Radio Echo Sounding (RES) investigations at Talos Dome (East Antarctica): bedrock topography and ice thickness

Radio echo sounding measurements were collected during two Antarctic expeditions to determine the ice thickness and the sub-glacial morphology of Talos Dome in the region around 72°48'S; 159°06'E (about 6400 km2) on the edge of the East Antarctic plateau adjacent to Victoria Land in the western Ross Sea sector. The increasing interest in this region is due to the fact that in this area the ice accumulation is higher than in other sites in East Antarctica. Because of this, Talos Dome could be a new site for a project of a deep ice core drilling to obtain information on climate changes near the coast of Antarctica. In this frame, the knowledge of the bedrock topography is of great importance to choose the best location for the drilling site. In this paper, airborne radio echo sounding results from two Antarctic expeditions (1997 and 1999) are presented. Bedrock topography in bi- and three-dimensions for the Talos Dome region are discussed

From the Sun to Earth: effects of the 25 August 2018 geomagnetic storm

Abstract. On 25 August 2018 the interplanetary counterpart of the 20 August 2018 coronal mass ejection (CME) hit Earth, giving rise to a strong G3 geomagnetic storm. We present a description of the whole sequence of events from the Sun to the ground as well as a detailed analysis of the observed effects on Earth's environment by using a multi-instrumental approach. We studied the ICME (interplanetary-CME) propagation in interplanetary space up to the analysis of its effects in the magnetosphere, ionosphere and at ground level. To accomplish this task, we used ground- and space-collected data, including data from CSES (China Seismo-Electric Satellite), launched on 11 February 2018. We found a direct connection between the ICME impact point on the magnetopause and the pattern of Earth's auroral electrojets. Using the Tsyganenko TS04 model prevision, we were able to correctly identify the principal magnetospheric current system activating during the different phases of the geomagnetic storm. Moreover, we analysed the space weather effects associated with the 25 August 2018 solar event in terms of the evaluation of geomagnetically induced currents (GICs) and identification of possible GPS (Global Positioning System) losses of lock. We found that, despite the strong geomagnetic storm, no loss of lock had been detected. On the contrary, the GIC hazard was found to be potentially more dangerous than other past, more powerful solar events, such as the 2015 St Patrick's Day geomagnetic storm, especially at latitudes higher than 60∘ in the European sector

A functional calcium-transporting ATPase encoded by chlorella viruses

Calcium-transporting ATPases (Ca2+ pumps) are major players in maintaining calcium homeostasis in the cell and have been detected in all cellular organisms. Here, we report the identification of two putative Ca2+ pumps, M535L and C785L, encoded by chlorella viruses MT325 and AR158, respectively, and the functional characterization of M535L. Phylogenetic and sequence analyses place the viral proteins in group IIB of P-type ATPases even though they lack a typical feature of this class, a calmodulin-binding domain. A Ca2+ pump gene is present in 45 of 47 viruses tested and is transcribed during virus infection. Complementation analysis of the triple yeast mutant K616 confirmed that M535L transports calcium ions and, unusually for group IIB pumps, also manganese ions. In vitro assays show basal ATPase activity. This activity is inhibited by vanadate, but, unlike that of other Ca2+ pumps, is not significantly stimulated by either calcium or manganese. The enzyme forms a 32P-phosphorylated intermediate, which is inhibited by vanadate and not stimulated by the transported substrate Ca2+, thus confirming the peculiar properties of this viral pump. To our knowledge this is the first report of a functional P-type Ca2+-transporting ATPase encoded by a virus

The ISIS Project: Indications for Future Near-Earth Plasma Studies through Future Galileo Satellites

The Earth’s plasmasphere variability is a consequence of the Sun’s forcing, determining our planet’s space weather. Plasmaspheric dynamics could be entirely caught only by studying together global and local proxies of the state of this extended system. The ISIS project (Inter-Satellite & In Situ plasmaspheric monitoring and modelling) aimed to design a system for the continuous monitoring of the Earth’s plasmasphere based on the future Galileo satellites. The efforts and expertise of ISC-CNR (Institute for Complex Systems of the National Research Council of Italy), INGV (Istituto Nazionale di Geofisica e Vulcanologia) and TAS-I (Thales Alenia Space - Italy) were put together in this work of assessment. ISIS Team proposed new experimental facilities of the Galileo satellites, designed to realize inter-satellite and in situ measurements to monitor global and local quantities; in particular, a scalable system of Langmuir probes was suggested, while the TEC along all possible inter-satellite ray paths throughout the plasmasphere could be monitored via phase- and group-delay analysis of inter-satellite radio signals

