A case study in catchment hydrochemistry: Conflicting interpretations from hydrological and chemical observations

Soil water, stream water, groundwater and rain water were sampled through a storm event in a moorland catchment. Samples were analysed for major ions and deuterium. Chloride and deuterium are used as tracers to enable separation of the stream runoff hydrograph into three components: rain, soil and groundwater. The results indicate that rain water arrives in the stream quickly during the event and contributes a significant volume to the runoff peak. The chemical signal in the rain water is, however, significantly damped, apparently due to mixing with soil water held in the catchment before the event. This is further modified before reaching the stream, apparently through mixing with a deeper groundwater component. Interpretation of tracer, chemistry and hydrological data to present an integrated picture of catchment hydrochemical response is difficult due to problems in the chemical and conceptual definition of the flow components.     

Tidal encounters of ellipsoidal granular asteroids with planets

We investigate planetary fly-bys of asteroids using an approximate volume-averaged method that offers a relatively simple, but very flexible, approach to study the rotational dynamics of ellipsoids. The asteroid is considered to be a deformable, prolate ellipsoid, with its interior being modeled as a rigid-granular material. Effects due to the asteroid's rotation, its self-gravity and gravitational interaction with the planet are included. Using a simplified approach allows us to explore in detail the mechanics of asteroid's deformations and disruptions during planetary encounters. We also compare our results with those obtained by Richardson et al. [Richardson, D.C., Bottke Jr., W.F., Love, S.G., 1998. Icarus 134, 47-76] who used a large numerical code. We find that many of the features reported by them can indeed be captured by our rather simple methodology, and we discuss the reasons why some of our results differ from theirs.     

Atmospheric Imaging Assembly Response Functions: Solving the Fe viii Problems with Hinode EIS Bright Point Data

The Atmospheric Imaging Assembly (AIA) onboard the Solar Dynamics Observatory is a state-of-the-art imager with the potential to perform an unprecedented time-dependent multi-thermal analysis at every pixel on scales that are short compared to the radiative and conductive cooling times. Recent results, however, have identified missing spectral lines in the CHIANTI atomic physics database, which is used to construct the instrument response functions. This is not surprising since the wavelength range from 90 Å to 140 Å has rarely been observed with solar spectrometers, and atomic data for many of these ions are simply not available in the literature. We have performed a differential emission measure analysis using simultaneous AIA and Hinode/EIS observations of six X-ray bright points. Our results not only support the conclusion that CHIANTI is incomplete near 131 Å, but more importantly, suggest that the peak temperature of the Fe viii emissivity/response is likely to be closer to log T=5.8 than to the current value of log T=5.7. Using a revised emissivity/response calculation for Fe viii, we find that observed AIA 131-Å flux can be underestimated by ≈?1.25, lower than previous comparisons. With these adjustments, not only the AIA 131-Å data, but also the EIS Fe viii lines, match the remainder of the bright-point data better. In addition, we find that CHIANTI is reasonably complete in the AIA 171- and 193-Å bands. For the AIA 211-, 335-, and 94-Å channels, we recommend that more work be done with AIA–EIS DEM comparisons using observations of active-region cores, i.e. coronal structures with more emission measure at warmer temperatures than our bright points. Then a variety of EIS iron lines could be directly compared with AIA data.     

Further Evidence Suggestive of a Solar Influence on Nuclear Decay Rates

Recent analyses of nuclear decay data show evidence of variations suggestive of a solar influence. Analyses of datasets acquired at the Brookhaven National Laboratory (BNL) and at the Physikalisch-Technische Bundesanstalt (PTB) both show evidence of an annual periodicity and of periodicities with sidereal frequencies in the neighborhood of 12.25 year^?1 (at a significance level that we have estimated to be 10^?17). It is notable that this implied rotation rate is lower than that attributed to the solar radiative zone, suggestive of a slowly rotating solar core. This leads us to hypothesize that there may be an ??inner tachocline?? separating the core from the radiative zone, analogous to the ??outer tachocline?? that separates the radiative zone from the convection zone. The Rieger periodicity (which has a period of about 154 days, corresponding to a frequency of 2.37 year^?1) may be attributed to an r-mode oscillation with spherical-harmonic indices l=3,m=1, located in the outer tachocline. This suggests that we may test the hypothesis of a solar influence on nuclear decay rates by searching BNL and PTB data for evidence of a ??Rieger-like?? r-mode oscillation, with l=3,m=1, in the inner tachocline. The appropriate search band for such an oscillation is estimated to be 2.00??C?2.28 year^?1. We find, in both datasets, strong evidence of a periodicity at 2.11 year^?1. We estimate that the probability of obtaining these results by chance is 10^?12.     

