The climatological mean atmospheric transport under weakened Atlantic thermohaline circulation climate scenario

Global atmospheric transport in a climate subject to a substantial weakening of the Atlantic thermohaline circulation (THC) is studied by using climatological Green’s functions of the mass conservation equation for a conserved, passive tracer. Two sets of Green’s functions for the perturbed climate and for the present climate are evaluated from 11-year atmospheric trajectory calculations, based on 3-D winds simulated by GFDL’s newly developed global coupled ocean–atmosphere model (CM2.1). The Green’s function analysis reveals pronounced effects of the climate change on the atmospheric transport, including seasonally modified Hadley circulation with a stronger Northern Hemisphere cell in DJF and a weaker Southern Hemisphere cell in JJA. A weakened THC is also found to enhance mass exchange rates through mixing barriers between the tropics and the two extratropical zones. The response in the tropics is not zonally symmetric. The 3-D Green’s function analysis of the effect of THC weakening on transport in the tropical Pacific shows a modified Hadley cell in the eastern Pacific, confirming the results of our previous studies, and a weakening (strengthening) of the upward and eastward motion to the south (north) of the Equator in the western Pacific in the perturbed climate as compared to the present climate.     

An observational test of the stress accumulation model based on seismicity preceding the 1992 Landers, CA earthquake

We test the Bowman and King [Bowman, D.D., King, G.C.P., 2001a, Accelerating seismicity and stress accumulation before large earthquakes. Geophys. Res. Lett., 28 (21), 4039–4042, Bowman, D.D., King, G.C.P., 2001b. Stress transfer and seismicity changes before large earthquakes. C. R. Acad. Sci. Paris, 333, 591–599] Stress Accumulation model by examining the evolution of seismicity rates prior to the 1992 Landers, California earthquake. The Stress Accumulation (SA) model was developed to explain observations of accelerating seismicity preceding large earthquakes. The model proposes that accelerating seismicity sequences result from the tectonic loading of large fault structures through aseismic slip in the elasto-plastic lower crust. This loading progressively increases the stress on smaller faults within a critical region around the main structure, thereby causing the observed acceleration of precursory activity. A secondary prediction of the SA model is that the precursory seismicity rates should increase first at the edges of the critical region, with the rates gradually rising over time at closer distances to the main fault. We test this prediction by examining year-long seismicity rates between 1960 and 2004, as a function of distance from the Landers rupture. To quantify the significance of trends in the seismicity rates, we auto-correlate the data, using a range of spatial and temporal lags. We find weak evidence for increased seismicity rates propagating towards the Landers rupture, but cannot conclusively distinguish these results from those obtained for a random earthquake catalog. However, we find a strong indication of periodicity in the rate fluctuations, as well as high correlation between activity 130–170 km from Landers and seismicity rates within 50 km of the Landers rupture temporally offset 1.5–2 years. The implications of this spatio–temporal correlation will be addressed in future studies.     

The Getting of the Nganabbarru: Observations and reflections on Aboriginal buffalo hunting in northern Australia

Nganabbarru , or water buffalo ( Bubalus bubalis ), is frequently hunted by Aboriginal men, and buffalo meat is an important food source for many Arnhem Land Aboriginal communities. The experience of buffalo hunting trips with Aboriginal men who reside at Korlohbidahdah outstation in central Arnhem Land is used as a point of departure to consider the relationships between Aboriginal people and megaherbivores in the past and the present, and to explore the complexity of feral animal management in cross-cultural settings. This enquiry raised the question of the cultural conception of feral animals and demonstrates that there is no simple answer to the question: what is a buffalo? Buffaloes have been the focus of a colonial economic industry and are iconic of the Territorian way of life. However, they spread economically significant livestock diseases and cause widespread environmental damage. In the 1980s feral buffalo populations were the target of the Brucellosis and Tuberculosis Eradication Campaign (BTEC) control program. The failure to continue control programs following the cessation of BTEC program and inadequate consultation with Aboriginal landowners has meant that today's land managers are once again faced with conflicting views about controlling feral buffalo populations on Aboriginal land and within National Parks like Kakadu. It is concluded that there are genuine, previously overlooked opportunities for cross-cultural collaboration in managing feral buffaloes. Cross-disciplinary research involving ecologists, anthropologists, linguists, economists and environmental historians is required to help develop sustainable and culturally appropriate feral animal control programs.     

