First View of the Extended Green-Line Emission Corona At Solar Activity Minimum Using the Lasco-C1 Coronagraph on Soho     

R. Schwenn  B. Inhester  S. P. Plunkett  A. Epple  B. Podlipnik  D. K. Bedford  C. J. Eyles  G. M. Simnett  S. J. Tappin  M. V. Bout  P. L. Lamy  A. Llebaria  G. E. Brueckner  K. P. Dere  R. A. Howard  M. J. Koomen  C. M. Korendyke  D. J. Michels  J. D. Moses  N. E. Moulton  S. E. Paswaters  D. G. Socker  O. C. St. Cyr  D. Wang 《Solar physics》1997,175(2):667-684

The newly developed C1 coronagraph as part of the Large-Angle Spectroscopic Coronagraph (LASCO) on board the SOHO spacecraft has been operating since January 29, 1996. We present observations obtained in the first three months of operation. The green-line emission corona can be made visible throughout the instrument's full field of view, i.e., from 1.1 R⊙ out to 3.2 R⊙ (measured from Sun center). Quantitative evaluations based on calibrations cannot yet be performed, but some basic signatures show up even now: (1) There are often bright and apparently closed loop systems centered at latitudes of 30° to 45° in both hemispheres. Their helmet-like extensions are bent towards the equatorial plane. Farther out, they merge into one large equatorial ‘streamer sheet’ clearly discernible out to 32 R⊙. (2) At mid latitudes a more diffuse pattern is usually visible, well separated from the high-latitude loops and with very pronounced variability. (3) All high-latitude structures remain stable on time scales of several days, and no signature of transient disruption of high-latitude streamers was observed in these early data. (4) Within the first 4 months of observation, only one single ‘fast’ feature was observed moving outward at a speed of 70 km s^-1 close to the equator. Faster events may have escaped attention because of data gaps. (5) The centers of high-latitude loops are usually found at the positions of magnetic neutral lines in photospheric magnetograms. The large-scale streamer structure follows the magnetic pattern fairly precisely. Based on our observations we conclude that the shape and stability of the heliospheric current sheet at solar activity minimum are probably due to high-latitude streamers rather than to the near-equatorial activity belt. Supplementary material to this paper is available in electronic form at http://dx.doi.org/10.1023/A:1004948913883  相似文献   

Rural Canterbury. Celebrating its History     

Richard Bedford 《New Zealand geographer》2002,58(2):81-82

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Excursion to Kingswood and Walton-on-the-hill: Saturday,July 2nd, 1898     

W. Whitaker  W.P.D. Stebbing  Bedford McNeill 《Proceedings of the Geologists' Association. Geologists' Association》1898,15(10):456-458

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First discovery of cryptotephra in Holocene peat deposits of Estonia, eastern Baltic     

TIIT HANG  STEFAN WASTEGÅRD  SIIM VESKI  ATKO HEINSALU 《Boreas: An International Journal of Quaternary Research》2006,35(4):644-649

This article reports the first discovery of middle Holocene cryptotephra from a peat sequence in Estonia, eastern Baltic. Two sequences, Mustjärve and Parika (located 110 km apart), were chosen for a pilot study aimed at finding traces of tephra fallout during the middle Holocene. Peat accumulation at both sites started in the early Holocene (c. 9500–9000 ¹⁴C yr BP; c . 11 000–10000 cal. yr BP) and continued throughout the whole Holocene. The radiocarbon-dated intervals between c. 2000 and 5000 ¹⁴C yr BP (c. 2000–5500 cal. yr BP) were chosen from both sites for the study. Colourless tephra shards were identified at 312–316 cm below the peat surface in the Mustjärve peat sequence, while no tephra was found in peat of the same age at Parika. Electron microprobe analyses suggest a correlation with the initial phase of the Hekla-4 eruption (c. 4260 cal. yr BP), although the age-depth model indicated an age around 4900 cal. yr BP. Small concentrations of colourless to light brown tephra shards at 266–270 cm in the Mustjärve sequence indicate that the Kebister tephra (c. 3750 cal. yr BP) might also be present, but geochemical analyses were not possible. The low concentration and small size of the tephra particles indicate that Estonian bogs are probably on the verge of where tephrochronology is possible in northwestern Europe. Further studies of full Holocene sequences are required in order to discover traces of other ash plumes reaching as far east as the eastern Baltic area.  相似文献   

Immigrant and locally bom Pacific Island Polynesians: Two populations?     

