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991.
Although the urban heat island (UHI) is a well-documented phenomenon, relatively little information in the literature is available about its impact on summer extreme heat event (EHE). As UHI is characterized by increased temperature, it can potentially increase the magnitude and duration of EHEs within cities. Based on daily maximum temperature records from 62 observation stations in Zhejiang province from the period 1971-2011 and satellite-measured nighttime light imagery from the Defense Meteorological Satellite Program (DMSP) Operational Linescan System (OLS) during 1992-2010, we analyzed the long-term change of summer EHEs and its association with the rapid urbanization process. The results could be concluded as follows: (1) Zhejiang has experienced rapid urbanization and dramatic growth in urban areas in the past two decades, especially after 2000. (2) The summer mean maximum temperature and the 95th percentile of summer daily maximum temperature in most of its stations have increased, with the most significant increase occurring in the highly urbanized areas including the city belt around Hangzhou Bay, Taizhou–Wenzhou and Jinghua–Yiwu city belts. (3) The hot days and hot-day degrees, defined by both daily 95th percentile and the threshold of 35℃, show that the UHI effect causes additional hot days and heat stress in urban stations compared to rural stations. The results in this study suggest that the UHI effect should be determined and incorporated in preparing high temperature forecasts in cities.  相似文献   
992.
This work is based upon results of interpretation of about 8872 km-long regional seismic lines acquired in 2011 within the international project Geology Without Limits in the Black Sea. The seismic lines cover nearly the entire Black Sea Basins, including Russia, Turkey, Ukraine, Romania and Bulgaria sectors. A new map of acoustic basement relief and a new tectonic structure scheme are constructed for the Black Sea Basins. The basement of the Black Sea includes areas with oceanic crust and areas with highly rifted continental crust. A chain of buried seamounts, which were interpreted as submarine volcanoes of Late Cretaceous (Santonian to Campanian) age, has been identified to the north of the Turkish coast. On the Shatsky Ridge, probable volcanoes of Albian age have also been recognized. Synorogenic turbidite sequences of Paleocene, Eocene and Oligocene ages have been mapped. In the Cenozoic, numerous compressional and transpressional structures were formed in different parts of the Black Sea Basin. During the Pleistocene–Quaternary, turbidites, mass-transport deposits and leveed channels were formed in the distal part of the Danube Delta.  相似文献   
993.
A super El Ni?o event occurred in the equatorial Pacific during 2015-2016,accompanied by considerable regional eco-hydro-climatic variations within the Mindanao Dome(MD)upwelling system in the tropical western Pacific.Using timeseries of various oceanic data from 2013 to 2017,the variability of eco-hydro-climatic conditions response to the 2015/2016 super El Ni?o in the upper 300 m of the MD region are analyzed in this paper.Results showed that during the 2015/2016 super El Ni?o event,the upwelling in the MD region was greatly enhanced compared to those before and after this El Ni?o event.Upwelling Rossby waves and the massive loss of surface water in the western Pacific were suggested to be the main reasons for this enhanced upwelling.De-creased precipitation caused by changes in large-scale air-sea interaction led to the increased surface salinities.Changes in the struc-tures of the thermohaline and nutrient distribution in deep waters contributed to the increased surface chlorophyll a,suggesting a po-sitive effect of El Ni?o on surface carbon storage in the MD region.Based on the above analysis,the synopsis mechanism illustrating the eco-hydro-climatic changing processes over the MD upwelling system responding to the El Ni?o event was proposed.It high-lights the prospect for the role played by El Ni?o in local eco-hydro-climatic effects,which has further profound implications for understanding the influence of the global climate changes on the ocean carbon cycle.  相似文献   
994.
This paper presents biostratigraphical and stable isotope data obtained from core CM92–43, which was recovered from the central Adriatic as part of a comprehensive investigation of the palaeoenvironmental history of the basin. The data span the period of the Last Glacial–Holocene (LG–H) transition (ca. 18000 to 8000 GRIP ice-core yr BP). Regional biozones are defined on the basis of characteristic assemblages of planktic Foraminifera, and these are compared with other foraminiferal biostratigraphical schemes from the southern Adriatic and the Tyrrhenian Sea. Variations in relative abundance of selected planktic Foraminifera and in selected pollen types are shown alongside variations in δ18O and δ13C obtained from Globigerina bulloides and relative abundance of Globigerinoides ex. gr. ruber. The data are compared with the GRIP ice-core record and the event stratigraphy scheme based on this record, and it is concluded that the climate forcing mechanisms that controlled climate variations in the North Atlantic region during the LG–H transition also extended their influence into the Mediterranean region over the same period. Copyright © 1999 John Wiley & Sons, Ltd.  相似文献   
995.
