Search results for "SOI"
showing 10 items of 4823 documents
Aerosol layers from the 2008 eruptions of Mount Okmok and Mount Kasatochi: In situ upper troposphere and lower stratosphere measurements of sulfate a…
2010
In 2008 Mount Okmok and Mount Kasatochi started erupting on 12 July and 7 August, respectively, in the Aleutians, depositing emissions of trace gases and aerosols as high as 15.2 km into the atmosphere. During an aircraft campaign, conducted over Europe in between 27 October and 2 November 2008, the volcanic aerosol was measured by an Aerodyne aerosol mass spectrometer, capable of particle chemical composition measurements covering a size diameter range between 40 nm and 1 mm. In the volcanic aerosol layer enhanced submicron particulate sulfate concentrations of up to 2.0 mg mâÂÂ3 standard temperature and pressure (STP) were observed between 8 and 12 km altitude, while background values …
Electrical conductivity of magma in the course of crystallization controlled by their residual liquid composition.
2005
International audience; The electrical conductivity of a magma in the course of crystallization was experimentally investigated in the temperature range of 1350–1018°C. Large samples of basaltic composition with a homogeneous crystal content were synthesized in a gas mixing furnace at 1 atm pressure. The samples were analyzed by electron microprobe. The relative proportions of the phases as a function of temperature were determined. Depending on temperature, the phase assemblies included quenched silicate liquid, ±plagioclase, ±pyroxene, ±Fe-Ti oxides. The crystal content varied from 0 to 80 wt %. In response to partial crystallization, the residual liquid changed composition from basalt, t…
Anisotropic scaling of tectonic stylolites: A fossilized signature of the stress field?
2010
International audience; [1] Vertical stylolites are pressure solution features, which are considered to be caused by horizontal tectonic loading, with the largest principal compressive stress being (sub-) parallel to the Earth's surface. In the present study we analyze the roughness of such tectonic stylolites from two tectonic settings in southern Germany and northeastern Spain, aiming to investigate their scaling properties with respect to the stress during formation. High-resolution laser profilometry was carried out on opened stylolite surfaces of nine samples. These data sets were then analyzed using one-and two-dimensional Fourier power spectral approaches. We found that tectonic styl…
A Laboratory Dust Generator Applying Vibration to Soil Sample: Mineralogical Study and Compositional Analyses
2020
International audience; A laboratory study was carried out using a vibrating system (SyGAVib) to produce aerosols from four soils collected in the central Tunisian region around Sfax. The aim of this device is to mimic dust emission by natural wind erosion. Using compositional analysis, the dust produced was compared to (i) dust generated in a wind tunnel by the same soils, (ii) fine sieved and (iii) original bulk soils, and (iv) naturally occurring aerosol samples collected in the same area. The relative quartz content strongly decreases from bulk to fine soils, and again from fine soils to both wind tunnel and vibration‐generated aerosols. Compositional data analysis (CoDA) clearly shows …
Interannual variability of Greenland winter precipitation sources: 2. Effects of North Atlantic Oscillation variability on stable isotopes in precipi…
2008
[1] A new Lagrangian moisture source diagnostic is applied to identify the atmospheric conditions relevant for the fractionation of stable water isotopes during evaporation over the ocean and subsequent transport to Greenland. Northern Hemisphere winter months with positive and negative North Atlantic Oscillation (NAO) index are studied on the basis of ERA-40 reanalysis data. Diagnosed moisture transport conditions are supplied to a Rayleigh-type isotope fractionation model to derive estimates for the isotopic composition of stable isotopes in winter precipitation on the Greenland plateau for the two NAO phases. Because of changes in atmospheric circulation, moisture source locations for pr…
Temperature-based and radiance-based validations of the V5 MODIS land surface temperature product
2009
[1] The V5 level 2 land surface temperature (LST) product of the Moderate Resolution Imaging Spectroradiometer (MODIS) was validated over homogeneous rice fields in Valencia, Spain, and the Hainich forest in Germany. For the Valencia site, ground LST measurements were compared with the MOD11_L2 product in the conventional temperature-based (T-based) method. We also applied the alternative radiance-based (R-based) method, with in situ LSTs calculated from brightness temperatures in band 31 through radiative transfer simulations using temperature and water vapor profiles and surface emissivity data. At the Valencia site, profiles were obtained from local radiosonde measurements and from Natio…
Adjusted Normalized Emissivity Method for surface temperature and emissivity retrieval from optical and thermal infrared remote sensing data
2003
[1] A methodology for the retrieval of surface temperatures and emissivities combining visible, near infrared and thermal infrared remote sensing data was applied to Digital Airborne Imaging Spectrometer (DAIS) data and validated with coincident ground measurements acquired in a multiyear experiment held in an agricultural site in Barrax, Spain. The Adjusted Normalized Emissivity Method (ANEM) is based on the use of visible and near infrared data to estimate the vegetation cover and model the maximum emissivity according to the Vegetation Cover Method. The pixel-dependent maximum emissivity is used as the initial guess of the Normalized Emissivity Method to obtain the surface temperature an…
Intermittent release of transients in the slow solar wind: 1. Remote sensing observations
2010
[1] The Heliospheric Imager (HI) instruments on board the STEREO spacecraft are used to analyze the solar wind during August and September 2007. We show how HI can be used to image the streamer belt and, in particular, the variability of the slow solar wind which originates inside and in the vicinity of the streamer belt. Intermittent mass flows are observed in HI difference images, streaming out along the extension of helmet streamers. These flows can appear very differently in images: plasma distributed on twisted flux ropes, V-shaped structures, or “blobs.” The variety of these transient features may highlight the richness of phenomena that could occur near helmet streamers: emergence of…
Interannual variability of Greenland winter precipitation sources: Lagrangian moisture diagnostic and North Atlantic Oscillation influence
2008
[1] We present a new Lagrangian diagnostic for identifying the sources of water vapor for precipitation. Unlike previous studies, the method allows for a quantitative demarcation of evaporative moisture sources. This is achieved by taking into account the temporal sequence of evaporation into and precipitation from an air parcel during transport, as well as information on its proximity to the boundary layer. The moisture source region diagnostic was applied to trace the origin of water vapor for winter precipitation over the Greenland ice sheet for 30 selected months with pronounced positive, negative, and neutral North Atlantic Oscillation (NAO) index, using the European Centre for Medium-…
A spatially consistent downscaling approach for SMOS using an adaptive window
2017
The European Space Agency (ESA)'s Soil Moisture and Ocean Salinity (SMOS) is the first spaceborne mission using L-band radiometry to monitor the Earth's global surface soil moisture (SM). After more than 7 years in orbit, many studies have contributed to improve the quality and applicability of SMOS-derived SM maps. In this research, a novel downscaling algorithm for SMOS is proposed to obtain high-resolution (HR) SM maps at 1 km (L4), from the ∼40 km native resolution of the instrument. This algorithm introduces the concept of a shape adaptive moving window as an improvement of the current semi-empirical downscaling approach at SMOS Barcelona Expert Center, based on the “universal triangle…