Relationship between Age and Oxygen along Line W in the Northwest Atlantic Ocean     

Jordan L. Thomas  Darryn W. Waugh  Anand Gnanadesikan 《Ocean Science Journal》2020,55(2):203-217

The relationship between age and oxygen is one that is often assumed in oceanography to be relatively simple. Because oxygen utilization rates are difficul  相似文献   

Brokering Trust in Citizen Science     

Mat Gilfedder  James E. M. Watson  Thomas G. Campbell  Brian L. Sullivan  Hugh P. Possingham 《社会与自然资源》2019,32(3):292-302

Citizen science (CS) information requires systematic review that incorporates a range of interests and concerns. Yet, there has been little research on what might constitute reviewing best practice to ensure CS is trusted by contributors and users of the data. Insights from a survey of all 1134 reviewers who curate the global eBird Project highlight the knowledge-brokering work involved to ensure CS data are trusted by both citizens and science. Drawing on scholarship focused on key drivers of useable knowledge for natural resource decision-making, we consider CS reviewing best practice to ensure CS can be useful to the producers and users of this knowledge. We find that CS reviewers need to be motivated to provide appropriate feedback to improve CS data, commit to reviewing practice that is respected by citizens, and ensure the information published is credible and be reviewed by a supportive and accountable network of fellow reviewers.  相似文献   

Modelling the spatial dynamics of Mainland China-born migrants in Australia     

Siqin Wang  Thomas Sigler  Jonathan Corcoran  Yan Liu 《The Australian geographer》2019,50(2):201-219

Over the past two decades, migration from Mainland China (MC) to Australia has become increasingly significant. In contrast to previous migrant waves, post-2000 MC-born migrants in Australia are more likely to be highly skilled and/or financially independent, and often migrate under skilled, business and investment visa programs. Though scholarship has explored various facets of MC-born migrants’ settlement in Australian cities, the spatial dynamics of settlement, and change over time associated with these shifts in socio-economic profile, have remained unexplored. This paper draws on three census periods, and employs a local indicator of spatial autocorrelation together with a geographically weighted regression. We conclude that the settlement patterns of MC-born migrants in Australia do not follow the ‘straight-line’ assumptions of spatial assimilation theory, nor are they tied explicitly to socio-economic factors in the majority of capital cities. Instead, the settlement patterns of MC-born migrants vary by city: Sydney and Melbourne display the most spatially segmented settlement patterns; while Adelaide and Perth exhibit increasing levels of concentration as the number of MC-born migrants grows. Results indicate that while MC-born migrants are somewhat likely to cluster at the early stage of group formation, within-group spatial patterns are articulated by social attributes as the group grows in size and significance in a metropolitan context.  相似文献   

Ceres’ spectral link to carbonaceous chondrites—Analysis of the dark background materials          下载免费PDF全文

Michael Schäfer  Tanja Schäfer  Matthew R. M. Izawa  Edward A. Cloutis  Stefan E. Schröder  Thomas Roatsch  Frank Preusker  Katrin Stephan  Klaus‐Dieter Matz  Carol A. Raymond  Christopher T. Russell 《Meteoritics & planetary science》2018,53(9):1925-1945

Ceres’ surface has commonly been linked with carbonaceous chondrites (CCs) by ground‐based telescopic observations, because of its low albedo, flat to red‐sloped spectra in the visible and near‐infrared (VIS/NIR) wavelength region, and the absence of distinct absorption bands, though no currently known meteorites provide complete spectral matches to Ceres. Spatially resolved data of the Dawn Framing Camera (FC) reveal a generally dark surface covered with bright spots exhibiting reflectance values several times higher than Ceres’ background. In this work, we investigated FC data from High Altitude Mapping Orbit (HAMO) and Ceres eXtended Juling (CXJ) orbit (~140 m/pixel) for global spectral variations. We found that the cerean surface mainly differs by spectral slope over the whole FC wavelength region (0.4–1.0 μm). Areas exhibiting slopes ?1 constitute only ~3% of the cerean surface and mainly occur in the bright material in and around young craters, whereas slopes ≥?10% μm^?1 occur on more than 90% of the cerean surface; the latter being denoted as Ceres’ background material in this work. FC and Visible and Infrared Spectrometer (VIR) spectra of this background material were compared to the suite of CCs spectrally investigated so far regarding their VIS/NIR region and 2.7 μm absorption, as well as their reflectance at 0.653 μm. This resulted in a good match to heated CI Ivuna (heated to 200–300 °C) and a better match for CM1 meteorites, especially Moapa Valley. This possibly indicates that the alteration of CM2 to CM1 took place on Ceres.  相似文献   

How can we model subsurface stormflow at the catchment scale if we cannot measure it?     

