Surface roughness and geological mapping at subhectometer scale from the High Resolution Stereo Camera onboard Mars Express

The quantitative measurement of surface roughness of planetary surfaces at all scales provides insights into geological processes. A characterization of roughness variations at the scale of a few tens of meters is proposed that complements the analysis of local topographic data of the martian surface at kilometer scale, as achieved from the Mars Orbiter Laser Altimeter (MOLA) data, and at the subcentimeter scale using photometric properties derived from multi-angular observations. Relying on a Gabor filtering process, an algorithm developed in the context of image classification for the purpose of texture analysis has been adapted to handle data from the High Resolution Stereo Camera (HRSC). The derivation of roughness within a wavelength range of tens of meters, combined with analyses at even longer wavelengths, gives an original view of the martian surface. The potential of this approach is evaluated for different examples for which the geological processes are identified and the geological units are mapped and characterized in terms of roughness.     

Closure of a hyperextended system in an orogenic lithospheric pop‐up,Western Pyrenees: The role of mantle buttressing and rift structural inheritance

The Early Cretaceous hyperextended Mauléon rift is localized in the north‐western Pyrenean orogen. We infer the Tertiary evolution of the Mauléon basin through the restoration of a 153‐km‐long crustal‐scale balanced cross‐section of the Pyrenean belt, which documents at least 67 km (31%) of orogenic shortening in the Western Pyrenees. Initial shortening, accommodated through inversion of inherited crustal structures, led to formation of a pop‐up structure, in which the opposite edges underwent similar shortening with different tectonic reactivation styles, localized versus. distributed. Underthrusting of the Iberian margin accommodated further convergence, forming the Axial Zone antiformal stack of crustal nappes within a lithospheric pop‐up. Thin‐skinned and thick‐skinned structures propagated outward from the heart of this pop‐up, a block of strong mantle acting as a buttress inhibiting complete inversion of the Mauléon rift basin.     

Practical versus absolute salinity measurements: New advances in high performance seawater salinity sensors

Optical salinity sensors described here measure directly the seawater refractive index and thus enable a measurement of the seawater density and composition variation. We detail the measurement dependence to environmental parameters (in particular temperature and pressure) compared to conductivity sensors, and demonstrate that it may be advantageous to directly measure refractive index rather than electrical conductivity and so obtain a more direct route to density and absolute salinity.     

Indication of paleoecological evidence on the evolution of alpine vegetation productivity and soil erosion in central China since the mid-Holocene

Although alpine ecosystems have been commonly recognized as sensitive to recent climate change, few studies have examined its impact on the long-term productivity of vegetation and soil erosion. Using paleoecological records, these two aspects were examined in the alpine zone of the Taibai Mountains(elevation, 3767 m) in monsoon-dominated East Asia since the middle Holocene. Proxies for the productivity of vegetation and severity of soil erosion from high-resolution alpine lacustrine records show that the productivity and soil erosion were closely related to mean annual temperature and summer precipitation from the East Asian Summer Monsoon(EASM), respectively. Specifically, when the mean annual temperature was low and precipitation was abundant, during 5800–4000 calendar years before the present(cal. yr BP), the alpine ecosystem was characterized by low vegetation productivity and severe soil erosion. However, the productivity increased and soil erosion decreased from 4000 cal. yr BP onwards. These results highlight the role of paleoecological evidence in studying ecosystem services on longer time scales, which is significant in making policies for sustainable development under climate change in regions for which such long-term monitoring data are not available.     

Europium isotopic variations in Allende CAIs and the nature of mass-dependent fractionation in the solar nebula

We measured the ¹⁵³Eu/¹⁵¹Eu ratio by MC-ICP-MS for a terrestrial basalt, two terrestrial soils, and four meteorites (whole rocks and/or chondrules of Bjurböle, Forest City, Murchison, and Allende) and found no isotopic variations. By contrast, two CAI separates from two different pieces of Allende show a ¹⁵³Eu deficit of up to one per mil. Such a shortage in the heavy isotopes, which had also been identified in Allende CAIs for Sr [Patchett, P.J. 1980b. Sr isotopic fractionation in Allende chondrules: a reflection of solar nebular processes. Earth Planet. Sci. Lett.50, 181-188], cannot reflect evaporative fractionation. The lack of Sm isotope fractionation in the same samples further makes fractionation by purely kinetic processes an unlikely cause of the anomalous Eu isotopic composition. An alternative interpretation is condensation from a vapor already significantly depleted in Eu, but in such a scenario the fate of the missing material is unclear. We therefore prefer yet another interpretation, based on the low ionization potential of Eu (and Sr), in which electromagnetic separation of the ionized gas preferentially depletes the nebular gas in heavy isotopes.     

