Assessing climate change impacts on hydrology from an ensemble of regional climate models,model scales and linking methods – a case study on the Lule River basin

This paper investigates how using different regional climate model (RCM) simulations affects climate change impacts on hydrology in northern Europe using an offline hydrological model. Climate change scenarios from an ensemble of seven RCMs, two global climate models (GCMs), two global emissions scenarios and two RCMs of varying resolution were used. A total of 15 climate change simulations were included in studies on the Lule River basin in Northern Sweden. Two different approaches to transfer climate change from the RCMs to hydrological models were tested. A rudimentary estimate of change in hydropower potential on the Lule River due to climate change was also made. The results indicate an overall increase in river flow, earlier spring peak flows and an increase in hydropower potential. The two approaches for transferring the signal of climate change to the hydrological impacts model gave similar mean results, but considerably different seasonal dynamics, a result that is highly relevant for other types of climate change impacts studies.     

Oceanography of Glacier Bay,Alaska: Implications for biological patterns in a glacial fjord estuary

Alaska, U.S.A, is one of the few remaining locations in the world that has fjords that contain temperate idewater glaciers. Studying such estuarine systems provides vital information on how deglaciation affects oceanographic onditions of fjords and surrounding coastal waters. The oceanographic system of Glacier Bay, Alaska, is of particular interest ue to the rapid deglaciation of the Bay and the resulting changes in the estuarine environment, the relatively high oncentrations of marine mammals, seabirds, fishes, and invertebrates, and the Bay’s status as a national park, where ommercial fisheries are being phased out. We describe the first comprehensive broad-scale analysis of physical and iological oceanographic conditions within Glacier Bay based on CTD measurements at 24 stations from 1993 to 2002. easonal patterns of near-surface salinity, temperature, stratification, turbidity, and euphotic depth suggest that freshwater nput was highest in summer, emphasizing the critical role of glacier and snowmelt to this system. Strong and persistent tratification of surface waters driven by freshwater input occurred from spring through fall. After accounting for seasonal nd spatial variation, several of the external physical factors (i.e., air temperature, precipitation, day length) explained a large mount of variation in the physical properties of the surface waters. Spatial patterns of phytoplankton biomass varied hroughout the year and were related to stratification levels, euphotic depth, and day length. We observed hydrographic atterns indicative of strong competing forces influencing water column stability within Glacier Bay: high levels of freshwater ischarge promoted stratification in the upper fjord, while strong tidal currents over the Bay’s shallow entrance sill enhanced ertical mixing. Where these two processes met in the central deep basins there were optimal conditions of intermediate tratification, higher light levels, and potential nutrient renewal. These conditions were associated with high and sustained hlorophylla levels observed from spring through fall in these zones of the Bay and provide a framework for understanding he abundance patterns of higher trophic levels within this estuarine system.     

The creative reconstruction of the Internet: Google and the privatization of cyberspace and DigiPlace

The Internet has often been portrayed as the ultimate leveler of information where existing hierarchies of power and privilege are undermined by meritocracy. Some websites and functions are, however, more equal than others. In particular, search engines such as Google have been a key means to construct meaning out of disorder. This ordering (or enclosing of the Internet commons), however, comes at a cost as a location within the top 10 Google search results, marks the boundary (albeit a fluid one) between the core and the periphery of the Internet. The recent incorporation of spatial elements into the Google indexing raises fresh and geographically relevant concerns. This article focuses on the construction, access and use of Google derived rankings to deploy geo-referenced information in the physical environment and the way this melding of code and place affects how people interact with place. Using the theoretical concept of DigiPlace this article analyzes how Google Maps and Google Earth are structured and shape what appears (and what does not) in cyberspace and DigiPlace. Of particular concern are the implications of a private corporation controlling this new space.     

Non-destructive estimation of potato leaf chlorophyll from canopy hyperspectral reflectance using the inverted PROSAIL model

Optimizing nitrogen (N) fertilization in crop production by in-season measurements of crop N status may improve fertilizer N use efficiency. Hyperspectral measurements may be used to assess crop N status by estimating leaf chlorophyll content. This study evaluated the ability of the PROSAIL canopy-level reflectance model to predict leaf chlorophyll content. Trials were conducted with two potato cultivars under different N fertility rates (0–300 kg N ha⁻¹). Canopy reflectance, leaf area index (LAI) and leaf chlorophyll and N contents were measured. The PROSAIL model was able to predict leaf chlorophyll content with reasonable accuracy later in the growing season. The low estimation accuracy earlier in the growing season could be due to model sensitivity to non-homogenous canopy architecture and soil background interference before full canopy closure. Canopy chlorophyll content (leaf chlorophyll content × LAI) was predicted less accurately than leaf chlrophyll content due to the low estimation accuracy of LAI for values higher than 4.5.     

