Search results for "lcsh:QC801-809"
showing 10 items of 42 documents
The marine activities performed within the TOMO-ETNA experiment
2016
<p>The TOMO-ETNA experiment was planned in order to obtain a detailed geological and structural model of the continental and oceanic crust beneath Mt. Etna volcano and northeastern Sicily up to the Aeolian Islands (southern Italy), by integrating data from active and passive refraction and reflection seismic methodologies, magnetic and gravity surveys. This paper focuses on the marine activities performed within the experiment, which have been carried out in the Ionian and Tyrrhenian Seas, during three multidisciplinary oceanographic cruises, involving three research vessels (“Sarmiento de Gamboa”, “Galatea” and “Aegaeo”) belonging to different countries and institutions. During the o…
A Fast Imaging Technique Applied to 2D Electrical Resistivity Data
2014
A new technique is proposed to process 2D apparent resistivity datasets, in order to obtain a fast and contrasted resistivity image, useful for a rapid data check in field or as a starting model to constrain the inversion procedure. In the past some modifications to the back-projection algorithm, as well as the use of filtering techniques for the sensitivity matrix were proposed. An implementation of this technique is proposed here, considering a two-step approach. Initially a damped least squares solution is obtained after a full matrix inversion of the linearized geoelectrical problem. Furthermore, on the basis of the results, a subsequent filtering algorithm is applied to the Jacobian ma…
Multimessenger Binary Mergers Containing Neutron Stars: Gravitational Waves, Jets, and γ-Ray Bursts
2021
Neutron stars (NSs) are extraordinary not only because they are the densest form of matter in the visible Universe but also because they can generate magnetic fields ten orders of magnitude larger than those currently constructed on earth. The combination of extreme gravity with the enormous electromagnetic (EM) fields gives rise to spectacular phenomena like those observed on August 2017 with the merger of a binary neutron star system, an event that generated a gravitational wave (GW) signal, a short γ-ray burst (sGRB), and a kilonova. This event serves as the highlight so far of the era of multimessenger astronomy. In this review, we present the current state of our theoretical understand…
Multi-point galactic cosmic ray measurements between 1 and 4.5 AU over a full solar cycle
2019
The radiation data collected by the Standard Radiation Environment Monitor (SREM) aboard ESA missions INTEGRAL (INTErnational Gamma-Ray Astrophysics Laboratory), Rosetta, Herschel, Planck and Proba-1, and by the high-energy neutron detector (HEND) instrument aboard Mars Odyssey, are analysed with an emphasis on characterising galactic cosmic rays (GCRs) in the inner heliosphere. A cross calibration between all sensors was performed for this study, which can also be used in subsequent works. We investigate the stability of the SREM detectors over long-term periods. The radiation data are compared qualitatively and quantitatively with the corresponding solar activity. Based on INTEGRAL and Ro…
A network of magnetometers for multi-scale urban science and informatics
2018
The magnetic signature of an urban environment is investigated using a geographically distributed network of fluxgate magnetometers deployed in and around Berkeley, California. The system hardware and software are described and initial operations of the network are reported. The sensors measure vector magnetic fields at a 3960 Hz sample rate and are sensitive to 0.1 nT/Hz. Data from individual stations are synchronized to ±120 µs using global positioning system (GPS) and computer system clocks and automatically uploaded to a central server. We present the initial observations of the network and preliminary efforts to correlate sensors. A wavelet analysis is used to stud…
Sun-Earth System Interaction studies over Vietnam: an international cooperative project
2006
International audience; During many past decades, scientists from various countries have studied separately the atmospheric motions in the lower atmosphere, in the Earth's magnetic field, in the magnetospheric currents, etc. All of these separate studies lead today to the global study of the Sun and Earth connections, and as a consequence, new scientific programs (IHY- International Heliophysical Year, CAWSES- Climate and Weather in the Sun-Earth System) are defined, in order to assume this new challenge. In the past, many scientists did not have the possibility to collect data at the same time in the various latitude and longitude sectors. Now, with the progress of geophysical sciences in …
In search of traceability: two decades of calibrated Brewer UV measurements in Sodankylä and Jokioinen
2016
Abstract. The two Brewer spectrophotometers of the Finnish Meteorological Institute at Jokioinen and Sodankylä have been operated according to the highest levels of the WMO∕GAW (World Meteorological Organization∕Global Atmosphere Watch) recommendations with rigorous quality control and quality assurance. The calibration of the instruments is based on annual recalibrations of primary standard lamps in the VTT MIKES Metrology National Standards Laboratory in Finland and an exhaustive measurement program with measurements of standard and working lamps in the on-site optical laboratories. Over the years, the maintenance of the calibration has produced data sets of approximately 2000 lamp scans …
Data flow of spectral UV measurements at Sodankylä and Jokioinen
2016
Abstract. The data flow involved in a long-term continuous solar spectral UV irradiance monitoring program is investigated and structured to provide an overall view on the multiphase process from data acquisition to the final products. The program employing Brewer spectrophotometers as measuring instruments is maintained by the Finnish Meteorological Institute (FMI) ever since the 1990s at two sites in Finland: Sodankylä (67° N) and Jokioinen (61° N). It is built upon rigorous operation routines, processing procedures, and tools for quality control (QC) and quality analysis (QA) under continuous development and evaluation. Three distinct levels of data emerge, each after certain phase in th…
Sampling of an STT event over the Eastern Mediterranean region by lidar and electrochemical sonde
2005
A two-wavelength ultraviolet (289–316nm) ozone Differential Absorption Lidar (DIAL) system is used to perform ozone measurements in the free troposphere in the Eastern Mediterranean (Northern Greece). The ozone DIAL profiles obtained during a Stratosphere-to-Troposphere Transport (STT) event are compared to that acquired by an electrochemical ozonesonde, in the altitude range between 2 and 10 km. The measurement accuracy of these two instruments is also discussed. The mean difference between the ozone profiles obtained by the two techniques is of the order of 1.11 ppbv (1.86%), while the corresponding standard deviation is 4.69 ppbv (8.16%). A case study of an STT event which occurred on 29…
A Brief Review of Ground Penetrating Radar Investigation Results of Ice Caps on Galindez, Winter and Skua Islands (Wilhelm Archipelago, Antarctica) f…
2019
This paper represents results of GPR surveying of the ice caps on Galindez (–64.24716W; –65.24992S), Winter (–64.25954W; –65.24944S) and Skua (–64.26530W; –65.25309S) islands (Wilhelm Archipelago, Antarctica) for the period April 2017 — January 2019. The main objectives were identification of the ice layering, monitoring of interglacial heterogeneities (crevasses, interglacial channels and voids) and measurements of the ice thickness. Methods: Surveying on the glaciers has been done with ground coupled shielded bowtie antenna VIY3-300 (300 MHz) GPR and with air coupled dipole Zond 12-e (75 MHz) antenna system. Monitoring investigation of glacier’s interior has been done with VIY3-300. Zond …