Richard Bedford 《New Zealand geographer》1985,41(2):80-83

At a huihuinga organised during the Conference on Pacific Studies at the University of Auckland in August 1985, there was a spirited exchange of views among participants on residence of Pacific Island Polynesians in New Zealand. As part of a wider critique of Pakeha cultural hegemony and superiority several Maori speakers stressed that Pacific Island Polynesians were manuhiri (visitors) in New Zealand and, like most of the people of European descent, they had "overstayed their permits" in the eyes of the tangata whenua . In responding to these claims, speakers from Samoa and Fiji sought to dispell a myth, still widely held in New Zealand, that the great majority of resident Pacific Island Polynesians were born in the islands. They reminded participants at the Auckland Conference that almost half of the people classed on the basis of ethnicity as Pacific Islanders in the 1981 census had been born in New Zealand. They were not "immigrants".  相似文献   

Distinguished Geographers     

Richard  Bedford Hon Treasurer  NZGS 《New Zealand geographer》2005,61(2):161-166

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Holocene humidity fluctuations in Sweden inferred from dendrochronology and peat stratigraphy   总被引：1，自引：0，他引：1  

BJÖRN ERIK GUNNARSON  ERS BORGMARK  STEFAN WASTEGÅRD 《Boreas: An International Journal of Quaternary Research》2003,32(2):347-360

Tree-ring and peat stratigraphy data were examined back to 5000 BC in order to identify and compare humidity changes in Fennoscandia. The temporal variation in distribution of Scots pine ( Pinus sylvestris L.) was used as a measure of past lake-level fluctuations in central Sweden. The chronology, which spans 2893 BC–AD 1998 with minor gaps in AD 887–907 and 1633–1650 BC and with additional floating chronologies back to 4868 BC, was cross-dated and fixed to an absolute timescale using a chronology from Torneträsk, northern Sweden. The peat stratigraphy from the Stömyren peat bog, south-central Sweden, was transformed into humification indices to evaluate humidity changes during the past 8000 years. The peat chronology is established by four tephra datings and eight ¹⁴C datings. Synchronous periods of drier conditions, interpreted from regeneration and the mortality pattern of pine, tree-ring chronology and peat humification, were recognized at c. 4900–4800 BC, 2400–2200 BC, 2100–1800 BC, 1500–1100 BC, AD 50–200, AD 400–600 and AD 1350–1500. Possible wetter periods were encountered at 3600–3400 BC, 3200–2900 BC, 2200–2100 BC, 1700–1500 BC, 1100–900 BC, 100 BC-AD 50, AD 200–400, AD 750–900 and AD 1550–1700. The wet and dry periods revealed by the tree rings and peat stratigraphy data indicate considerable humidity changes in the Holocene.  相似文献   

Managed Temporary Labour Migration of Pacific Islanders to Australia and New Zealand in the Early Twenty-first Century     

Richard Bedford  Charlotte Bedford  Janet Wall  Margaret Young 《The Australian geographer》2017,48(1):37-57

ABSTRACT

Circular migration was one of several enduring themes in Graeme Hugo’s highly productive research career. Although his specialist field was Asian population movement, during the 2000s he became increasingly interested in labour migration in the Pacific Islands. This paper reviews the development of two managed circular migration schemes targeting Pacific labour that emerged following the UN High-level Dialogue on International Migration and Development in 2006. New Zealand’s Recognised Seasonal Employer (RSE) scheme and Australia’s Seasonal Worker Program (SWP) have attracted international attention as the kind of ‘best practice’ temporary labour migration schemes that Hugo had in mind when he emphasised the positive contributions that circular forms of mobility could make to development in both source and destination countries. The two schemes have transformed mobility between the participating countries and have played a major role in the negotiations over a free-trade agreement between Pacific Forum countries, including Australia and New Zealand. Although the schemes have been in operation for almost 10 years, this paper argues that they are not becoming ‘business as usual’; they embody complex systems of relationships between multiple stakeholders that require ongoing management to ensure that they do not become traps for low-skilled, low-paid ‘permanent’ temporary workers.  相似文献   

The Population Conference: ‘Talkfest’ or Turning Point?     

Richard Bedford  Elsie Ho 《New Zealand geographer》1998,54(1):50-54

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Excursion to Weldon,Dene, and Gretton: Saturday,April 29th, 1899     

Beeby Thompson  Bedford McNeill 《Proceedings of the Geologists' Association. Geologists' Association》1899,16(5):226-231

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