INFORMATION YIELD FROM FOREST IMAGES IN DIFFERENT SPECTRAL BANDS

Remote sensing imagery in the visible, infrared, and microwave regions of the spectrum is compared with features on the ground at a test site in western Sverdlovsk Oblast. Particular attention is paid to information obtainable on the forest cover—e.g., physiognomy and floristic composition, stand density, age of timber cuttings—and how such information about the test site varies according to wavelength. Translated by Larry Richardson, Glen-dale, CA 91202 from: Geografiya i prirodnyye resursy, 1992, No. 4, pp. 166-167.     

The three-dimensional geometry of the heliospheric current sheet

The three-dimensional geometry of the heliospheric current sheet seen from fixed points in interplanetary space is constructed for idealized (sinusoidal) magnetic neutral lines (equators) and for an observed magnetic equator on the basis of the “kinematic method” developed by Hakamada and Akasofu (1982). The cross-sections of the wavy current sheet at distances 1, 2 and 5 a.u. are also constructed for the idealized magnetic neutral lines.     

Effects of atmospheric circulation and boundary layer structure on the dispersion of suspended particulates in the Seoul metropolitan area

Summary A three-dimensional non-hydrostatic numerical model and lagrangian particle model (random walk model) were used to investigate the effects of the atmospheric circulation and boundary layer structure on the dispersion of suspended particulates in the Seoul metropolitan area. Initially, emitted particulate matter rises from the surface of the city towards the top of the convective boundary layer (CBL), owing to daytime thermal heating of the surface and the combined effect of an onshore wind with a westerly synoptic-scale wind. A reinforcing sea-valley breeze directed from the coast toward the city of Seoul, which is enclosed in a basin and bordered by mountains to its east, disperses the suspended particulate matter toward the eastern mountains. Total suspended particulate concentration (TSP) at ground level in the city is very low and relatively high in the mountains. Radiative cooling of the surface produces a shallow nocturnal surface inversion layer (NSIL) and the suspended particulate matter still present near the top of the CBL from the previous day, sinks to the surface. An easterly downslope mountain wind is directed into the metropolitan area, transporting particulate matter towards the city, thereby recycling the pollutants. The particulates descending from the top of the NSIL and mountains, combine with particulates emitted near the surface over the city at night, and under the shallow NSIL spread out, resulting in a maximum ground level concentration of TSP in the metropolitan area at 2300 LST. As those particles move toward the Yellow Sea through the topographically shaped outlet west of Seoul city under the influence of the easterly land breeze, the maximum TSP concentration occurs at the coastal site. During the following morning, onshore winds resulting from a combined synoptic-scale westerly wind and westerly sea breeze, force particulates dispersed the previous night to move over the adjacent sea and back over the inland metropolitan area. The recycled particulates combine with the particulates emitted from the surface in the central part of the metropolitan area, producing a high TSP and again rise towards the top of the CBL ready to repeat the cycle.     

Quantification of stability improvement of a dump through biological reclamation

An integrated study on biological stabilisation of a dump slope has indicated that biological reclamation with grass and tree species should be considered for long term stability of this coal mine dump in India. The grasses have greater soil binding capacity and help to control soil erosion and improve dump stability. Native grasses such as Bamboo (Dendrocalmus strictus) and Kashi (Saccharum spontaneum) are the important constituents of grass species which can stabilise the dump slopes. Field observation of growth performance of grasses have indicated that mean grass height, root depth and below-ground root biomass are 185 cm (±68), 45 cm (±5) and 467 g m^–2 (±170), respectively after three years of grass growth on Mudidih overburden dump slope in India. The growth performance of tree species, namely Sisum (Dalbergia sisoo) and Subabool (Leucena lecocephala), in terms of height, diameter increment, below-ground biomass and root depth have shown mean values of 219 cm (±94), 48 mm (±6), 4.0 kg m^–2 (±1.5) and 1 m (±0.1), respectively. This acts as biological fertility which helps in root proliferation and enhancement of dump stability. From the numerical modelling it is suggested that roots of these grass and tree species have significantly enhanced the factor of safety of dump from 1.4 to 1.8 and therefore have a positive role in maintaining long term stability.     

Recent volcanism at Schonchin and Cinder Buttes,northern California

Recent volcanism on the northern flank of the Medicine Lake Highland consists of a series of basalt to andesite spatter and cinder cones and their associated flows. Two particular structures, Cinder Butte and Schonchin Butte, have erupted materials that are very similar in terms of age, volume, modal mineralogy, and many major and trace elements. Significant differences with respect to TiO₂, K₂O, P₂O₅, Sr, Ba, Zr, and LREE can be related to possible changes in the mineralogy within the source region of these volcanic rocks. Apatite and priderite are the two minor constituents that best satisfy the constraints set by the mineral and chemical data. An inhomogeneous upper mantle or lower crust beneath the Medicine Lake Highland is indicated.     

