FAUST observations of ultraviolet sources in the direction of Coma

We analyse an ultraviolet observation toward the Coma cluster by means of the FAUST shuttle-borne telescope. We detect 56 candidate sources to a signal-to-noise ratio of 6.5. Most sources have optical counterparts in existing catalogues and are stars. 10 sources with no listed counterparts were observed at the Wise Observatory. We present identifications based on low-resolution spectrophotometry, and discuss the foreground stars and the galaxies, all in the foreground of the Coma cluster. The FAUST image yields a higher fraction of hot evolved stars than either of the North Galactic Pole or the Virgo regions, analysed previously. We identify these tentatively as cooling white dwarfs in the Coma Berenices (Mel 111) open cluster.     

Uncertainty, Complexity and Concepts of Good Science in Climate Change Modelling: Are GCMs the Best Tools?

In this paper we explore the dominant position of a particular style of scientific modelling in the provision of policy-relevant scientific knowledge on future climate change. We describe how the apical position of General Circulation Models (GCMs) appears to follow logically both from conventional understandings of scientific representation and the use of knowledge, so acquired, in decision-making. We argue, however, that both of these particular understandings are contestable. In addition to questioning their current policy-usefulness, we draw upon existing analyses of GCMs which discuss model trade-offs, errors, and the effects of parameterisations, to raise questions about the validity of the conception of complexity in conventional accounts. An alternative approach to modelling, incorporating concepts of uncertainty, is discussed, and an illustrative example given for the case of the global carbon cycle. In then addressing the question of how GCMs have come to occupy their dominant position, we argue that the development of global climate change science and global environmental management frameworks occurs concurrently and in a mutually supportive fashion, so uniting GCMs and environmental policy developments in certain industrialised nations and international organisations. The more basic questions about what kinds of commitments to theories of knowledge underpin different models of complexity as a normative principle of good science are concealed in this mutual reinforcement. Additionally, a rather technocratic policy orientation to climate change may be supported by such science, even though it involves political choices which deserve to be more widely debated.     

Bathymetry and Canyons of the western Solomon Sea

The floor of the western Solomon Sea (for new bathymetric map see inside back cover of this issue) is dominated by the arched and ridged basement of the Solomon Sea Basin, the partly-sediment-filled New Britain Trench, and a more completely filled trench, the Trobriand Trough. There is a deep basin where the trenches join (149° Embayment), and a silled basin west of the New Britain Trench (Finsch Deep). Submarine canyons descend from the west and south to the 149° Embayment. Abyssal fans and plains are structurally defined and locally disturbed by young faults. Probable submerged pinnacle reefs stand in water depths as great as 1,200 m.     

Dispersal patterns of the eggs and larvae of spring-spawning fish in the Irish Sea, UK

Many marine species produce pelagic propagules which, because of their life-history characteristics and the local hydrodynamics, can disperse considerable distances from the point of release. Distances travelled are affected by factors such as: release time and location, egg and larval stage duration, local environmental conditions and active swimming and settlement behaviours. Understanding such dispersal patterns is important for the design of effective ecosystem-conservation strategies. We used a regional scale, coupled physical-biological model for the Irish Sea to simulate the possible dispersal of eggs and larvae of five species of fish with contrasting early life histories (cod Gadus morhua, plaice Pleuronectes platessa, witch Glyptocephalus cynoglossus, sprat Sprattus sprattus and pogge Agonus cataphractus). The hydrodynamic model was forced with meteorological data for 1995, a year when extensive plankton surveys were conducted in the Irish Sea. A particle tracking method featuring particle release (spawning) and species-dependent particle development and behaviour was then run based on flow and temperature fields from the hydrodynamical model. Modelled larval distributions and settlement areas corresponded favourably with observations from field sampling. The settlement destinations (or onset of shoaling for sprat) were affected both by their initial spawning location and by the species-specific development rates and behaviours coded into the model. Eggs and larvae typically remained within 160 km of their spawning origin, although a minority travelled up to 300 km. Even in a relatively enclosed sea such as the Irish Sea, fish eggs and larvae can be dispersed over 100s of km. This provides a major challenge for the design of effective spatial management strategies if it is necessary to protect a species across its life-history stages. Further progress in the design of effective conservation measures for species or communities will need an integrated approach taking account of key aspects of early life history and behaviour.     

