The influence of ionospheric absorption on mid-latitude whistler mode signal occurrence from VLF transmitters

Whistler mode signals from VLF transmitters received at Faraday, Antarctica (65° S, 64° W) during 1986–1991 show an annual variation in the number of hours over which signals are observed, with a maximum in June and a minimum in December. The variation was larger at solar minimum than at maximum and can be understood in terms of changes in absorption of VLF signals in the D-region, where the high geographic latitude of Faraday plays an important role in producing low attenuation levels during the austral winter. In contrast, very little such variation was observed at Dunedin, New Zealand (46° S, 171° E) in 1991. Nighttime whistler mode signals have start and end time trends that are consistent with the influence of F-region absorption. Increases in whistler mode occurrence appear to be associated with periods of high geomagnetic activity at solar maximum but not during solar minimum. A possible mechanism involving decreased F-region absorption is discussed.     

Gravity-wave motions in the mesosphere and lower thermosphere observed at Mawson,Antarctica

We present the results of MF radar observations of mean winds and waves in the height range 78–108 km at Mawson (67°S, 63°E), Antarctica. The measurements were made in the period from 1984 to 1990. Climatologies of the prevailing zonal and meridional circulations made with a 12-day time resolution show that the mean circulation remained relatively stable over the 6 yr of observation. Climatologies of gravity-wave motions in the 1–24 h period range were also generated. These reveal that the r.m.s. amplitudes of horizontal wave motions near the mesopause (~90 km) are about 30 m s⁻¹, and that there is some anisotropy in the motions, especially at heights below 90 km. Meridional amplitudes are larger than zonal amplitudes, which suggests a preference for wave propagation in the north-south direction. Comparisons with MST radar wind observations made near the summer solstice at Poker Flat, Alaska (65°N) and at Andøya, Norway (69°N) show similarities with the Mawson observations, but the wave amplitudes and mean motions are larger in magnitude at the northern sites. This suggests hemispheric differences in wave activity that require further study.     

Experimental estimates of electron density variations at the reflection height of VLF signals

To study the behaviour of the electron concentration at the reflection level of very low frequency (VLF) waves, two years of phase and amplitude records of the 12.9 kHz signals emitted from Omega-Argentina (43.20°S; 294.60°E) and received at Tucumán (26.90°S; 294.70°E) have been used. The experimental results are compared with values derived from the International Reference Ionosphere model (IRI-79). The experimental data show a seasonal variation not predicted by the model. Differences are explained in terms of changes of night-time atomic oxygen concentration, which control the electron density profile at the base of the night-time D-region, not taken into account in the IRI model. Values of atomic oxygen necessary to explain VLF data are comparable with published data.     

Late Triassic megaspores from the Amery Group,Prince Charles Mountains,East Antarctica

Cantrill, D. J., & Drinnan, A. N., 1994:03:28. Late Triassic megaspores from the Amery Group, Prince Charles Mountains, East Antarctica. Alcheringa 18, 71–78. ISSN 0311-5518.

Megaspores referable to the genera Cabochonicus Batten & Ferguson 1987 and Minerisporites Potonié 1956 are a common component of the palaeoflora recovered from the Jetty Member within the Flagstone Bench Formation of the Amery Group. The known ranges of these two genera, in conjunction with the macrofloral remains, suggest a Late Triassic age. Two new species, Cabochonicus sinuosus and Minerisporites triangulatus, are described. Scanning electron microscopic examination of the spores indicates that standard palynological treatment of megaspores can result in sculptural degradation, possibly leading to incorrect generic assignment.     

Satellite observations of signals from a Soviet mid-latitude VLF transmitter in the magnetic-conjugate region

The results of the Intercosmos-19 satellite experiment which receives VLF signals arriving via a magnetospheric path have been examined. The reception zone in the magnetically conjugate region (MCR) has been shown to be centred near the L-value (2.6) of the transmitter of 15 kHZ radio waves. The received signals arrive at the MCR with wave normal angles to the geomagnetic field, ψ, far from the resonance cone. These results indicate an effective amplification of the signal in the magnetosphere by 10–15 dB and effective ducting of VLF waves across the equatorial plane of the magnetosphere.     

