The role of atmospheric teleconnection in the subtropical thermal forcing on the equatorial pacific     

WANG Lu  YANG Haijun 《大气科学进展》2014,31(4):985-994

The equatorial response to subtropical Pacific forcing was studied in a coupled climate model.The forcings in the western,central and eastern subtropical Pacific all caused a significant response in the equatorial thermocline,with comparable magnitudes.This work highlights the key role of air-sea coupling in the subtropical impact on the equatorial thermocline,instead of only the role of the ＂oceanic tunnel＂.The suggested mechanism is that the cyclonic （anticyclonic） circulation in the atmosphere caused by the subtropical surface warming （cooling） can generate an anomalous upwelling （downwelling） in the interior region.At the same time,an anomalous downwelling （upwelling） occurs at the equatorward flank of the forcing,which produces anomalous thermocline warming （cooling）,propagating equatorward and resulting in warming （cooling） in the equatorial thermocline.This is an indirect process that is much faster than the ＂oceanic tunnel＂ mechanism in the subtropical impact on the equator.  相似文献   

GIS软件测评推动了技术与产品的发展   总被引：5，自引：1，他引：4  

方裕  景贵飞 《地理信息世界》2003,1(1):12-15,19

总结了1996年以来，国内GIS软件测评工作的情况，评价了国产GIS软件的性能，与国外优秀软件之间的优势互补，以及国产GIS软件的发展前途。  相似文献   

Surface Waters of the NW Iberian Margin: Upwelling on the Shelf versus Outwelling of Upwelled Waters from the Rías Baixas     

X. A. lvarez-Salgado  J. Gago  B. M. Míguez  M. Gilcoto  F. F. Prez 《Estuarine, Coastal and Shelf Science》2000,51(6):821

A set of hydrographic surveys were carried out in the Ría of Vigo (NW Spain) at 2–4 d intervals during four 2–3 week periods in 1997, covering contrasting seasons. Residual exchange fluxes with the adjacent shelf were estimated with a 2-D, non-steady-state, salinity–temperature weighted box model. Exchange fluxes consist of a steady-state term (dependent on the variability of continental runoff) and a non-steady-state term (dependent on the time changes of density gradients in the embayment). More than 95% of the short-time-scale variability of the exchange fluxes in the middle and outer ría can be explained by the non-steady-state term that, in turns, is correlated (R²>75%) with the offshore Ekman transport. Conversely, 96% of the variability of exchange fluxes in the inner ría rely on the steady-state term. The outer and middle ría are under the direct influence of coastal upwelling, which enhances the positive residual circulation pattern by an order of magnitude: from 10²to 10³ m³s⁻¹. On the contrary, downwelling provokes a reversal of the circulation in the outer ría. The position of the downwelling front along the embayment depends on the relative importance of Ekman transport (Q_x, m³s⁻¹km⁻¹) and continental runoff (R, m³s⁻¹). When Q_x/ R>7±2 the reversal of the circulation affects the middle ría. Our results are representative for the ‘Rías Baixas’, four large coastal indentations in NW Spain. During the upwelling season (spring and summer), 60% of shelf surface waters off the ‘Rías Baixas’ consist of fresh Eastern North Atlantic Central Water (ENACW) upwelled in situ. The remaining 40% consists of upwelled ENACW that previously enters the rías and it is subsequently outwelled after thermohaline modification. During the downwelling season (autumn and winter), 40% of the warm and salty oceanic subtropic surface water, which piled on the shelf by the predominant southerly winds, enters the rías.  相似文献   

Amending Soils with Hydrogels Increases the Biomass of Nine Tree Species under Non‐water Stress Conditions     

Lawrence J. B. Orikiriza  Hillary Agaba  Mnason Tweheyo  Gerald Eilu  John David Kabasa  Aloys Hüttermann 《洁净——土壤、空气、水》2009,37(8):615-620

