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The newly discovered Weddell Fan, Antarctica, covers 0.75 million km2. The adjacent continental shelf is characterized by deep, rugged topography; the inner shelf is covered by a grounded polar ice sheet. The upper fan has numerous deep, V-shaped canyons that intersect a slope-base, leveed fan valley. Piston cores from the valley contain disorganized gravel grading upward into graded gravel and sand. Levee cores contain interbedded hemipelagic sediments and fine-grained turbidites. The lower fan is sand-rich. Sediment supply to the fan apparently occurred before development of glacial shelf topography and during a more temperate glacial setting. 相似文献
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In order to plan strategies for adaptation to climate change, the current effects of climate on economic growth need to be
understood. This study reviews evidence of climate effects on economic growth and presents original analysis of the effect
in Sub-Saharan Africa (SSA). Case studies from the literature demonstrate that historically, climate has had significant and
negative effects on household income, agricultural productivity and economic growth in SSA. This study focuses on the effects
hydroclimatic variability on economic growth in the countries of SSA. We utilize a new national level precipitation statistic
that incorporates spatial and temporal variability within each country. Country level economic growth statistics are analyzed
in panel regressions. Persistent negative precipitation anomalies (drought) are found to be the most significant climate influence
on GDP per capita growth. Temperature and precipitation variability show significant effects in some cases. Results imply
the consideration of hydroclimatic risks, namely drought, may be the priority concern for adaptation to a changing climate
for Sub-Saharan Africa. This conclusion is contrary to the premise of many climate change impact assessments that focus on
temperature increases as the primary concern. 相似文献
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Guest Editor Rahul Sharma 《Marine Georesources & Geotechnology》2013,31(1):61-62
Abstract Several physical aspects of continuous subbottom profiling are presented, and their relationship to operating characteristics of profiling instruments is discussed. Interpretation of data produced by shallow‐penetration continuous profilers, such as the SONIA system, is a process of transformation of the continuous measurement of the travel times of reflected sound pulses into geologic phenomena. Essentially, the continuous profiler is a geologic tool; interpretation of the data is based on geologic observation and reasoning, irrespective of the further use of the information obtained in applied science. However, interpreters must have sufficient knowledge of the geophysical system and of the equipment design to be in a position to evaluate the significance of their interpretation. 相似文献
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Alan Longhurst 《Estuarine, Coastal and Shelf Science》1983,17(3):261-285
An approximate carbon budget for the Sierra Leone River Estuary and adjacent inner continental shelf indicates that phytoplankton production is balanced by grazers only in the wet season estuary; on the continental shelf, and in the dry season estuary, phytoplankton production exceeds demand of consumer populations by 70–90%. Regional production is dominated by the dry season estuary where diatom blooms support large population of the phytophagous clupeid fish Ethmalosa fimbriata. It is suggested that as well as what is used in bacterial respiration, not quantified in the study, important amounts of inshore organic carbon production are available for export, or burial, or both, either in inshore mudbanks or at the shelf edge by slumping. This carbon budget for a tropical continental shelf having neither coral-reefs nor coastal upwelling appears to correspond with what is emerging as a generic distinction between shelves and open ocean ecosystems: surplus production on shelves, balance between producers and consumers in the open ocean. 相似文献