Mean winds in the winter middle atmosphere above northern Scandinavia

Wind measurements which were carried out during the MAP/WINE Campaign in northern Scandinavia between 2 December 1983 and 24 February 1984 are used to derive background winds and monthly as well as winter mean values from the ground up to 90 km altitude. These mean winds compare favourably to the wind field proposed for the revised CIRA 86, which is deduced from satellite measurements. The vertical structure of the zonal monthly means is similar in both data sets during January and February. The winter mean zonal winds are observed to be slightly stronger in the stratosphere and lower mesosphere during the MAP/WINE winter than the satellite winds proposed for CIRA 86. The long term mean meridional winds are in good agreement up to 60 km. They indicate a dominant influence of quasistationary planetary waves up to 90 km and an ageostrophic poleward flow between 60 km and 85 km over northern Scandinavia, which maximizes at 76 km at about 8 m s⁻¹. The observed short term variability of the wind is discussed with respect to a possible impact of saturating gravity waves on the momentum budget of the middle atmosphere.     

Interannual fluctuations of the stratospheric temperature over the north polar region

The monthly means for the years 1964–1991 of 30 hPa temperatures over the North Pole and averaged over the 70–90°N region are analyzed. A multiple regression model is used to find long-term monthly trends and possible linear associations between these temperatures and the QBO, ENSO, and the 11-yr solar cycle. The model's residuals are examined for detection of other periodic interannual fluctuations in Arctic temperatures.It is found that the interannual variations of temperature at 30 hPa over the Arctic are a superposition of the oscillations due to the QBO, ENSO, the 11-yr solar cycle, and approximate 6-yr periodic fluctuations of unknown origin. The QBO, ENSO, and the solar cycle effects in the Arctic temperature explain about 35% of the total variance of the temperature monthly anomalies. In winter, the QBO, ENSO, and the 11-yr solar cycle signals in the temperature data depend on the phase of the equatorial QBO. The polar vortex seems to be warmer (colder) than normal when the West (East) phase of the equatorial QBO in a period of high solar activity. The monthly temperature trends over the Arctic show seasonal variations with positive trends in February and March. The year-round trends (sum of the monthly trends) are about −0.5 K per decade.     

Variation in the taphonomic effect of scavengers in semi‐arid Australia linked to rainfall and the El Niño Southern Oscillation

Scavenging is one of the primary taphonomic processes shaping the final composition of fossil faunal assemblages. The taphonomic effect of scavengers is variable and must be understood in the context of the causes of that variation. In this study, we investigated relationships between the El Niño Southern Oscillation (ENSO), variable rainfall and scavenging on 20–40 kg mammal carcasses in semi‐arid New South Wales over four years. Following periods of above‐average rainfall (coincident with the La Niña phase of the ENSO), there was an increased availability of non‐carrion food and scavenging activity was moderate. Following below‐average rainfall (coincident with the El Niño phase of the ENSO), foraging options diminished, leading to a greater importance of carrion in the diet of scavengers and a resultant increase in carcass disturbance, transport and destruction by scavengers. Feral pigs (Sus scrofa) and red foxes (Vulpes vulpes) were the most taphonomically significant scavengers in the study. Australian ravens (Corvus coronoides) and wedge‐tailed eagles (Aquila audax) were active scavengers throughout the period of the study, but had little impact on bone survival. Lace monitors (Varanus varius) also fed mostly on soft tissue and were only present seasonally. We found that climate variability in the form of short‐term oscillation can result in significant variation in the impact of scavengers on carcasses and may be an important consideration when evaluating site formation scenarios and biases in fossil faunal assemblages. Copyright © 2006 John Wiley & Sons, Ltd.     

ENSO influence on Holocene Aboriginal populations in Queensland, Australia

In the Pacific region, the onset of modern El Niño/Southern Oscillation (ENSO) activity at approximately 5000 years ago may have played a significant role in the development of cultures in the Pacific basin. Within Australia, similar trends in population and resource use have been identified but largely ascribed to cultural changes. To test human responses to changing ENSO activity through the Holocene we analysed a comprehensive suite of 710 radiocarbon ages from archaeological sites in ENSO-sensitive Queensland. We observe a dramatic and sustained increase in landscape activity at inland sites from 4860 ± 15 years ago, statistically indistinguishable from the timing of the onset of modern ENSO activity. Subsequent changes in long-term activity directly impacted on human populations indicating that once established, ENSO maintained a continuous influence on disparate cultures throughout the Pacific basin.     

