厄尔尼诺现象及预测现状     

王彰贵  刘克威  陈幸荣  谭晶  文岩 《海洋预报》2005,22(Z1):140-146

厄尔尼诺现象是目前发现的最明显气候异常信号.本文简短地介绍了厄尔尼诺的研究和预测现状,指出厄尔尼诺的预测水平还很低,其主要因素是一、没有建立起全球立体的厄尔尼诺监测网;二、研究局限于热带太平洋或热带印度洋-太平洋;三、缺乏多尺度相互作用的深入研究.另外,本文描述了厄尔尼诺发生前热带太平洋大气-海洋环流异常的几个特征.  相似文献   

Grain size,La/Yb and Th/Sc of settling particles in the western North Pacific: Evidence for lateral transport of small Asian loess     

Nobuhiro Maeda  Shinichiro Noriki  Hisashi Narita 《Journal of Oceanography》2007,63(5):803-812

To understand the transport process of lithogenic particles in the ocean, we measured the grain size distributions of lithogenic particles and measured the opal, La, Yb, Th, and Sc concentrations of the settling particles collected from time-series sediment traps at Sta. KNOT (44°N, 155°E, water depth 5320 m) from June 2002 to May 2004. The annual mean lithogenic particle flux observed at the lower sediment trap (5100 m) was twice as high as that at the upper sediment trap (770 m). The contribution of Asian loess estimated by the La/Yb and the Th/Sc ratios in the lower layer was greater than that in the upper layer. The fluxes of small lithogenic particles with sizes of 3–4 μm at the lower layer (5 to 65 mg/m²/day) were approximately four times larger than that at the upper layer (0.6 to 27 mg/m²/day). These results indicate that the horizontal addition of small particle sizes of Asian loess is a main factor in the increase of lithogenic particles at the lower layer. The temporal variations in the small lithogenic particle flux at the lower layer had a positive correlation with those at the upper layer (r = 0.71). The small lithogenic particle fluxes showed a strong positive correlation with the opal fluxes (r = 0.9). We therefore conclude that the small lithogenic particles were laterally transported and scavenged by the formation of aggregates with opal.  相似文献   

El Niño phenomenon in simple ocean data assimilation data     

GUI Maochang  WU Lingjuan 《海洋学报(英文版)》2005,24(4):43-53

[1]Battisti D S. 1988. The dynamics and  相似文献   

Understanding the Development of the 2018/19 Central Pacific El Ni?o     

Chengyang GUAN  Xin WANG  Haijun YANG 《大气科学进展》2023,40(1):177-185

A central Pacific(CP) El Ni?o event occurred in 2018/19. Previous studies have shown that different mechanisms are responsible for different subtypes of CP El Ni?o events(CP-I El Ni?o and CP-II El Ni?o). By comparing the evolutions of surface winds, ocean temperatures, and heat budgets of the CP-I El Ni?o, CP-II El Ni?o, and 2018/19 El Ni?o, it is illustrated that the subtropical westerly anomalies in the North Pacific, which led to anomalous convergence of Ekman flow and surface warming in the ...  相似文献   

Seasonal Prediction of the Record-Breaking Northward Shift of the Western Pacific Subtropical High in July 2021     

Shuai HU  Tianjun ZHOU  Bo WU  Xiaolong CHEN 《大气科学进展》2023,40(3):410-427

The unprecedented Zhengzhou heavy rainfall in July 2021 occurred under the background of a northward shift of the western Pacific subtropical high(WPSH). Although the occurrence of this extreme event could not be captured by seasonal predictions, a skillful prediction of the WPSH variation might have warned us of the increased probability of extreme weather events in Central and Northern China. However, the mechanism for the WPSH variation in July2021 and its seasonal predictability are still un...  相似文献   

Partitioning of Ni between olivine and siliceous eclogite partial melt: experimental constraints on the mantle source of Hawaiian basalts   总被引：1，自引：0，他引：1  

