Distinction between the Storegga tsunami and the holocene marine transgression in coastal basin deposits of western Norway

Many coastal lakes were inundated by both the Storegga tsunami (7000 ¹⁴C yr BP) and the mid-Holocene sea-level rise (the Tapes transgression) in western Norway. The tsunami eroded lake bottoms and deposited graded and/or massive beds of sand, rip-up clasts, and coarse plant material. By contrast, when the rising sea entered the lakes, it deposited only gyttja, silt and fine sand, without causing much erosion of the underlying lake sediments. Storegga tsunami deposits in some coastal lakes were interpreted previously as ordinary marine sediments from the Tapes transgression. Our reinterpretation of these deposits shows that the transgression maximum phase was reached after 6500 yr BP, more than 1000 yr later than previously inferred for the coast of Sunnmøre. The new data cannot be combined in a shoreline diagram without showing the 6000 yr BP and 7000 yr BP shorelines as slightly warped. © 1998 John Wiley & Sons, Ltd.     

AN ATMOSPHERIC MOTION EQUATION BUILT ON THE CONSERVATIVE RELATIONSHIP OF THE ANGULAR MOMENTUM EXCHANGE BETWEEN THE SOLID EARTH AND THE ATMOSPHERE ON SEASONAL-ANNUAL TIMESCALE

Within the seasonal-annual timeseale,there exists an angular momentum conservative exchange relationship be-tween the solid earth and the atmosphere,and their angular momentum exchange not only can cause variations inlength-of-day(LOD)but also can express anomalies in atmospheric general circulation.Therefore,their angular mo-mentum exchange mechanism should be introduced into the general circulation model.Considering the angular momentum anomalous exchange caused by the air-earth interface friction effect,awhole-layer atmospheric motion equation is derived in this paper including the earth spin anomalous friction forceparameterized by using the change in the earth rotation rate.Through analysing the equation,it shows that the magni-tude of the earth spin anomalous friction force is the same as that of Coriolis force on seasonal-annual timescale.     

水稻冠层光谱反射特性的动态变化研究

通过对早稻整个生长期内冠层反射光谱特性动态变化的系统研究表明:①在整个水稻生长期内,水稻冠层反射光谱的比值植被指数(RVI)值呈有规律的变化,在抽穗前,随移栽后天数增加,RVI值也逐渐增大,至抽穗前达到最大值;而抽穗后,则随着移栽后天数的增加,RVI值逐渐下降,至收割前降至最低值;②积温与RVI之间存在着较密切的关系,通过对不同生育期积温与RVI之间进行的线性回归分析表明,在抽穗前,积温与RVI值之间呈极显著正相关;而抽穗后,积温与RVI之间呈极显著的负相关。在遥感估产中,这种水稻冠层反射光谱特性的变化对于校正生育期的估产偏差和提高估产精度可能有重要意义。     

植被生态对气候变化和人类活动的响应 ——以陕西省榆林能源化工基地为例

全球气候变化和人类活动双重作用对生态环境的影响是当今研究的热点问题.本文以国家级榆林能源化工基地为研究区,以MODIS遥感数据为依据,以归一化差值植被指数NDVI为参数,研究了植被生态的时空分布规律,分析了植被生态与降水、地貌、地下水、包气带岩性等自然条件的关系,揭示了人类活动对植被生态正负两方面的影响.研究结果表明,自然条件控制着植被生态的格局,植被生态具有明显的水平分带性,由东南向西北,随着降水量的减少、蒸发量和干燥度的增加,植被状况由好变差;2000年以来区内植被状况总体呈现好转的趋势,其中71.22％的区域好转,28.43％的区域基本维持不变,0.35％的区域退化.植被生态对气候变化尤其是降水量的年际变化具有敏感的响应,煤炭和地下水资源开采等人类活动对植被生态总体上造成负面影响,退耕还林(草)、限耕禁牧政策的实施是研究区植被生态总体呈现好转趋势的根本原因.     