Variabilité et fréquence des cycles de gel‐dégel dans la région de Québec, 1977–2006

Freeze‐thaw cycles are most common at the beginning or near the end of the winter season. These cycles have various effects on the ecosystems of Eastern Canada, affecting both biotic and abiotic components of temperate cold environments. Using air temperature minima and maxima from four meteorological stations close to Québec City, we determined the frequency of daily freeze‐thaw cycles for the last 30 years. The results show no significant increase in the number of freeze‐thaw cycles despite a small increase in air temperature. Polynomial curves describing the relationship between mean air temperatures and the number of freeze‐thaw cycles were calculated. Based on these equations and anticipating a climate change scenario, we projected future freeze‐thaw cycles. Assuming a 5 °C increase in mean air temperatures by 2100, we estimated that the number of days with a freeze‐thaw cycle could increase by approximately 20 days per winter. The increase in the number of such cycles will be concentrated during the coldest months of the winter (January and February).     

Climatologies of semi-diurnal and diurnal tides in the middle atmosphere (70–110 km) at middle latitudes (40–55°)

The radars utilized are meteor (2), medium-frequency (2) and the new low-frequency (1) systems: analysis techniques have been exhaustively studied internally and comparatively and are not thought to affect the results. Emphasis is placed upon the new height-time contours of 24, 12 h tidal amplitudes and phases which best display height and seasonal structures; where possible high resolution (10 d) is used (Saskatoon) but all stations provide monthly mean resolution. At these latitudes the semi-diurnal tide is generally larger than the diurnal (10–30 m s⁻¹ vs. < 10 ms⁻¹), and displays less month to month variability. The semi-diurnal tide does show significant regular seasonal structure; wavelengths are generally small (⩽50 km) in winter, large in summer (≲ 100 km), and these states are separated by rapid equinoctial transitions. There is some evidence for less regularity toward 40°C. Coupling with mean winds is apparent. The diurnal tide has weaker seasonal variations; however there is a tendency for vertical wavelengths and amplitudes to be larger during summer months. On occasions in winter and fall wavelengths may be less than 50 km. Again the seasonal transitions are in phase with reversals of the zonal wind. Agreement with new numerical models is to be shown encouraging.     

Late Pleistocene marine birds from southern Peru: distinguishing human capture from El Niño-induced windfall

The Central Andean hyperarid littoral has abundant marine fauna that would have been attractive to the earliest inhabitants. Whether people hunted or scavenged marine animals during the terminal Late Pleistocene have social and technological implications for understanding ancient Andean foraging. The periodic phenomenon of El Niño/Southern Oscillation (ENSO) disrupts marine food chains and results in the death of significant numbers of marine vertebrates and microorganisms. The onset of ancient El Niño events may have created a subsistence opportunity for human coastal inhabitants along the Pacific coast of the Central Andes when large numbers of guano-producing birds (cormorants, boobies, and pelicans) became weak and eventually died. The remains of numerous marine birds dominate the Late Pleistocene archaeological site of Quebrada Tacahuay in far southern Peru. This Terminal Pleistocene occupation dating to 10,770–10,290 years ago (uncalibrated radiocarbon years; 12,880–11,970 calendar years ago) was buried and sealed by an apparent ancient El Niño-induced debris flow. Using characteristics of the faunal assemblage I assess whether people hunted marine birds or ENSO created a subsistence opportunity for people to either scavenge a catastrophic assemblage or collect a community of vulnerable birds prior to the debris flow. I present avian skeletal part frequencies, butchering patterns, and the quantities and variety of marine bony fishes. An analysis of vertebrate taxonomic and skeletal composition in conjunction with an analysis of site context does not support the hypothesis that paleoenvironmental conditions generated an opportunity for the facile collection of either dead or weak birds. In contrast, the faunal data suggest that humans actively hunted, captured, and consumed healthy marine birds. When evaluating the possible role of environmental fluctuations on human behavior and diet, researchers must consider not only the taphonomy of the most abundant remains, but also how other vertebrate taxa in a region are affected as well as the archaeological context.     

