北极海冰变化的时间和空间型

利用 4 4a(195 1～ 1994年 )北极海冰密度逐月资料 ,分析提出了一种与北极冰自然季节变化相吻合的分季法 ,并根据这种分季法 ,使用EOF分解 ,揭示了北极各季海冰面积异常的特征空间型及其对应的时间变化尺度。结果表明 :(1)北极冰面积异常变化的关键区 ,冬季 (2～ 4月 )主要位于北大西洋一侧的格陵兰海、巴伦支海和戴维斯海峡以及北太平洋一侧的鄂霍次克海和白令海 ,夏季 (8～ 10月 )则主要限于从喀拉海、东西伯利亚海、楚科奇海到波佛特海的纬向带状区域内 ,格陵兰海和巴伦支海是北极海冰面积异常变化的最重要区域 ;(2 )春 (5～ 7月 )、秋 (11月～次年 1月 )季各主要海区海冰面积异常基本呈同相变化 ,夏季东西伯利亚海、楚科奇海、波佛特海一带海冰面积异常和喀拉海呈反相变化 ,而冬季巴伦支海、格陵兰海海冰面积异常和戴维斯海峡、拉布拉多海、白令海、鄂霍次克海的海冰变化呈反相变化 ;(3)北极冰总面积过去 4 4a来确实经历了一种趋势性的减少 ,并且叠加在这种趋势变化之上的是年代尺度变化 ,其中春季 (5～ 7月 )海冰面积异常变化对年平均北极冰总面积异常变化作出了主要贡献 ;(4)位于北太平洋一侧极冰面积异常型基本具有半年的持续性 ,而位于北大西洋一侧极冰面积异常型具有半年至一年的持续性     

ON THE PREDICTION OF TROPICAL CYCLONE LANDFALL AND INFLUENCE ON SOUTHERN CHINA USING MONTHLY OLR ANOMALIES FOR PRIME SUMMER

With the OLR data,the landfall and activity of tropical cyclones(TC) in southern China over a 20-year period(1975～1994) are studied.The result shows that the variation of the monthly anomalous OLR is somewhat teleconnected with the TC activity in southern China.The former is used to predict short-term climate for the latter over months with frequent or no TC influence.To some externt,the relationship between the TC activity in southern China and the monthly mean OLR anomalies is dependent on the climatological location of the subtropical high in northwestern Pacific region.     

IMPROVEMENTS OF A DISTRIBUTED HYDROLOGY MODEL DHSVM AND ITS CLIMATOLOGICAL-HYDROLOGICAL OFF-LINE SIMULATIONAL EXPERIMENTS

The advanced distributed hydrology-soil-vegetation model DHSVM,developed by Wigmostaet al.(1994)is introduced from US Pacific Northwest National Laboratory.To apply DHSVM inChina for the first time some improvements have been made in terms of the basin characteristics:1)to change evapotranspiration model,using the improved Penman-Monteith approach in place ofthe original one;2)to change the model structure,inserting datasets from 4 stations to grid cellsfor each river basin,instead of datasets from one or two stations;3)to develop new hydrology,vegetation and soil parameterization schemes for improving the simulated results,with focus oncalculation and adjustment of 11 parameters,such as soil porosity (?),field capacity θ_(fc),leaf areaindex LAI,stochastic resistance γ_s,among the total 33 parameters.Then the improved DHSVM isdriven by observed datasets for Luanhe River Basin and Sanggan River Basin,respectively.Thesimulated evapotranspiration(ET),runoff,snow water equivalent,water table,soil moisture andpercolation are then gained as DHSVM outputs.The simulated ET shows that the highest peakappears in May or June instead of July or August.This is consistent with the real situations,owing to the improvement of ET model.The simulated runoff process and flood peak are quiteconsistent with the observed ones.The model efficiency values for Luanhe River and SangganRiver Basins are 0.89 and 0.82,respectively,which shows high simulating ability of the modelsystem for both relatively humid and dry basins.     

