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1.
Mean winds and tides have been measured by the LF and MF radar systems at Collm and Saskatoon respectively. Semidiurnal tide amplitudes and phases near 90 km evidence very similar monthly variations. A detailed comparison of mean wind and tidal profiles (85–110 km) in the Septembers of 4 years shows some differences however, which are consistent with regional (Europe-Canada) differences in the mean background winds.  相似文献   

2.
Meteor wind measurements made at Obninsk during MAC/SINE and MAC/EPSILON, and in the summer and autumn of other years since 1973, are reported. The zonal wind, which is presumed to be in the 93–95 km height region, is generally westerly, and the meridional wind is mainly northerly. Quasi-two-day oscillations are studied, as are semidiurnal tides. There is some evidence for a 22-yr periodicity in the amplitude of the semidiurnal tide  相似文献   

3.
The medium frequency radar (∼ 2.2 MHz) at Saskatoon has been run continuously since 1978 and the Meteor Radar at Monpazier ran continuously for ∼ 10 day intervals in most months of 1979/1980. The radars are separated by ∼ 8000 km. Because of the excellent quality of the data, spectral and harmonic analyses have been completed from ∼ 70 to 100km and oscillations with periods of ∼ 6h–6days studied.There are substantial similarities in the mean zonal winds, both with regard to magnitudes and times of seasonal reversals; also in annual and semi-annual oscillations. In general, the semi-diurnal tide has similar amplitudes, phases and vertical wavelengths : there are consistent summer (long λ) and winter (short λ) characteristics, with rapid transitions between them. Differences between the timing of these transitions and in some of the mid-season tides are discussed. The diurnal tide is less regular and of smaller amplitude at both locations, often being too small to reliably characterize at Monpazier. However, seasonal variations between summer and winter months may be discerned.In addition to the 24 and 12 h tidal oscillations, which traditionally are studied in most detail, there is clear evidence for additional osculations near 6,8, ∼ 10 and ∼ 16 h and longer periods of ∼ 2 and ∼ 5 days. The amplitudes of these are often comparable or larger than the ‘dominant’ 24 and 12 h tides. The monthly and seasonal variations of these additional oscillations are studied, as a function of height, at the two locations. There is evidence for large scale (global) and small scale (local) disturbances in the wind field.  相似文献   

4.
5.
Winds data from three radar systems in the U.S.S.R. G.D.R. and Canada, which are well-spaced along the 52°N latitude circle, are used to illustrate longitudinal/regional variations in the dynamics of the upper middle atmosphere 80–97 km. Responses to the stratospheric warming of 1982/3 are noted at all three locations, but the zonal wind does not reverse at Badary, consistent with the flow there being eastward during all months of the year. Planetary wave period oscillations (2–30 days) are observed at all locations, and highly significant cross-spectral coherences exist between the three stations.  相似文献   

6.
7.
Comparisons are made between data from the unique Saskatoon medium frequency radar set, which is continuous from mid 1978–1983 and the ROCOB data from Primrose Lake, which is only 340 km northwest of Saskatoon. Until 1981 there were 2–3 firings per week and now there are 4–5 per month. While the final agreement is satisfactory, special care was required when matching the two regions: particular problems are the low rocket sampling rate and the unexpectedly large amplitude of the diurnal tide. Combination of the two data sets is made.The Canadian zonal winds are quite similar to CIRA 72, especially in the summer months, however, the winter winds show much more systematic variability due to 12- and 6-month periods of oscillation and stratwarms. Canadian meridional winds differ significantly from existing data models.  相似文献   

8.
Wind measurements using a meteor trail radar which performed during two June solstice and three December solstice months were analysed to study the tidal winds over Trivandrum (8.5°N). The ter-diurnal (8 h) component of wind was found to be as significant as the diurnal and semi-diurnal components. The modulations in the altitude profiles of amplitude and phase of the tidal wind components are interpreted to be due to higher order tidal modes. The amplitudes and vertical wavelengths of the tidal modes observed in the meteor zone are discussed.  相似文献   

9.
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.  相似文献   

10.
Mean winds at 60–90 km altitudes observed with the MU radar (35°N, 136°E) in 1985–1989 are presented in this paper. The zonal wind at 70 km became westward and eastward in summer and winter, respectively, with a maximum amplitude of 45 m s−1 westward in early July and 80 m s−1 eastward at the end of November. The meridional wind below 85 km was generally northward with the amplitudes less than 10 m s−1. In September to November, the meridional wind at 75–80 km becomes as large as 20–30 m s−1. Those zonal wind profiles below 90 km show good coincidence with the CIRA 1986 model, except for the latter half of winter, from January to March, when the observational result showed a much weaker eastward wind than the CIRA model. The height of the reversal of the summer wind from westward to eastward was determined as being 83–84 km, which is close to the CIRA 1986 model of 85 km. The difference between the previous meteor radar results at 35–40°N, which showed the reversal height below 80 km, could be due to interannual variations or the difference in wind measurement technique. In order to clarify that point, careful comparative observations would be necessary. These mean winds were compared with Adelaide MF radar observations, and showed good symmetry between the hemispheres, including the summer reversal height, except for the short period of eastward winds above Kyoto and the long period over Adelaide.  相似文献   

