Origin of a trend in ECMWF wind analysis and its objective removal     

B N Goswami  H Annamalai 《Journal of Earth System Science》1996,105(2):101-117

The suitability of the European Centre for Medium Range Weather Forecasting (ECMWF) operational wind analysis for the period 1980–1991 for studying interannual variability is examined. The changes in the model and the analysis procedure are shown to give rise to a systematic and significant trend in the large scale circulation features. A new method of removing the systematic errors at all levels is presented using multivariate EOF analysis. Objectively detrended analysis of the three-dimensional wind field agrees well with independent Florida State University (FSU) wind analysis at the surface. It is shown that the interannual variations in the detrended surface analysis agree well in amplitude as well as spatial patterns with those of the FSU analysis. Therefore, the detrended analyses at other levels as well are expected to be useful for studies of variability and predictability at interannual time scales. It is demonstrated that this trend in the wind field is due to the shift in the climatologies from the period 1980–1985 to the period 1986–1991.  相似文献   

莫高窟崖顶防沙工程的效益分析   总被引：6，自引：7，他引：6  

凌裕泉  屈建军 《中国沙漠》1996,16(1):13-18

４年防沙实践证明：莫高窟崖顶防沙试验的工程设计构思是正确的，设计依据科学可靠，防护效益显著。对保护石窟和壁画已经起到重要的作用．其具体防护作用是：１）直接控制偏西风向洞窟搬运沙量的９５％左右；２）洞前夜间积沙减少了８０％以上；３）外围栅栏对来自主风向的外侧积沙的侧导率平均为３５％；对内侧积沙的侧导率，在偏东风作用下可达５７．５１％，在偏西风作用下平均为１５．８９％．上述防沙作用均具有明显的季节变化。  相似文献   

香港海湾沙坝发育过程中的风沙作用     

王为 《中国沙漠》1996,16(2):120-126

海湾沙坝是香港海岸一种主要的沉积地貌，以大屿山岛贝澳湾的沙坝最为典型。关于贝澳湾古（内）沙坝的成因曾有过较多的争论，但各种成因假说都缺乏有力的证据支持。本文分析了湾内沉积物特征和沉积过程与海平面变化的关系，揭示了风沙在海湾沙坝发育过程中所起的作用。古（内）沙坝的沉积成分随着内沙坝向上加积贝壳含量急剧减少，其上部沉积成分已明显不同于外沙坝和现代海滩，而与其前后的干泻湖上部相似，显示了沉积过程中沉积物来源的变化。内沙坝的沉积物粒径向上变细，分选向上变好，而粒径最小处不在沙坝的最上部，则是在贝壳含量开始向上减少的高度，表明沉积动力随着沉积来源的变化而改变。电镜扫描也显示内沙坝上部的部分颗粒不是来自海滩，具有磨圆差、缺乏水下撞击痕迹以及上翻解理与贝壳状断口共存的特征。内外沙坝下部海滩岩的高度、位置与年代还表明内外沙坝间的沉积高度与海平面变化无关。研究表明：香港海湾沙坝发育过程向上加积的动力由原来的海动力变为风动力；随岸线向海推进内沙坝的沉积物来源由来自海滩物质变为同时来自海滩物质及干泻湖上层物质，只有风才能堆积这些物质；内外沙坝间的沉积高度差只是风积高度不同的结果，与海平面变化无关；海湾内风沙作用并不显著。  相似文献   

INTERACTION BETWEEN WAVES AND TIDE-SURGE MOTION AND A JOINT WAVE-TIDE SURGE MODEL   总被引：1，自引：0，他引：1  

尹宝树  王涛  M.I.El-Sabh 《中国海洋湖沼学报》1996,14(4):349-356

This paper describes in detail the interaction between waves, tides and storm surges and covers theeffects of wave on tides and storm surges and the influence of tides plus storm surges on waves. Some pro-blems deserving attention and improvements are put forward. And finally a combined wave-tide-surge numerical model YE-JWTSM is presented,with all relevant interaction processes considered, includ-ing wave-dependent surface wind stress and bottom-stress as well as current-induced refrac-tion and frequency shift.  相似文献   

江苏吕四小庙洪淹没性潮汐汊道的稳定性   总被引：9，自引：0，他引：9  

喻国华  陆培东 《地理学报》1996,51(2):127-134

运用沉积学、地貌学和海洋动力学方法，对小庙洪水道进行了历史演变、现代动态及稳定性分析，提出淹没性潮汐道的稳定性。淹没性潮汐道的开发利用必须顺应汊道自然演变规律，并考虑其内部稳定性差异。  相似文献   

