The westward intrusion of south Pacific water at the western tip of the New Guinea Island     

KIM Eung  JEON Dongchull  Hadikusumah 《海洋学报(英文版)》2013,32(1):24-31

From the eastern Indonesian cruise from November 14 to 23, 2007, CTD (conductivity, temperature, depth profiler) /ADCP (acoustic Doppler current profiler)casting and seawater sampling were done at 25 stations around Waigeo Island near New Guinea Island. It was found overall westward intrusion of the south Pacific waters into the Seram Sea and southward spreading of the north and south Pacific waters into the Seram Sea. There is westward residual flow along the channel between Waigeo and New Guinea within upper 200 m with the maximum speed up to 50 cm/s, and much weaker eastward flow in the lower layer (< 10 cm/s) due to blocking by the shallow sill at the west of the Dampier Strait. The abrupt change of bottom topography induces active horizontal and vertical mixing which results in a three-layered current system with a major through-flow of -0.99 Sv (Sv = 10 6 m 3 /s) into the Seram Sea; the transports in the upper and the lower layers are -1.14 Sv and -0.24 Sv (westward), respectively, and in the middle there is a return flow with the transport of +0.39 Sv (eastward).  相似文献   

Macro- and megafauna communities in three deep basins of the South-East Atlantic     

《Deep Sea Research Part I: Oceanographic Research Papers》2013

During ‘Meteor’ expedition ‘DIVA 2’ in 2005 the abyssal macro- and megafauna communities were studied in the northern Cape Basin, in the northern Angola Basin and in the eastern and western Guinea Basin. Water depths varied between 5040 and 5670 m.Surface deposit feeding or predatory ophiuroids dominated the megafaunal community in the northern Cape Basin, sponges, sipunculids and fish in the northern Angola Basin, and asteroids, crustaceans and fish in the eastern Guinea Basin, while in the western Guinea Basin sipunculids dominated.In the northern Cape Basin, peracarid crustaceans were the dominant macrofaunal group, followed by polychaetes and bivalves. In the Guinea Basin, polychaetes, peracarid crustaceans and bivalves dominated, although omnivorous or predatory free-living nematodes of macrofaunal size (>0.5 mm) made up 40–60% of the total abundance, with maxima in the western basin.The chlorophyll a content of sediments was lower in the northern Cape and Angola Basins than in the Guinea Basin, which was consistent with the differences in water masses, primary production and flux rate of organic matter in the three basins of the South-East Atlantic. The differences in structure and function of the macro- and megafauna communities in the three basins correlated with the differences in the amount of food reaching the seafloor in tropical and subtropical settings.  相似文献   

哈马黑拉涡旋的季节变异研究   总被引：1，自引：0，他引：1  

翟方国  胡敦欣  王庆业 《海洋科学》2013,37(11):85-94

利用1992年1月～2006年11月期间的ECCO2海洋同化数据资料,研究了海洋上层50m平均的哈马黑拉涡旋的季节变异特征。结果表明,哈马黑拉涡旋在5月开始出现,7月达到最强,3月和4月消失,这主要取决于新几内亚沿岸流的季节变化。新几内亚沿岸流4～11月为西北向,从12月到次年的2月为东南向。随着西北向新几内亚沿岸流的增强,哈马黑拉涡旋开始出现并增强。而随着西北向新几内亚沿岸流的减弱和反向,哈马黑拉涡旋减弱并消失。同时棉兰老海流在夏季的增强也有利于哈马黑拉涡旋增强。旨在研究哈马黑拉涡旋的季节变异特征及其影响因子,为进一步探讨其垂向结构、年际变异等时空变化特征和该区域的环流特征提供研究基础。  相似文献   

Land cover changes and landscape pattern dynamics in Senegal and Guinea Bissau borderland     

