热带对流层顶层结构的变化特征和趋势     

辛玉姣  田文寿 《气候与环境研究》2011,16(3):378-388

利用1989～2008年欧洲中期天气预报中心高时空分辨率的再分析资料以及1980～2019年的大气化学—气候模式模拟资料分析了热带对流层顶层(Tropical Tropopause Layer,T TL)结构的变化特征,并且预测了其未来变化趋势.结果表明,TTL结构存在明显的季节和空间变化.其厚度在北半球的春、秋两季比...  相似文献   

Hydrothermal pattern of frozen soil in Nam Co lake basin,the Tibetan Plateau   总被引：3，自引：0，他引：3  

Keming Tian  Jingshi Liu  Shichang Kang  Iain B. Campbell  Fei Zhang  Qianggong Zhang  Wei Lu 《Environmental Geology》2009,57(8):1775-1784

Hydrothermal processes and the regimes of frozen soil formed in alpine regions with glaciers and lake area are complex and important for ecological environment but have not been studied in Tibet. Based on soil temperature and moisture data from October 2005 to September 2006 collected in the Nam Co lake basin, Tibetan Plateau (TP), those questions were discussed. The mean annual air temperature was −3.4°C with 8 months below 0°C. Air and soil temperature varied between −25.3~13.1°C and −10.3~8.8°C, respectively. Soil moisture variations in the active layer were small with the minimum value of 1.4%, but were influenced greatly by snowmelt, rainfall and evaporation, varying up to 53.8%. The active layer froze later, thawed earlier and was thinner, however, the lower altitude limit of permafrost is higher than that in most areas of TP. The effects of soil moisture (unfrozen water content) on soil temperature, which were estimated through proposed models, were more significant near ground surface than the other layers. The surface soil temperature decreased with snowcover, the effect of cold snow meltwater infiltration on soil thermal conditions was negligible, however, the effect of rainfall infiltration was evident causing thermal disruptions.  相似文献   

寒区有隔热层的圆形隧道温度场解析解   总被引：9，自引：2，他引：7  

张耀  何树生  李靖波 《冰川冻土》2009,31(1):113-118

在多年冻土地区修建隧道,会影响到多年冻土的热稳定性,目前一般采用在隧道衬砌中设置隔热层的方法来防止冻土嗣岩融化.根据隧道现场实测的气温资料,考虑正弦曲线规律变化的对流换热边界条件,建立了一次衬砌、隔热层、二次衬砌及围岩4层结构的圆形隧道热传导方程.运用微分方程求解方法和贝塞尔特征函数的正交和展开定理,对4个热传导方程进行了求解,得到隧道一次衬砌、隔热层、二次衬砌及同岩4层结构温度场的解析解,将计算结果与现场实测结果进行比较,吻合良好.计算结果还表明,在衬砌中铺设厚5 cm、导热系数为0.03 W·m-1·℃-1的隔热层可以保证风火山隧道围岩不发生季节性融化.该解析解可用于验证其它数值方法的计算结果,也便于工程设计人员和施工人员对同类寒区隧道进行温度场的计算,因而具有一定的工程应用价值.  相似文献   

铁路碎石道碴层通风阻力参数试验研究   总被引：3，自引：1，他引：2  

张明义  刘德仁  李双洋  赵爱国 《冰川冻土》2009,31(2):372-376

铁路碎石道碴层能被看作高渗透率的多孔介质,由于其具有较好的通风特性,它的存在改变了寒区铁路路基的顶部热交换条件,对路基温度场产生不可忽视的影响.为了能够实现对寒区铁路路基温度场的更合理预测,基于对铁路碎石道碴层传热和通风特性的研究现状,通过风洞试验对铁路碎石道碴层的通风特性及通风阻力参数进行了试验研究.试验中选用的铁路碎石道碴平均粒径为4.2cm,孔隙率为0.433,对不同空洞风速条件下铁路碎石道碴层中的压力梯度和渗流速度进行了测试分析.结果表明:铁路碎石道碴层中空气渗流速度随着压力梯度的增大而增大,其内部压力梯度与渗流速度之间存在良好的二次非线件关系.通过计算得到铁路碎石道碴层的渗透率和惯性阻力系数,为寒区铁路路基热稳定性的数值研究提供了参数依据.  相似文献   

青藏高原北缘古近纪石英砂表面特征及其古环境意义   总被引：5，自引：0，他引：5  

宋春晖  孟庆泉  夏维民  徐丽  苗运法  杨用彪  胡思虎 《沉积学报》2009,27(1):94-103

中国西北干旱化和风成记录的研究已取得重要进展,但对亚洲内陆干旱化和亚洲冬季风开始时间的认识目前仍存在分歧。利用扫描电镜,通过对青藏高原北缘广大典型地区古近系中类似风成堆积的红色砂层石英砂微形态详细研究,发现这些红色砂层中绝大部分石英砂颗粒表面具有流水搬运和改造的磨光面与V型坑微形态特征组合,与现代塔克拉玛干沙漠、阿尔金山北缘洪积扇上的现代风沙沉积物石英砂颗粒表面的麻面与蝶形坑组合不同。粒度分析也显示这些沉积物的粒度曲线特征与风成黄土和现代沙丘粒度曲线有明显差别。结合沉积特征认为青藏高原北缘古近纪期间不存在大范围的风沙沉积物,推断亚洲冬季风此时可能尚未激发,而该期的干旱环境可能是由行星风系副热带高压控制的干旱炎热气候以及全球变冷事件造成。  相似文献   

