Low frequency geomagnetic field fluctuations at cap and low latitude during October 29-31, 2003

On October-November 2003 complex interplanetary structures, originated by a series of solar eruptions, hit the Earth, triggering violent Sun-Earth connection events. In this paper we analyze the low frequency geomagnetic field fluctuations detected on the ground during Oct. 29-31, 2003, a time period characterized by extremely high solar wind speed values and by out-of-ecliptic interplanetary magnetic field orientation for intervals of several hours. We analyze geomagnetic field measurements at four high latitude stations located in the polar cap, three in the southern and one in the northern hemisphere. From a comparison with simultaneous measurements at low latitude, we address the question of the global character of the observed phenomena. The results show, for selected time intervals, the occurrence of simultaneous fluctuations at all the stations, with high coherence even between high and low latitude; it is interesting that these fluctuations are detected during open magnetospheric conditions, when the high latitude stations are situated well within the polar cap, i.e. far from closed field lines

Low frequency geomagnetic field fluctuations in Antarctica: comparison between two polar cap stations

We present a statistical analysis of low frequency (~0.5-5 mHz, periods ~3-30 min) geomagnetic field fluctuations at the Antarctic stations Mario Zucchelli Station (TNB, formerly Terra Nova Bay) and Scott Base (SBA), which are located at the same geomagnetic latitude but with 1-hr difference in MLT (Table 1). The two stations are usually in the polar cap, at the footprint of open geomagnetic field lines, but around local geomagnetic noon they approach the polar cusp. This study focuses on the coherence and phase difference between the fluctuations at the two stations. The analysis is based on 1-min values of the horizontal H component measured during the entire years 2001-2002. The coherence and phase difference have been computed for each 2-hours interval with a step-size of 1 hour. Station TNB is run by INGV; data from SBA are provided by INTERMAGNET CD-ROMs. Interplanetary magnetic field (IMF) and solar wind (SW) data from ACE spacecraft have been downloaded from OMNI database. Interplanetary data have been delayed by 1 hour to take into account the average SW transit time from ACE to Earth

The Earth’s passage of coronal mass ejecta on October 29-31, 2003: ULF geomagnetic field fluttuations at very high latitude

We study ULF geomagnetic field fluctuations detected on October 29-31, 2003, when the Earth’s arrival of solar wind CMEs produced major geomagnetic storms; these solar wind structures are characterized by extremely high plasma speed and long-duration intervals with northward interplanetary magnetic field. The analyzed geomagnetic field data are from four high latitude stations (three in Antarctica), located deep in the polar cap. The analysis is extended also to low latitude European stations, in order to discriminate between local and global magnetospheric phenomena

Twenty years of geomagnetic field observations at Mario Zucchelli Station (Antarctica)

During the 1986-87 austral summer a geomagnetic observatory was installed at Terra Nova Bay. During the first years both geomagnetic field time variation monitoring and absolute measurements were carried out only during summer. Since 1991 variometer measurements are automatically performed during the whole year, while absolute measurements are still performed only during summer. In spite of this, interesting observations were obtained during the life (quite long for Antarctica) of the geomagnetic observatory. In particular in this paper some of the most relevant results are briefly presented: studies about secular variation, daily variation (and its dependence from solar cycle and seasons) and geomagnetic higher frequency variations, such as geomagnetic pulsations

Twenty years of geomagnetic field observations at Mario Zucchelli Station (Antarctica)

During the 1986-87 austral summer a geomagnetic observatory was installed at Terra Nova Bay. During the first years both geomagnetic field time variation monitoring and absolute measurements were carried out only during summer. Since 1991 variometer measurements are automatically performed throughout the year, while absolute measurements are still performed only during summer. In spite of this, interesting observations were obtained during the life (quite long for Antarctica) of the geomagnetic observatory. In particular, this paper briefly presents some of the most important results: studies on secular variation, daily variation (and its dependence from solar cycle and seasons) and geomagnetic higher frequency variations, such as geomagnetic pulsations

The contribution of geomagnetic observatories and magnetic models to the study of secular variation and jerks in Antarctica