Study of nuclear decays during a solar eclipse: Thule Greenland 2008

A new prediction technique based on logarithmic values is proposed to predict the maximum amplitude (R _m) of a solar cycle from the preceding minimum aa geomagnetic index (aa _min). The correlation between lnR _m and lnaa _min (r=0.92) is slightly stronger than that between R _m and aa _min (r=0.90). From this method, cycle 24 is predicted to have a peak size of R _m(24)=81.7(1±13.2%). If the suggested error in aa (3 nT) before 1957 is corrected, the correlation coefficient between R _m and aa _min (r=0.94) will be slightly higher, and the peak of cycle 24 is predicted much lower, R _m(24)=52.5±13.1. Therefore, the prediction of R _m based on the relationship between R _m and aa _min depends greatly on the accurate measurement of aa.     

Upper Ordovician graptolites from the Wagonga Beds near Batemans Bay,New South Wales

Two graptolite faunas are described from outcrops of the Wagonga Beds near Batemans Bay on the south coast of N.S.W. They are of late Eastonian and early Bolindian age. The faunas have been found in two geographically separate localities and, in spite of structural complexities, it is now suggested that the greater part of the Wagonga Beds was deposited in the Late Ordovician. The chert and volcanicrich Wagonga Beds were accumulated prior to, or as contemporaneous lateral facies equivalents of, the thick undifferentiated Upper Ordovician ‘slates and grey‐wackes unit’ that crops out in the same general region.     

Lower/middle tropospheric ozone variability in Senegal during pre-monsoon and monsoon periods of summer 2008: observations and model results

During the summer (8 June through 3 September) of 2008, 9 ozone profiles are examined from Dakar, Senegal (14.75°N, 17.49°W) to investigate ozone (O₃) variability in the lower/middle troposphere during the pre-monsoon and monsoon periods. Results during June 2008 (pre-monsoon period) show a reduction in O₃ concentrations, especially in the 850–700 hPa layer with Saharan Air Layer (SAL) events. However, O₃ concentrations are increased in the 950–900 hPa layer where the peak of the inversion is found and presumably the highest dust concentrations. We also use the WRF-CHEM model to gain greater insights for observations of reduced O₃ concentrations during the monsoon periods. In the transition period between 26 June and 2 July in the lower troposphere (925–600 hPa), a significant increase in O₃ concentrations (10–20 ppb) occur which we suggest is caused by enhanced biogenic NO_X emissions from Sahelian soils following rain events on 28 June and 1 July. The results suggest that during the pre-monsoon period ozone concentrations in the lower troposphere are controlled by the SAL, reducing ozone concentrations through heterogeneous chemical processes. At the base of the SAL we also find elevated levels of ozone, which we attribute to biogenic sources of NO_X from Saharan dust that are released in the presence of moist conditions. Once the monsoon period commences, lower ozone concentrations are observed and modeled which we attribute to the dry deposition of ozone and episodes of ozone poor air that is horizontally transported into the Sahel from low latitudes by African Easterly Waves (AEWs).     

Microbially induced formation of ooid-like coated grains in the Late Cretaceous methane-seep deposits of the Nakagawa area, Hokkaido, northern Japan

Abstract   Ooid-like coated grains are found in the Late Cretaceous methane-seep deposits in the Nakagawa area, Hokkaido, Japan. The coated grains were examined using macro- and microscopic observations, electron-probe microanalysis, and biomarker analysis. They are round- to oval-shaped, with nuclei consisting of fractured sediment and micritic envelopes. The fractures probably occurred as a result of increasing hydrostatic pressure when the sediment was still unconsolidated or weakly consolidated. Biomarker analysis revealed that two types of molecules, crocetane and PMI, are predominant in the hydrocarbon fraction with highly negative carbon isotopic composition as low as −122‰ ( vs Vienna Peedee Belemnite). These data suggest that the coated grains were formed under the influence of anaerobic oxidation of methane, near the sediment/seawater interface. The presence of such grains indicates that methane-containing pore water reached the sea floor at that time.