微细浸染型金矿中原生矿石向氧化矿石转化机理探讨   总被引：5，自引：2，他引：5  

刘显凡  张兴春 《矿物学报》1997,17(4):501-506

本文以黔西南和桂西北微细浸染型金矿为例，讨论了该类型金矿原生矿石和氧化矿石中金的赋存状态差异，并从晶体化学和地球化学角度作了赋存原理分析，进而重点探讨了两类矿石中粘土矿物的表生淋滤转化的化学模式，为开展原生矿石的选冶工艺研究提供了新的思路。  相似文献   

湘南─粤北铁锰多金属矿床的表生风化作用          下载免费PDF全文

朱恺军  黄金水  姚国龙 《地质找矿论丛》1997,12(3):68-75

湘南－粤北是我国一个重要的铁锰多金属矿化带，该矿化带中重要的铁锰多金属矿 经历了海相沉积，热液改造和表生风化等多种地质作用。由沉积作用和热液改造作用形成的原生铁锰多金属矿化岩石，由于其中的成矿元素Ｆｅ，Ｍｎ，Ｐｂ，Ｚｎ和Ａｇ的含量低，有害元素Ｓ的含量高，工业价值不大。  相似文献   

360阶地球重力场模型DQM94A及其精度分析   总被引：4，自引：2，他引：4       下载免费PDF全文

夏哲仁  林丽  石磐 《地球物理学报》1995,38(6):788-795

介绍了适用于中国地区的３６０阶地球重力场模型ＤＱＭ９４Ａ．精度分析结果表明，应用局部积分改进的谱权综合法计算的３６０阶地球重力场模型ＤＱＭ９４Ａ，在表示中国境外地球重力场时，与用改进的基本模型ＯＳＵ９１Ａ精度相当；表示中国及其周边地区地球重力场的精度如下，用模型计算的３０＇×３０＇和１°×１°平均重力异常与相应实测结果较差的均方根基分别为±９．３０×１０^－５ｍ／ｓ２和±７．６５×１０^－５ｍ／ｓ２，在中国３７个ＧＰＳ点上，由ＤＱＭ９４Ａ计算的大地水准面高的精度为±０．８８ｍ．  相似文献   

Multiscale Combined Action and Disturbance Characteristics of Pre-summer Extreme Precipitation Events over South China     

Hongbo LIU  Ruojing YAN  Bin WANG  Guanghua CHEN  Jian LING  Shenming FU 《大气科学进展》2023,40(5):824-842

The dominant frequency modes of pre-summer extreme precipitation events(EPEs) over South China(SC) between1998 and 2018 were investigated. The 67 identified EPEs were all characterized by the 3–8-d(synoptic) frequency band.However, multiscale combined modes of the synoptic and three low-frequency bands [10–20-d(quasi-biweekly, QBW);15–40-d(quasi-monthly, QM); and 20–60-d(intraseasonal)] accounted for the majority(63%) of the EPEs, and the precipitation intensity on the peak wet day was larger th...  相似文献   

The climate change research that makes the front page: Is it fit to engage societal action?     

《Global Environmental Change》2023

By growing awareness for and interest in climate change, media coverage enlarges the window of opportunity by which research can engage individuals and collectives in climate actions. However, we question whether the climate change research that gets mediatized is fit for this challenge. From a survey of the 51,230 scientific articles published in 2020 on climate change, we show that the news media preferentially publicizes research outputs found in multidisciplinary journals and journals perceived as top-tier. An in-depth analysis of the content of the top-100 mediatized papers, in comparison to a random subset, reveals that news media showcases a narrow and limited facet of climate change knowledge (i.e., natural science and health). News media selectivity reduces climate change research to the role of a sentinel and whistleblower for the large-scale, observed, or end-of-century consequences of climate change for natural Earth system components. The social, economic, technological, and energy aspects of climate change are curtailed through mediatization, as well as local and short-term scales of processes and solutions. Reviewing the social psychological mechanisms that underlie behavioral change, we challenge the current criteria used to judge newsworthiness and argue that the consequent mediatization of climate change research fails to breed real society engagement in actions. A transformative agenda for the mediatization of climate change research implies aligning newsworthiness with news effectiveness, i.e., addressing the extent to which communication is effective in presenting research that is likely to produce behavioral change.  相似文献