陆相层序地层学理论体系及其发展趋势

笔者在综合了国内外大量学者研究成果的基础之上，以全新的角度，从陆相层序几何学和陆相层序充填动力学两个方面，初步总结了陆相层序地层的特征，研究难点，层序的内部构成和外部构成。地层的控制因素。并且简略地归纳了陆相层序地层学的模式。展望了未来陆相层序地层学的发展趋势及其前景。     

安徽省巢湖市环境地质特征

通过对安徽省巢湖市环境地质背景特征的论述,以及对地质灾害现状和趋势的分析研究,提出了合理开发利用和保护该市地质环境的对策建议。     

A Geo‐spatial study for analysing temporal responses of NDVI to rainfall

Climate change has become a serious concern worldwide owing to its multifaceted impact upon the physical as well as socio‐economic environment (IPCC, 2013). Vulnerability to climate change is much higher in the developing countries like India, where the economy is mainly agro‐based and productivity from the agricultural sector is dependent upon summer monsoon rainfall. Hence, assessing the quantitative relationship between vegetation patterns and climatic influence has become an increasingly important study conducted on regional and global scales. As vegetation cover plays a key role in conserving the natural environment, studying the spatio‐temporal trend of vegetation is crucial in identifying changes in the natural environment. We analysed the spatial responses of SPOT‐VGT NDVI to TRMM based rainfall during a sixteen year period (1998–2013) in the Bundelkhand region of Central India. The Normalized Difference Vegetation Index (NDVI) has proven to be a strong indicator of global vegetation productivity. Among climatic factors, rainfall robustly influences both spatial and temporal outline of NDVI. In this study, we used linear regression for analysing the statistical relationship among NDVI and rainfall and their trends. The study reveals a varying pattern of vegetation dynamics in response to rainfall over the area.     

塔里木河流域60 a来天然径流变化趋势分析

利用塔里木河流域近60 a的地表径流、气温和降水量资料,通过趋势分析、突变检验、年代际分析等方法分析了塔里木河流域地表径流变化的时空差异性,探讨了塔里木河流域天然径流变化对气温、降水量变化的响应。研究表明：近60 a来塔里木河流域三源流径流整体存在增加的趋势,但干流径流存在减少的趋势;塔里木河流域三源流增加强度在1993年前后从强到弱依次为阿克苏河、叶尔羌河、和田河,进入2000年后从强到弱依次为和田河、叶尔羌河、阿克苏河;塔里木河流域三源流径流强度增加主要受降水增加和由气温增加引起的融雪径流增加的双重影响。     

黄河源区径流长期演变特征与趋势预测模型研究

利用小波分析方法对黄河源区径流数据系列的多尺度变化特征、突变点及变化趋势进行了分析.结果表明:黄河源区年径流量具有8a、15a、22a和36a左右的变化周期,其中8a、36a左右的周期变化最为显著.这些周期变化表明,2007年后流量将呈增加的趋势;1928、1982年和1985年是径流变化趋势重要的转变点.在小波分解的基础上,基于BP神经网络模型构建了黄河源区年径流量的长期动态预报模型,利用该模型对未来10a的流量变化进行了预测,并对其预报结果进行了分析.     

基于BP神经网络模型的雷电潜势预报

为了使用神经网络较好地解决在雷电潜势预报中常见的非线性问题,本文通过计算南京地区2008年6～8月46个对流参数与雷电发生的相关系数,选取了与雷电发生关系较好的刀、SI、CIN等7个对流参数作为BP神经网络的输入因子。利用2008年的资料所建立的BP神经网络模型,预报了南京地区2009年6～8月的雷暴活动潜势,结合实际雷暴发生情况,得到此模型的POD为80．9％,FAR为9．5％,CSI为74．5％,PDFD为2．9％,FOM为19．1％。表明该BP模型预报准确率较高,性能稳定,有较好的推广价值。     

鲁西南大气降水与农田需水的供求状况及变化趋势

应用彭曼(Penman)法,并考虑对不同作物发育阶段的订正,估算了鲁西南地区的农田需水量。通过农田需水量与有效降水量差值分析,对二者的供求状况进行了评估。同时还分析了1961～2002年降水量和农田需水量的历史资料序列,发现二者都呈递减趋势,且递减的速度较为接近。