西昆仑山区湖泊初探

本文论述了西昆仑山区湖泊的分布、成因、水化学特征以及其演化历史与高原隆升、古气候变化、高山冰川进退之间的关系。研究结果表明,该区湖泊主要靠暖季高山带的冰雪融水补给,故矿化度的变化与其距补给源的远近密切相关;它们在第四纪期间的演化是高原构造隆升和全球气候变化二者作用的结果;根据现有资料,该区湖泊的演化历史可大致分为3个阶段,即距今4.6万年以前的大湖期,晚更新世晚期的湖面波动期和全新世的湖泊退缩期。     

Simulating the impacts of climate variation and land-cover changes on basin hydrology: A case study of the Suomo basin

1 Motivation In the summer of 1998, areas along the middle and lower reaches of the Yangtze River suffered a damag- ing flood. Causes of the flooding became a hot topic on mass media after the disaster. Deforestation on the upstream areas was widely blamed as the major reason for the flooding. Some scientists, however, disproved the point of view. They believed that the impact of land use and land cover changes (LUCC) was over- stated[1]. Actually, the controversy over forest hydrol- ogy h…     

Increased winter-spring precipitation from the last glaciation to the Holocene inferred from a δ~(13)C_(org) record from Yili Basin(Xinjiang,NW China)

The nature and dynamics of climate change in central Asia since the late Pleistocene are controversial. Moreover,most of the published studies focus mainly on the evolution of moisture conditions, and there have been few attempts to address changes in seasonality. In this study, records of δ¹³C_org, TOC, TN, C/N and grain size were obtained from lacustrine sediments at Yili Basin, Xinjiang, NW China. Our aim was to reconstruct the trend in seasonality of precipitation from the last glaciation to the Holocene. The organic matter content of the sediments is derived predominantly from terrestrial plants. The δ¹³C_orgvalues vary from-19.4‰ to-24.8‰, indicating that the vegetation was dominated by C_3 plants. Winter-spring precipitation is identified as the factor determining the relative proportions of C_3 and C_4 plants in the region. A negative trend in δ¹³C_orgcorresponding to an increase in the relative abundance of C_3 plants indicate a trend of increasing winter-spring precipitation from the last glaciation to the Holocene. The increased incidence of wintertime storms in the interior of Asia is suggested to result in the increase of winterspring precipitation in the Holocene.     

湖北宜昌地区下奥陶统生物礁古生态学研究

宜昌地区下奥陶统主要为一套台地相碳酸盐沉积,间夹页岩,其中的特征沉积为发育有较多的生物礁。造礁生物主要有海绵类、瓶筐石类、有柄棘皮类、苔藓虫及蓝细菌和Pulchrilamina等。在下奥陶统含礁层系中识别出四种生物相：(1)壳类生物相：发育有Tritoechia-Pelmatozans群落和Tritoechia-Pomatotrema群落;(2)礁生物相：包括Batostoma群落、Calathium--Archaeoscyphia群落、Pelmatozoans--Batostoma群落、Archeoscyphia群落和Calathium--Cyanobacteria群落;(3)静水生物相：发育有Acanthograptus--Dendrogptus群落和Yichangopora群落;(4)异地生物相：产有异地埋藏群,即Nanorthis--Psilocephlina埋藏群。含礁层系存在四个海平面变化旋回,生物礁的发育明显受海平面的升降速率与容纳空间增长速率的控制。生物礁多形成于高海平面时期。由于本区的海平面在上升过程中存在多个次一级旋回,致使生物礁具有数量多、分布广以及厚度薄和规模小等特点。造礁群落存在着演替和取代两种形式,前者有利于生物礁的发育,后者则表现为礁体的衰亡。     

2000—2016年广西防城金花茶自然保护区关键生态环境参数时空变化

植被覆盖度(FVC)和叶面积指数(LAI)作为关键生态环境参数,其时空动态变化的遥感监测对揭示陆地生态环境演变规律与科学监管生态环境具有重要意义.本文基于2000—2016年GLASS产品的植被覆盖度和叶面积指数数据,对广西防城金花茶国家级自然保护区FVC和LAI的时空动态变化进行监测.研究结果表明:①2000—201...