Comparison of geostrophic and observed winds in the upper mesosphere over Saskatoon,Canada

Thicknesses derived from SAMS (Stratospheric and Mesospheric Sounder, on-board Nimbus 7) and 30 mbar height analyses based on radiosondes have been combined to give monthly mean height charts of the upper mesosphesre, (0.01 mbar level, approximately 78–80 km). Four years of data are available, 1979–1982.Based on this material, the geostrophic winds were derived for the grid point 50°N, 110°W and compared with winds observed over Canada (52°N, 107°W) using the Saskatoon medium frequency (MF) radar. Agreement, especially in the summer months, was very good, however, significant ageostrophy was evident in autumnal and winter months. Possible causes are confluence associated with large scale circulations and gravity wave drag.     

Spatial‐temporal patterns of snow cover in western Canada

Snow cover is often measured as snow‐water equivalent (SWE), which refers to the amount of water stored in a snow pack that would be available upon melting. Snow cover and SWE represent a source of local snow‐melt release, and are sensitive to regional and global atmospheric circulation, and changes in climate. Monitoring SWE using satellite‐based passive microwave radiometry has provided nearly three decades of continuous data for North America. The availability of spatially and temporally extensive SWE data enables a better understanding of the nature of space‐time trends in snow cover, changes in these trends and linking these trends to underlying landscape and terrain characteristics. To address these interests, we quantify the spatial pattern of SWE by applying a local measure of spatial autocorrelation to 25 years of mean February SWE derived from passive microwave retrievals. Using a method for characterizing the temporal trends in the spatial pattern of SWE, temporal trends and variability in spatial autocorrelation are quantified. Results indicate that within the Canadian Prairies, extreme values of SWE are becoming more spatially coherent, with potential impacts on water availability, and hazards such as flooding. These results also highlight the need for Canadian ecological management units that consider winter conditions.     

Seasonal variations of day-time ionisation flows inferred from a comparison of calculated and observed NmF2

This paper reports on a comparison of calculated and observed monthly mean day-time ionospheric F2-peak density (NmF2) at a chain of stations from Japan to Australia for both solar minimum (1976) and solar maximum (1980). Nm values are calculated using the MSIS model for the observed peak heights (hmF2) and a simplified version of the continuity equation for day-time equilibrium conditions. The observed NmF2 values are always higher than the calculated ones in winter. This implies that a substantial downward flow of ionisation from above into the winter ionosphere is induced by the strongly poleward winter neutral wind which drives the ionisation down the field lines, lowering the peak height hmF2. In summer, winds are smaller, and the fluxes are more upward in comparison to winter. The seasonal variation of the ionisation fluxes and neutral winds are estimated for solar minimum, and compared with results of detailed calculations.     

Mesolithic shellfish exploitation in SW Italy: seasonal evidence from the oxygen isotopic composition of Osilinus turbinatus shells

Oxygen isotope analyses were carried out on the topshell Osilinus turbinatus from archaeological sites with the aim to investigate the temporal exploitation patterns by Mesolithic groups inhabiting coastal caves in SW Italy. In order to assess the present day O. turbinatus intra-annual δ¹⁸O variability, living specimens were collected monthly at Marina di Camerota (SW Italian peninsula). Their shell-edges were analysed and the seasonal results were compared with archaeozoological material. Our findings show that Mesolithic O. turbinatus exploitation was carried out almost exclusively during the colder and intermediary seasons (e.g. autumn, winter, spring), with very sporadic harvesting during the warmer seasons. Results suggest a possible regional exploitation pattern of O. turbinatus by Mesolithic groups inhabiting this region.     

Tethered mobility and riparian resource exploitation among Neolithic hunters and herders in the Galana River basin,Kenyan coastal lowlands

Abstract

Human activity along the Galana River inside Tsavo National Park, Kenya extends from 6000 years BP until at least 1300 years BP. This time period in East Africa predates and includes the Pastoral Neolithic – geographically and temporally linked early cattle-herding cultures comprised of autonomous communities with loose cultural connections to one another. Data from some sites located in the Great Rift Valley, Lake Victoria Basin and Central Kenyan Highlands indicate that after 3000 years BP, residential mobility patterns increased and pastoralists adopted a strong dependence on maintaining and culling herds of domesticated animals. This pattern is not borne out in Tsavo, where artefact analyses indicate that people had restricted mobility and relied primarily on exploitation of an endoaquatic resource base. This study hypothesises that subdecadal periodicity in El Niño/Southern Oscillation index (ENSO) along with a general trend toward aridification of East African landscapes provided the environmental backdrop for a subsistence regime focused primarily within riparian environments of the Coastal Lowlands region.     