Geophysical survey at Talos Dome, East Antarctica: the search for a new deep-drilling site

Talos Dome is an ice dome on the edge of the East Antarctic plateau; because accumulation is higher here than in other domes of East Antarctica, the ice preserves a good geochemical and palaeoclimatic record. A new map of the Talos Dome area locates the dome summit using the global positioning system (GPS) (72˚47’ 14’’S, 159˚04’ 2’’E; 2318.5m elevation (WGS84)). A surface strain network of nine stakes was measured using GPS. Data indicate that the stake closest to the summit moves south-southeast at a few cma–1. The other stakes, located 8 km away, move up to 0.33ma–1. Airborne radar measurements indicate that the bedrock at the Talos Dome summit is about 400m in elevation, and that it is covered by about 1900m of ice. Snow radar and GPS surveys show that internal layering is continuous and horizontal in the summit area (15 km radius). The depth distribution analysis of snow radar layers reveals that accumulation decreases downwind of the dome (north-northeast) and increases upwind (south-southwest). The palaeomorphology of the dome has changed during the past 500 years, probably due to variation in spatial distribution of snow accumulation, driven by wind sublimation. In order to calculate a preliminary age vs depth profile for Talos Dome, a simple one-dimensional steady-state model was formulated. This model predicts that the ice 100m above the bedrock may cover one glacial–interglacial period.Published423-4323.8. Geofisica per l'ambienteJCR Journalreserve

The ISIS Project: Indications for Future Near-Earth Plasma Studies through Future Galileo Satellites

The Earth’s plasmasphere variability is a consequence of the Sun’s forcing, determining our planet’s space weather. Plasmaspheric dynamics could be entirely caught only by studying together global and local proxies of the state of this extended system. The ISIS project (Inter-Satellite & In Situ plasmaspheric monitoring and modelling) aimed to design a system for the continuous monitoring of the Earth’s plasmasphere based on the future Galileo satellites. The efforts and expertise of ISC-CNR (Institute for Complex Systems of the National Research Council of Italy), INGV (Istituto Nazionale di Geofisica e Vulcanologia) and TAS-I (Thales Alenia Space - Italy) were put together in this work of assessment. ISIS Team proposed new experimental facilities of the Galileo satellites, designed to realize inter-satellite and in situ measurements to monitor global and local quantities; in particular, a scalable system of Langmuir probes was suggested, while the TEC along all possible inter-satellite ray paths throughout the plasmasphere could be monitored via phase- and group-delay analysis of inter-satellite radio signals.Published1A. Geomagnetismo e Paleomagnetismo2A. Fisica dell'alta atmosferaN/A or not JCRope

The ISIS Project: Indications for Future Near-Earth Plasma Studies through Future Galileo Satellites

The Earth’s plasmasphere variability is a consequence of the Sun’s forcing, determining our planet’s space weather. Plasmaspheric dynamics could be entirely caught only by studying together global and local proxies of the state of this extended system. The ISIS project (Inter-Satellite & In Situ plasmaspheric monitoring and modelling) aimed to design a system for the continuous monitoring of the Earth’s plasmasphere based on the future Galileo satellites. The efforts and expertise of ISC-CNR (Institute for Complex Systems of the National Research Council of Italy), INGV (Istituto Nazionale di Geofisica e Vulcanologia) and TAS-I (Thales Alenia Space - Italy) were put together in this work of assessment. ISIS Team proposed new experimental facilities of the Galileo satellites, designed to realize inter-satellite and in situ measurements to monitor global and local quantities; in particular, a scalable system of Langmuir probes was suggested, while the TEC along all possible inter-satellite ray paths throughout the plasmasphere could be monitored via phase- and group-delay analysis of inter-satellite radio signals

Reversals in nature and the nature of reversals

The asymmetric shape of reversals of the Earth's magnetic field indicates a possible connection with relaxation oscillations as they were early discussed by van der Pol. A simple mean-field dynamo model with a spherically symmetric $\alpha$ coefficient is analysed with view on this similarity, and a comparison of the time series and the phase space trajectories with those of paleomagnetic measurements is carried out. For highly supercritical dynamos a very good agreement with the data is achieved. Deviations of numerical reversal sequences from Poisson statistics are analysed and compared with paleomagnetic data. The role of the inner core is discussed in a spectral theoretical context and arguments and numerical evidence is compiled that the growth of the inner core might be important for the long term changes of the reversal rate and the occurrence of superchrons.Comment: 24 pages, 12 figure