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Global increase in record-breaking monthly-mean temperatures 总被引：2，自引：1，他引：1
The last decade has produced record-breaking heat waves in many parts of the world. At the same time, it was globally the warmest since sufficient measurements started in the 19th century. Here we show that, worldwide, the number of local record-breaking monthly temperature extremes is now on average five times larger than expected in a climate with no long-term warming. This implies that on average there is an 80 % chance that a new monthly heat record is due to climatic change. Large regional differences exist in the number of observed records. Summertime records, which are associated with prolonged heat waves, increased by more than a factor of ten in some continental regions including parts of Europe, Africa, southern Asia and Amazonia. Overall, these high record numbers are quantitatively consistent with those expected for the observed climatic warming trend with added stationary white noise. In addition, we find that the observed records cluster both in space and in time. Strong El Niño years see additional records superimposed on the expected long-term rise. Under a medium global warming scenario, by the 2040s we predict the number of monthly heat records globally to be more than 12 times as high as in a climate with no long-term warming. 相似文献
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Ebenebe sand deposits from the designated Imo Formation (southeastern Nigeria) were evaluated using geologic, geochemical, and geotechnical techniques to ascertain the suitability for use as fine aggregate and industrial material. Results show that this formation consists of mainly quartz that show predominance of angular to subrounded sphericity, oblate to equant mineral shapes, while elongate and platy shaped grains are rare. It exhibits poorly sorted and well-graded particles that range from fine to coarse sand-sized grains. Of all the specimens taken from this geological deposit, geochemistry is dominated by a very high percentage of SiO2 (>?96%). The concentrations of Al2O3 and Fe2O3 vary from 0.58 to 2.2% and 0.09 to 0.89%, respectively. Sands show insignificant activity on soaking with water and caustic soda which demonstrate the paucity of deleterious minerals and organics. The properties of the sand deposits are evaluated based on the depositional and geomorphological environment and processes. The properties of the Ebenebe sand deposits were compared with the characteristics of other sand deposits having proven service performance and those specified by some referenced standards which implies that the studied sands possess a high potential for use as aggregate as well as industrial material, with some beneficiation. 相似文献
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Stratigraphic and structural interpretative studies have been carried out within the paralic sequence of Agbada Formation in the Niger Delta Basin. The method of study involved integrating sequence stratigraphic techniques with well logs, biostratigraphy, and 3D regional seismic data obtained from several producing fields in the Coastal Swamp depobelt of the onshore Niger Delta Basin. This was targeted at establishing regional sequence stratigraphic and structural framework from well log correlation and seismic mapping so as to better define hydrocarbon leads. Well log correlation using stratigraphic bounding surfaces such as maximum flooding surfaces (MFSs) and sequence boundaries (SBs) indicates that the stratigraphic package was deposited within the Middle to Late Miocene (8.5 to 12.1 Ma) age. Recognized depositional sequences revealed differential thickening and thinning of the associated system tracts (lowstand system tract (LST), transgressive system tract (TST), and highstand system tract) (HST)). This observed stratal behavior has been attributed to the influence of syndepositional tectonic structures that characterize the Coastal Swamp depobelt, which lies within the extensional zone. Flattening of MFSs at various ages indicates observable basinward shift of the depositional center. The genetic units of LST and HST serve as good hydrocarbon reservoir whereas HST and TST constitutes mainly the source and seal packages rocks in the area. Structural interpretation revealed the occurrence of simple/faulted rollover anticline, collapsed crest, regional hanging wall and footwall, horst block, and subdetachment fault structural styles that constitute the key hydrocarbon entrapment mechanisms. Structural top maps show fault-dependent closures which dominate the extensional zone, which could form possible hydrocarbon leads and prospects that should be targeted during exploration studies for development. 相似文献
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In porous sediments of the Ishikari Lowland, there is a gradual increase in the background geothermal gradient from the Ishikari
River (3–4 °C 100 m–1) to the southwest highland area (10 °C 100 m–1). However, the geothermal gradient at shallow depths differs in detail from the background distribution. In spite of convective
heat-flow loss generally associated with groundwater flow, heat flow remains high (100 mW m–2) in the recharge area in the southwestern part of the Ishikari basin, which is part of an active geothermal field. In the
northeastern part of the lowland, heat flow locally reaches 140 mW m–2, probably due to upward water flow from the deep geothermal field. Between the two areas the heat flow is much lower. To
examine the role of hydraulic flow in the distortion of the isotherms in this area, thermal gradient vs. temperature analyses
were made, and they helped to define the major components of the groundwater-flow system of the region. Two-dimensional simulation
modeling aided in understanding not only the cause of horizontal heat-flow variations in this field but also the contrast
between thermal properties of shallow and deep groundwater reservoirs.
Electronic Publication 相似文献
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