降水对江浙沪PM_(2.5)的清除效率研究     

范凡  陆尔  葛宝珠  王自发 《气象科学》2019,39(2):178-186

为了解不同程度的降水对江浙沪地区大气PM_(2.5)的清除作用,搜集了2014—2016年该地区41个城市的降水和PM_(2.5)观测数据,通过对比2 a非降水和全时段PM_(2.5)平均浓度的差异,发现前者显著高于后者,说明降水对该地区PM_(2.5)具有清除作用。利用降水前与降水期间PM_(2.5)的浓度差异作为降水对PM_(2.5)的清除率,降水后与降水期间的浓度差异作为雨后浓度回升的增加率,分别研究了目标区域不同时期、不同降雨量以及不同降雨时长对PM_(2.5)的清除效果。结果显示:(1)与江浙沪南部地区不同的是,北部地区降水清除率与降水前浓度存在正相关,降水后浓度的增加与当地的排放量呈正相关。(2)当降水量为30 mm或者降水时长为36 h时,清除率增幅减缓,说明降水对PM_(2.5)的清除效率存在着阈值。  相似文献   

伊犁河谷初冬降水条件下风廓线雷达评估分析     

刘凡  杨莲梅 《沙漠与绿洲气象(新疆气象)》2019,13(5):34-40

对伊犁河谷地区初冬降水条件下风廓线雷达资料评估其数据获取率并与探空资料进行对比分析,定义两者风向偏差在10°以内或风速偏差在1 m/s范围的样本为有效样本,分别用E_v和E_d表示风速有效样本比率(风速有效样本数/总样本数)和风向有效样本比率(风向有效样本数/总样本数)。结果显示:超过80%数据获取率的高度,降雨时为3000 m,降雪时达到预设2000 m;降雪时E_v和E_d均比无降水时高,且降雪量大小与风廓线的探测高度呈正相关,降雪量大小对E_d有明显影响,对E_v无明显影响;比较不同高度数据,降雪时0～3 km范围的E_v和E_d值均比无降水时高30%左右,无降水时3～5 km范围的E_d接近100%。  相似文献   

Precipitation‐runoff processes in Shimen hillslope micro‐catchment of Taihang Mountain,north China     

Shumin Han  Yonghui Yang  Tong Fan  Dengpan Xiao  Juana Paul Moiwo 《水文研究》2012,26(9):1332-1341

Precipitation runoff is a critical hillslope hydrological process for downslope streamflow and piedmont/floodplain recharge. Shimen hillslope micro‐catchment is strategically located in the central foothill region of Taihang Mountains, where runoff is crucial for water availability in the piedmont corridors and floodplains of north China. This study analyzes precipitation‐runoff processes in the Shimen hillslope micro‐catchment for 2006–2008 using locally designed runoff collection systems. The study shows that slope length is a critical factor, next only to precipitation, in terms of runoff yield. Regression analysis also shows that runoff is related positively to precipitation, and negatively to slope length. Soil mantle in the study area is generally thin and is therefore not as critical a runoff factor as slope length. The study shows a significant difference between overland and subsurface runoff. However, that between the 0–10 and 10–20 cm subsurfaces is insignificant. Runoff hardly occurs under light rains (<10 mm), but is clearly noticeable under moderate‐to‐rainstorm events. In the hillslope catchment, vertical infiltration (accounting for 42–84% of the precipitation) dominates runoff processes in subsurface soils and weathered granite gneiss bedrock. A weak lateral flow (at even the soil/bedrock interface) and the generally small runoff suggest strong infiltration loss via deep percolation. This is critical for groundwater recharge in the downslope piedmont corridors and floodplains. This may enhance water availability, ease water shortage, avert further environmental degradation, and reduce the risk of drought/flood in the event of extreme weather conditions in the catchment and the wider north China Plain. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

GIS‐evaluation of two slope‐calculation methods regarding their suitability in slope analysis using high‐precision LiDAR digital elevation models     

M. Irfan Ashraf  Zhengyong Zhao  Charles P.‐A. Bourque  Fan‐Rui Meng 《水文研究》2012,26(8):1119-1133

  相似文献   

环境水样中铀、钍、镭和铅同位素及其比值的系统分析     

顾鼎祥  汪苓  陈明秀  范梅英 《铀矿地质》1988,(4)

本文研究了从5L水中用铁、铅、钡和铈作载体,系统分析~(234)U、~(238)U、~(228)Th、~(230)Th~(232)Th、~(224)Ra、~(226)Ra、~(228)Ra和~(210)Pb的含量或比值。铀、钍经Fe(OH)_3沉淀富集后用TBP萃淋树脂柱分离,用激光荧光和比色法测定,同位素比值用α谱仪测量,化学回收率在90％以上,测量下限分别为1μg/L和3μg/L。镭、铅经硫酸盐沉淀富集后,用EDTA在不同pH条件下分离,~(224)Ra和~(226)Ra用射气法测定,~(228)Ra和~(210)Pb分别用其β子体~(228)Ac和~(210)Bi在低本底β装置上测量,测量下限分别为2.5×10~(-2)、8×10~(-3)、4×10~(-3)和5×10~(-3)Bq/L。  相似文献   