First Dynasonde observations of F-region plasma flow at Halley,Antarctica

Plasma flow vectors have been derived from data recorded by the Advanced Ionospheric Sounder (operating as a Dynasonde) at Halley, Antarctica (76°, 27°W). Single bulk flow vectors derived from the motion of echo reflection surfaces in the overhead F-region ionosphere are consistent both with plasma flow vectors, poleward of Halley, observed simultaneously by the PACE HF radar and also, for various levels of geomagnetic activity, with published mean plasma flow at the same invariant geomagnetic latitude (62°). The results demonstrate application of the method and lend support to existing evidence that the velocity measured by this kind of technique, at least for moderate to active geomagnetic activity at high latitudes, represents ionospheric plasma flow.     

An asymmetry in the direction of arrival of whistlers at Sanae,Antarctica

The directions of arrival of over 1300 whistlers have been measured at Sanae, Antarctica and it is shown that whistlers arriving from lower latitudes than the station predominantly come from the west. In this paper we report on the observations and discuss the possible reasons for this asymmetric distribution of arrival bearings.     

Simultaneous observations of the quasi 2-day wave at Mawson,Antarctica, and Adelaide,South Australia

Observations of the Austral quasi 2-day wave at Mawson, Antarctica (67°S, 63°E) are presented and compared with those from Adelaide (35°S, 138°E). The data were obtained from partial-reflection radars which have been measuring winds continuously since mid-1984, and the results presented here are the first to record the 2-day wave in middle atmosphere winds from Mawson. They show that 2-day period oscillations of 10–15 m s⁻¹ are a regular feature of the high latitude southern hemisphere summer. The wide longitude and latitude separation of the radar stations permits estimates of propagation velocity and latitude phase structure, and results are consistent with the passage of a westward travelling Rossby-gravity (3, 3) wave.     

Characteristics and frequency of occurrence of Trimpi events recorded during 1982 at Sanae,Antarctica

‘Trimpi’ amplitude perturbations on VLF signals received at Sanae, Antarctica, have been identified using a new computerised technique. Our survey of 1982 data, taken during magnetically disturbed times, shows that events of short duration (<25 s) constitute 60% of all events detected and that all events found are amplitude attenuations with deviations from quiescent levels ranging up to 90%. It is unusual, at Sanae, to observe the causative whistler with a Trimpi event. This, together with further evidence from Trimpi occurrence statistics, may suggest that the gyroresonant interactions responsible for some of the events occur with non-ducted whistler mode waves. A method for estimating the extent of the precipitation region is presented.     

A petrified cycad trunk from the Late Cretaceous of the Larsen Basin,Antarctica

Cetricycas antarcticus gen. et sp. nov. occurs in the Late Coniacian to Campanian Lachman Crags Member of the Santa Marta Formation, Marambio Group, James Ross Island, Antarctica. The petrified trunk comprises a thick pith containing thin and thick walled parenchymous cells, vascular traces surrounded by a thin layer of loose secondary wood. Medullary bundles arise inside the wood zone and pass outwards through multiseriate medullary rays. The trunk anatomy indicates assignment to the Cycadales, and the presence of medullary bundles indicates the affinities with a clade comprising Lepidozamia, Macrozamia, and Encephalartos. This clade is presently confined to Australia and Africa, but fossil representatives extend the geographic range to India, South America and now Antarctica.     

Taxonomic status of the Eocene penguins Orthopteryx gigas Wiman, 1905 and Ichtyopteryx gracilis Wiman, 1905 from Antarctica

Traditionally, the systematics of the Seymour Island fossil penguins has been based on Wiman's groups defined by the robustness and size of isolated postcranial bones. However, current evaluations of fossil penguins necessitate that new species be established when the specimens include at least a tarsometatarsus or in some cases a humerus. Accordingly, neither of the two species reviewed herein (Orthopteryx gigas and Ichtyopteryx gracilis) are represented by remains sufficiently complete to validate a new taxon. Orthopteryx gigas is based on an isolated synsacrum lacking diagnostic characters. Ichtyopteryx gracilis is based on a tarsometatarsus but with insufficient preservational quality to justify discrimination of the species. For these reasons both Orthopteryx gigas and Ichtyopteryx gracilis should be considered nomen dubia.     