Effects of rapid changes in temperature on two estuarine crustaceans

Weight specific oxygen consumption (Q_O2) patterns of the amphipod, Gammarus sp. (acclimated to 5°, 15° and 25°C) and of juvenile blue crabs, Callinectes sapidus (15° and 25°C) were used to evaluate the potential effect of exposure to rapid temperature changes simulating once-through power plant pumped entrainment. Amphipods at all acclimation temperatures and blue crabs at 15°C responded to the temperature changes by increasing Q_O2 above pre-exposure levels after the thermal increase and then returning to pre-exposure levels. The response was judged to be a normal physiological compensation response, not a thermal stress response, as suggested by some investigators. Significant differences were found among seasonal Q_O2, patterns in both species; Q_O2, increased with increasing acclimation temperature. However, no seasonal stress effects were found as a result of exposure to the temperature changes. This implies that the effects of ΔT's up to 10°C from power plants of this design should have no significant impact on these organisms.     

A GPS and Cold Ocean Brightness Temperature Calibration of the ERS-2 and TOPEX/Poseidon Microwave Radiometers

Sea-level change studies from altimetric satellites are reliant on range stability of the sea surface heights computed from orbital positioning and geophysically corrected data. One such correction, namely the wet tropospheric delay induced by the highly variable atmospheric water vapor content, is provided by radiometers onboard ERS-2 and TOPEX/Poseidon (T/P). In this study the long-term stability of the ERS-2 microwave radiometer (E2MR) and the T/P microwave radiometer (TMR) are investigated with the observed drift in the brightness temperatures approximated by reference to the coldest temperatures over the oceans. The E2MR stability is characterized by a gain anomaly fall in 1996 and a drift in the 23.8 GHz channel. For the TMR, investigations show that the dominant drift is about 0.2 K/year in the 18 GHz channel over the first 7-8 years but stabilizing and even decreasing slightly thereafter. In contrast, the 21 GHz and 37 GHz channels are comparatively stable. Utilizing correction formulae a modified wet tropospheric range is inferred from “small-change” analysis of the radiometric correction given on the altimetric Geophysical Data Records. The accuracy of this formulism is validated by independent comparison against GPS derived wet tropospheric delays inferred at 14 coastal IGS stations with near continuous data from September 1992 through to the present day. Comparisons between GPS results for ERS-2 and T/P show that the E2MR path delay is 14 mm short. For T/P, the spatial distribution of the wet tropospheric enhancement is further investigated to show that the nonuniformity can equate to a deviation in sea-level height change of about 0.1 mm/year compared with global average sea-level change. Finally, the altimetric range stability of T/P is revisited by comparison against time series from the global network of tide gauges. Analysis shows that the validated TMR drift correction results in a residual trend of -0.27 ± 0.11 mm/yr which is not significant at the 3σ level.     

Children's Geographies: Tracing The Evolution and Involution of a Concept

This essay traces the evolution of children's geographies as a concept through three phases. First, in the early 1970s as a beginning impression influenced heavily by developmental and environmental psychology. Second, beginning around 1990, children's geographies cohered politically as geographers focused on young people's identity through feminism and Marxism, and global policy initiatives on children's rights. The third phase, covering the last couple of decades, coming from issues of political identity, challenges what we think we know about young people and their geographies, and also advocates a set of loose theories about the ways young people create and re‐create spaces and themselves. Cognate disciplines coming to geography for insights about children and their worlds characterize this current phase. To offset this seeming linear progression the essay also notes an involution of the concept that defies clear categories and sequences, but suggests the fluidity of tensions and accommodations that comprises children's geographies.