Zhengrong Wang  Glenn A. Gaetani 《Contributions to Mineralogy and Petrology》2008,156(5):661-678

Olivine is abundant in Earth’s upper mantle and ubiquitous in basaltic lavas, but rarely occurs in eclogite. Partial melts of eclogite are, therefore, not in equilibrium with olivine, and will react with peridotite as they migrate through the upper mantle. If such melts erupt at Earth’s surface, their compositions will be highly modified and they may be olivine-saturated. We investigated experimentally the reaction between olivine and siliceous eclogite partial melt, and determined element partitioning between olivine and the melt produced by this reaction. Our results demonstrate that mixing of reacted eclogite partial melt with primitive basalt is capable of producing the positive correlation between melt SiO₂ content and olivine Ni content observed in some Hawaiian lavas. Experiments were carried out by equilibrating eclogite partial melt or basalt with San Carlos olivine at 1 bar and 1,201–1,350°C. Our results show that eclogite partial melts equilibrated with mantle olivine retain their high SiO₂, low FeO and MgO characteristics. Further, olivine-melt partition coefficients for Ni measured in these experiments are significantly larger than for basalt. Mixing of these melts with primitive Hawaiian tholeiitic lavas results in crystallization of high-Ni olivines similar to those in Makapuu-stage Koolau lavas, even though the mixed magmas have only moderate Ni contents. This results from a hyperbolic increase of the Ni partition coefficient with increasing polymerization of the mixed melt. Note that while eclogite partial melt in contact with peridotite will equilibrate with pyroxene as well as olivine, this will have the effect of buffering the activity of SiO₂ in the reacted melt at a higher level. Therefore, an eclogite partial melt equilibrated with harzburgite will have higher SiO₂ than one equilibrated with dunite, enhancing the effects observed in our experiments. Our results demonstrate that an olivine-free “hybrid” pyroxenite source is not required to explain the presence of high-Ni olivines in Hawaiian lavas and, therefore, indicate that the proportion of eclogite in the Hawaiian plume is less than has been estimated in recent studies.  相似文献   

Nickel enrichment in mantle olivine beneath a volcanic front   总被引：4，自引：1，他引：3  

Satoko Ishimaru  Shoji Arai 《Contributions to Mineralogy and Petrology》2008,156(1):119-131

We found abnormally Ni-rich olivine (Fo = 93) with up to 5.3 wt% of NiO, ten times higher than the ordinary mantle value (0.4 wt%), in a highly metasomatized mantle peridotite xenolith from Avacha volcano, the Kamchatka arc, Russia. The Ni enrichment displays outward diffuse circular domains (<1 mm across) in fine-grained (mostly <100 μm) olivine-rich parts. Associated metasomatic orthopyroxene also shows high NiO (<1.1 wt%). Such high Ni concentrations in olivine cannot be attained in ordinary residual or cumulus peridotites, but are achievable via diffusion from Ni-rich sulfide melt. Sulfur-bearing silicic melt, the main metasomatic agent for the Avacha peridotites, separated sulfide melt, which was fractionated to be Ni-rich at relatively low temperatures. This is a new way of mobility and redistribution of Ni in the mantle, which is active in the mantle wedge, especially beneath a volcanic front.  相似文献   