Spatial Variation of Sea-Spray Fluxes over a Mediterranean Coastal Zone Using a Sea-State Model

We first deal with sea-spray flux estimates for short fetch conditions in coastal Mediterranean areas. To this end, a sea-state dependent model for the whitecap fraction was included in three different formulations for the sea-spray source function. A comparison with the sea-spray fluxes, calculated on the basis of aerosol size distributions measured at the island of Porquerolles located south off the French Riviera, evaluates the predictions of different whitecap dependant flux formulations. Then we deal with the spatial distribution of the whitecap fraction and the sea-spray fluxes in the study area. To achieve this, a whitecap dependant flux formulation was forced by a wave numerical model that was implemented in the study area. Experimental results on wave conditions have been used to adjust the model in the Mediterranean coastal area. Numerical simulations of wave and whitecap coverage have been carried out during typical regional wind events, and they show a nonhomogeneous distribution of the sea-surface production over the northern Mediterranean as a consequence of the spatial variation of the sea state. In particular, we note the occurrence of a narrow band of high sea-surface production following the northern coast and along the east part of the Gulf of Lions.     

Retrieval of aerosol optical properties over the Beijing area using POLDER/PARASOL satellite polarization measurements

Aerosol optical properties over Beijing and Xianghe under several typical weather conditions (clear sky, light haze, heavy pollution and dust storm) are derived from POLDER (POLarization and Directionality of the Earths Reflectances)/PARASOL (Polarization and Anisotropy of Reflectances for Atmospheric Sciences coupled with Observations from a Lidar) multi-directional, multi-spectral polarized signals using a more reliable retrieval algorithm as proposed in this paper. The results are compared with those of the operational retrieval algorithm of POLDER/PARASOL group and the ground-based AERONET (AErosol RObotic NETwork)/PHOTONS (PHOtometrie pour le Traitement Operational de Normalisation Satellitaire) measurements. It is shown that the aerosol optical parameters derived from the improved algorithm agree well with AERONET/PHOTONS measurement. The retrieval accuracies of aerosol optical thickness (AOT) and effective radius are 0.06 and 0.05 mu m respectively, which are close to or better than the required accuracies (0.04 for AOT and 0.1 mu m for effective radius) for estimating aerosol direct forcing.     

Leaching experiments on a Mn-rich slag from the recycling of alkaline batteries – Solid phase characterization and geochemical modeling

Square sections of a Mn-rich slag from an alkaline battery recycling plant were submitted to 6-month batch leaching procedures. High-Purity Water (HPW), acidic (pH 4) and alkaline (pH 12) conditions were used in order to observe the behavior of primary solid phases as well as the constituent elements (Mn, Mg, Al, Si, Ca). The experiments were coupled with both KINDIS(P) modeling and mineralogical study (SEM-EDS). Experimental results showed that the Mn-rich slag was sensitive to acidic conditions which induced the dissolution of primary phases. Moreover, pH 4 conditions did not result in the formation of newly formed solid products, leading to the greatest mobilization of metallic elements (especially Mn). Alkaline conditions favored the precipitation of secondary phases, especially rhodochrosite, calcite and Mg-saponite, inducing low mobilization of the contained elements. The KINDIS(P) modeling allowed the stability of primary phases and newly formed products to be predicted. Although the modeled results have to be considered with caution, they allow the assessment and understanding of future environmental behavior of the solid material in given conditions. In this case, the reuse of Mn-rich slag in acidic conditions has to be avoided because of the acidic dissolution of the primary phases.