K—Ar Geochronology and Evolution of Cenozoic Volcanic Rocks in Eastrn China   总被引：6，自引：0，他引：6  

王慧芬  杨学昌 《中国地球化学学报》1989,8(1):1-14

Cenozoic volcanic rocks widespread in eastern China constitute an important part of the circum-Pacific volcanic belt.This paper presents more than 150K-Ar dates and a great deal of petrochemical analysis data from the Cenozoic volcanic rocks distributed in Tengchong,China‘s southeast coast,Shandong,Hebei,Nei Monggol and Northeast China.An integrated study shows that ubiquitous but uneven volcanic activities prevailed from the Eogene to the Holocene,characterized as being multi-eqisodic and multicycled.For example,in the Paleocene(67-58Ma),Eocene(57-37.5Ma),Miocene(22-18,16-19Ma),Pliocene(8-3Ma),and Early Pleistocene-Middle Pleistocene(1.2-0.5Ma) there were upsurges of volcanism,while in the Oligocene there was a repose period.In space,the older Eogene volcanic rocks are distributed within the region or in the central part of the NE-NNE-striking fault depression,while the younger Neogene and Quaternary volcanic rocks are distributed in the eastern and western parts.Petrologically,they belong essentially to tholeiite-series and alkali-series basalts,with alkalinity in the rocks increasing from old to youg.The above regularities are controlled by both global plate movement and regional inherent tectonic pattern.  相似文献   

Rayleigh 阻尼作用下斜拉桥扭转振动     

范家参  罗永康 《地震研究》1988,(4)

在侧向风力或侧向水平地源力作用下,斜拉桥容易发生扭转振动。本文采用非线性Rayleigh阴尼,它能反映在低速振动时有激发而加速振动,至一定高速后又衰减的完整振动过程。对非线性的统辖方程及定解条件,先使之无量纲化,再按非线性项的系数这个小参数展开未知函数,得到线性化的各级近似方程。把待求函数展成梁轴坐标的Fourier级数,其系数为待定的时间函数,应用Fourier级数的正交性,得到求解未知时间函数的二阶常微分方程,完全类似单自由度质点在线性粘滞性阻尼作用下的统辖方程,其解为已知。  相似文献   

AN OBSERVATIONAL STUDY OF THE MESO-β SCALE MOVING SYSTEMS IN THE MEIYU FRONT          下载免费PDF全文

Yu Zhihao  Lu Hancheng  Fan Xianzhong 《Acta Meteorologica Sinica》1988,2(4):436-449

The new concept and analysis method for the rainfall peak are introduced in this paper,and an obser-vational study of a heavy rain case in the Meiyu front has been made with finer radiosonde and precipitationdata.It has found in this case that there are a lot of meso-β scale systems associated with the rainfall peaksin the Meiyu front.Meso-β scale systems can be divided into two kinds,i.e.,the moving and standing types.The moving type is characterized by the unstable gravity wave and has a path corresponding to the meso-α scalerain belts in the direction.The discussion about the meso-β systems is made by using the symmetric andtransversal wave instability theory.  相似文献   

辽宁省金矿集中区及其与构造样式的关系   总被引：1，自引：0，他引：1  

王有爵  李忠  范垂祥 《吉林大学学报(地球科学版)》1988,(2)

本文将辽宁省金矿划分四种类型,十个主要金矿集中区。这些集中区均受华北地台东西向基底构造活动带及中生代太平洋板块俯冲影响、所产生的北西向构造挤压带和北东向构造—岩浆岩带的复合作用控制。它们分别处于太不洋成矿带的内带(辽东)和外带(辽西)。并以郯庐断裂为轴线,构成了两大“U”字形,类似共轭曲线展布的构造样式。根据深部地球物理资料,综合分析了控制金矿集中区构造样式的形成机制。区内脉状金矿大都分布在深断裂(深度大于五公里断裂)带附近。  相似文献   

山东招掖金矿带稀土元素地球化学特征初步研究   总被引：1，自引：0，他引：1  

范永香  周群辉 《地球科学》1988,(2)

本文提出了解决本区某些地质问题的新信息。认为不同地质体具有大体相似的稀土元素配分模型,成岩成矿关系密切,具有继承性演化特点。各类花岗质岩石由胶东群变质岩经混合岩化作用形成。成矿热液富含[CO_3]~(2-)或[HCO_3]~-,金在黄铁矿和石英中富集,与∑REE、LREE的含量及∑Ce/∑Y、Ce/Yb、La/Yb比值呈正相关。上述参数可用作该类金矿床矿化富集规模和强度的评价标志。  相似文献