A conceptual hydrologic model for a forested Carolina bay depressional wetland on the Coastal Plain of South Carolina,USA

This paper describes how climate influences the hydrology of an ephemeral depressional wetland. Surface water and groundwater elevation data were collected for 7 years in a Coastal Plain watershed in South Carolina USA containing depressional wetlands, known as Carolina bays. Rainfall and temperature data were compared with water‐table well and piezometer data in and around one wetland. Using these data a conceptual model was created that describes the hydrology of the system under wet, dry, and drought conditions. The data suggest this wetland operates as a focal point for groundwater recharge under most climate conditions. During years of below‐normal to normal rainfall the hydraulic gradient indicated the potential for groundwater recharge from the depression, whereas during years of above‐normal rainfall, the hydraulic gradient between the adjacent upland, the wetland margin, and the wetland centre showed the potential for groundwater discharge into the wetland. Using high‐resolution water‐level measurements, this groundwater discharge condition was found to hold true even during individual rainfall events, especially under wet antecedent soil conditions. The dynamic nature of the hydrology in this Carolina bay clearly indicates it is not an isolated system as previously believed, and our groundwater data expand upon previous hydrologic investigations at similar sites which do not account for the role of groundwater in estimating the water budget of such systems. Copyright © 2007 John Wiley & Sons, Ltd.     

Flow of Canadian basin deep water in the Western Eurasian Basin of the Arctic Ocean

The LOMROG 2007 expedition targeted the previously unexplored southern part of the Lomonosov Ridge north of Greenland together with a section from the Morris Jesup Rise to Gakkel Ridge. The oceanographic data show that Canadian Basin Deep Water (CBDW) passes the Lomonosov Ridge in the area of the Intra Basin close to the North Pole and then continues along the ridge towards Greenland and further along its northernmost continental slope. The CBDW is clearly evident as a salinity maximum and oxygen minimum at a depth of about 2000 m. The cross-slope sections at the Amundsen Basin side of the Lomonosov Ridge and further south at the Morris Jesup Rise show a sharp frontal structure higher up in the water column between Makarov Basin water and Amundsen Basin water. The frontal structure continues upward into the Atlantic Water up to a depth of about 300 m. The observed water mass division at levels well above the ridge crest indicates a strong topographic steering of the flow and that different water masses tend to pass the ridge guided by ridge-crossing isobaths at local topographic heights and depressions. A rough scaling analysis shows that the extremely steep and sharply turning bathymetry of the Morris Jesup Rise may force the boundary current to separate and generate deep eddies.     

FIRST RESULTS OF THE SUMER TELESCOPE AND SPECTROMETER ON SOHO – I. Spectra and Spectroradiometry

SUMER – the Solar Ultraviolet Measurements of the Emitted Radiation instrument on the Solar and Heliospheric Observatory (SOHO) – observed its first light on January 24, 1996, and subsequently obtained a detailed spectrum with detector B in the wavelength range from 660 to 1490 Å (in first order) inside and above the limb in the north polar coronal hole. Using detector A of the instrument, this range was later extended to 1610 Å. The second-order spectra of detectors A and B cover 330 to 805 Å and are superimposed on the first-order spectra. Many more features and areas of the Sun and their spectra have been observed since, including coronal holes, polar plumes and active regions. The atoms and ions emitting this radiation exist at temperatures below 2 × 10⁶ K and are thus ideally suited to investigate the solar transition region where the temperature increases from chromospheric to coronal values. SUMER can also be operated in a manner such that it makes images or spectroheliograms of different sizes in selected spectral lines. A detailed line profile with spectral resolution elements between 22 and 45 mÅ is produced for each line at each spatial location along the slit. From the line width, intensity and wavelength position we are able to deduce temperature, density, and velocity of the emitting atoms and ions for each emission line and spatial element in the spectroheliogram. Because of the high spectral resolution and low noise of SUMER, we have been able to detect faint lines not previously observed and, in addition, to determine their spectral profiles. SUMER has already recorded over 2000 extreme ultraviolet emission lines and many identifications have been made on the disk and in the corona.     

Elemental composition from gamma‐ray spectroscopy of the NEAR‐Shoemaker landing site on 433 Eros

Abstract— Elemental composition and composition ratios derived from gamma‐ray measurements collected by the NEAR‐Shoemaker spacecraft while on the surface of 433 Eros are reported. Performance of the gamma‐ray spectrometer (GRS) during cruise and orbit is reviewed. The best gamma‐ray data were collected on the surface of Eros after the spacecraft's controlled descent on 2001 February 12. Methods used in spectral analysis, to convert peak areas to incident photons, and photons to elemental composition are described in some detail. The elemental abundance of K and the Mg/Si, Fe/Si, Si/O and Fe/O abundance ratios were determined. The Mg/Si and Si/O ratios and the K abundance are roughly chondritic, but the Fe/Si and Fe/O ratios are low compared to expected chondritic values. Three possible explanations for the apparent Fe depletion are considered.     

Review of crystal diffraction and its application to focusing energetic gamma rays

The basic features of crystal diffraction and their application to the construction of a crystal diffraction lens for focusing energetic gamma rays are described using examples from the work performed at the Argonne National Laboratory. Both on-axis and off-axis performance are discussed. The review includes the use of normal crystals, bent crystals, and crystals with variable crystal-plane spacing to develop both condenser-type lenses and point-to-point imaging lenses.     

An experimental approach to estuarine microplankton ecology

An experimental approach was used in determining which factors, natural or man made, had the greatest impact on estuarine microplankton ecology. In microcosms, filled with natural water of <5‰, 10‰, 18‰ and > 26‰ salinity, the impact of high organic load (glucose), shading, Cu and a heavy metal mixture on the microplankton populations was monitored. Naturally occurring perturbations were of much greater impact to estuarine ecology than the addition of heavy metals in concentrations five to ten times that which are known to occur in moderately polluted estuaries.