Some of the most interesting features of the geomagnetic field and its time variations are displayed in polar areas. Observatory monthly means usually provide an excellent opportunity to study the temporal changes of the magnetic field at a given location. Unfortunately, on the Antarctic continent the distribution of the permanent ground- based observatories does not permit a uniform coverage of the examined area. Furthermore, the magnetic records are characterized by intense external disturbances and noise that make the analysis of the magnetic field difficult. To improve our knowledge of the secular variation and detect the presence of secular variation impulses (geomagnetic jerks) in Antarctica, we use both observatory data and the CM4 quiet time magnetic field model. In particular CM4 improves our knowledge of geomagnetic jerks over Antarctica through the study of the sign changes of the secular acceleration maps

Geomagnetic field observations in Antarctica at the geomagnetic observatories at Terra Nova Bay and DomeC

During the 1986-87 austral summer a geomagnetic observatory was installed at the Italian Antarctic Base Mario Zucchelli Station (TNB, geographic coordinates:74.7S, 164.1E; corrected geomagnetic coordinates: 80.0S, 307.7E; magnetic local time MLT=UT-8). In the first years the measurements of the geomagnetic field were carried out only during summer expeditions. Since 1991 the recording was implemented with an automatic acquisition system operating through the year. More recently,after two short test surveys, from October 2004 a geomagnetic French-Italian observatory was installed on the Antarctic plateau (Dome C, DMC), very close to the geomagnetic pole (geographic coordinates: 75.1S, 123.4E; corrected geomagnetic coordinates:88.8S, 55.6E; magnetic local time MLT=UT-1). In this work we present some results obtained from TNB observations coming from almost twenty years of observations and also the preliminary results obtained from the analysis of the first year of data from DMC

EARTH'S MAGNETISM AT THE SOUTH POLE: A VIEW FROM INLAND AND COASTAL STATIONS AND FROM TEMPORARY INSTALLATIONS

Contributions to the knowledge of the Earth’s magnetism from polar regions is extremely important to understand the planetary phenomena which occur both below and above the Earth’s surface. At those areas the Earth’s magnetic field is stronger and the spatial and temporal changes are enhanced. At the same time polar regions are areas scarcely covered by observations for the adverse environmental conditions. We report the experience gained in years of management and maintenance of permanent stations (Mario Zucchelli, Dumont d’Urville (Victoria Land) and Concordia stations, Dome C) as well as temporary installations (Talos Dome) in Antarctica, showing how different acquisition systems, analysis and interpretation of data allow the scientific communities to contribute to originating important theories, models and results

Ground magnetometric surveys end integrated geophysical methods for solid buried waste detection: a case study

The detection of illegal buried waste by means of geophysical techniques has recently become a major effort in shallow geophysical investigations. In particular, detection and location of underground metallic storage tanks can be accomplished using different instruments and techniques. In this paper we describe the results of an investigation carried out in a tuff quarry in Riano Flaminio (north Rome, Italy). A preliminary magnetometric survey revealed the existence of anomalous zones in the analysed region. Excavation in some of the selected areas confirmed that the anomalies were generated by underground magnetic material: over 160 steel drums were found. After their removal, a new magnetometric survey was performed. On the basis of the new map, a multifrequency induction survey, a geoelectrical profile and GPR measurements were taken to extend the characterization of the subsoil

The Kinetic Interpretation of the DGLAP Equation, its Kramers-Moyal Expansion and Positivity of Helicity Distributions

According to a rederivation - due to Collins and Qiu - the DGLAP equation can be reinterpreted (in leading order) in a probabilistic way. This form of the equation has been used indirectly to prove the bound $|\Delta f(x,Q)| < f(x,Q)$ between polarized and unpolarized distributions, or positivity of the helicity distributions, for any $Q$. We reanalize this issue by performing a detailed numerical study of the positivity bounds of the helicity distributions. To obtain the numerical solution we implement an x-space based algorithm for polarized and unpolarized distributions to next-to-leading order in $\alpha_s$, which we illustrate. We also elaborate on some of the formal properties of the Collins-Qiu form and comment on the underlying regularization, introduce a Kramers-Moyal expansion of the equation and briefly analize its Fokker-Planck approximation. These follow quite naturally once the master version is given. We illustrate this expansion both for the valence quark distribution $q_V$ and for the transverse spin distribution $h_1$.Comment: 38 pages, 27 figures, Dedicated to Prof. Pierre Ramond for his 60th birthda