Thorium-234 as a tracer of spatial,temporal and vertical variability in particle flux in the North Pacific

An extensive ²³⁴Th data set was collected at two sites in the North Pacific: ALOHA, an oligotrophic site near Hawaii, and K2, a mesotrophic HNLC site in the NW Pacific as part of the VERTIGO (VERtical Transport In the Global Ocean) study. Total ²³⁴Th:²³⁸U activity ratios near 1.0 indicated low particle fluxes at ALOHA, while ²³⁴Th:²³⁸U ～0.6 in the euphotic zone at K2 indicated higher particle export. However, spatial variability was large at both sites—even greater than seasonal variability as reported in prior studies. This variability in space and time confounds the use of single profiles of ²³⁴Th for sediment trap calibration purposes. At K2, there was a decrease in export flux and increase in ²³⁴Th activities over time associated with the declining phase of a summer diatom bloom, which required the use of non-steady state models for flux predictions. This variability in space and time confounds the use of single profiles of ²³⁴Th for sediment trap calibration purposes. High vertical resolution profiles show narrow layers (20–30 m) of excess ²³⁴Th below the deep chlorophyll maximum at K2 associated with particle remineralization resulting in a decrease in flux at depth that may be missed with standard sampling for ²³⁴Th and/or with sediment traps. Also, the application of ²³⁴Th as POC flux tracer relies on accurate sampling of particulate POC/²³⁴Th ratios and here the ratio is similar on sinking particles and mid-sized particles collected by in-situ filtration (>10–50 μm at ALOHA and >5–350 μm at K2). To further address variability in particle fluxes at K2, a simple model of the drawdown of ²³⁴Th and nutrients is used to demonstrate that while coupled during export, their ratios in the water column will vary with time and depth after export. Overall these ²³⁴Th data provide a detailed view into particle flux and remineralization in the North Pacific over time and space scales that are varying over days to weeks, and 10's–100's km at a resolution that is difficult to obtain with other methods.     

On mass transport in deep water waves

Summary Various formulations of the mass-transport problem are compared for progressive waves in deep water. In order to calculate the mass-transport velocity as a function of depth in the main body of the fluid, it is necessary to include the effect of viscous wave attenuation. It is shown that the usual assumptions of periodicity in distance and attenuation with time or periodicity in time and attenuation with distance, are both physically unsatisfactory. The first does not specify a unique solution, and the second is incompatible with the assumption of zero surface stress. A certain critical constant tangential wind stress will maintain strictly time-periodic deep water waves. The corresponding attenuation with distance is then calculated to order ³. A constant tangential stress greater or less than the critical causes waves, necessarily decaying with distance, to grow or decay with time.     

Use of Carbonatites in the Production of Precipitated Calcium Carbonate: A Case Study from Eppawala,Sri Lanka

The study investigates the possibility of using carbonatite in the production of precipitated calcium carbonate (PCC). We made use of fresh apatite-rich carbonatites found at the phosphate mining sites at Eppawala, Sri Lanka. Analyses of the fresh carbonatite were performed with the aid of optical microscopy, powder X-ray diffraction (XRD), atomic absorption spectrophotometry (AAS), UV/visible spectrophotometry (UVVS), and thermo gravimetric analysis (TGA). Quicklime obtained from calcinations of carbonatites was used in synthesizing PCC via a lime-soda process. The end product was analyzed with XRD, TGA, AAS, and UVVS. Results revealed that the most common CO₃ ^2? phase available in fresh carbonatites is calcite (>65%). The Ca-rich CO₃ ^2? phase can be distinguished easily from other available minerals because its mode of occurrence in carbonatite matrix is different to that of other minerals. The results of TGA show that the decomposition of CO₃ ^2? phase initiates at about 340°C, which leads to lower energy consumption during calcinations. Post-magmatic hydrothermal process may have been the cause of the formation of thermally unstable CO₃ ^2? phases. Hydration of quicklime from the carbonatite yields much higher Ca²⁺ in the solution than from marble under the same experimental conditions. The synthesized PCC particles are in the calcite polymorphic form. The purity of PCC varies from 96 to 98 wt%. The maximum precipitable CaCO₃ from 1 g of quicklime is about 1.1 g. Hence, fresh carbonatites has great economic potential for the production of PCC.     

Fatty acid profiles of benthic environment associated with artificial reefs in subtropical Hong Kong

Artificial reefs can enhance habitat heterogeneity, especially in seabed degraded by bottom-dredging and trawling. However, the trophodynamics of such reef systems are not well understood. This study provided baseline data on trophic relationships in the benthic environment associated with artificial reefs in late spring and mid summer of subtropical Hong Kong, using fatty acid profiles as an indicator. Data from sediments collected at the reef base, materials from sediment traps deployed on top and bottom of the reefs, total particulate matter from the water column and oyster tissues from reef surface were subjected to principal component analysis. Results showed variations of fatty acid profiles in the total particulate matter, upper sediment trap and oyster tissue samples collected in the two samplings, indicating seasonal, trophodynamic changes within the reef system. The wastes produced by fish aggregating at the reefs can also contribute a source of biodeposits to the nearby benthic environment.     

Seasonal cycle of surface circulation in the coastal North Indian Ocean

Monthly-mean winds and currents have been used to identify the driving mechanisms of seasonal coastal circulation in the North Indian Ocean. The main conclusions are: (i) the surface circulation off Arabia is typical of a wind-driven system with similar patterns of longshore current and wind stress; (ii) circulation off the west coast of India is consistent with the dynamics of a wind-driven eastern boundary current only during the southwest monsoon. During the northeast monsoon it is possible that the influence of the interior flow is important. (iii) There are at least three mechanisms that influence the surface circulation off the east coast of India: wind-stress, influence of fresh-water run off and contribution of the interior flow. It is difficult at present to assess the relative importance of these three processes.