Practical Experiences with Films, Cameras and Navigation Systems

The first author commenced his experiences with aerial photography in 1945, when he joined the Royal Air Force (RAF). The aerial cameras used at that time were the Williamson F24 and F52, with Ilford HP3 and FP3 panchromatic films. Subsequently the Williamson F95 camera was tested against the USAF Sonne 11 camera. During his final years in the RAF, a variety of film types was employed: colour, monochrome infra-red and false colour infra-red. Additional experience was gained when the author was employed by the International Training Centre (ITC), The Netherlands and he saw the further development of the air camera from the Wild RC8 and Zeiss (Oberkochen) RMK 15/23 to the Wild RC20, Zeiss (Jena) LMK and Zeiss (Oberkochen) RMK TOP. He predicts that the future lies with digital cameras.
The second author started working with aerial photography in the 1950s. Details are given of cameras, visual navigation sights and survey aircraft dating from that period. Overseas operations, carried out mainly by Hunting Surveys and Fairey Surveys, posed particular problems because the majority of the work there was undertaken without the aid of existing maps. The introduction of external navigation systems is described, from the Decca ship navigation system, through the GNS-200 VLF/Omega low frequency radio system to INS, the Inertial Navigation System. The author later joined the ITC, which enabled him to participate in trials of the Computer-controlled Photo Navigation System. Eventually practical experience was gained with differential GPS, particularly in countries in southeast Asia. Aerial photography currently appears to benefit less from financial investment than the photographic, aviation and survey industries. However, the satisfaction of making a significant contribution to major overseas development projects outweighs the frustration of lack of acceptance of plans for the future of the air survey industry.     

New equipment and processing for magnetotelluric remote reference observations

Robust estimates of magnetotelluric and geomagnetic response functions are determined using the coherency and expected uniformity of the magnetic source field as quality criteria. The method is applied on data sets of three simultaneously recording sites. For the data acquisition we used a new generation of geophysical equipment (S.P.A.M. MkIII), which comprises novel concepts of parallel computing and networked, digital data transmission. The data-processing results show that the amount of noise on the horizontal components of the magnetic field varies considerably in time, between sites and over the frequency range. The removal of such contaminated data beforehand is essential for most data-processing schemes, as the magnetic channels are usually assumed to be free of noise. The standard remote reference method is aimed at reducing bias in response function estimates. However, this does not necessarily improve their precision as our results clearly show. With our method, on the other hand, we can filter out source field irregularities, thereby providing suitable working conditions for the robust algorithm, and eventually obtain considerably improved results. Contrary to previous concepts, we suggest rejecting as much data as feasible in order to concentrate on the remaining parts of high-quality observations.     

Petrology and geochronology of basalt breccia from the 1996 earthquake swarm of Loihi seamount, Hawaii: magmatic history of its 1996 eruption

 Samples of basalt were collected during the Rapid Response cruise to Loihi seamount from a breccia that was probably created by the July to August 1996 Loihi earthquake swarm, the largest swarm ever recorded from a Hawaiian volcano. ²¹⁰Po–²¹⁰Pb dating of two fresh lava blocks from this breccia indicates that they were erupted during the first half of 1996, making this the first documented historical eruption of Loihi. Sonobuoys deployed during the August 1996 cruise recorded popping noises north of the breccia site, indicating that the eruption may have been continuing during the swarm. All of the breccia lava fragments are tholeiitic, like the vast majority of Loihi's most recent lavas. Reverse zoning at the rim of clinopyroxene phenocrysts, and the presence of two chemically distinct olivine phenocryst populations, indicate that the magma for the lavas was mixed just prior to eruption. The trace element geochemistry of these lavas indicates there has been a reversal in Loihi's temporal geochemical trend. Although the new Loihi lavas are similar isotopically and geochemically to recent Kilauea lavas and the mantle conduits for these two volcanoes appear to converge at depth, distinct trace element ratios for their recent lavas preclude common parental magmas for these two active volcanoes. The mineralogy of Loihi's recent tholeiitic lavas signify that they crystallized at moderate depths (∼8–9 km) within the volcano, which is approximately 1 km below the hypocenters for earthquakes from the 1996 swarm. Taken together, the petrological and seismic evidence indicates that Loihi's current magma chamber is considerably deeper than the shallow magma chamber (∼3–4 km) in the adjoining active shield volcanoes. Received: 21 August 1997 / Accepted: 15 February 1998     