11.
The spectra of long period wind oscillations in the meteor zone over Trivandrum are presented. The spectral amplitudes were found to be much larger during June 1984 when the QBO in the stratospheric zonal wind was in a strong easterly phase compared with June 1987 when the zonal winds at the altitude of maximum QBO were weak westerlies. Zonal wind amplitudes for periods of 15 and 5 days were found to be most significant during these two June months. The amplitudes of these two oscillations in meridional wind were found to be as large as the amplitudes in the zonal wind. The vertical wavelength in both zonal wind and meridional winds of the 15-day oscillation is very large whereas for the 5-day oscillation the vertical wavelengths were 80 and 65 km during June 1984 and June 1987, respectively. The results are discussed.  相似文献   

12.
When seasonal variations were eliminated by evaluating 12-month running means, the ionospheric parameters foE, foF2 and hmF2 at Juliusruh (54.6°N, 13.4°E) showed large solar cycle variations. However, when further 3-yr running averages were evaluated and subtracted, QBO (Quasi-biennial oscillations) were noticed in all these parameters. Sunspot series did not reveal a QBO, but geomagnetic Ap did show a QBO. The peaks of the ionospheric QBO and QBO of Ap could be roughly compared, with lags or leads of a few months. Also, these compared roughly with the well-known QBO peaks of tropical stratospheric (50 mb) zonal winds. Similar analyses at other locations are warranted.  相似文献   

13.
A real-time-winds (RTW) system from Saskatoon operated with the Tromsø MF (partial reflection) radar system on a continuous basis in the period June–December 1987. This interval includes MAC/SINE and EPSILON. Profiles with 3-km resolution were obtained every 5 min—weak ionization and few geomagnetic disturbances limited the observations normally to 80–110 km. However, daily mean winds, diurnal and semidiurnal tidal characteristics (amplitudes, phases and wavelengths) and gravity wave characteristics (intensities, mean directions) are available throughout this interval. This is particularly valuable in defining the background state for some experiments, e.g. rockets, and for comparison with related parameters from the lidar and other radars (EISCAT, SOUSY-VHF). Comparisons with these dynamical parameters from Saskatoon (52 N) are made : the zonal circulation was weaker at Troms0, tidal amplitudes smaller, and summer 12-h tidal wavelengths shorter ( ~ 80 km vs ~ 100 km). The fall transition for this tide occurred in September at Troms0, earlier than observed elsewhere.  相似文献   

14.
Two series of measurements of horizontal wind velocity, one performed in winter 1990 at 44°N latitude, and the other in summer 1988 at 69°N latitude, were subjected to a spectral analysis. The two series covered a height interval of 11–15 km centred at about the same height (92.5km in winter, 91.5km in summer). In both cases the slopes of the spectra were close to −3. A dominant wavelength (if it existed) must have been larger than the height interval covered.  相似文献   

15.
Faunal remains from archeological sites worldwide, especially feces and regurgitated pellets, are usually subjected to paleoparasitological examination, allowing the identification of past animal parasites. In this study, we analyzed 10 samples of South American camelid dung, which played an important role for the ancient human groups in the South-Central Andes, dated between 341 and 1635 calCE, from the Iluga Túmulos site (Pampa del Tamarugal, Tarapacá region, Atacama Desert, Chile). Microscopy examination revealed parasite remains in seven samples, in which oocysts of Eimeria macusaniensis and eggs of Lamanema chavezi/Nematodirus lamae, Trichuris sp., Moniezia sp., capillariids, strongylids, and unidentified nematodes were found. Although some of these species pose a potential health risk to camelids, most are not considered to be of major zoonotic importance, which could explain the absence of these parasites on human coprolites from this site analyzed previously. This first paleoparasitological study on camelid fecal remains from northern Chile sheds light on the occurrence of gastrointestinal parasites and its relationship with Andean ancient human populations and the environment.  相似文献   

16.
Traditionally Mesolithic hunter–gatherer cultures are supposed to have lived in a primeval forest environment with a closed vegetation cover during the Early and Mid-Holocene. It is not until the onset of subsequent Neolithic agricultural societies that the development of more expansive open areas is assumed. Therefore our perception of the Mesolithic economy in the European lowlands is highly affected by the idaea of adaptation to dense forest environments and a very stable system of resource exploitation. However, recent palaeoenvironmental studies provide evidence that areas of open landscapes must have existed at least temporarily during the Mesolithic and evoke the question whether human impact may be accountable for this.  相似文献   