略论淅川和尚岭喜秋楚墓

1990年河南省文物研究所、南阳地区文物研究所、淅川县博物馆在淅川县仓房乡陈庄村行政村东沟村的和尚岭上抢救发掘了二座楚墓。原简报作者曹桂岑同志认为两墓为春秋中期后段的楚箴尹克黄夫妇墓。主要依据为M1中所出“克黄之鼎”鼎及收缴的铜     

Costulatotheca schleigeri (Hyolitha: Orthothecida) from the Walhalla Group (Early Devonian) at Mount Pleasant,central Victoria,Australia

Earp, C., 29 January 2019. Costulatotheca schleigeri (Hyolitha: Orthothecida) from the Walhalla Group (Early Devonian) at Mount Pleasant, central Victoria, Australia. Alcheringa. Alcheringa 43, 220–227. ISSN 0311-5518

A number of hyolith fragments (including one operculum), found in Early Devonian marine turbidites at Mt Pleasant, near Alexandra, central Victoria, are described as Costulatotheca schleigeri gen. et sp. nov., the first confirmed record of the order Orthothecida in the Devonian of Australia. Index fossils found at this locality (Uncinatograptus sp. cf. U. thomasi and Nowakia sp. ex gr. N. acuaria) indicate an age of Pragian or earliest Emsian. The taphonomy of rare rafted shelly fossils indicates that flysch deposition occurred in a very-low-energy environment into which there were occasional bursts of high-energy turbidites carrying allochthonous fossils from shallower water.

Clement Earp [omaiosys@yahoo.com.au], 1 De Havilland Place, Onerahi, Whangarei 0110, New Zealand.     

河南灵宝西坡遗址动物群及相关问题

本文对河南灵宝西坡仰韶文化中期遗址2000年和2001年度出土的动物骨骼进行了分析,试图复原该区域当时的生态环境和经济生活。结果表明,家畜已取代野生动物成为人们肉食消费的主要对象,这一变化与仰韶文化中期该地区人口规模和密度的显著增大同时发生,其深层次原因需从多学科角度进一步研究。     

Gazella (Bovidae,Ruminantia) remains from the Siwalik Group of Pakistan

Khan, M.A., Babar, M.A., Akhtar, M., Iliopoulos, G., Rakha, A. & Noor, T., November 2015. Gazella (Bovidae, Ruminantia) remains from the Siwalik Group of Pakistan. Alcheringa 40, xxx–xxx. ISSN 0311-5518.

New gazelle fossils are described from the Siwalik Group of Pakistan. The material includes horncores, maxilla and mandible fragments, and isolated teeth. The available samples are assigned to three Gazella species: Gazella sp. in the Lower Siwalik Subgroup (ca 14.2–11.2 Ma), and G. lydekkeri and G. superba in the Middle Siwalik Subgroup (ca 10.2–3.4 Ma). Based on a review of the Siwalik Group gazelles, G. padriensis is synonymized with G. lydekkeri. Gazella superba Pilgrim, 1939 sensu stricto is a large form and is a valid species of the genus in the Siwalik Group.

Muhammad Akbar Khan [akbaar111@yahoo.ca], Muhammad Adeeb Babar [babar_fcc2005@yahoo.com], Muhammad Akhtar [drakhtarfdrc@hotmail.com], Allah Rakha [babar.441@googlemail.com], Tuba Noor [akbar.zool@pu.edu.pk], Abu Bakr Fossil Display & Research Centre, Department of Zoology, Quid-e-Azam Campus, Punjab University (54590), Lahore, Pakistan; George Iliopoulos [borelakias@gmail.com], Geology Department of the University of Patras, Patras, Greece.     

辽宁康平姜家沟出土的一组石雕佛像及年代

通过本文介绍的佛教造像,对造型、服饰等进行研究和探讨,以确定其制作的年代.     

扎鲁特旗额日格吐鲜卑墓

1986年9月,通辽市科尔沁区运输公司修路队在通(通辽)霍(霍林郭勒市)公路施工中,偶然发现一处古墓群,当时未引起工人重视,遭到破坏。事后我馆得到消息,很快赶赴现场,进行了实地调查。     

开鲁县福兴地鲜卑墓

1983年9月,通辽市开鲁县建华乡福兴地一村民在村东挖沙取土时发现一墓葬,已遭破坏。通辽市博物馆闻讯后,会同开鲁县文管所、公安局前往调查处理,并收回部分文物。现将此墓情况报告如下。     

2002年内蒙古林西县井沟子遗址西区墓葬发掘纪要

遗址位于林西县双井店乡敖包吐村井沟子自然村北约400米处,西北距林西县政府所在地林西镇约40公里,南距双井店乡政府所在地约7公里(图一)。该遗址于1989年赤峰市文物普查时发现。1998年林西县文管所所长王刚曾报导了遗址内被破坏的一座墓葬,并确定了这里存在规模