《Applied geography (Sevenoaks, England)》2017

Different levels of climatic, agricultural, demographic, political and socioeconomic change have been detected in West African countries. For many years the human impact on the region was negligible, due to the low population density. However, in the last decades, demographic increase has accelerated exploitation of the natural resources and consequently the degradation of the ecosystems. Land cover degradation and landscape changes are more or less pronounced according to politic and socio-economic conditions of each country. In this study, a region located on the borderland of north Guinea-Bissau and south Senegal, is analyzed with regard to land cover and landscape trends, considering the socio-economic factors that drive them and the borderline effect. In this analysis, remote sensing data (Landsat TM, ETM+ and OLI data) were used to obtain four land cover maps for the years 1990, 2002, 2010 and 2015. The results show a similar landscape behavior in both countries, directly related to similar socio-economic practices. Forest area increase in both countries and there is a reduction in Agriculture/Bare soil areas until 2010. Main causes may be associated to the rural exodus, resulting from the conflict for independence of Casamance, which affects the borderland region of Senegal and Guinea Bissau, or to the conversion of agricultural areas into cashew orchards. In opposition, between 2010 and 2015, Forest area decrease and Agriculture/Bare soil increase, due to the recent trend of conversion of old cashew orchards into traditional fields of cereals and peanut. An increase in landscape fragmentation is observed in the period under analysis, revealing a heterogenization trend, which can be related to the adoption of similar human practices, in the last decades.  相似文献   

BOOK REVIEWS     

《The Professional geographer》1986,38(2):195-222

Book Reviewed in this article: The Vanishing Farmland Crisis, Critical Views of the Movement to Preserve Agricultural Land . John Baden Protecting Farmlands . Frederick R. Steiner and John E. Theilacker Ecological Effects of Fire in South African Ecosystems . Peter de V. Booysen and Neil M. Tainton Geography in China . Wu Chuanjun , Wang Nailiang , Lin Chao and Zhao Songqiao Resource Inventory and Baseline Study Methods for Developing Countries . Francis Conant , Peter Rogers , Marion Baumgardner , Cyrus Mc Kell , Raymond Dasmann, and Priscilla Reining Principles of Remote Sensing . Paul J. Curran Famine As A Geographical Phenomenon . Bruce Currey and Graeme Hugo The Suburban Squeeze: Land Conversion and Regulation in the San Francisco Bay Area . David E. Dowall Senses of Place . John Eyles Uneven Development and the Geographical Transfer of Value . D. K. Forbes and P. J. Rimmer Issues in Wilderness Management . Michael Frome Land-use and Prehistory in South-east Spain , The London Research Series in Geography 8. Antonio Gilman and John B. Thornes with Stephen Wise Regions in Question, Space, Development Theory and Regional Policy . Charles Gore The Colorado River: Instability and Basin Management . William L. Graf Hazardous Waste Sites: The Credibility Gap . Michael R. Greenberg and Richard F. Anderson Peasants, Subsistence Ecology, and Development in the Highlands of Papua New Guinea . Lawrence S. Grossman Silver Cities: The Photography of American Urbanization, 1839-1915 Peter B. Hales Silicon Landscapes . Peter Hall and Ann Markusen Remaking Ibieca: Rural Life in Aragon under Franco . Susan F. Harding The European Energy Challenge: East and West . George W. Hoffman The Global Climate . John T. Houghton The Urban Jobless in Eastern Africa . Abel G. M. Ishumi . The Tourist: Travel in Twentieth-Century North America . John A. Jakle City and Society: An Outline for Urban Geography . R. J. Johnston Residential Segregation, The State and Constitutional Conflict in American Urban Areas . R. J. Johnston Accessibility and Utilization: Geographical Perspectives on Health Care Delivery . Alun E. Joseph and David R. Phillips To the Heart of Asia: The Life of Sven Hedin . George Kish North American Culture , Vol 1. Ary J. Lamme III Past and Present in the Americas: A Compendium of Recent Studies . John Lynch Ethnicity in Contemporary America: A Geographical Appraisal . Jesse O. Mc Kee The Shell Countryside Book . Richard Muir and Eric Duffey 1990 Planning Conference Series. Proceedings of the National Geographic Areas Conference . Proceedings of the Regional Geographic Areas Conferences Wood, Brick, and Stone: The North American Settlement Landscape . Vol. 2: Barns and Farm Structures . Allen G. Noble Bangladesh: Biography of a Muslim Nation . Charles Peter O'donnell  相似文献   

