Search results for "Geophysics"

THE QUANTITATIVE RECORDING OF SEISMIC EVENTS WITH EXTREMELY LARGE AMPLITUDE VARIATIONS BY DISCONTINUOUS GAIN CONTROL*

1963

A transistorized combination of multivibrators is described, by which the gain is set according to a time programme. This equipment allows quantitative recording of seismic events with extremely large amplitude variations. Some possible applications of this recording system to seismic research are discussed. ZUSAMMENFASSUNG Es wird eine transistorisierte Zeitschalterkombination beschrieben, die zur Einstellung vorgewahlter Verstarkungsstufen nach Zeitprogramm dient. Mit dieser Anordnung lassen sich seismische Vorgange mit beliebigen Amplituden-Anderungen quantitativ erfassen. Es werden einige Beispiele der seismischen Forschung diskutiert, bei denen diese Regis-triertechnik erfolgreich eing…

Can inertia-gravity waves persistently alter the tropopause inversion layer?

2014

Previous simulations of baroclinic life cycles have shown, among many other features, the evolution of a tropopause inversion layer (TIL) as well as the spontaneous emission of inertia-gravity waves (IGWs). This study suggests that the latter two are related to each other, i.e., that IGWs may affect the TIL in a persistent manner. The IGWs are emitted along the jet and grow to large amplitudes, leading to the appearance of low-gradient Richardson numbers that indicate Kelvin-Helmholtz instability. Ensuing energy dissipation, local heating, and turbulence may persistently alter the thermodynamical structure of the tropopause region and, therefore, contribute to TIL formation or alter an exis…

<i>Editorial Note</i>A case of plagiarism: "Modelling of the wave fields by the modification of the matrix metho…

2014

Comparison of the dynamics of the AU and PC indices

1998

The properties of AU and PC data were analyzed with different methods. It is shown that the dynamical behavior of the AU and PC time series, as analyzed by the structure function (SF), are very similar, while the SF of the AL time series shows different behavior. The SF of the AL data has a slope of 0.5 up to about 2 hours, after which it quickly decreases to about 0.1. On the other hand the slope of the SFs of AU and PC data continuously decreases to about 0.2, and in a longer time scale. It is suggested that the dissipative auroral electrojet currents have a characteristic time scale of 2 hours, and this underlies the AL dynamics. In contrast with this, the nondissipative Hall currents th…

Solar radiation extinction, sky radiation, sky light polarization and aerosol particle total number and size distribution on the Island Maui (Hawaii)

1968

During April 1964 and from August through September 1965 measurements have been performed on the Maui Island, Hawaii. The results can be summarized as follows: a) the spectral extinction coefficient has a diurnal variation. The greatest value is found during noon. Its wavelength dependency shows an ‘anomalous extinction’, the maximum of extinction is to be found at 0.55 μ (Figures 1–3). b) the spectral radiance distribution of the total sky indicates the tendency that the aerosol size distribution does not follow a continuous power law. The exponent for small particles seems to bev*1 μ (Figure 8). d) the distribution of spectral degree of sky light polarization shows two maxima of polarizat…

Neutrino tomography of the Earth

2018

Cosmic-ray interactions with the nuclei of the Earth's atmosphere produce a flux of neutrinos in all directions with energies extending above the TeV scale. However, the Earth is not a fully transparent medium for neutrinos with energies above a few TeV. At these energies, the charged-current neutrino-nucleon cross section is large enough so that the neutrino mean-free path in a medium with the Earth's density is comparable to the Earth's diameter. Therefore, when neutrinos of these energies cross the Earth, there is a non-negligible probability for them to be absorbed. Since this effect depends on the distance traveled by neutrinos and on their energy, studying the zenith and energy distri…

A new method reveals more TGFs in the RHESSI data

2012

[1] This letter presents a new search algorithm for identifying Terrestrial Gamma ray Flashes (TGFs) in the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) data. The algorithm has been applied to data from the period 2004–2006 and we have found more than twice as many TGFs as previously reported. The new TGFs follow the same geographical and seasonal variations as the previously reported TGFs. The match percentage between the new TGFs and World Wide Lightning Location Network (WWLLN) data is comparable to the RHESSI catalog TGFs. Our results shows that previous searches only identified the most intense events, and that there might be a large population of faint TGFs.

Do organics contribute to small particle formation in the Amazonian upper troposphere?

2008

3-D cloud-resolving model simulations including explicit aerosol physics and chemistry are compared with observations of upper tropospheric (12 km) aerosol size distributions over the Amazon Basin. ...

Zircon M257 - a homogeneous natural reference material for the ion microprobe U-Pb analysis of zircon

2008

We introduce and propose zircon M257 as a future reference material for the determination of zircon U-Pb ages by means of secondary ion mass spectrometry. This light brownish, flawless, cut gemstone specimen from Sri Lanka weighed 5.14 g (25.7 carats). Zircon M257 has TIMS-determined, mean isotopic ratios (2s uncertainties) of 0.09100 ± 0.00003 for 206pb/238U and 0.7392 ± 0.0003 for 207pb/235U. Its 206pb/238U age is 561.3 ± 0.3 Ma (unweighted mean, uncertainty quoted at the 95% confidence level); the U-Pb system is concordant within uncertainty of decay constants. Zircon M257 contains ∼ 840 μg g−1 U (Th/U ∼ 0.27). The material exhibits remarkably low heterogeneity, with a virtual absence of…

Inhomogeneous-strain-induced magnetic vortex cluster in one-dimensional manganite wire

2020

Abstract Mixed-valance manganites with strong electron correlation exhibit strong potential for spintronics, where emergent magnetic behaviors, such as propagation of high-frequency spin waves and giant topological Hall Effects can be driven by their mesoscale spin textures. Here, we create magnetic vortex clusters with flux closure spin configurations in single-crystal La0.67Sr0.33MnO3 wire. A distinctive transformation from out-of-plane domains to a vortex state is directly visualized using magnetic force microscopy at 4 K in wires when the width is below 1.0 μm. The phase-field modeling indicates that the inhomogeneous strain, accompanying with shape anisotropy, plays a key role for stab…