Number Of Key Sites Research Articles

How well do atmospheric reanalyses reproduce observed winds in coastal regions of Mexico?

AbstractAtmospheric reanalyses are widely used for understanding the past and present climate. They have become increasingly used within the renewable energy sector for assessing wind and solar resources for different regions of the globe in conjunction with observations. Mexico is a country with considerable potential for wind energy production, especially around coastal sites and therefore the characterization of wind resource in these areas of the country is imperative for the most beneficial use of these resources. In this study, we assess how well three global reanalyses, namely ERA‐Interim, ERA5 and MERRA‐2, can reproduce wind observations at a number of key sites across the country. We find that the reanalyses' ability to reproduce these observations is highly variable between different regions in Mexico. Correlation coefficients are around 0.9 in the south of the country where the winds are strongest, but much lower (around 0.5) in Baja California Sur due to the complex coastal topography of the region. ERA5 outperforms ERA‐Interim and MERRA‐2 consistently across the vast majority of sites and so this reanalysis is recommended for local wind power studies. The consistently improved performance compared with ERA‐Interim shows the value of the increased spatial resolution of ERA5. However, in the south and east of Mexico, despite having the highest correlations, ERA5 also has the largest bias, meaning that it underestimates winds consistently across most of the country. Poor correlations between ERA5 and the observations in Veracruz are considered as a case study to understand potential drivers of low wind biases.

The Development of a Prison Mental Health Unit in England: Understanding Realist Context(s)

A pragmatic solution for the provision of care for prisoners with serious mental illness, who are often subject to delays in hospital transfer, is the creation of specialist prison units. This paper analyses the development of a prison unit in England for prisoners with ‘serious mental illness’. The unit was developed within over-lapping health and justice contexts, including expectations, pressures and priorities, which impacted on the outcomes expected and achieved. The methodology included attendance at Steering group meetings, analysis of a minimum dataset, and interviews with key stakeholders. A number of key sites of contestation are analyzed including: admission criteria; aims; activities; staffing; the physical environment; and discharge.

The first directly dated evidence for Palaeolithic occupation on the Indian coast at Sandhav, Kachchh

South Asia has a rich Palaeolithic heritage, and chronological resolution for this record has substantially improved over the past decade as a result of focused, interdisciplinary research at a number of key sites. Expanding the spatial diversity of dated Palaeolithic sites in South Asia grows increasingly important to examine how patterns of change through time vary within and between the region’s diverse habitats. Critically, alternate models of modern human dispersals into South Asia highlight the significance of either coastal or continental routes of dispersal, but currently no coastal Palaeolithic sites directly dating to the timeframe of human expansions are known. Our previous research in Kachchh was the first study to clearly identify the presence of Palaeolithic sites in Late Pleistocene landscapes in close proximity to the Indian Ocean coastline. Here, we present the first results of surface survey and test excavation at the site of Sandhav (Kachchh, India), approximately 25 km from the modern shoreline. We characterise the geomorphology of the landscape, highlighting multiple phases of alluvial aggradation and post-depositional carbonate formation, associated with Palaeolithic artefacts. To date, excavations have tested the uppermost Pleistocene deposit, yielding a small collection of fresh Middle Palaeolithic artefacts associated with a luminescence age dating to the first half of MIS 5 (∼114 ka), which provides a minimum age for Late Acheulean artefacts in underlying units. We discuss our findings in the context of debates surrounding the timing, lithic technologies, and ecologies associated with the expansions of modern humans into South Asia.

Nest-site characteristics and aspects of the breeding biology of the endangered Timneh Parrot Psittacus timneh in Guinea-Bissau

Timneh Parrots Psittacus timneh are endemic to the moist forests of West Africa. Concerns over rapid declines in populations due to overharvesting for the pet trade and forest loss prompted the species’ categorisation as Endangered on the IUCN Red List of Threatened Species in 2016. Despite these threats, few data exist on their biology in the wild, impeding the development of effective conservation initiatives to protect populations. One of the few recorded breeding sites for this species occurs in the Bijagós Archipelago in Guinea-Bissau, where chicks have been historically harvested from nests and forest clearance for agriculture is common. We investigated the breeding ecology of Timneh Parrots in the Bijagós Archipelago focusing on two islands that harbour the densest populations. Specifically, we describe nest-site characteristics, breeding phenology and reproductive productivity. Timneh Parrots were found to use secondary nest cavities in 17 species of trees, predominantly nesting in trees between 20 m and 50 m in height. Nest cavities were generally aggregated, with a density of up to 14 nests ha−1 in some areas, although nests also occurred in isolated large trees. The distribution of nests likely reflected a heterogeneous distribution of large trees containing suitable nest cavities, emphasising the importance of protecting mature trees. Nesting efforts were initiated between early January until late March, suggesting that nest surveillance efforts to deter poaching can be efficiently focused at a small number of key sites during February to May each year, when fledgling chicks are most likely to be present. These data further suggest that the population may be limited by the availability of suitable nest cavities and that the installation of artificial nest cavities could help increase the breeding population.

