Search results for "PLAN"
showing 10 items of 24706 documents
Disambiguating the soils of Mars
2020
Abstract Anticipated human missions to Mars require a methodical understanding of the unconsolidated bulk sediment that mantles its surface, given its role as an accessible resource for water and as a probable substrate for food production. However, classifying martian sediment as soil has been pursued in an ad hoc fashion, despite emerging evidence from in situ missions for current and paleo-pedological processes. Here we find that in situ sediment at Gusev, Meridiani and Gale are consistent with pedogenesis related to comminuted basalts mixing with older phyllosilicates – perhaps of pluvial origin – and sulfates. Furthermore, a notable presence of hydrated amorphous phases indicates signi…
High-resolution 40Ar/39Ar chronostratigraphy of the post-caldera (<20 ka) volcanic activity at Pantelleria, Sicily Strait
2011
Abstract The island of Pantelleria (Sicily Strait), the type locality for pantellerite, has been the locus of major caldera-forming eruptions that culminated, ca. 50 ka ago, in the formation of the Cinque Denti caldera produced by the Green Tuff eruption. The post-caldera silicic activity since that time has been mostly confined inside the caldera and consists of smaller-energy eruptions represented by more than twenty coalescing pantelleritic centers structurally controlled by resurgence and trapdoor faulting of the caldera floor. A high-resolution 40Ar/39Ar study was conducted on key units spanning the recent (post-20 ka) intracaldera activity to better characterize the present-day status…
X-ray flare oscillations track plasma sloshing along star-disk magnetic tubes in Orion star-forming region
2018
Pulsing X-ray emission tracks the plasma echo traveling in an extremely long magnetic tube that flares in an Orion Pre-Main Sequence (PMS) star. On the Sun, flares last from minutes to a few hours and the longest-lasting typically involve arcades of closed magnetic tubes. Long-lasting X-ray flares are observed in PMS stars. Large-amplitude (~20%) long-period (~3 hours) pulsations are detected in the light curve of day-long flares observed by the Advanced CCD Imaging Spectrometer (ACIS) on-board Chandra from PMS stars in the Orion cluster. Detailed hydrodynamic modeling of two flares observed on V772 Ori and OW Ori shows that these pulsations may track the sloshing of plasma along a single l…
The influence of the wind direction and plants on the variability of topsoil magnetic susceptibility in industrial and urban areas of southern Poland
2016
Volume magnetic susceptibility (κ) was measured on the soil surface and in the vertical topsoil profile within a 300 km2 area located in an urban-industrial conurbation. The results were compared to plant species compositions in the forest storeys, elevation above sea level, and terrain geomorphology. The content and mineral composition of the magnetic fraction were determined in the soil horizons. It was found that the extent of the area with enhanced topsoil magnetic susceptibility was similar to the dominant wind direction (south–west). Enhanced κ values were observed for the soil at the forest margin on the leeward side of the emitters as well as at sites located on exposed local elevat…
Short-Term Vegetation Recovery after a Grassland Fire in Lithuania: The Effects of Fire Severity, Slope Position and Aspect
2016
In Lithuania, fire is frequently used by farmers as a tool to remove dry grass, improve soil nutrient status and help soil tilling. However, little is known about the ecological impacts of these fires, including vegetation recovery. The objective of this work is to study the impacts of a spring grassland fire on vegetation recuperation on an east-facing (A) and a west-facing slope (B), considering fire severity and slope position, 10, 17, 31 and 46 days after the fire. Because of their effects on fire behaviour, aspect, steepness and heterogeneity of topography favoured higher fire severity on slope B than on slope A. Three different slope positions were identified on slope A – flat top, mi…
Assessing and Modeling Soil Detachment Capacity by Overland Flow in Forest and Woodland of Northern Iran
2020
Land use has significant effects on the erosion process, since it influences the soil detachment capacity by causing an overland flow (Dc). The effects of different land uses on the rill detachment capacity have not been explained in depth, and the hydraulic parameters providing accurate estimates of this soil property have not been completely identified. This study quantifies Dc at low flow rates in woodland and forestland, compared to two other land uses (cropland and grassland), in the Saravan watershed (Northern Iran), and develops prediction models of Dc and rill erodibility (Kr). Dc was measured on undisturbed soil samples, collected in the four land uses, and characterized in terms o…
Slow-Mode Magnetoacoustic Waves in Coronal Loops
2021
Rapidly decaying long-period oscillations often occur in hot coronal loops of active regions associated with small (or micro-) flares. This kind of wave activity was first discovered with the SOHO/SUMER spectrometer from Doppler velocity measurements of hot emission lines, thus also often called "SUMER" oscillations. They were mainly interpreted as global (or fundamental mode) standing slow magnetoacoustic waves. In addition, increasing evidence has suggested that the decaying harmonic type of pulsations detected in light curves of solar and stellar flares are likely caused by standing slow-mode waves. The study of slow magnetoacoustic waves in coronal loops has become a topic of particular…
Understanding the Origins of Problem Geomagnetic Storms Associated with "Stealth" Coronal Mass Ejections.
2021
Geomagnetic storms are an important aspect of space weather and can result in significant impacts on space- and ground-based assets. The majority of strong storms are associated with the passage of interplanetary coronal mass ejections (ICMEs) in the near-Earth environment. In many cases, these ICMEs can be traced back unambiguously to a specific coronal mass ejection (CME) and solar activity on the frontside of the Sun. Hence, predicting the arrival of ICMEs at Earth from routine observations of CMEs and solar activity currently makes a major contribution to the forecasting of geomagnetic storms. However, it is clear that some ICMEs, which may also cause enhanced geomagnetic activity, cann…
A space weather tool for identifying eruptive active regions
2019
Funding: UK Science and Technology Facilities Council (UK) through the consolidated grant ST/N000609/1 and the European Research Council (ERC) under the European Union Horizon 2020 research and innovation program (grant agreement No. 647214); UK STFC via the Consolidated Grant SMC1/YST025 and SMC1/YST037 (S.L.Y.); UK STFC and the ERC (SynergyGrant: WHOLE SUN, Grant Agreement No. 810218) for financial support (DHM). One of the main goals of solar physics is the timely identification of eruptive active regions. Space missions such as Solar Orbiter or future Space Weather forecasting missions would largely benefit from this achievement.Our aim is to produce a relatively simple technique that c…
High‐resolution stimulated Raman spectroscopy and analysis of line positions and assignments for the ν 2 and ν 3 bands of 13 C 2 H 4
2016
High-resolution stimulated Raman spectra of13C2H4 in the regions of the ν2 and ν3 Raman active modes have been recorded at two temperatures (145 and 296 K) based on the quasi continuous-wave (cw) stimulated Raman spectrometer at Instituto de Estructura de la Materia IEM-CSIC in Madrid. A tensorial formalism adapted to X2Y4 planar asymmetric tops with D2h symmetry (developed in Dijon) and a program suite called D2hTDS (now part of the XTDS/SPVIEW spectroscopic software) were proposed to analyze and calculate the high-resolution spectra. A total of 103 and 51 lines corresponding to ν2 and ν3 Raman active modes have been assigned and fitted in wavenumber with a global root mean square deviatio…