Economical digital photomicroscopy

Public domain software has been developed for remote exposure control of a consumer digital camera for use in photomicroscopy. A computer-controlled shutter release and remote control of various camera functions are essential to avoid mechanical disturbance of the microscope and slide during the imaging procedure. These features have previously been available only with expensive professional models. The digital images of diatom specimens obtained with this system captured the same detail as conventional photographs. The setup can therefore be used as a cost-effective tool for documenting taxonomic information of microscopically small organisms. In combination with the fast data transfer rates available via the Internet, microscopical studies can now be performed faster, more reliably, and more consistently.     

Characterization of coal-mine refuse as backfilling material

Summary With increased production and more stringent regulations for air, water and ground pollution control, the safe and environmentally acceptable disposal of coal-mine refuse is becoming ever more demanding. Backfilling may provide an environmentally acceptable method for the disposal of waste materials. Increased resource recovery, enhanced ventilation control, and minimizing surface subsidence, underground coal-mine fires and spontaneous combustion of coal are potential advantages of backfilling. In this paper the physical and mechanical properties of coal-mine waste from different sites are described and the effects of these properties on the duty requirements of fill material are assessed. As a result of testing, it is concluded that if improving ground control is the only reason for backfilling, coal refuse alone does not appear to be a suitable stowing material. If coal-refuse disposal is also a consideration, then it may be more attractive as a stowing material.     

Geographies on the Move: A Practical and Theoretical Approach to the Mobile Interview

This article considers the mobile interview method's utility to geography through five strengths: the ability to (1) produce spatially grounded and place-specific data, (2) access subtler and more complex meanings of place, (3) create opportunities for flexible and collaborative conversation with participants in situ, (4) build rapport and adjust participant–researcher power dynamics, and (5) efficiently produce rich geographic data. Practical, technical, ethical, and epistemological considerations are discussed. We expand methodological exploration of disempowered individuals' experiences of home, neighborhood, and urban space. The mobile interview offers a valuable, underutilized method for geographers to better understand the coconstitutive relationship between self and place.     

Ionospheric spread-F at Huancayo,sunspot activity and geomagnetic activity

A superposed-epoch method is used to investigate the occurrence of spread-F at Huancayo relative to days of high sunspot activity and also relative to days of high geomagnetic activity. A good correlation is found between days of high A_p, index and high spread-F occurrence for a pre-sunrise interval of a few hours. When 3-hourly K_p indices are used they show a peak value approximately 6 hr prior to an above-average occurrence of spread-F. It is suggested that this pre-sunrise spread-F is associated with ionospheric height rises which are produced by travelling disturbances, initiated in polar regions at times of high geomagnetic activity.     

Ionospheric spread-F at Huancayo,sunspot activity and geomagnetic activity

A superposed-epoch method is used to investigate the occurrence of spread-F at Huancayo relative to days of high sunspot activity and also relative to days of high geomagnetic activity. A good correlation is found between days of high A_p index and high spread-F occurrence for a pre-sunrise interval of a few hours. When 3-hourly k_p indices are used they show a peak value approximately 6 hr prior to an above-average occurrence of spread-F. It is suggested that this pre-sunrise spread-F is associated with ionospheric height rises which are produced by travelling disturbances, initiated in polar regions at times of high geomagnetic activity.     

Chemical and isotopic variations in an iron-rich lava flow from the Kirkpatrick Basalt,north Victoria Land,Antarctica: implications for low-temperature alteration

Chemical and isotopic (Sr, O, H) variations have been examined in an iron-rich lava flow of the Kirkpatrick Basalt from the Mesa Range in north Victoria Land, Antarctica. The flow is homogeneous with respect to the less mobile elements, whereas variations observed in K, Na, Si, Fe, and Rb result largely from alteration of glassy matrix material. Whole-rock Rb–Sr isotope data fall along a poorly-defined 103 Ma array attributed to secondary mobilization of Rb during the mid-Cretaceous. Alteration at that time is suggested by paleomagnetic data and would also account for discordant K–Ar dates. Whole-rock ¹⁸O values vary from +5.8 to +8.2 and a plagioclase separate has a ¹⁸O value of +5.6, reflecting the original composition of the magma. The range of ¹⁸O values for the whole-rock samples results from low-temperature alteration occurring primarily in the Jurassic and/or mid-Cretaceous. Whole-rock D values (-201 to -243) are markedly depleted, approaching equilibrium with modern meteoric water. In light of these data, variable Sr and O isotopic ratios in the underlying sequence of flows, previously interpreted in terms of an assimilation-fractionation model, may largely reflect post-magmatic alteration.