Geographical Information Model of Terrestrial Ecosystems of the White Sea Lowland

The results of building the geoinformation model of terrestrial ecosystems by Landsat spectral space modeling are reported. The spectral space model accurately reflects the natural structure of the forest and mire cover, which is related to the type of Quaternary deposits and the type of water and mineral nutrition. An enhanced technique for 3D visualization of the spectral model was applied, allowing to identify several classes of paludified pine forests and types of mires in the lowland. The fragment described in the paper completes the first phase of building the geoinformation model of terrestrial ecosystems of the north-taiga subzone of Eastern Fennoscandia. The fundamental difference of this model from the traditional ones, generated by methods of “supervised classification”, is that instead of the number of key sites on the ground, chosen more or less subjectively, the result here depends on an objective, measurable biophysical parameter, i. e. the position of the ecosystem in the spectral space of the scanner image.

Simulating the interannual variability of major dust storms on Mars using variable lifting thresholds

The redistribution of a finite amount of martian surface dust during global dust storms and in the intervening periods has been modelled in a dust lifting version of the UK Mars General Circulation Model. When using a constant, uniform threshold in the model’s wind stress lifting parameterisation and assuming an unlimited supply of surface dust, multiannual simulations displayed some variability in dust lifting activity from year to year, arising from internal variability manifested in surface wind stress, but dust storms were limited in size and formed within a relatively short seasonal window. Lifting thresholds were then allowed to vary at each model gridpoint, dependent on the rates of emission or deposition of dust. This enhanced interannual variability in dust storm magnitude and timing, such that model storms covered most of the observed ranges in size and initiation date within a single multiannual simulation. Peak storm magnitude in a given year was primarily determined by the availability of surface dust at a number of key sites in the southern hemisphere. The observed global dust storm (GDS) frequency of roughly one in every 3years was approximately reproduced, but the model failed to generate these GDSs spontaneously in the southern hemisphere, where they have typically been observed to initiate. After several years of simulation, the surface threshold field—a proxy for net change in surface dust density—showed good qualitative agreement with the observed pattern of martian surface dust cover. The model produced a net northward cross-equatorial dust mass flux, which necessitated the addition of an artificial threshold decrease rate in order to allow the continued generation of dust storms over the course of a multiannual simulation. At standard model resolution, for the southward mass flux due to cross-equatorial flushing storms to offset the northward flux due to GDSs on a timescale of ∼3years would require an increase in the former by a factor of 3–4. Results at higher model resolution and uncertainties in dust vertical profiles mean that quasi-periodic redistribution of dust on such a timescale nevertheless appears to be a plausible explanation for the observed GDS frequency.

The British Lower Palaeolithic of the early Middle Pleistocene

The archaeology of Britain during the early Middle Pleistocene (MIS 19–12) is represented by a number of key sites across eastern and southern England. These sites include Pakefield, Happisburgh 1, High Lodge, Warren Hill, Waverley Wood, Boxgrove, Kent's Cavern, and Westbury-sub-Mendip, alongside a ‘background scatter’ lithic record associated with the principal river systems (Bytham, pre-diversion Thames, and Solent) and raised beaches (Westbourne–Arundel). Hominin behaviour can be characterised in terms of: preferences for temperate or cool temperate climates and open/woodland mosaic habitats (indicated by mammalian fauna, mollusca, insects, and sediments); a biface-dominated material culture characterised by technological diversity, although with accompanying evidence for distinctive core and flake (Pakefield) and flake tool (High Lodge) assemblages; probable direct hunting-based subsistence strategies (with a focus upon large mammal fauna); and generally locally-focused spatial and landscape behaviours (principally indicated by raw material sources data), although with some evidence of dynamic, mobile and structured technological systems. The British data continues to support a ‘modified short chronology’ to the north of the Alps and the Pyrenees, with highly sporadic evidence for a hominin presence prior to 500–600 ka, although the ages of key assemblages are subject to ongoing debates regarding the chronology of the Bytham river terraces and the early Middle Pleistocene glaciations of East Anglia.

Prolonged coexistence of humans and megafauna in Pleistocene Australia

Recent claims for continent wide disappearance of megafauna at 46.5 thousand calendar years ago (ka) in Australia have been used to support a "blitzkrieg" model, which explains extinctions as the result of rapid overkill by human colonizers. A number of key sites with megafauna remains that significantly postdate 46.5 ka have been excluded from consideration because of questions regarding their stratigraphic integrity. Of these sites, Cuddie Springs is the only locality in Australia where megafauna and cultural remains are found together in sequential stratigraphic horizons, dated from 36-30 ka. Verifying the stratigraphic associations found here would effectively refute the rapid-overkill model and necessitate reconsideration of the regional impacts of global climatic change on megafauna and humans in the lead up to the last glacial maximum. Here, we present geochemical evidence that demonstrates the coexistence of humans and now-extinct megafaunal species on the Australian continent for a minimum of 15 ka.

