integrated, interactive, and user-friendly environment in which one can import a dataset, customize key analysis parameters, apply multiple methods on the same signal and then export high-quality, publication-ready figures. These are only a few of the many distinguishing features of INA.
Sexual harassment in STEM continues to be a pervasive barrier to women’s full participation in the sciences. Many studies conclude that workplace culture and lack of clear policies and practices exacerbate the risks of sexual harassment. Remote research environments, such as field stations and ocean platforms, bring additional risk to researchers. Participants already face acute safety concerns related to the remoteness of the field station or oceanographic vessels, fewer and less clear policies and enforcement regulations are in place, and multiple institutions bear responsibility, leading to a challenging environment for preventing and handling incidents. This workshop explored the factors that permit sexual harassment in remote research, and aimed to develop practices to prevent and respond to harassment in the field. The California State University Desert Studies Center and the Center for Ocean Leadership convened workshop in March, 2021 to address sexual harassment in field science. Over three days, field and ocean science leadership and practitioners came together with leadership from professional societies and academia, and experts in sociology, policy, and social justice. The goals were to: 1) open a dialogue between sexual harassment experts and the field research community to develop best practices and recommendations; 2) build coordination and consistency in policy setting and enforcement across field stations and oceanographic platforms; 3) develop processes to monitor the reporting of sexual harassment instances occurring at remote field locations; and 4) promote a safe culture for scientists conducting research at remote field stations and on oceanographic vessels. The workshop compiled and developed best practices and recommendations in four key areas: 1) culture change, 2) policy, 3) accountability, and 4) reporting. These recommendations were targeted at all facets of field and ocean sciences, from academic and research institutions, professional societies, and funding agencies, to departments and field research crews. Here we will give an overview of the workshop findings, with particular focus on the recommendations for research leadership.
On December 04, 2021, a total solar eclipse occurred over west Antarctica. Nearly an hour beforehand, a geomagnetic substorm onset was observed in the northern hemisphere. Eclipses are suggested to influence magnetosphere-ionosphere (MI) coupling dynamics by altering the conductivity structure of the ionosphere by reducing photoionization. This sudden and dramatic change in conductivity is not only likely to alter global MI coupling, but it may also introduce a variety of localized instabilities that appear in both hemispheres. Global navigation satellite system (GNSS) based observations of the total electron content (TEC) in the southern high latitude ionosphere during the December 2021 eclipse show signs of wave activity coincident with the eclipse peak totality. Ground magnetic observations in the same region show similar activity, and our analysis suggest that these observations are due to an “eclipse effect” rather than the prior substorm. We present the first multi-point interhemispheric study of a total south polar eclipse with local TEC observational context in support of this conclusion.
We present in-depth analysis of three southward-moving meso-scale (ion- to magnetohydrodynamic-scale) flux transfer events (FTEs) and subsequent crossing of a reconnecting electron-scale current sheet (ECS), which were observed on 8 December 2015 by the Magnetospheric Multiscale spacecraft near the subsolar magnetopause under southward and duskward magnetosheath magnetic field conditions. Our aims are to understand the generation mechanism of ion-scale magnetic flux ropes (ISFRs) and to reveal causal relationship among magnetic structures of the ECS, electromagnetic energy conversion, and kinetic processes in magnetic reconnection layers. Magnetic field reconstruction methods show that a flux rope with a length of about one ion inertial length existed and was growing in the ECS, supporting the idea that ISFRs can be generated from secondary magnetic reconnection in ECS. Grad-Shafranov reconstruction applied to the three FTEs shows that the FTE flux ropes had axial orientations similar to that of the ISFR in the ECS. This suggests that these FTEs also formed through the same secondary reconnection process, rather than multiple X-line reconnection at spatially separated locations. Four-spacecraft observations of electron pitch-angle distributions and energy conversion rate suggest that the ISFR had three-dimensional magnetic topology and secondary reconnection was patchy or bursty. Previously reported positive and negative values of , with magnitudes much larger than expected for typical magnetopause reconnection, were seen in both magnetosheath and magnetospheric separatrix regions of the ISFR. Many of them coexisted with bi-directional electron beams and intense electric field fluctuations around the electron gyrofrequency, consistent with their origin in separatrix activities.