BOOK REVIEWS     

《The Professional geographer》1983,35(4):488-524

Book Reviewed in this article: Main Street: Northeastern Oregon: The Founding and Development of Small Towns . Barbara Ruth Bailey . Food Politics: The Regional Conflict . David N. Balaam and Michael J. Carey , eds. The International Economy and Industrial Development: Trade and Investment in the Third World . R. Ballance , J. Ansari and H. Singer . Neighborhoods in Urban America . Ronald H. Bayor , ed. The English Heartland . By Robert Beckinsale and Monica Beckinsale . Regional Dimensions of Industrial Policy . Michael E. Bell and Paul S. Lande , eds. Tension Areas of the World . D. Gordon Bennett , ed. Latin America: an Introductory Survey . B. W. Blouet and O. M. Blouet , eds. Integration and Division: Geographical Perspectives on the Northern Ireland Problem . Frederick W. Boal and J. Neville H. Douglas , eds. Energy and Land Use . Robert W. Burchell and David Listokin , eds. Slopes and Weathering . Michael Clarke and John Small . Alaska's Rural Development . Peter G. Cornwall and Gerald Mc Beath , eds. The Politics of Park Design: A History of Urban Parks in America . Galen Cranz . World Congress on Land Policy, 1980, Proceedings . Matthew Cullen and Sharon Woolery , eds. Oregon Divided: A Regional Geography . Samuel N. Dicken and Emily F. Dicken . Urban Food Marketing and Third World Rural Development . T. Scarlett Epstein . South Africa: Spatial Frameworks for Development . T. J. D. Fair . Institutions and Geographical Patterns . Robin Flowerdew , ed. Industrialization of U.S. Agriculture, An Interpretive Atlas . Howard F. Gregor . Planning Theory: Prospects for the 1980s . Patsy Healy , Glen Mc Dougall and Michael J. Thomas , eds. Neighborhood Mobilization: Redevelopment and Response . Jeffrey R. Henig . The American Urban System: A Geographical Perspective . R. J. Johnston . Climate, History and the Modern World . Hubert H. Lamb . Climate and History: Studies in Past Climates and Their Impact on Man . T. M. L. Wigley , M. J. Ingram and G. Farmer . China: Railways and Agricultural Development, 1875–1935 . Ernest P. Liang . A Desirable Energy Future—A National Perspective . Robert S. Livingston , T. D. Anderson , T. M. Besmann , M. Olszewski , A. M. Perry , and C. D. West . Topothesia: Essays Presented to T. S. Ó Máille . B. S. Mac Aodha , ed. Transportation for the Poor: Research in Rural Mobility . Hal S. Maggied . Land Uses in American Cities . Harold M. Mayer and Charles R. Haves . Industrial Organisation and Location . Philip Mc Dermott and Michael Taylor . Human Adaptability: an Introduction to Ecological Anthropology . Emilio F. Moran . Regional Analysis and the New International Division of Labor . Frank Moulaert and Patricia W. Salinas , eds. The Nuclear War Atlas. Victoriaville, Quebec, Canada : Urbanization and Environmental Quality . Isao Orishimo . The Garden of Eden: The Botanic Garden and the Re-Creation of Paradise . John Prest . Earthfire, The Eruption of Mount St. Helens . Charles Rosenfeld and Robert Cooke . Contest for the South China Sea . Marwyn S. Samuels . The Future of the Wetlands: Assessing Visual-Cultural Values . Richard C. Smardon , ed. Tucson: the Life and Times of An American City. C. L. Sonnichsen . The Geography of Multinationals . Michael Taylor and Nigel Thrift , eds. Impact of Marine Pollution on Society . Virginia Tippie and Dana Kester . Reviving the Industrial City: the Politics of Urban Renewal in Lyon and Birmingham . Jerry A. Webman . Andean Reflections: Letters from Carl O. Sauer While on a South American Trip under a Grant from the Rockefeller Foundation, 1942 . Robert C. West , ed. Cartographic Drawing with Computers . P. Yoeli .  相似文献   

Diatom biostratigraphy of tsunami deposits: Examples from the 1998 Papua New Guinea tsunami     

Sue Dawson   《Sedimentary Geology》2007,200(3-4):328-335

Distinctive diatom assemblages may be associated with tsunami sediments and may often contrast with the assemblages found within sediments underlying the tsunami deposit as well as those associated with the modern coastal environment. Sediments associated with the 1998 tsunami that destroyed much of the Sissano lagoon area in northern Papua New Guinea have been investigated. Surface sediments from three transects across the sediment spit near Warapu have been examined for diatom content and preservation. The preservation is variable, and the data show an, often chaotic, assemblage that can be attributed to the tsunami waves incorporating and depositing diatoms from distinctive habitat zones during their runup and subsequent backwash. The diatoms identified within the Warapu sediments indicate an origin from within the inter-tidal and offshore area rather than from the beach–sand spit complex. The sand deposits disclose a high percentage, in excess of 75%, of broken diatom valves, and a predominance of centric (circular) species due to preferential preservation. The study demonstrates that the application of diatom biostratigraphy to modern tsunami deposits can be used in conjunction with other stratigraphical lines of evidence to interpret the source and provenance of historical and palaeo-tsunami deposits.  相似文献   