Late Cypriot I A maritime trade in action: underwater survey at MaroniTsaroukkasand the contemporary east Mediterranean trading system

The period from the late Middle Bronze Age to the start of the Late Bronze Age in the Levant, largely coeval with the Canaanite, ‘Hyksos“, 15th Dynasty of Egypt, is characterized by the appearance of Late Cypriot I A ceramics at a number of key sites in the east Mediterranean. The exact absolute dates to apply to this period have been the subject of controversy, in part inter-linked with debate over the date of the eruption of Thera, but scholarship recognises that this visible horizon of international trade must have been of considerable significance, especially on Cyprus itself. Here a dramatic shift in settlement to the coastal areas of the island at the beginning of the Late Cypriot period has long been recognized; this is also the time period of the formation of larger complex socio-political entities at the sites on Cyprus which go on to comprise the Late Cypriot ‘urban“ civilisation. Tombs of the relevant Middle Cypriot III–Late Cypriot I period are well known on Cyprus, but stratified settlement contexts on Cyprus, yet alone contexts directly related to such international trade, are scarce to non-existent. We report finds of just such direct relevance from a (currently) unique deposit as a result of an initial investigation of the seabed off the Late Cypriot site of MaroniTsaroukkason the south coast of Cyprus (MTSB Site 1). Consideration of these finds provides important new evidence for the Late Cypriot I A period; they also indicate routes to more sophisticated analyses of Cypriot–east Mediterranean interaction and the resolution of current problems in chronology. In particular, a review of Late Cypriot I A connections highlights the need to emphasise the central importance of the Canaanite pre-18th Dynasty (late Middle Bronze Age) world to the formative development of both Late Bronze Age Cyprus, and the Late Bronze Age Aegean.

Anatolian tree rings and a new chronology for the east Mediterranean Bronze-Iron Ages.

We report an extensive program of high-precision radiocarbon dating to establish the best date for a floating 1599-year Anatolian tree ring chronology that spans the later third millennium B.C. through the earlier first millennium B.C. This chronology is directly associated with a number of key sites and ancient personages. A previously suggested dating is withdrawn and is replaced by a robust new date fix 22 (+4 or -7) years earlier. These new radiocarbon wiggle-matched dates offer a unique independent resource for establishing the precise chronology of the ancient Near East and Aegean and help resolve, among others, a long-standing debate in favor of the so-called Middle Mesopotamian chronology.

Energetic Activities of Commoners

Sir Grahame Clark's interests in wetland archaeology were not restricted to his pioneering work at Star Carr and much of his writing was illuminated by his wide knowledge of the fruits of wetland research in many parts of the world. The paper presents the case for wetland archaeology, to show how it has expanded our knowledge of the past and has made prehistory more colourful and dynamic to both archaeologists and the public. In seeking the patterns of behaviour that existed in the past, six key elements contribute to our studies: environment and change; economy and subsistence; stratification and context; structures and activities; chronology and precision; and range of material culture. The evidence for all of these aspects is well-preserved in many wetland environments, and a number of key sites are identified and assessed for their contribution to prehistoric studies.

Inter-comparison of regional flood frequency procedures for Canadian rivers

This paper presents the results of a comparison of regional flood frequency procedures. The accuracy of regional quantile estimators as predictors of population quantiles at a number of key sites is examined. Reference sites have been selected with the basic requirement of at least 35 years of local flood records. Accurate at-site estimates of population quantiles can therefore be obtained at these locations. The regional estimators are used ignoring the local data. This is equivalent to flood estimation at an ungauged site. The case of some local information (10 years of records) is also considered. The bias and variance of the regional estimators are evaluated by comparing at-site and regional estimates. Two methodologies have been devised for the comparison of regional models: a regional bootstrap approach and an empirical Bayes approach. For each approach, a detailed description of the results of the various methods considered in the study is provided. It was shown that, in general, the two methodologies lead to similar results.

Pasture-woodland and its conservation in Britain

Pasture-woodland occurs as a wide range of types in Britain. It is particularly important for nature conservation in terms of its lichen, invertebrate and bird populations, and also for bat roosts and probably fungi. Its interest tends to complement that of coppice woods, the other major form in which ancient semi-natural woodland has survived. Pasture-woodland (including pollard trees) is widespread in Europe, but British examples of international importance have been identified. It is under threat from over-grazing and consequent lack of regeneration, but also some of its characteristic species may be lost if grazing is removed altogether. The lichen component of pasture-woodland is particularly sensitive to air pollution, while removal of fallen dead wood and felling of old trees may damage the invertebrate interest. There is a major need to produce site inventories and descriptions, to raise awareness of the special value of pasture-woodland, and to implement more widely me site management techniques that are being used successfully on a number of key sites at present. The isolation of many sites cannot be reduced in the short term, but in general terms old trees in the countryside must not be allowed to diminish further.

A light in the dark: archaeological wiggle matching and the absolute chronology of the close of the Aegean Late Bronze Age

The conventional chronology of the Aegean Late Bronze Age was challenged by P.J. James and his co-workers in Centuries of darkness (1991). The present paper is an exhaustive and critical re-examination of radiocarbon dates from a number of key sites in the region using the technique of probabilistic computer archaeological wiggle matching which concludes that the conventional arhcaeological chronology still holds good (whatever the flaws in its original construction) on the basis of the independent radiocarbon evidence.