The classical aim of the application of super absorbent polyacrylate (SAPs) hydrogels is the prolonging of plant survival under water stress. Their effect on plant growth during non‐water stress conditions is not known. This study examined the root and shoot biomass of seedlings of nine tree species; Eucalyptus grandis, Eucalyptus citriodora, Pinus caribaea, Araucaria cunninghamii, Melia volkensii, Grevillea robusta, Azadirachta indica, Maesopsis eminii and Terminalia superba. The seedlings were potted in five soil types; sand, sandy loam, loam, silt loam and clay. These were amended at two hydrogel levels: 0.2 and 0.4% w/w and grown under controlled conditions in a green house. Root and shoot growth responses of the seedlings were determined by measuring the dry weight of the roots, stems, leaves and twigs. The addition of either 0.2 or 0.4% hydrogel to the five soil types resulted in a significant increase of the root dry weight (p < 0.001) in eight tree species compared to the controls after 8 wk of routine watering. Also, the dry weight of stems and leaves and twigs were significantly (p < 0.001) higher in the nine tree species potted in hydrogel amended soil types than in the hydrogel free controls. These results suggested that hydrogel amendment enhances the efficiency of water uptake and utilization of photosynthates of plants grown in soils which have water contents close to field capacity.  相似文献   

基于SMO的德惠农电信息管理系统的设计与开发     

王晓娜  刘万崧  张旭晴  张猛  王洪昌  金丽华 《吉林大学学报(地球科学版)》2007,(Z1)

将GIS技术应用于传统的电力管理系统中,利用GIS管理空间数据的特点,实现GIS对电力系统的海量空间信息数据的管理,提高电力系统的生产效率、效益以及管理质量。结合德惠农电GIS系统的设计与开发工作,利用SuperMap Objects(SMO)专业软件开发平台,进行了系统的数据库和功能模块的设计与开发。  相似文献   

一次超级单体风暴多普勒天气雷达资料的低层风场反演研究   总被引：3，自引：9，他引：3       下载免费PDF全文

张少波  陆汉城  康建伟 《气象科学》2007,27(2):147-154

本文使用二维变分风场反演方法对浙江台州2003年4月12日一次超级单体风暴的多普勒天气雷达探测资料进行低层风场反演研究。二维变分方法以均匀风场反演结果作为初猜场,在目标泛函中加入散度和涡度约束作为正则项来降低不适定性的影响。反演得到的低层水平风场比较好的符合超级单体风暴的组织化的气流结构和强的风切变,通过对散度场垂直积分获得垂直速度,上升气流主要集中在强回波区域,下沉气流一个位于风暴前进的左侧的弱回波区,一个位于钩状回波的内侧。  相似文献   

贵州平坝县白云岩风化壳中稀土元素分布特征之初步研究   总被引：18，自引：2，他引：18       下载免费PDF全文

王世杰  季宏兵  孙承兴 《地质科学》2001,36(4):474-480

本文报道了平坝白云岩风化剖面风化前缘稀土元素超常规富集(总量达3%以上)现象及其特征,并通过主元素、稀土元素的测定,结合白云岩中“酸不溶物”的提取和代表性样品的化学淋溶实验研究,讨论了白云岩风化壳剖面稀土元素的分异特征,认为风化前缘稀土元素的富集是由3方面的因素共同作用造成的:1)对白云岩风化残积的继承;2)剖面上部一部分轻稀土淋滤聚积;3)碳酸盐岩中非均匀分布的原生含磷矿物风化产生的稀土磷酸盐矿物的聚集,后者是最重要的原因。  相似文献   

HD-STGPS超站仪在线路测设和工程放样中的应用研究   总被引：3，自引：1，他引：3  

黄全义  张正禄  罗年学  巢佰崇  郭际明 《测绘信息与工程》2002,27(1):28-30

论述了HD-STGPS超站仪的主要测量功能后，对其在导线测量，线路测设和工程放样方面的应用进行了分析探讨，对于超站仪在航天部 的应用具有指导意义。  相似文献   

The diversity of diversity: a critique of geodemographic classification   总被引：2，自引：0，他引：2  

David Voas  & Paul Williamson 《Area》2001,33(1):63-76

We report on an examination of two geodemographic classification systems based on an analysis of 1991 census variables, for districts, wards and census enumeration districts in England and Wales. We also review the associations among the variables examined, the extent to which certain underlying components might account for the overall variation and the types of areas that are least typical. The results show that small areas are different in many different ways; a few dimensions cannot provide enough information to describe an area fully. Diversity on most scales remains even after geodemographicclassification, emphasizing the advantages of task-specific classification.  相似文献   

特大型精密工程SSC测量投影方式的选择     

陈永奇 《武汉大学学报(信息科学版)》1993,(2)

目前世界上最大的工程超导超级对撞机(SSC)正在建造之中,作者参与这项大型精密工程测量的方案设计和部分咨询工作。根据工程的特点,设计测量投影方式是其中一项工作。本文讨论所设计的双重正形投影(stereographic double conformal projection)以及各种观测量投影归化中的问题。  相似文献