The representer method for data assimilation in single-phase Darcy flow in porous media

We apply the representer method, a data assimilation algorithm, to single-phase Darcy flow in porous media. The measurement array that yields the assimilated data can be expressed as a vector of linear functionals of pressure. The a priori discretization errors in the representer method are analyzed in terms of the convergence properties of the underlying numerical schemes used in each part of the algorithm. We formulate some proof-of-concept numerical experiments that illustrate the error analysis.     

Microprocessor systems as an aid to estuarine studies in the laboratory

Three systems are outlined which indicate the potential of microprocessor systems as control devices in the generation of specifically varying environmental mental conditions. The use of an RCA 1802 Cosmac microprocessor to generate salinity cycles, tidal cycles and temperature cycles is described.     

Simplified analysis of offshore piles under cyclic lateral loads

A simple theory for predicting the response to cyclic lateral loading of piles deeply driven in either soft clay or sand is presented and formulas given for calculating, among other things, deflection and internal bending moment along the pile. The theory assumes the soil resistance to deflection to be characterized by an initial elastic reaction up to a critical deflection level, followed by a yield reaction independent of further deflection. Soil parameters are estimated and the theory is shown to provide good correlation with existing field data.     

Two samplers for large-volume collection of chlorinated hydrocarbons

Two sampling devices for the in situ extraction of chlorinated hydrocarbons from water are described. Both samplers use the macroreticular adsorbent Amberlite XAD-2. They include a “fish” sampler which has been used to collect samples for PCB analysis from waters around the British Isles. Operation of this sampler causes a minimum of interruption to a ship's cruise programme and at the same time allows a large area to be surveyed. The second sampler is a self-powered in situ pump which is cheap to construct and can be left unattended to extract large volumes of water at a fixed station. The device is serviced by divers and samples may be collected daily on a routine sampling basis.     

Cisuralian coals of the Mullaley Sub-basin,northern New South Wales

The Mullaley Sub-basin of the Gunnedah Basin extends from Quirindi in the southeast, to north of Narrabri, to west of Dunedoo in northern New South Wales. There have been more than 100 boreholes sunk to basement investigating the (lower Permian) Cisuralian coal and coal seam gas resources of the Mullaley Sub-basin since the early 1990s. A desktop review of this open file information has allowed the formal correlation and naming of six Cisuralian coal members attaining a maximum 35 m of cumulative thickness within an upward coarsening sedimentary package totalling no more than 150 m. In ascending order, the coal members are: Bibblewindi (0–10 m), Bohena (3–18 m), Collygra (0.5–3 m), Coxs (1.5–4 m), Tullamullen (0.5–4 m) and Mooki (0.5–3 m).

Cisuralian coal seams in the Maules Creek Formation of the southern Mullaley Sub-basin are here correlated with those of the Greta Coal Measures at Werris Creek and Muswellbrook. It is apparent that basement paleotopography played a significant role in the Cisuralian coal development as coals are best developed where the sedimentary sequence is greater than 60 m thick, as there the thick seams (Bohena and Bibblewindi coal members) occur towards the base of the sequence. The maximum western limit of the Cisuralian coals (Rocky Glen Ridge) is further east than previously inferred with new drilling information showing the Porcupine Formation directly overlying the barren pelletoidal claystones of the Leard Formation or the underlying volcanics (Boggabri Volcanics/Werrie Basalt). Early marine transgressions at the top of the Maules Creek Formation have stopped development of the Mooki, Tullamullen and Coxs coal members in the northern and eastern Mullaley Sub-basin and allowed the development of localised paraconglomerate (diamictite) intervals up to 10 m thick. Thick (>20 m cumulative) coal occurrences are localised to the Jacks Creek and Pilliga East State Forest areas southwest of Narrabri. The coal resource potential of the Mullaley Sub-basin is estimated at 13–28 billion tonnes.     

Hector's dolphin movement patterns in response to height and direction of ocean swell

A central question to any understanding of ecology is how animals use their habitat, and how habitat use is influenced by temporally changing features of the environment. Previous research on Hector's dolphins at Akaroa Harbour, New Zealand suggested that dolphins leave inshore, harbour environments during or after rough weather. To test this hypothesis, visual sightings (2000–2012) and acoustic detections (2007–2008) of Hector's dolphins in Akaroa Harbour were modelled to test for a relationship with swell height and swell direction. Sighting rates and acoustic detection rates in Akaroa Harbour were significantly lower on days after big swell events and in some linear models after swell events from the south. These results indicate that swell events influence Hector's dolphin movements in and around Akaroa Harbour. Possible reasons for this behaviour are diverse and need further investigation. However, this information can be used both to predict daily dolphin movement for conservation and research purposes, and to suggest how dolphins may react in future if extreme weather events are becoming frequent.     

Compound-specific D/H ratios of the marine lakes of Palau as proxies for West Pacific Warm Pool hydrologic variability

We tested the use of hydrogen isotopic ratios (δD) of lipids in marine lake sediments from the Micronesian Republic of Palau against the instrumental record of the last century to assess their capacity to record past hydrological changes of the Western Pacific Warm Pool. δD values of the algal lipid biomarker dinosterol (δD_Dino) and the more generic palmitic acid (δD_PA) were found to be sensitive indicators of the intensity of regional precipitation, as recorded by the Southern Oscillation Index (SOI). The observed sensitivity is caused by the combined effect of: 1) The amount effect in tropical precipitation; 2) Dilution of the isotopically heavy saline surface waters with light precipitation; 3) A salinity effect on the biosynthetic D/H fractionation between lipid and lake water. Both lake water δD (δD_Lake) and δD_Dino could be expressed as a quadratic function of either precipitation or lake water salinity. δD_Dino values were used to reconstruct past hydrological changes of the region. Long-term variations in the strength and sign of the El Niño - Southern Oscillation (ENSO) since the Little Ice Age (LIA, ～1450–1850 A.D.) and during the early Holocene (～7–9 kyr BP) appeared to dominate decadal variability, and indicate very dry conditions during the LIA. Early Holocene δD_Dino values were on average ～10‰ higher than those of recent centuries, which we interpret as a result of millennial scale hydrologic and water mass changes on a global level. The similar ～35‰ range of δD changes during the early Holocene and last several centuries imply a similar range of decadal-centennial hydrologic variability during those two climate regimes. Our results indicate that a correlation exists between solar irradiance levels and tropical Pacific climate.     

Forensic geology at the International School Science Fair 2013

In July 2013 the International School Science Fair (ISSF) was hosted by Camborne Science and International Academy, Cornwall, UK. This meeting brings young talented scientists together from around the world to participate in workshops and activities highlighting current scientific developments. As part of ISSF 2013, a workshop on forensic geology was delivered to some of the international participants. This included the preparation of a map to show the mineralogical composition of the soils of the participating schools. The soil mineralogy was determined using automated mineral analysis based on scanning electron microscopy. In addition there were workshops on the recovery of geological trace evidence in a forensic context and the theory and practice of carrying out a geophysical search for hidden items. Data generated as part of this workshop are available to download from the International Union of Geological Sciences, Initiative on Forensic Geology website ( http://www.forensicgeologyinternational.com ).