Peter Chifflard  Theresa Blume  Katja Maerker  Luisa Hopp  Ilja van Meerveld  Thomas Graef  Oliver Gronz  Andreas Hartmann  Bernhard Kohl  Edoardo Martini  Christian Reinhardt‐Imjela  Martin Reiss  Michael Rinderer  Stefan Achleitner 《水文研究》2019,33(9):1378-1385

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Differential uplift on the boundary between the Eastern and the Southern European Alps: Thermochronologic constraints from the Brenner Base Tunnel     

Thomas Klotz  Hannah Pomella  Martin Reiser  Bernhard Fügenschuh  Massimiliano Zattin 《地学学报》2019,31(3):281-294

The Brenner Base Tunnel will connect Innsbruck (Austria) and Franzensfeste (Italy) by piercing two of the most important fault structures of the Alps: the Periadriatic fault system (PFS) and the Southern limit of Alpine metamorphism (SAM). (U‐Th)/He dating (apatite) and fission‐track analysis (apatite and zircon) on samples taken during excavation reveal a complex pattern of exhumation through time. The results yield temporal constraints for relative vertical block movement and fault activity. Furthermore, they indicate differential uplift of the northern block along the ~E–W striking PFS and allow locating the position of the SAM in the overtilted nappe stack south of the Tauern Window. Our data strongly support, for the first time, an ongoing north‐side‐up movement along this section of the PFS until at least the end of Miocene.  相似文献   

Fault zone hydrogeology in arid environments: The origin of cold springs in the Wadi Araba Basin,Egypt     

Mahmoud M. Khalil  Kay Hamer  Thomas Pichler  Abotalib Z. Abotalib 《水文研究》2021,35(5):e14176

The role of faults in controlling groundwater flow in the Sahara and most of the hyper-arid deserts is poorly understood due to scarcity of hydrological data. The Wadi Araba Basin (WAB), in the Eastern Sahara, is highly affected by folds and faults associated with Senonian tectonics and Paleogene rifting. Using the WAB as a test site, satellite imagery, aeromagnetic maps, field observations, isotopic and geochemical data were examined to unravel the structural control on groundwater flow dynamics in the Sahara. Analysis of satellite imagery indicated that springs occur along structurally controlled scarps. Isotopic data suggested that cold springs in the WAB showed a striking similarity with the Sinai Nubian aquifer system (NAS) water and the thermal springs along the Gulf of Suez (e.g., δ¹⁸O = −8.01‰ to −5.24‰ and δD = −53.09‰ to −31.12‰) demonstrating similar recharge sources. The findings advocated that cold springs in the WAB represent a natural discharge from a previously undefined aquifer in the Eastern Desert of Egypt rather than infiltrated precipitation over the plateaus surrounding the WAB or through hydrologic windows from deep crystalline basement flow. A complex role of the geological structures was inferred including: (1) channelling of the groundwater flow along low-angle faults, (2) compartmentalization of the groundwater flow upslope from high-angle faults, and (3) reduction of the depth to the main aquifer in a breached anticline setting, which resulted in cold spring discharge temperatures (13–22°C). Our findings emphasize on the complex role of faults and folds in controlling groundwater flow, which should be taken into consideration in future examination of aquifer response to climate variability in the Sahara and similar deserts worldwide.  相似文献   

Beyond slash-and-burn: The roles of human activities,altered hydrology and fuels in peat fires in Central Kalimantan,Indonesia     

Jenny E. Goldstein  Laura Graham  Sofyan Ansori  Yenni Vetrita  Andri Thomas  Grahame Applegate  Andrew P. Vayda  Bambang H. Saharjo  Mark A. Cochrane 《Singapore journal of tropical geography》2020,41(2):190-208

