Search results for "Geophysics"

Characterizing weld pool surfaces from polarization state of thermal emissions

2013

International audience; In this Letter, a vision-based remote sensing methodology is proposed to measure the topography of weld pool surfaces from one single view. Thermal radiations emitted by the hot liquid metal at a wavelength within the arc plasma blind spectral window are acquired by a wavefront division polarimetric system. The refractive index of the liquid metal and the topography of the weld pool surface are inferred from the polarimetric state of the thermal radiations.

Seasonal and Inter-annual Variation of Evapotranspiration in Amazonia Based on Precipitation, River Discharge and Gravity Anomaly Data

2019

We analyzed seasonal and spatial variations of evapotranspiration (ET) for five Amazon sub-basins and their response to the 2015/16 El Nino episode using a recently developed water-budget approach. ET varied typically between similar to 7 and 10 cm/month with exception of the Xingu basin for which it varied between 10 and 15 cm/month. Outstanding features of ET seasonality are (i) generally weak seasonality, (ii) two ET peaks for the two very wet catchments Solimoes and Negro, with one occurring during the wet season and one during the drier season, and (iii) a steady increase of ET during the second half of the dry season for the three drier catchments (Madeira, Tapajos, Xingu). Peak ET oc…

Spring to summer changes in the West African monsoon through NCEP/NCAR reanalyses (1968–1998)

2002

[1] This article focuses on the spring to summer evolutions of the West African monsoon from an energetic point of view; it uses NCEP/NCAR reanalyses along with observed and simulated rainfall data over the period 1968–1998. The results show that the West African monsoon can be viewed as a coupled ocean-atmosphere-land system phased with the zenithal evolution of solar radiation which maintains its thermally direct circulation by pumping, from the surface, enthalpy mainly in spring and latent energy in summer. In this context the horizontal energy gradients in the boundary layer play a key role during the spring to summer transition. At the beginning of spring, the moist static energy (MSE)…

Monitoring of Cueva Larga, Puerto Rico—A First Step to Decode Speleothem Climate Records

2017

This study presents results of an ongoing cave monitoring program at Cueva Larga, Puerto Rico. The monitoring includes monthly analyses of stable isotope ratios of rain and drip water, and trace element ratios of drip water and cave air parameters. Drip sites are above growing speleothems offering the unique chance to calibrate geochemical variations in speleothems in order to reconstruct past climate conditions. Seasonal rainfall patterns above Cueva Larga show characteristic stable isotope values. The wet season is characterized by more negative δ18O and δD values and a maritime deuterium excess (+10‰). The dry season has more positive δ18O and δD values and elevated deuterium excess (>15…

Extreme dry spell detection and climatology over the Mediterranean Basin during the wet season

2016

The E-OBS precipitation gridded data set v.10.0 is used to detect very long dry spell (VLDS) events over the entire Mediterranean Basin for the 1957–2013 period, during the wet season (September to April). The main objective is to characterize these events as climatic objects, in terms of location, spatial extent, duration, and temporal variability. In this study, 76 VLDS events were detected in the Mediterranean Basin and grouped into four spatial patterns: scattered localized (with 25 events), northeast Mediterranean (11 events), West Mediterranean (15 events), and southeast Mediterranean (25 events). Each pattern shows seasonality in events. Most of the scattered localized, northeast, an…

Climate Adjustments over Africa Accompanying the Indian Monsoon Onset

2010

Abstract Rainfall and circulation changes accompanying the Indian monsoon onset are examined, focusing on the African continent and neighboring areas. The Indian Meteorological Department official monsoon onset dates over Kerala (MOK; on average on 1 June) are used. Composites are formed at a pentad (5 days) time scale to compare pre- and postonset conditions. Climate Prediction Center (CPC) Merged Analysis of Precipitation (CMAP) data for 1979–2007 indicate that a substantial rainfall decrease over several parts of Africa is associated with MOK. Significant rainfall anomalies, after removal of the mean seasonal cycle, are found in eastern Africa and the nearby western Indian Ocean. Indian …

Massenbewegungen im Saar-Nahe-Gebiet unter Berücksichtigung des Verwitterungsverhaltens der Pelite

1985

Mass movements are geologic processes which cause a lot of damage. The object of this project was the investigation of mass movements in Rotliegendes rocks of the Saar-Nahe-region, SW-Germany. Field and laboratory work was employed to achieve a better understanding of the processes.

2016

AbstractDetermining the manganese concentration in shells of freshwater bivalves provides a unique way to obtain information about climate and environmental changes during time-intervals that pre-date instrumental data records. This approach, however, relies on a thorough understanding of how manganese is incorporated into the shell material –a point that remained controversial so far. Here we clarify this issue, using state-of-the-art X-ray absorption and X-ray emission spectroscopy in combination with band structure calculations. We verify that in the shells of all studied species manganese is incorporated as high-spin Mn2+, i.e. manganese always has the same valence as calcium. More impo…

Element variability in the coralline alga Lithophyllum yemenense as archive of past climate in the Gulf of Aden (NW Indian Ocean)

2017

This study presents the first algal thallus (skeleton) archive of Asian monsoon strength and Red Sea influence in the Gulf of Aden. Mg/Ca, Li/Ca, and Ba/Ca were measured in Lithophyllum yemenense from Balhaf (Gulf of Aden) using laser ablation inductively coupled plasma mass spectrometry, and Mg/Ca ratio oscillation was used to reconstruct the chronology (34 y). Oscillations of element rates corresponding to the algal growth between 1974 and 2008 were compared with recorded climate and oceanographic variability. During this period, sea surface temperatures (SST) in Balhaf recorded a warming trend of 0.55 degrees C, corresponding to an increase in Mg and Li content in the algal thallus of 2.…

Thermo-mechanical volume change behaviour of Opalinus Clay

2016

The paper examines the thermo-mechanical volume change behaviour of Opalinus Clay in relation to different stress conditions and overconsolidation ratio (OCR) values and evaluates the impact of temperature on some hydro-mechanical properties of this material. To this aim, a focused experimental campaign consisting in high-temperature/high-pressure oedometric tests has been carried out. The results show that the thermo-mechanical volume change behaviour of Opalinus Clay is heavily affected by the OCR: thermal expansion is found when the heating is carried out at high OCR, whereas irreversible thermal compaction is observed when heat is applied at a vertical effective stress that is sufficien…