中国中始新世—早更新世构造事件与应力场   总被引:5,自引:0,他引:5  
中始新世—渐新世(52—23.3Ma)的华北构造期是以太平洋板块朝NWW方向位移为主要特征,使我国大陆受到近东西向的挤压,造成一系列近南北向的褶皱、逆掩断层和许多走向近东西的正断层、单断箕状盆地。此构造事件的发生可能与始新世末期北美、加勒比海和东太平洋的大量微玻璃陨石的坠落、冲击有关。中新世--早更新世(23.30.7Ma)的喜马拉雅构造期是以印度—澳大利亚板块与菲律宾海板块向北推移为主要特征,造成喜马拉雅山和日本列岛南部的俯冲带,使我国西部发育走向近东西的褶皱、逆掩断层系,而在东部地区则形成许多走向近南北的深切地幔的正断层系.并使南海与日本海再次张开。出现洋壳。喜马拉雅构造事件可能与印度洋、南亚、澳大利亚附近地区的微玻璃陨石群的冲击有关。  相似文献   
996.
陆相二叠一三叠系界线划分和事件   总被引:1,自引:0,他引:1  
我国陆相二叠—三叠系界线的划分主要依据古脊椎动物,孢粉,双壳类、介形虫和古植物等.这些化石组合特征在界线附近都有明显的变化.这种变化不仅可以用来划分界线,而且结合在界线附近其它非生物(沉积物的粒度和颜色等)的异常变化,可以看出在二叠—三叠纪之交曾发生过某种事件.  相似文献   
997.
本文通过1997年ENSO事件发展过程的分析总结出以下的主要特点和预报信息:(1)行星尺度的海气耦合和局地海气耦合同时的气作用,形成了太平洋中部和东部的同时增温;  相似文献   
998.
对2009年2月4日08时到11时30分,呼和浩特市区出现的微量雨夹雪、雾、道路结冰的复杂天气进行原因分析。结果表明:由于受500hPa弱的短波槽及850hPa槽前西南暖湿气流的共同影响,形成了全市大部的微量雨夹雪;雨夹雪落地融化与地面进行热量交换,致使低于0℃的地面结了薄冰;雾主要出现在呼和浩特市区,一方面是由于适合的温度范围、高湿度条件、以及微风有关,另一方面冬季市区污染物较重,在低层存在逆温的情况下,污染物扩散能力较差,使水汽产生大量的凝结核,从而形成了雾,雾中及地水汽直接凝华也对地面结冰起到了作用。  相似文献   
999.
通过对南沙群岛海区94-10柱样浮游有孔虫碳氧同位素组成、粒度组成及全岩样14C测年的研究,发现南沙群岛海区在末次冰期结束后的转暖过程中发生了两次明显的气候回返事件,即事件Ⅰ(约12—11kaBP)和事件Ⅱ(约10—8kaBP),其中事件Ⅰ可能为新仙女木事件;在末次冰期结束后的气候转暖过程中,东亚古季风演化具有不稳定性和突发性的特点。  相似文献   
1000.
The Great Xing'an Range (GXR), Northeast (NE) China, is a major polymetallic metallogenic belt in the eastern segment of the Central Asian Orogenic Belt. The newly discovered Xiaokele porphyry Cu (–Mo) deposit lies in the northern GXR. Field geological and geochronological studies have revealed two mineralization events in this deposit: early porphyry‐type Cu (–Mo) mineralization, and later vein‐type Cu mineralization. Previous geochronological studies yielded an age of ca. 147 Ma for the early Cu (–Mo) mineralization. Our 40Ar/39Ar dating yielded 40Ar/39Ar plateau ages of 124.8 ± 0.4 to 124.3 ± 0.4 Ma on K‐feldspar in altered Cu‐mineralized diorite porphyrite dikes that represent the overprinting vein‐type Cu mineralization, consistent with zircon U–Pb ages of the diorite porphyrite (126.4 ± 0.5 to 125.0 ± 0.5 Ma). The Cr and Ni contents and Mg# of the Xiaokele diorite porphyrites are high. The diorite porphyrites at Xiaokele are enriched in light rare‐earth elements (REEs), and large‐ion lithophile elements (e.g., Rb, Ba, and K), are depleted in heavy REEs and high‐field‐strength elements (e.g., Nb, Ta, and Ti), and have weak negative εHf(t) values (+0.29 to +5.27) with two‐stage model ages (TDM2) of 1,164–845 Ma. Given the regional tectonic setting in Early Cretaceous, the ore‐bearing diorite porphyrites were likely formed in an extensional environment related to lithospheric delamination and asthenospheric upwelling induced by subduction of the Paleo‐Pacific Plate. These tectonic events caused large‐scale magmatic activity, ore mineralization, and lithospheric thinning in NE China.  相似文献   
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