Conversion of kinetic energy from synoptic scale disturbance to low-frequency fluctuation over the Yangtze River valley in the summers of 1997 and 1999

In order to investigate the conversion of kinetic energy from a synoptic scale disturbance （SSD; period≤seven days） to a low-frequency fluctuation （LFF; period〉seven days）, the budget equation of the LFF kinetic energy is derived. The energy conversion is then calculated and analyzed for the summers of 1997 and 1999. The results show that the energy conversion from the SSD to the LFF is obviously enhanced in the middle and lower troposphere during the heavy rainfall, suggesting this to be one of mechanisms inducing the heavy rainfall, although the local LFF kinetic energy may not be enhanced.     

藏东类乌齐地区成矿带和找矿远景区的划分及特征

2007-2009年,笔者参加了西藏区调队进行的1∶5万类乌齐县等四幅区域地质调查,开展了矿产方面的工作,参考了四川区调队1∶20万洛隆幅(1990)和类乌齐幅(1993)区调报告等有关矿产资料,完成了成矿地质条件分析和成矿规律总结等工作,本文介绍测区成矿带和找矿远景区的划分。1区域地质概况     

Factors controlling the spatial and temporal variability of dust emissions

New field measurement techniques are allowing researchers to better understand how surficial properties affect the temporal and spatial variability of dust emissions. In this paper we review the current understanding of the dust emission process and present new field measurements that examine how three surface properties： roughness, crust strength, and temporal changes of surface properties affect dust emissions. These data were collected using three unique measurement systems developed by our team. Roughness exerts considerable control on the entrainment threshold and emissions of dust from a surface. We have carried out a series of experiments designed to quantify roughness effects on aeolian sediment entrainment and transport in a shear stress partitioning framework. Our results show that the model of Raupach et al. （1993） provides very good agreement with available data to predict the amount of shearing stress on the intervening surface among roughness elements, relatively independent of their size and distribution. However, element size affects the aeolian sediment transport process beyond that attributable only to the reduction of surface shear stress caused by the roughness. Additional interactions of the elements with the saltation cloud appear to reduce the transport efficiency and potentially dust emissions as well. The effect of crust strength on dust emissions was assessed using a newly-developed pin penetrometer, which can measure crust strength in-situ. Previous researchers suggested that variation in crust strength even within a small area could lead to considerable spatial variability in dust emissions. Our measurements showed that crust strength is highly variable over a scale of centimeters. This variability may help to explain some of the observed scatter in field measurements of dust emissions for what appear to be homogeneous surfaces. Variability of dust emissions in time and space was also evaluated using a new instrument, the Portable In-Situ Wind Erosion Lab （PI-SWERL） developed to measure dust emissions from soil surfaces.     

1961—2017年北疆初终霜日及霜期时空变化特征

利用1961—2017年北疆37个地面气象站逐日最低气温观测资料,结合常规气象统计方法,分析北疆地区初、终霜日和霜期的时空演变特征.结果表明:(1)北疆平均初霜日以2.2 d·(10a)-1速率推迟;平均终霜日以1.7 d·(10a)-1速率提前;平均霜期以3.9 d·(10a)-1速率缩短;初、终霜日和霜期的主周期均...     

2000—2015年柴达木盆地植被覆盖度时空变化及其与环境因子的关系

基于MODIS-NDVI、DEM和气象数据,分析柴达木盆地2000—2015年植被覆盖度(FVC)时空变化特征,并与降水、温度、日照时数、相对湿度、蒸散量和海拔进行相关、偏相关或叠加分析,探讨FVC与各环境因子的关系。结果表明:FVC整体自东南向西北内陆呈半环状递减,FVC集中在20%以下,人类活动及径流等打破植被地带性规律;2000—2015年FVC明显改善,广泛分布于盆地中西部地区,2001—2002年年际变化最显著;FVC与降水、相对湿度以正相关为主,与温度关系不显著,与日照时数和蒸散量主要为负相关,降水对FVC贡献最大,温度通过影响蒸散量等间接影响FVC,而土壤蒸发对蒸散量的影响大于植物蒸腾;FVC与等高线空间分布较吻合,FVC在2 800~2 900 m和4 600~4 700 m出现两个峰值,4 700 m以上FVC迅速降低。     

准格尔丘陵沟壑区五分地沟流域土地覆盖分析

以准格尔丘陵沟壑区五分地沟流域为研究区,应用彩红外航片和IKONOS卫星影像,绘制了1987、2002年土地覆盖/植被类型图,并数字化基于地面土地利用调查绘制的1979年土地利用图.利用景观格局指数,评价了研究区土地覆盖/植被空间格局现状及土地覆盖类型动态变化;并以ETM 数据为信息源,绘制了2002年土地覆盖/植被类型图.研究表明:2002年研究区土地覆盖/植被呈现出一个耕地、草地、人工乔木林和人工灌木林以及种植稀疏灌木的草地高度镶嵌的景观格局特征;20年内土地覆盖类型发生了显著的变化,景观异质性增强.基于研究区景观的高度破碎化,绘制小流域精细尺度土地覆盖图,高空间分辨率遥感数据十分必要.     

快速城市化进程中农村居民点用地变化及驱动力研究——以长株潭城市群为例

以长株潭城市群为研究案例,利用土地利用详查数据、社会经济统计数据和实地调查资料等多种数据源,运用相对变化率、主成分分析和多元回归分析相结合的方法对快速城市化进程中的长株潭城市群农村居民点用地变化的轨迹、空间地域分异特征及驱动力进行了分析。研究结果表明:①长株潭城市群农村居民点用地总量及人均量呈递减趋势,但仍然呈粗放利用状态;②长株潭城市群农村居民点用地变化率呈高位态势且地域分异明显,交通区位条件优越、经济发达的地区相对变化率较大;③应用主成分分析法将影响长株潭城市群农村居民点用地变化的因子归纳为区域经济发展、科技进步及政策制度3类,应用多元回归分析方法可知各影响因子对农村居民点用地变化的影响作用大小不同,农林牧渔总产值、粮食总产量和全社会固定资产投资的影响作用较大。     

水泥粉喷桩在软基中的应用

简要阐述了水泥粉喷桩设计要求、施工工艺、效果检测,对地基承载力的影响,具有广阔的应用前景。     

李克强会见浙江省第七地质大队先进事迹报告团

中共中央政治局常委、国务院副总理李克强21日在人民大会堂亲切会见了全国模范地质队—浙江省第七地质大队先进事迹报告团。他说,要围绕经济社会发展和应对国际环境变化的需要,弘扬地质工作者牢记使命、献身事业的优良传统,大力实施找矿突破战略行动,立足国内增强能源资源保障能力,更好地服务现代化建设。