Upwelling and river runoff as sources of dissolved nitrous oxide to the Alsea estuary,Oregon

Surface waters of Alsea Bay, an unpolluted estuary on the Oregon coast, were analysed for nitrous oxide, nitrate and nitrite on a weekly or biweekly basis during the summer of 1979. The estuary was found to be a variable source of N₂O to the atmosphere. Large and rapid increases in the concentrations of N₂O, NO₃^?, and NO₂^? occurred at the beginning of the sampling period and are attributed to the influx of nutrient-rich upwelling water into the estuary with the tide. The subsequent decline in concentrations of nitrate, nitrite and nitrous oxide over the remainder of the summer is attributed to a decrease in upwelling intensity, a decline in nitrification rates and to assimilatory nitrate reduction. Measurements of nitrous oxide at six stations along the Alsea River were also made in September and October before and after the onset of the rainy season. Samples taken after flood conditions were established were systematically 50% higher than pre-flood samples. The data suggest that soil runoff results in elevated concentrations of N₂O in rivers.     

Assessing the Vibrational Frequencies of the Cathedral of Cologne (Germany) by Means of Ambient Seismic Noise Analysis

Ambient seismic noise measurements were conducted inside the Cathedral of Cologne (Germany) for assessing its frequencies of vibration and for checking whether these occur in the range where soil amplification is expected. If this is the case, damages may increase in case of an earthquake due to an increased structural response of the building. Analysis of the ratio between the horizontal and vertical components of the spectra recorded at stations located inside the building as well as the ratio between the corresponding components of the spectra recorded simultaneously inside the building and at a reference station placed in the basement of the cathedral indicated several modes of vibration. Facilitated by these results an assessment of the seismic vulnerability was attempted for a 2D ground motion scenario using the finite element method.     

Orbital-scale record of the late Cenomanian–Turonian oceanic anoxic event (OAE-2) in the Tarfaya Basin (Morocco)

High sedimentation rates (up to 12 cm/kyear) of laminated organic carbon-rich biogenic limestones in the Tarfaya Basin provide an unusually high (millennial) resolution record of the late Cenomanian oceanic anoxic event (OAE-2). The global positive carbon-isotope excursion across the Cenomanian–Turonian corresponds to 11 light/dark sedimentary cycles. We interpret these cycles as a response to orbital obliquity variation and estimate the duration of the complete excursion as 440 kyear or one long eccentricity cycle. On this timescale, the main increase in ¹³C values occurred over a short time interval of less than 20 kyear in the late Cenomanian and reached a first maximum approximately 15 kyear prior to the bulk (mainly coccoliths) ¹⁸O-derived sea surface maximum temperature that occurs coeval to the extinction of Rotalipora cushmani. Organic carbon-accumulation rates follow obliquity cycles, reaching a maximum approximately 10 kyear after the last occurrence of R. cushmani, then slowly decreasing during the early Turonian. Thus, the maximum temperature and the maximum organic carbon accumulation in the Tarfaya Basin lagged by at least 15 kyear behind the global carbon-isotope shift and a proposed reduction of atmospheric CO₂ content. The climate change across the Cenomanian/Turonian boundary probably occurred independent of CO₂ levels and may have been controlled by different greenhouse gases (water vapour and methane) and changes in ocean circulation (i.e., opening of the Equatorial Atlantic gateway)     

Membership in the open cluster NGC 2301

Astrometric cluster membership probabilities have been derived from proper motion of the open cluster NGC 2301. A comparison with previous investigations is presented.     

Hα manifestation of an energetic limb flare,June 21, 1980

The H observations of a limb flare, which were associated with exceptional gamma-ray and hard X-ray emission, are presented and discussed. The good spatial and temporal resolution of the H data allow us to investigate the detailed structure of the elevated flare loops and the intensity variations of the loops, footpoints and surrounding chromosphere during each phase of the flare event. A delay time of 12 s was found between at least one of the hard X-ray (28–485 keV) peaks and corresponding H intensity maximum at a loop footpoint. A comparison is made between this event and another well-observed limb flare with many similar characteristics to seek evidence for the large difference in their levels of energy release.     

On the inclusion of ground-based gravity measurements to the calibration process of a global rainfall-discharge reservoir model: case of the Durzon karst system (Larzac, southern France)

This work examines the relevance of the inclusion of ground-based gravity data in the calibration process of a global rainfall-discharge reservoir model. The analysis is performed for the Durzon karst system (Larzac, France). The first part of the study focuses on the hydrological interpretation of the ground-based gravity measurements. The second part of the study investigates further the information content of the gravity data with respect to water storage dynamics modelling. The gravity-derived information is found unable to either reduce equifinality of the single-objective, discharge-based model calibration process or enhance model performance through assimilation.     

Detection of a dry-frozen boundary inside Martian regolith

The present work investigates the time oscillations of the temperature at several depths of a Martian soil analogue made of two layers of different physical properties. The maximum temperature-time oscillation inside the Martian soil analogue, DT, and its derivative with depth, d(DT)/dz or DDT, can be analysed to understand the presence of a boundary between dry and frozen soil. The maximum temperature-time oscillation, DT, reduces by about one order of magnitude at the boundary between dry and frozen soil if a frozen layer is present. The reduction of DT at the boundary between two dry soils with different porosity is much smaller. DDT decreases by more than one order of magnitude at the boundary between dry and frozen soil if a frozen layer is present. The reduction of DDT at the boundary between two dry soils with different porosity is much smaller.     

Evolution of density in solar system ICES

Pores present in ices in the solar system do not remain unchanged. In isothermal conditions they shrink while in a thermal gradient they migrate towards the higher temperature and escape so that the ice densifies. This motion has been investigated for pure H₂O- and CO₂-ices in a very simple one-dimensional model assuming uniform thermal conductivity and temperature gradient. The results indicate that the densification of H₂O-ice is so slow that it could be significant only for icy satellites having an internal heat source. On the other hand, CO₂-ice densifies orders of magnitude faster and the effect should be important for the CO₂ component of cometary nuclei. No effect is expected for icy planetary rings.