A relationship between equatorial lower stratospheric QBO and El Niño

Cycle-to-cycle evolution of zonal wind QBO is studied making use of meteorological balloon and M-100 rocket data at Trivandrum (8.5°N, 77°E) for a period of about 19 yr from 1971 to 1990. The height of occurrence of zonal wind QBO maxima is found to vary systematically from one cycle to the next. The successive QBO maxima (easterly or westerly) occur progressively at greater heights and, after reaching a particular height, the next maximum (easterly or westerly) occurs at a lower height. Thereafter, the upward progression of the successive maxima starts again. It is found that the upward progression of the QBO maxima is closely associated with the occurrence of an El Niño event. A simple physical mechanism is suggested for this relationship between the QBO and El Niño. It is hypothesized that if the vertical wavelength of the Kelvin and mixed Rossby-gravity (MRG) waves are smaller during an El Nino event, the observed upward progression of the QBO maxima can be explained.     

Daily tidal,planetary wave,and gravity wave amplitudes over the Canadian prairies

Fifteen months of daily mean winds, semi-diurnal tides, and gravity waves observed from the Canadian Prairies MF radar network were examined to find correlations in their amplitude fluctuations. In all cases, the correlations of the wave/winds between the three sites were greater than 95% significant. Generally, while the correlations between the various wave/winds types were much weaker, there was evidence of gravity wave/tidal and tidal/mean wind interactions.     

NDVI variation and its relation to climate in Canadian ecozones

Parks Canada began the Northern Satellite Monitoring Program in 1997, with the objective of tracking large‐scale vegetation variation in Canadian ecosystems and helping land managers to develop appropriate management practices in response to climate change. Under this program, a sequence of 10‐day composite Advanced Very High Resolution Radiometer (AVHRR)‐derived Normalized Difference Vegetation Index (NDVI) data from 1985 to 2007 was examined to study seasonal and inter‐annual relationships between vegetation and climate data over Canadian ecosystems using statistical and wavelet analysis. Statistical analysis showed that temperature was the principal driver for seasonal variability in greenness, explaining more than 70 percent of seasonal variation in vegetation for most Canadian ecozones. In comparison with temperature, the relationships between NDVI and precipitation were weaker but still significant. Maximum annual NDVI showed increasing trends in Canadian ecozones during the study period, although increasing rates were spatially heterogeneous. Wavelet analysis confirmed that inter‐annual variation in NDVI was different at two ecozones in Canada. NDVI variation in the Northern Arctic was significant at scales of 3–4 years from 1997 to 2001, which was associated with temperature and precipitation variation. Comparatively, NDVI variation in the Boreal Shield was significant at scales of 5–8 years from 1991 to 1999, but did not correspond with climate variation.     

1987–1989 total ozone and ozone sounding observations in Northern Scandinavia and Antarctica,and the climatology of the lower stratosphere during 1965–1988 in Northern Finland

The total ozone observations of Tromsö (Northern Norway), Sodankylä (Northern Finland) and Murmansk (Northwestern Soviet Union) for 1987–1989 have been studied. Comparisons of the total ozone with stratospheric temperatures observed at Sodankylä have been made. These values have also been compared with the long-term mean total ozone at Tromsö and the long-term means of stratospheric temperatures at Sodankylä. No severe ozone depletions were observed. The exceptionally high total ozone values at these stations in February 1989 were connected to abnormally high stratospheric temperatures. The comparison of total ozone observed at roughly the same southern latitudes revealed great differences in the springtime.The 1989 ozone sounding observations of Sodankylä, Bear Island and Ny Ålesund (Spitzbergen) did not reveal any indications of pronounced ozone depletion. A comparative study of ozone, temperature and relative humidity indicated that the springtime variability of ozone in the lower stratosphere was clearly connected to meteorological variability. The lower tropospheric ozone had two distinct maxima, one in spring with large-scale photochemical causes and the other in summer connected with the emissions of hydrocarbons and oxides of nitrogen in Europe.Temperature observations made at Sodankylä over 24 yr revealed the existence of a potential for polar stratospheric cloud formation in the lower stratosphere in winter and early spring. A trend analysis of 50 hPa temperature revealed a negative trend of −0.16 K/yr in January and a positive trend of 0.15 K/yr in April; the annually-averaged trend was only −0.02 K/yr for this 24-yr period. When the January–February mean temperatures are separated according to the phase of the QBO in the tropical stratosphere, correlations between temperatures and sunspot numbers are found.     