Geology, Geochemistry and Minerogenesis of the Shijuligou Zinc–Copper Deposit in Gansu, China   总被引：1，自引：0，他引：1  

LI Wenyuan  DENG Jun  GAO Yongbao  GUO Zhouping  ZHANG Zhaowei  SONG Zhongbao 《《地质学报》英文版》2009,83(6):1052-1063

Abstract: The Shijuligou deposit was separated by an arcuate ductile shear zone cross the center of the deposit region, resulting in the difference between the southern and northern ore bodies. The lead (Pb) isotopic data of ores of the Shijuligou copper deposit have averages of 206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb in 17.634, 15.444, and 37.312, respectively. It has been shown that ore-forming metals originated from intrusive and extrusive rocks in the upper part of ophiolites. The sulfur isotopic data of pyrite and chalcopyrite in the northern part change from +7.61‰ to +8.09‰ and +4.95‰ to +8.88‰ in the southern part. Isotopes of δ18O in the Shijuligou copper deposit are between +11.1‰ and +18.6‰, with the calculated δ18OH2O at +0.65‰. It is suggested that the mineralized fluid is a mixture of magma fluid, meteorological water, and seawater through circulating and leaching metals from the volcanic rocks. The zircon uranium-lead (U–Pb) dating of gabbro is 457.9±1.2 Ma, and the lower crossing age of the discordant and concordia curves of pyroxene spilite of zircon is 454±15 Ma. It is indicated that the Shijuligou deposit formed in a new ocean crust (ophiolite) of the back-arc basin in the late Ordovician. Mineralization should occur in the intermittence period after strong volcanic activity, and the age should be the late Ordovician. Moreover, the mineralization of ophiolite-hosted massive sulfide deposits in the ancient orogenic belt of the late Ordovician in the northern Qilian Mountains was controlled by the primary fault/fracture, with the forming of a metallogenic hydrothermal system by a mixture of volcanic magma fluid and seawater, which circularly leached the metallogenic metals from the volcanic rocks, resulting in their accumulation. The ore bodies were transformed with morphology and metallogenic elements. Jasperoid is an important sign for prospecting such deposits. There were many island arcs in the continent of China. This study provides evidence for understanding and exploration of ophiolite-hosted massive sulfide deposits in western China, especially in the area of northern Qilian Mountains.  相似文献   

用标贯法对盘锦城区砂土液化进行等级分区     

王岩  杜军  田广明 《吉林地质》2009,28(3):67-70

本文针对盘锦城区砂土液化不良地质作用,采用工程地质勘察中的原位测试——标准贯入试验法结合前人在此所作的地质调查资料和工程地质勘察资料,按照《建筑抗震设计规范》（GB5001-2001）相关规定,对盘锦城区的砂土液化进行相应的等级分区,对于盘锦市今后的工程建设具有实用意义。  相似文献   

长岭凹陷潜在地热初步探讨     

王洪涛  赵向辉  陈家林  代丽霞  陆浩  陈殿义 《吉林地质》2009,28(1):51-56

根据长岭凹陷石油井地温测量和物探资料,从地热形成的4要素——储、盖、通、源以及地热具备的地质特征入手,分析了长岭凹陷潜在着地热资源。目前长岭盆地基本具备了储和盖,需要进一步寻找的是通和源。  相似文献   

城市陆面过程与边界层结构研究   总被引：6，自引：1，他引：5  

蒋维楣  王咏薇  张宁 《地球科学进展》2009,24(4):411-419

通过城市边界层观测、卫星遥感以及城市边界层数值模拟等途径,获取对城市陆面过程特性的认识,研究建立精细城市边界层模式,引入合理城市区陆面过程参数化方案,并进行城市边界层结构影响研究。研究结果表明：①城市下垫面能量平衡过程迥异于自然地表,引入合理的参数化方案是改善数值模拟性能的关键。②高分辨卫星观测信息是认识城市地表参数状况及其变化的有效途径。 ③人为热排放参数化方案的合理引入是准确描述地表能量平衡过程的又一重要课题。需根据实际情况确定人为热排放的引入方案及量值变化。④应从合理描述城市建筑物下垫面对热力输送及大气动力场的影响出发,研究建立了多层城市冠层模式。⑤应建立更完善的多尺度城市边界层模式系统并引入更新的城市效应参数化方案和数据同化处理,以增强并完善城市边界层数值模拟能力。  相似文献   

安徽省雾、霾、晴空天气的气象条件对比分析     

石春娥  邓学良  余金龙  张浩  杨元建 《气候与环境研究》2017,22(2):242-252

使用2008~2012年逐日地面观测资料,揭示了安徽不同地区雾、霾、晴空天气气象条件的差异,指出不同地区要根据本地特点建立雾、霾预报指标和预报方法。3类天气差异最大的地面气象要素是能见度和相对湿度。根据3种天气前一日和当日能见度和相对湿度分布特征,全省站点可以分为3类:1)从雾、霾到晴空,能见度递增、相对湿度递减,且差异显著,如合肥站;2)雾、霾天的能见度和相对湿度均很接近,但与晴空天差别较大,如阜阳站;3)能见度在雾、霾天无明显差别,但相对湿度在雾、霾天差异显著,如安庆站。地级市测站雾后即霾的可能性较大(大于50%),县城测站雾后即霾的可能性较低(低于25%)。垂直方向,雾时相对湿度随高度下降很快,850 h Pa中位值已降到20%(安庆)和45%(阜阳)以下,霾时相对湿度随高度下降缓慢,850 h Pa中位值仍在60%左右;另外,霾天边界层中上部风切变较小,雾天和晴空天边界层中上部都存在较大的风切变。  相似文献