Footprint prediction of scalar fluxes from analytical solutions of the diffusion equation

The use of analytical solutions of the diffusion equation for footprint prediction is explored. Quantitative information about the footprint, i.e., the upwind area most likely to affect a downwind flux measurement at a given height z, is essential when flux measurements from different platforms, particularly airborne ones, are compared. Analytical predictions are evaluated against numerical Lagrangian trajectory simulations which are detailed in a companion paper (Leclerc and Thurtell, 1990). For neutral stability, the structurally simple solutions proposed by Gash (1986) are shown to be capable of satisfactory approximation to numerical simulations over a wide range of heights, zero displacements and roughness lengths. Until more sophisticated practical solutions become available, it is suggested that apparent limitations in the validity of some assumptions underlying the Gash solutions for the case of very large surface roughness (forests) and tentative application of the solutions to cases of small thermal instability be dealt with by semi-empirical adjustment of the ratio of horizontal wind to friction velocity. An upper limit of validity of these solutions for z has yet to be established.     

Energy flow and elemental concentrations in the Steina River ecosystem (Black Forest, Germany)

Considering food web energetics and elemental cycling together allows the testing of hypotheses about the coevolution of biological systems and their physical environment. We investigated the energy flow and the distribution of 25 elements in the Steina River.¶We constructed an annual energy flow network and estimated the emergy ("embodied energy" that includes all the energy involved in a process) contributions of resources sustaining the system. Furthermore, we measured the concentration of various macronutrients, essential elements, and heavy metals in the physical environment and trophic compartments. Finally, we examined the hypothesis of a positive relationship between the "rarity" of an element and its tendency to bioaccumulate. To do so, we used transformity, the relative energy input required to sustain a compartment's net production or the concentration differential of an element between the living community and the physical environment.¶The resulting energy flow network is one of the most complete available for streams. In the Steina, over 99% of the energy input is transported through the system without being processed. Dissolved inorganic matter and sunlight are the largest inputs, but uptake efficiency is much higher for dissolved and particulate organic matter. Transformities of trophic compartments and elements span 6 to 7 orders of magnitude.¶The tendency to bioaccumulate was as predicted for most elements, with macronutrients showing no accumulation and heavy elements accumulating in high-transformity compartments. However, Na and K were found at highest concentrations in consumers, and Pb, Ga, and Cd in algae. Improved estimates may become possible as more knowledge is available on ecosystem flows. We suggest further ways of testing hypotheses about strategies of element processing.     

A comparison of total precipitation values estimated from measurements and a 1D cloud model

The purpose of this study is to establish a relation between observed total precipitation values and estimations from a one-dimensional diagnostic cloud model. Total precipitation values estimated from maximum liquid water content, maximum vertical velocity, cloud top height, and temperature excess are also used to provide an equation for the total precipitation prediction. Data for this study were collected in Istanbul during the autumns of 1987 and 1988. The statistical models are developed with multiple regression technique and then comparatively verified with independent data for 1990. The multiple regression coefficients are in the range of 75% to 80% in the statistical models. Results of the test showed that total precipitation values estimated from the above techniques are in good agreement, with correlation coefficient between 40% and 46% based on test data for 1990.     

Approaches to environmental restoration of a polluted harbour with submerged archaeology: the Alexandria case study

Many invaluable underwater buildings of archaeological interest in Alexandria were discovered in 1996 at different sites in the Eastern Harbour of Alexandria. There is a belief that the best way to protect these invaluable heritages is to transfer them to an underwater park or museum. Obviously, the execution of such a project depends essentially upon the water quality (including water transparency) improving in the future. The harbour is presently polluted by discharge of wastewater effluents from different sources. It has recently been decided to restore this important coastal area through: (1) stopping the direct discharge of wastewater effluents into this semi-enclosed harbour in 1993 and (2) gradually reducing the discharge of the municipal wastewater through marine outfalls at two sites lying at the outer sides of the harbour. Zero discharge is expected to be effective by the end of the year 2001. The present work, therefore, is a follow up of the study of water quality in the harbour after 1993: in 1996 and 1999-2000. The water quality of an open sea reference station was also studied for comparison. The results reveal occurrence of an improvement of the environmental conditions in the harbour. The water has turned from being eutrophic to mesotrophic. The harbour is expected to become meso/oligotrophic as soon as the complete cessation of the discharge from the two outside sources is attained.     