长江中下游流域旱涝急转事件特征分析及其与ENSO的关系   总被引：4，自引：0，他引：4  

闪丽洁  张利平  张艳军  佘敦先  夏军 《地理学报》2018,73(1):25-40

基于长江中下游流域75个雨量站1960-2015年的日降水资料,通过对原有的旱涝急转指数加以改进,定义了日尺度旱涝急转指数（Dry-Wet Abrupt Alternation Index, DWAAI）,全面分析长江中下游流域夏季（5-8月）旱涝急转事件的时空演变特征,并讨论了旱涝急转事件与事件发生前太平洋海表温度的关系。结果表明：① 改进的DWAAI综合考虑了事件前后期旱涝差异与急转快慢程度,筛选事件更加全面。② 总体来说,自20世纪60年以来,流域内发生旱涝急转事件的区域范围越来越广,事件频率和强度均具有逐年增长趋势。旱涝急转事件主要发生在5月和6月,且汉江水系、中游干流区间、洞庭湖水系北部和鄱阳湖水系西北部地区为事件高发区。③ 旱涝急转事件与事件发生前Nino 3.4区域海温持续异常偏低存在一定关系。在发生时间上,La Ni?a现象具有一定的先兆作用,41.04%的事件发生在La Ni?a现象衰亡期或现象结束后8个月内;在事件强度上,流域内站点的DWAAI与事件发生前第1~6个月的Nino 3.4区域海温异常值存在显著的负相关性,尤其是在鄱阳湖水系和中游干流区间,二者负相关性最强。研究结果可以为长江中下游流域防洪抗旱工作提供一定的依据。  相似文献   

气候要素及El Niño/La Niña事件对中国陆地NPP变化的影响     

崔林丽  史军  肖风劲 《地理学报》2018,73(1):54-66

植被净初级生产力（NPP）是表征陆地生态系统碳循环的重要指标,也是人类社会赖以生存与发展的物质基础。基于遥感—过程耦合模型（GLOPEM-CEVSA模型）模拟的中国区域NPP数据和气象站点观测资料以及厄尔尼诺/拉尼娜（El Ni?o/La Ni?a）事件信息,利用GIS空间分析技术和数理统计方法研究了中国植被NPP的时空格局、动态变化以及气候要素和El Ni?o/La Ni?a气候事件对其影响。结果表明,1982-2011年,中国植被NPP总体上以5.66 gCm^-2(10a)^-1的趋势增长,空间上,植被NPP在中国西部和东北北部、东部地区增加,而在东北中部、华北平原、内蒙中东部、长三角和珠三角地区减少。中国江淮地区植被NPP的降低与日照时数的减少具有较好的对应关系,在华北地区和新疆北部,NPP的增减取决于降水量的增减。东北地区日照时数的增加和气温的升高则是NPP增加的主要原因。就全国整体而言,在El Ni?o年植被NPP增加的区域略多于减少的区域,在La Ni?a年NPP增加的区域则与减少的区域基本相等,日照时数是造成El Ni?o年与La Ni?a年植被NPP差异的主要气候因子。未来需要更加关注辐射、极端气候事件以及人为空气污染对中国不同地区植被的影响。  相似文献   

创新从土地类型到自然区划综合研究——倪绍祥先生的地理学思想与学术贡献     

刘彦随 《地理研究》2018,37(3):473-479

倪绍祥先生1939年6月生于江苏省无锡市。1964年本科毕业于北京大学地质地理系,1967年硕士毕业于华东师范大学地理系。曾在南京大学任教10余年,1983-1985年赴英国吕丁大学地理系进修遥感与土地资源。1994-2016年在南京师范大学地理科学学院任教。在50多年的科学研究与教育生涯中,倪先生矢志不渝、学贯东西、开拓创新,在自然地理学、遥感地学分析、自然资源评价等方面取得了丰硕成果和杰出成就。他先后主持或参加国家、部委及地方重点科研项目10余项,荣获教育部科技进步奖、江苏省科技进步奖、原国家土地管理局科技进步奖、江苏省哲学社会科学优秀成果奖、全国首届优秀地理图书奖等多项奖励,被授予“中国自然资源学会优秀科技工作者”“江苏省优秀科技工作者”“江苏省普通高校优秀学科带头人”“江苏省优秀研究生导师”等荣誉称号。倪先生从事地理学研究的学术思想与成就,主要归纳为土地类型与土地评价研究、资源利用与保护研究、环境遥感与草地蝗虫研究、综合自然地理研究等4个方面,为创新发展中国土地资源科学、综合自然地理学研究及专业学科建设、人才培养、学术交流做出了重要贡献。  相似文献