Evolution of metamorphic volatiles during exhumation of microdiamond-bearing granulites in the Western Gneiss Region, Norway

Fluid inclusions in garnet, kyanite and quartz from microdiamond-bearing granulites in the Western Gneiss Region, Norway, document a conspicuous fluid evolution as the rocks were exhumed following Caledonian high- and ultrahigh-pressure (HP–UHP) metamorphism. The most important of the various fluid mixtures and daughter minerals in these rocks are: (N₂ + CO₂ + magnesian calcite), (N₂ + CO₂ + CH₄ + graphite + magnesian calcite), (N₂ + CH₄), (N₂ + CH₄ + H₂O), (CO₂) and (H₂O + NaCl + CaCl₂ + nahcolite). Rutile also occurs in the N₂ + CO₂ inclusions as a product of titanium diffusion from the garnet host into the fluid inclusions. Volatiles composed of N₂ + CO₂ + magnesian calcite characterise the ambient metamorphic environment between HP–UHP (peak) and early retrograde metamorphism. During progressive decompression, the mole fraction of N₂ increased in the fluid mixtures; as amphibolite-facies conditions were reached, CH₄ and later, H₂O, appeared in the fluids, concomitant with the disappearance of CO₂ and magnesian calcite. Graphite is ubiquitous in the host lithologies and fluid inclusions. Thermodynamic modelling of the metamorphic volatiles in a graphite-buffered C-O-H system demonstrates that the observed metamorphic volatile evolution was attainable only if the f _O2 increased from c. −3.5 (±0.3) to −0.8 (±0.3) log units relative to the FMQ oxygen buffer. External introduction of oxidising aqueous solutions along a system of interconnected ductile shear zones adequately explains the dramatic increase in the f _O2. The oxidising fluids introduced during exhumation were likely derived from dehydration of oceanic crust and continental sediments previously subducted during an extended period of continental collision in conjunction with the Caledonian orogeny. Received: 15 December 1997 / Accepted: 25 May 1998     

The breakdown of potassium feldspar at high water pressures

The equilibrium position of the reaction between sanidine and water to form “sanidine hydrate” has been determined by reversal experiments on well characterised synthetic starting materials in a piston cylinder apparatus. The reaction was found to lie between four reversed brackets of 2.35 and 2.50 GPa at 450 °C, 2.40 and 2.59 GPa at 550 °C, 2.67 and 2.74 GPa at 650 °C, and 2.70 and 2.72 GPa at 680 °C. Infrared spectroscopy showed that the dominant water species in sanidine hydrate was structural H₂O. The minimum quantity of this structural H₂O, measured by thermogravimetric analysis, varied between 4.42 and 5.85 wt% over the pressure range of 2.7 to 3.2 GPa and the temperature range of 450 to 680 °C. Systematic variation in water content with pressure and temperature was not clearly established. The maximum value was below 6.07 wt%, the equivalent of 1 molecule of H₂O per formula unit. The water could be removed entirely by heating at atmospheric pressure to produce a metastable, anhydrous, hexagonal KAlSi₃O₈ phase (“hexasanidine”) implying that the structural H₂O content of sanidine hydrate can vary. The unit cell parameters for sanidine hydrate, measured by powder X-ray diffraction, were a = 0.53366 (±0.00022) nm and c = 0.77141 (±0.00052) nm, and those for hexasanidine were a = 0.52893 (±0.00016) nm and c = 0.78185 (±0.00036) nm. The behaviour and properties of sanidine hydrate appear to be analogous to those of the hydrate phase cymrite in the equivalent barium system. The occurrence of sanidine hydrate in the Earth would be limited to high pressure but very low temperature conditions and hence it could be a potential reservoir for water in cold subduction zones. However, sanidine hydrate would probably be constrained to granitic rock compositions at these pressures and temperatures. Received: 6 May 1997 / Accepted: 2 October 1997