Simulating CO<Subscript>2</Subscript> transport into the ocean from a CO<Subscript>2</Subscript> lake at the seafloor using a <Emphasis Type="Italic">z</Emphasis>- and a <Emphasis Type="Italic">σ</Emphasis>-coordinate model

The ocean takes up approximately 2 GT carbon per year due to the enhanced CO₂ concentrations in the atmosphere. Several options have been suggested in order to reduce the emissions of CO₂ into the atmosphere, and among these are CO₂ storage in the deep ocean. Topographic effects of dissolution and transport from a CO₂ lake located at 3,000-m depth have been studied using the z-coordinate model Massachusetts Institute of Technology general circulation model (MITgcm) and the σ-coordinate model Bergen ocean model (BOM). Both models have been coupled with the general ocean turbulence model (GOTM) in order to account for vertical subgrid processes. The chosen vertical turbulence mixing scheme includes the damping effect from stable stratification on the turbulence intensity. Three different topographic scenarios are presented: a flat bottom and the CO₂ lake placed within a trench with depths of 10 and 20 m. The flat case scenario gives good correlation with previous numerical studies of dissolution from a CO₂ lake. When topography is introduced, it is shown that the z-coordinate model and the σ-coordinate model give different circulation patterns in the trench. This leads to different dissolution rates, 0.1 μmol cm^− 2 s^− 1 for the scenario of a 20-m-deep trench using BOM and 0.005–0.02 μmol cm^− 2 s^− 1 for the same scenario using the MITgcm. The study is also relevant for leakages of CO₂ stored in geological formations and to the ocean.     

Nighttime subvisual high-latitude auroras

Special methods for processing TV images have been used to study the characteristics of nighttime auroras based on the observations at high-latitude observatories on Spitsbergen. Weak subvisual auroras (SVAs), originating 3°–4° north of brighter auroras in the auroral oval, have been detected in the interval 1900-0400 MLT. The average lifetime of SVAs is approximately 7 min, and the average velocity of the equatorward shift is ～0.6 km/s. SVAs were observed during relatively quiet periods, when the IMF B _z component is mainly positive. However, SVAs are not polar-cap auroras since they are oriented from east to west rather than toward the Sun. The optical observations indicate that the SVA intensity is 0.2–0.5 and 0.1–0.3 kR in the 630 and 557.7 nm emissions, respectively. The average ratio of the emission intensities (I ₅₅₇₇/I ₆₃₀₀) is about 0.5. According to the direct satellite observations, the SVA electron spectrum has a maximum at 0.4–1.0 keV. In this case the energy flux of precipitating electrons is approximately an order of magnitude as low as such a flux in brighter auroral arcs in the auroral oval.     

iGeoTrans – a novel iOS application for GPS positioning in geosciences

The iGeoTrans is an iOS application designed for navigation purposes for iPhone, iPad and iPod Touch. This application uses Global Positioning System (GPS), Assisted GPS system, GLONASS, Wi-Fi and Cellular Network for positioning. The iGeoTrans has included datum transformations and map projections that enable users to convert the collected data between different coordinate systems for almost all areas in the world. In addition, other features are also included such as distance, area measurements, and GPS results could be exported to the AutoCad dxf format for GIS softwares. The average horizontal and vertical root mean square errors (RMSEs) for the static test are around 4.11 and 3.51?m, respectively. The horizontal RMSE for the dynamic outdoor test is around 2.72?m. The iGeoTrans application can be used to support surveying, mapping and geosciences fieldworks for any area in the world.     

Extending the known distribution of the Vedde Ash into Siberia: occurrence in lake sediments from the Timan Ridge and the Ural Mountains,northern Russia

Tephra shards from the Vedde Ash eruption have been identified in two lakes from northwestern Russia and the Polar Ural Mountains. This is the most distal and easternmost occurrence of this regional tephra marker horizon found so far and it extends the area of the Vedde Ash tephra more than 1700 km further east than previously documented. This means that particles the size of fine sand have travelled more than 4000 km from the Katla volcano source, south Iceland. These findings offer a new possibility to correlate archives over a very long distance in the time period around the Younger Dryas.     

A comparison of Martian albedo features with topography

Martian albedo features photographed from the Earth are compared with the topography observed by Mariner 9. We present three Lambert azimuthal equal-area charts prepared to facilitate the comparison. No correlation between large-scale albedos and topography can be generalized, but several different kinds of relationships seem to be indicated in particular regions. Examples of these are discussed.     

U–Pb TIMS age constraints on the evolution of the Neoproterozoic Meatiq Gneiss Dome,Eastern Desert,Egypt

Ages are used to constrain the temporal evolution of the Meatiq Gneiss Dome, Eastern Desert, Egypt, by dating (ID-TIMS) pre-, syn-, and post-tectonic igneous rocks in and around the dome. The Um Ba’anib Orthogneiss, comprising the deepest exposed structural levels of the dome, has a crystallization age of 630.8 ± 2 Ma. The overlying mylonites are interpreted to be a thrust sheet/complex (Abu Fannani Thrust Sheet) of highly mylonitized metasediments (?), migmatitic amphibolites, and orthogneisses with large and small tectonic lenses of less-deformed intrusives. Two syn-tectonic diorite lenses in this complex have crystallization ages of 609.0 ± 1.0 and 605.8 ± 0.9 Ma, respectively. The syn-tectonic Abu Ziran diorite, cutting across the tectonic contact between mylonite gneisses of the Abu Fannani Thrust Sheet and a structurally overlying thrust sheet of eugeoclinal rocks (“Pan-African nappe”), has a magmatic emplacement age of 606.4 ± 1.0 Ma. Zircons from a gabbro (Fawakhir ophiolite) within the eugeoclinal thrust sheet yielded a crystallization age of 736.5 ± 1.2 Ma. The post-tectonic Fawakhir monzodiorite intrudes the ophiolitic rocks and has an emplacement age of 597.8 ± 2.9 Ma. Two other post-tectonic granites, the Arieki granite that intrudes the foliated Um Ba’anib Orthogneiss, and the Um Had granite that cuts the deformed Hammamat sediments, have emplacement ages of 590 ± 3.1 and 596.3 ± 1.7 Ma, respectively. We consider formation of the Meatiq Gneiss Dome to be a young structural feature (<631 Ma), and our preferred tectonic interpretation is that it formed as a result of NE–SW shortening contemporaneous with folding of the nearby Hammamat sediments around 605–600 Ma, during oblique collision of East and West Gondwana.     

Late glacial and holocene 10Be production rates for western Norway

We present a new regional calibration of the ¹⁰Be production rate from two well‐dated surfaces in southern Norway: a rock avalanche with ¹⁴C‐dated wood and a precisely dated Younger Dryas moraine. Calculated ¹⁰Be production rates are 4.26 ± 0.13 and 4.65 ± 0.14 at g^?1 a^?1 for the Lal/Stone and Lifton scaling models, respectively. Our regional production rate for southern Norway is 5% lower than the canonical global ¹⁰Be production rate with lower uncertainties. Our ¹⁰Be production rate agrees with regional ¹⁰Be production rates from north‐eastern North America and New Zealand. The ¹⁰Be production rate estimate presented here can be used to improve the precision and accuracy of exposure‐dated ice‐marginal features, as well as other surfaces, in northern Europe. Copyright © 2011 John Wiley & Sons, Ltd.