Formation conditions and the environmental state of fresh groundwater in dimitrovgrad area by isotopic-hydrochemical data

Integrated uranium-isotopic and microhydrochemical studies were used to develop an indicator model of formation and circulation of drinking groundwater of Neogene-Quaternary deposit and to assess their current ecological state. The paths of subsurface flows of infiltration recharge are identified and traced, and the zones of deep-water inflow are identified and delimited. The total pollution index of groundwater from Neogene-Quaternary aquifer system was found to far in excess of the acceptable level because of an elevated concentrations of iron, manganese, and phosphorus of anthropogenic and deep-seated origin.     

Numerical simulation of the influence of stationary mesoscale orographic waves on the meridional circulation and ozone fluxes in the middle atmosphere

The authors’ parameterization of the dynamic and thermal action of stationary orographic waves generated by the Earth’s surface relief is included into the model of general circulation of the middle and upper atmosphere. Numerical simulation of the general circulation in the troposphere and stratosphere was performed and the influence of stationary orographic waves propagating upward from the Earth’s surface on the meridional and vertical velocity was studied. It is shown that the allowance for the dynamic and thermal action of these waves in the numerical model leads to changes by up to 20–30% in the meridional circulation and ozone fluxes associated with it at heights of the ozone layer maximum.     

Quantitative estimation of local geomagnetic activity relative to the level of the magnetically quiet period in 2009

A new method for determining geomagnetic activity based on calculation of the hourly amplitudes of geomagnetic field variations at ground-based observatories has been developed. Observations performed in 2009, when unusually low solar and geomagnetic activity was registered, were used as a reference level. The described method was used to estimate the energy of local geomagnetic activity; such energy is estimated for observatories in the Earth’s Northern and Southern hemispheres, and a total estimation is made for both hemispheres and for the entire Earth’s surface during large magnetic storms. These are used to compare characteristics of magnetic storm intensity based on the classical Kp and Dst indices and calculated energy estimate.     

Analysis of thick, non-planar boundaries using the discontinuity analyser

The advent of missions comprised of phased arrays of spacecraft, with separation distances ranging down to at least mesoscales, provides the scientific community with an opportunity to accurately analyse the spatial and temporal dependencies of structures in space plasmas. Exploitation of the multi-point data sets, giving vastly more information than in previous missions, thereby allows unique study of their small-scale physics. It remains an outstanding problem, however, to understand in what way comparative information across spacecraft is best built into any analysis of the combined data. Different investigations appear to demand different methods of data co-ordination. Of the various multi-spacecraft data analysis techniques developed to affect this exploitation, the discontinuity analyser has been designed to investigate the macroscopic properties (topology and motion) of boundaries, revealed by multi-spacecraft magnetometer data, where the possibility of at least mesoscale structure is considered. It has been found that the analysis of planar structures is more straightforward than the analysis of non-planar boundaries, where the effects of topology and motion become interwoven in the data, and we argue here that it becomes necessary to customise the analysis for non-planar events to the type of structure at hand. One issue central to the discontinuity analyser, for instance, is the calculation of normal vectors to the structure. In the case of planar and ‘thin’ non-planar structures, the method of normal determination is well-defined, although subject to uncertainties arising from unwanted signatures. In the case of ‘thick’, non-planar structures, however, the method of determination becomes particularly sensitive to the type of physical sampling that is present. It is the purpose of this article to firstly review the discontinuity analyser technique and secondly, to discuss the analysis of the normals to thick non-planar structures detected in magnetometer data.     

Structural and geotechnical impacts of surface rupture on highway structures during recent earthquakes in Turkey

The most significant damage on highway bridges during the recent earthquakes in Turkey (Kocaeli and Duzce earthquakes) and Taiwan (Chi–Chi earthquake) was the result of fault ruptures traversing transportation infrastructure. This phenomenon and its consequences accentuate the need to examine surface rupture hazards and to identify those areas at risk. This understanding can help to develop remedial measures for both structural and geotechnical engineering. For that purpose, damage to highway bridges during the recent events was reviewed. The total collapse of the highway overpass in Arifiye, during the Kocaeli earthquake, was investigated. The major problems under consideration (in Arifiye) were: (i) dislodging of the bridge spans, and consequently, the total separation of the reinforced concrete girders from the piers; and (ii) the stability of a mechanically stabilized earth wall (MSEW) system under extreme loading conditions. The results of the structural and geotechnical investigations presented herein can be taken in consideration to improve transportation infrastructure against surface rupture hazards.