Near-annual landscape-scale fires in Indonesia's peatlands have caused severe air pollution, economic losses, and health impacts for millions of Southeast Asia residents. While the extent of fires across the peatland surface has been widely attributed to widespread peatland drainage for plantation agriculture, fires that transition from surface into sub-surface soil-based fires are the source of the most dangerous air pollution. Yet the mechanisms by which this transition occurs have rarely been considered, particularly in diversely managed landscapes. Integrating physical geography methods, including active fire scene evaluations and hydrological monitoring, with qualitative methods such as retrospective fire scene evaluations and semi-structured interviews, this article discusses how and why sub-surface peat fire transition occurs in an intensively altered peatland ecosystem in Indonesia's Central Kalimantan province. We demonstrate that variable water table levels and flammable surface vegetation (fire fuels) are co-produced socio-political and biophysical phenomena that enable the conditions in which surface fire is likely to transition into peat fire and increase landscape vulnerability to ongoing, uncontrollable annual fires. This localized understanding of peat fire transition counters normative causal narratives of tropical fire such as ‘slash-and-burn’, with implications for the management of new fire regimes in inhabited landscapes.  相似文献   

A new approach for measuring surface hydrological connectivity     

Joshua M. Wolstenholme  Mark W. Smith  Andy J. Baird  Thomas G. Sim 《水文研究》2020,34(3):538-552

The development of surface hydrological connectivity is a key determinant of flood magnitude in drylands. Thresholds in runoff response may be reached when isolated runoff-generating areas connect with each other to form continuous links to river channels, enabling these areas to contribute to flood hydrographs. Such threshold behaviour explains observed nonlinearities and scale dependencies of dryland rainfall–runoff relationships and complicates attempts at flood prediction. However, field methods for measuring the propensity of a surface to transmit water downslope are lacking, and conventional techniques of infiltration measurement are often inappropriate for use on non-agricultural drylands. Here, we argue for a reconceptualization of the dryland surface runoff process, suggesting that the downslope transfer of water should be considered alongside surface infiltration; that is, there is a need for the “aggregated” measurement of infiltration and overland flow hydraulics. Surface application of a set volume of water at a standardized rate generates runoff that travels downslope; the distance it travels downslope is determined by infiltration along the flow, integration of flow paths, and flow resistance. We demonstrate the potential of such a combined measurement system coupled with structure-from-motion photogrammetry to identify surface controls on runoff generation and transfer on dryland hillslopes, with vegetation, slope, surface stone cover, and surface roughness all having a significant effect. The measurement system has been used on slopes up to 37° compared with the flat surface typically required for infiltration methods. On average, the field workflow takes ~10–15 min, considerably quicker than rainfall simulation. A wider variety of surfaces can be sampled with relative ease, as the method is not restricted to stone and vegetation-free land. We argue that this aggregated measurement represents surface connectivity and dryland runoff response better than standard hydrological approaches and can be applied on a much greater variety of dryland surfaces.  相似文献   

Expressions to determine temperatures and emission measures for solar X-ray events from GOES measurements     

R. J. Thomas  R. Starr  C. J. Crannell 《Solar physics》1985,95(2):323-329

We have developed expressions which give the effective color temperatures and corresponding emission measures for solar X-ray events observed with instruments onboard any of the GOES satellites. Since 1976, these satellites have been used to monitor continuously the full-Sun X-ray emission in two broadband wavelength intervals (approximately 0.5–4 Å and 1–8 Å) with a time resolution of 3 s. To simulate the solar X-ray input at a variety of plasma temperatures, we used theoretical spectra provided by D. L. McKenzie. These spectra were folded through the wavelength dependent transfer functions for the two GOES detectors as given by Donnelly et al. (1977). The resulting detector responses and their ratio as a function of plasma temperature were then fit with simple analytic curves. Over the entire range between 5 and 30 million degrees, these fits reproduce the calculated color temperatures within 2% and the calculated emission measures within 5%. With the theoretical spectra provided by McKenzie, we can determine similar expressions for any pair of broadband X-ray detectors whose sensitivities are limited to wavelengths between 0.2 and 100 Å.  相似文献