黄山风景区客流波动的多时间尺度特征分析

基于黄山风景区1987年1月至2010年12月的月度客流数据,运用TRAMO/SEATS方法和小波分析方法分析了黄山风景区客流的季节性变化和多时间尺度特征,结果表明：黄山风景区客流季节性变化显著,不仅存在月度波动性,而且季节性波动呈现年度变化性,客流淡季过长,淡季与平季、旺季落差过大是黄山风景区面临的经营难题;具有6个月、12个月、29个月和60个月不同时间尺度的周期变化,其中12个月的周期振荡最为明显,具有全域性;另外,6个月和12个月的时间特征尺度体现了黄山风景区客流由于季节性因素形成的年内季节性变化和年间的周期性变化,而29个月和60个月的时间特征尺度初步判断为由我国旅游业波动周期、景区外围区域经济周期和危机事件冲击影响共同作用所形成.最后,本文提出了一些对应性策略.     

“The Black Tile in the Mosaic”: Austin Chesterfield Clarke and the Canadian Literary Tradition

This paper engages selected moments in Austin Clarke’s literary journey to argue that in spite of his involvement in the development of Canadian literature (CanLit) during the 1960s and 1970s, the Canadian literary establishment continues to pay little critical attention to his contributions. This lack of recognition is specifically evident in recent writings about Canadian literature and the literary figures who spearheaded its development after Canada’s Multiculturalism policy of 1971. Canada’s becoming officially multicultural required a new narrative of Canada and new literary depictions of Canadians in their national literature, as ethnically diversified but of a single citizenship. I argue that Clarke’s legacy as a Black writer should be given more prominence in Canadian institutions because today this legacy is under threat of erasure as the number of Canadian Black voices telling mainstream stories about Black people’s experiences is evidently in decline.     

The Potential of Tree Rings in Eucalyptus pauciflora for Climatological and Hydrological Reconstruction

We investigate the causes of variability in a tree‐ring chronology comprising data from Eucalyptus pauciflora Sieb. Ex. Spreng. at the alpine treeline on the Kosciuszko Plateau in New South Wales, Australia. Following verification of crossdating in a subset of the available data, we found that ring width correlates significantly with net radiation, precipitation and mean minimum and maximum air temperature during the preceding winter and spring of the growing season. Our results for spring are consistent with the impact of climate on tree growth in alpine woodlands reported in previous studies. Analyses of snow‐depth data revealed negative correlations with ring width throughout winter and spring. Our results indicate that low temperature and high precipitation during winter negatively affect the growth of E. pauciflora by prolonging spring snow cover. Ring width also correlates significantly with an index of soil dryness and flow in rivers with their headwaters in the Kosciuszko plateau. Given the apparent sensitivity of our chronology to climate and snow conditions, our results suggest that tree‐ring chronologies comprising data from E. pauciflora at the alpine treeline have potential for climatological and hydrological reconstruction in southeast Australia.     

On stone-boiling technology in the Upper Paleolithic: behavioral implications from an Early Magdalenian hearth in El Mirón Cave,Cantabria, Spain

Stone boiling is one of the principal cooking methods used by hunter-gatherer societies. The present paper proposes behavioral and organizational inferences as to how stone boiling was incorporated into hunter-gatherer subsistence practices through an examination of a shallow-basin hearth in an Early Magdalenian level (c. 15,500 ¹⁴C B.P.) of El Mirón Cave, Cantabria (northern Spain). Exploratory analysis of spatial patterns of archaeological remains (bones, lithic artifacts, and fire-cracked rocks) and use-life analysis of fire-cracked rocks demonstrate that the hearth was used and maintained during visits of humans who preyed mainly on ibex and red deer near the site. The relative accessibility of these ungulates and cost-induced technology of stone boiling suggest the implication that stone boiling was employed to maximize the energy and nutrition obtained from carcasses of these game taxa under the circumstance of resource intensification.