17.
The San Juan Basin of the American Southwest is home to some of the best known architecture in pre-Columbian North America. Although many faunal assemblages have been reported for individual sites, there has been little synthesis of hunting and husbandry in these farming communities. In an attempt to understand changing animal usage over time in the San Juan Basin, we use three indices to investigate the usage of artiodactyls, lagomorphs and turkeys. These three taxonomic groups formed the bulk of meat diets between Basketmaker II and Pueblo III times (A.D. 1–1300). Our analysis indicates that artiodactyls declined over time in relation to lagomorphs. Turkeys increased in the northern regions when compared to lagomorphs. Cottontails increased when compared to jackrabbits over time. We suggest that as human populations increased in the San Juan Basin, artiodactyls were more intensely hunted. People then began to raise more turkeys in favorable regions, and also hunted more lagomorphs in relation to artiodactyls. Deforestation, also as a result of increased human populations, would have created conditions more favorable for cottontails than jackrabbits in many areas.  相似文献   

18.
Z. Zhu  C. Yu  W. Luo  Y. Miao  Z. Lu  L. Liu  J. Yang 《Archaeometry》2020,62(1):130-140
In order to identify accurately the circular object contained in the ceramic pot excavated from Jurou Li's grave of the Jin dynasty (1115–1234 ce ) in Xi'an, Shaanxi, China, mass spectrometry was applied to determine the amino acid sequences of the residual proteins extracted from the sample, after preliminary starch grain analysis. The sequences were searched against a standard protein sequence database. The proteins extracted were identified as originating from domesticated barley (Hordeum vulgare), soybean (Glycine max), and fermentative microorganisms (Kluyveromyces lactis, Lipomyces starkeyi, Wickerhamomyces ciferrii, Nadsonia fulvescens and Zygosaccharomyces rouxii). These findings indicate that the extremely degraded object in the ceramic pot was made from barley by fermentation with the addition of soy sauce, providing direct evidence of culinary culture in the Jin dynasty.  相似文献   

19.
This paper focuses on the period of the political separation of the Netherlands and Belgium (1830–1839). Both countries were in a state of war for almost a decade, which resulted in massive troop deployments along their borders and the militarisation of the landscape. The principal objects of study are the Dutch army camps at Rijen and Oirschot near the Belgian border, which to date have barely received any scholarly attention. Both camps were almost 2 km across and offered accommodation to up to 12,000 infantry soldiers. They will be studied from an archaeological-historical perspective, focusing on the spatial and social dimensions of the camps and their place in the wider landscape. The camps are representative of the final stage of pre-industrial warfare in Europe, which is characterised by a continuation of many eighteenth century and Napoleonic traditions.  相似文献   

20.
O’Gorman, J.P., Salgado, L., Varela, J., & Parras, A., 2013. Elasmosaurs (Sauropterygia, Plesiosauria) from the La Colonia Formation (Campanian–Maastrichtian), Argentina. Alcheringa 37, 257–265. ISSN 0311-5518.

Elasmosaur postcranial remains from the La Colonia Formation (Campanian–Maastrichtian), Chubut Province, Patagonia, Argentina, are described. The new material has small dimensions and caudal vertebrae with parapophyses strongly projected laterally—characters shared with some Elasmosauridae indet. from the coeval Allen Formation, Río Negro Province, Argentina. These features reinforce the similarities between the plesiosaur faunas to the north and south of the Somún Curá Plateau. The small size of these elasmosaurs may be palaeoecologically related to the marginal marine depositional environment of the sedimentary host rocks.

José P. O’Gorman [joseogorman@fcnym.unlp.edu.ar], División Paleontología Vertebrados, Museo de La Plata, Universidad Nacional de La Plata, Paseo del Bosque s/n., B1900FWA, La Plata, Argentina and [CONICET (Consejo Nacional de Investigaciones Científicas y Técnicas)]; Leonardo Salgado [salgadoleito@yahoo.com.ar], Instituto de Investigación en Paleobiología y Geología, Universidad Nacional de Río Negro, Isidro Lobo y Belgrano, 8332 General Roca, Argentina and [CONICET]; Julio Varela [julioadrianvarela@hotmail.com], and Ana Parras [aparras@exactas.unlpam.edu.ar], INCITAP (CONICET-UNLPam), Facultad de Ciencias Exactas y Naturales, Universidad Nacional de La Pampa, Uruguay 151, 6300 Santa Rosa, La Pampa, Argentina. Received 27.7.2012; revised 19.10.2012; accepted 27.10.2012.  相似文献   

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