Kimberlites of the Man craton, West Africa     

E.M.W. Skinner  D.B. Apter  C. Morelli  N.K. Smithson 《Lithos》2004,76(1-4):233-259

The Man craton in West Africa is an Archaean craton formerly joined to the Guyana craton (South America) that was rifted apart in the Mesozoic. Kimberlites of the Man craton include three Jurassic-aged clusters in Guinea, two Jurassic-aged clusters in Sierra Leone, and in Liberia two clusters of unknown age and one Neoproterozoic cluster recently dated at 800 Ma.

All of the kimberlites irrespective of age occur as small pipes and prolific dykes. Some of the Banankoro cluster pipes in Guinea, the Koidu pipes in Sierra Leone and small pipes in the Weasua cluster in Liberia contain hypabyssal-facies kimberlite and remnants of the so-called transitional-facies and diatreme-facies kimberlite. Most of the Man craton kimberlites are mineralogically classified as phlogopite kimberlites, although potassium contents are relatively low. They are chemically similar to mica-poor Group 1A Southern African examples.

The Jurassic kimberlites are considered to represent one province of kimberlites that track from older bodies in Guinea (Droujba 153 Ma) to progressively younger kimberlites in Sierra Leone (Koidu, 146 Ma and Tongo, 140 Ma). The scarcity of diatreme-facies kimberlites relative to hypabyssal-facies kimberlites and the presence of the so-called transitional-facies indicate that the pipes have been eroded down to the interface between the root and diatreme zones. From this observation, it is concluded that extensive erosion (1–2 km) has occurred since the Jurassic. In addition to erosion, the presence of abundant early crystallizing phlogopite is considered to have had an effect on the relatively small sizes of the Man craton kimberlites.  相似文献   

The temporal series of the New Guinea 29 April 1996 aftershock sequence     

D. Caccamo  F.M. Barbieri  S. D’Amico 《Physics of the Earth and Planetary Interiors》2005,153(4):175-180

The aim of our search is the analysis of aftershock temporal series following a mainshock with magnitude M ≥ 7.0. Investigating aftershock behavior may find the key to explain better the mechanism of seismicity as a whole.In particular, the purpose of this work is to highlight some methodological aspects related to the observation of possible anomalies in the temporal decay. The data concerning the temporal series, checked according to completeness criteria, come from the NEIC-USGS data bank. Here we carefully analyze the New Guinea 29 April 1996 seismic sequence.The observed temporal series of the shocks per day can be considered as a sum of a deterministic contribution (the aftershock decay power law, n(t) = K·(t + c)^−p + K₁) and of a stochastic contribution (the random fluctuations around a mean value represented by the above mentioned power law). If the decay can be modeled as a non-stationary Poissonian process where the intensity function is equal to n(t) = K·(t + c)^−p + K₁, the number of aftershocks in a small time interval Δt is the mean value n(t)·Δt, with a standard deviation .  相似文献   

Hydrologic and sediment modelling studies in the environmental impact assessment of a major tropical dam project     

G. Pickup 《地球表面变化过程与地形》1980,5(1):61-75

A computer-based study of the impact of the proposed Wabo hydroelectric scheme on the Purari River, Papua New Guinea was carried out. The HEC-6 model, Scour and Deposition in Rivers and Reservoirs developed by the Hydrologic Engineering Centre was used to simulate the effect of the dam on sediment transport and erosion in the lower Purari. Two runs with the model were carried out. The first one was used to establish baseline conditions and the second modelled dam impact. Before the study was carried out, data had to be collected on channel geometry, sediment input, river bed material size composition and hydraulic conditions in the river. Supplementary models also had to be developed to fill in gaps in runoff records and to describe flow in the river during power generation. Results of the investigation indicate that limited erosion will occur because of bed-armouring and the river will adjust towards a new equilibrium condition quite rapidly. The sediment output of the river into the Purari delta will change, load in the clay, silt and sand/gravel fractions decreasing by 22, 53 and 78 per cent respectively.  相似文献