Anisotropy of ionospheric irregularities determined from the amplitude of satellite signals at a single receiver

A new method of determining the anisotropy parameters of small-scale irregularities in the ionospheric F region is presented and experimental results are shown. The method is based on observations of amplitude fluctuations of radio waves transmitted by satellites flying above the F region. In practice, Russian navigational satellites are used and both the amplitude and the phase of the signal is measured on the ground level. The method determines both the field-aligned anisotropy and the field-perpendicular anisotropy and orientation of the spatial spectrum of the irregularities, assuming that the contours of constant power have an elliptic shape. A possibility of applying the method to amplitude tomography is also discussed. Using a chain of receivers on the ground level, one could locate the regions of small-scale irregularities as well as determine their relative intensities. Then the large-scale background structures could be mapped simultaneously by means of ordinary ray tomography using the phase observations, and therefore the relations of small-scale and large-scale structures could be investigated.     

Understanding and modeling basin hydrology: interpreting the hydrogeological signature

Basin landscapes possess an identifiable spatial structure, fashioned by climate, geology and land use, that affects their hydrologic response. This structure defines a basin's hydrogeological signature and corresponding patterns of runoff and stream chemistry. Interpreting this signature expresses a fundamental understanding of basin hydrology in terms of the dominant hydrologic components: surface, interflow and groundwater runoff. Using spatial analysis techniques, spatially distributed watershed characteristics and measurements of rainfall and runoff, we present an approach for modelling basin hydrology that integrates hydrogeological interpretation and hydrologic response unit concepts, applicable to both new and existing rainfall‐runoff models. The benefits of our modelling approach are a clearly defined distribution of dominant runoff form and behaviour, which is useful for interpreting functions of runoff in the recruitment and transport of sediment and other contaminants, and limited over‐parameterization. Our methods are illustrated in a case study focused on four watersheds (24 to 50 km²) draining the southern coast of California for the period October 1988 though to September 2002. Based on our hydrogeological interpretation, we present a new rainfall‐runoff model developed to simulate both surface and subsurface runoff, where surface runoff is from either urban or rural surfaces and subsurface runoff is either interflow from steep shallow soils or groundwater from bedrock and coarse‐textured fan deposits. Our assertions and model results are supported using streamflow data from seven US Geological Survey stream gauges and measured stream silica concentrations from two Santa Barbara Channel–Long Term Ecological Research Project sampling sites. Copyright © 2004 John Wiley & Sons, Ltd.     

ON THE OCCURRENCE OF LYSTROSAURUS IN SINKIANG~1

The presence of Dicynodontia in Sinkiang was first made manifest by the beautiful skull described in the same number of the Bulletin, (see above 563) as Dicynodon sinkianensis sp. nov. Recently, a second skull also collected by     

Rare earth elements in Huronian (Lower Proterozoic) sedimentary rocks: Composition and evolution of the post-Kenoran upper crust

The Huronian sequence (Lower Proterozoicl. north of Lake Huron, contains tillites and abundant fine-grained sedimentary rocks. Analyses of rare earth elements (REE) in the matrix of tillite samples from the Gowganda Formation (~ 2.3 Gal is considered to be a reasonable estimate of upper crustal REE abundances for the region north of Lake Huron at the time of Gowganda deposition. The average is characterized by a moderately steep pattern (σLREEσHREE = 9.1) and a slight negative europium anomaly ($\text{Eu}\text{Eu1}\text{= 0.89}$). This pattern is similar to estimates of the composition of the surface of the Canadian Shield and is intermediate between estimates of typical Archean and post-Archean sedimentary rocks. REE patterns for framework granitoid clasts from the tillite suggest that K-rich granites, which were apparently unimportant in the formation of Archean sedimentary rocks, were abundant in the source regions of the Gowganda Formation. This may explain the intermediate nature of the Gowganda pattern.Comparison of the tillites and associated Gowganda mudstones suggests that previous estimates of upper crustal REE abundances, which were based on the analyses of fine-grained sedimentary rocks, may be systematically high. Relative distributions, however, are the same.Analyses of mudstones from the McKim. Pecors. Serpent Gowganda Lorrain and Gordon Lake Formations suggest rapid evolution in the composition of the exposed upper crust at the close of the Kenoran orogeny. REE patterns at the base of the Huronian are similar to typical Archean sedimentary rocks. REE characteristics change up section: patterns at the top resemble typical post-Archean sedimentary rocks.It is inferred that an essentially episodic change from an early exposed upper crust dominated by a tonalite-greenstone suite to one approximating granodioritic composition is recorded in Huronian sedimentary rocks. A deviation from the evolutionary trend of the Huronian, documented in the Gowganda Formation, may be related to the glacial origin of the Gowganda.     

Processes controlling precipitation of carbonate cement and dissolution of silica in reef and near-reef settings

Carbonate cementation in the surface layer of reefs and beachrock eliminates porosity and partially replaces detrital quartz grains. The uptake and release of CO₂ by photosynthesis and respiration in reef communities cause a shift in the carbonate buffer system of seawater. Field studies and experimentation simulating the natural settings show minimum values of CO₂ (1.9 mmoles 1^?1) and HCO₃^? (2.4 meq 1^?1) in association with maximum values of pH (9.8) and O₂ (> 100% oxygen saturation) in waters covering corals and algae prior to sunset. The converse is true for these variables prior to sunrise, when minimum values of pH (7.6) and O₂ (<66% oxygen saturation) occur with maximum values of CO₂ (2.7 mmoles 1^?1) and HCO₃^? (2.7 meq 1^?1). Experimental tanks containing plain seawater showed almost no diurnal variability in pH (a constant 7.5–7.6) or O₂ (80–90% oxygen saturation) measurements. Seawater adjacent to reef biomass, with elevated pH and supersaturated with calcium carbonate, is periodically pumped into the underlying reef and beach sediments due to pressure-buildups between the reef framework or algal zones and open waters. Carbonate precipitation and quartz dissolution follow. As the system equilibrates, pH values progressively decrease.     

On the general character of coastal flow

It is well-known that some coastal currents such as the Florida Current have a recirculating region on their coastal side, while other currents such as the East Australian Current have no such region. Under the hypothesis that the form drag on a coastal current by an irregular coastal topography reduces the momentum transport of the current to a minimum for the given flow within the current, the hydraulic theory of coastal currents is used to explain this behaviour.     

The birthplaces of active regions and X-ray bright points

A comparison of soft X-ray pictures of the Sun (S-054 experiment of Skylab) with K-line spectroheliograms (Mount Wilson) shows that the X-ray bright points tend to emerge randomly throughout the Ca network pattern. However, all those bright points that developed into active regions emerged at the boundaries of network cells. This suggests that the magnetic flux of active regions comes from greater depths in the convection zone than the shallow flux that gives rise to the random emergence of bright points.Also Physics Department, C-011, University of California at San Diego, La Jolla, Calif., U.S.A.     

Genetic diversity of wild barley (Hordeum vulgare ssp. spontaneum) and its utilization for barley improvement

Wild barley (Hordeum vulgare spp. spontaneum) is the undisputed progenitor of cultivated barley and offers considerable potential as a genetic resource for barley improvement. Naturally occurring populations are distributed primarily across the Fertile Crescent, but secondary areas of diversity are also found in central Asia and Tibet. The pattern of its genetic diversity is non-random, and is structured on a global, regional and local scale. On a global scale, diversity follows ecogeography, while on a regional and local scale, it is more strongly determined by ecology. Populations growing in areas where the climate is unreliable and/or the soil is heterogeneous tend to retain the most diversity. A large number of accessions are currently conserved ex situ, but a high proportion of these have originated from the Fertile Crescent. Given the likelihood of future climate change, conserving germplasm both in situ and ex situ in the various regions where the species’ currently existing is a research priority. The value of H. vulgare spp. spontaneum for the improvement of cultivated barley lies largely in its potential contribution to the levels of attainable pathogen resistance and abiotic stress tolerance.     

观驾山—黑岛一带信息量法找金研究

本文以成矿地质模型为依据，对观驾山—黑山岛一带的化探、物探、遥感及地质等信息变量进行了详细的分析，选取了１０个信息变量２４个标志状态；在此基础上，运用信息量法对研究区内４５８个单元的信息量值进行计算，并由此确定了研究范围内的成矿远景区。事实表明，研究区信息量成矿预测是非常有效的     

On computation of equal area blocks

This paper describes a method of computing equal area elements (blocks) on the surface of a unit sphere. In this method, the surface is initially divided into a number of strips bounded by parallel circles. These strips are then divided into blocks with equal increment of longitude. The number of blocks may be different in different strips. Making use of this flexibility, we can (i) obtain blocks with ratios of (mean) horizontal sides to vertical sides that are close to unity (ii) minimize the number of polar blocks.