RESEARCHES ON SOIL ENVIRONMENTAL BACKGROUND VALUES IN TIBET     

张晓平  科扬川 《中国地理科学(英文版)》1995,5(1):56-65

ＲＥＳＥＡＲＣＨＥＳＯＮＳＯＩＬＥＮＶＩＲＯＮＭＥＮＴＡＬＢＡＣＫＧＲＯＵＮＤＶＡＬＵＥＳＩＮＴＩＢＥＴ￥ＺｈａｎｇＸｉａｏｐｉｎｇ（张晓平）ＫｅＹａｎｇｃｈｕａｎ（科扬川）（ＣｈａｎｇｃｈｕｎＩｎｓｔｉｔｕｔｅｏｆＧｅｏｇｒａｐｈｙ，ｔｈｅＣｈｉｎ...  相似文献   

山东省汛期小时降水过程时空分布特征   总被引：1，自引：1，他引：0  

董旭光  顾伟宗  邱粲  曹洁 《气象》2018,44(8):1063-1072

利用山东省74个气象站1961-2012年逐时降水观测数据,分析了山东省汛期(5-9月)短历时和持续性降水过程的时空分布特征。结果表明:(1)过程降水量和过程历时显著增大使得山东省汛期总降水量略有增加,持续性降水过程次数、过程降水量、过程历时的增加对总降水量增加的贡献最大。(2)短历时总降水量以鲁中山区、鲁东南地区最多,鲁东南沿海、半岛东部持续性总降水量最多;短历时过程降水量、平均雨强以鲁东南向西北方向经鲁中山区至德州一带最大,持续性过程降水量、平均雨强在半岛东部和鲁东南部分地区最大。(3)短历时峰值雨强以鲁中山区周边地区较大,持续性峰值雨强以鲁南、鲁东南、半岛东部较大。(4)鲁中山区、鲁南及半岛个别地区短历时降水一般开始于午后(13-18时),鲁中山区周边及半岛沿海一带多以夜雨为主,持续性降水过程开始时间多出现在夜间。  相似文献   

Numerical Study of the Influences of a Monsoon Gyre on Intensity Changes of Typhoon Chan-Hom(2015)     

Jia LIANG  Liguang WU  Guojun GU 《大气科学进展》2018,35(5):567-579

Typhoon Chan-Hom(2015) underwent a weakening in the tropical western North Pacific(WNP) when it interacted with a monsoon gyre, but all operational forecasts failed to predict this intensity change. A recent observational study indicated that it resulted from its interaction with a monsoon gyre on the 15–30-day timescale. In this study, the results of two numerical experiments are presented to investigate the influence of the monsoon gyre on the intensity changes of Typhoon Chan-Hom(2015). The control experiment captures the main observed features of the weakening process of Chan-Hom(2015) during a sharp northward turn in the Philippine Sea, including the enlargement of the eye size, the development of strong convection on the eastern side of the monsoon gyre, and the corresponding strong outer inflow. The sensitivity experiment suggests that intensity changes of Chan-Hom(2015) were mainly associated with its interaction with the monsoon gyre. When Chan-Hom(2015) initially moved westward in the eastern part of the monsoon gyre, the monsoon gyre enhanced the inertial stability for the intensification of the typhoon. With its coalescence with the monsoon gyre, the development of the strong convection on the eastern side of the monsoon gyre prevented moisture and mass entering the inner core of Chan-Hom(2015), resulting in the collapse of the eyewall. Thus, the weakening happened in the deep tropical WNP region. The numerical simulations confirm the important effects of the interaction between tropical cyclones and monsoon gyres on tropical cyclone intensity.  相似文献   

中国区域高分辨率多源降水观测产品的融合方法试验   总被引：5，自引：0，他引：5  

潘旸  谷军霞  宇婧婧  沈艳  师春香  周自江 《气象学报》2018,76(5):755-766

高质量、高分辨率降水产品研制对于数值天气模式检验、水文陆面模拟、山洪地质灾害监测有着重要意义。利用中国近4万自动气象站逐时降水资料、中国雷达定量降水估计和CMORPH卫星反演降水产品,开展0.05°×0.05°和0.01°×0.01°两种高分辨率下的三源降水融合方法研究试验,探讨如何有效引入雷达高分辨率信息来提高降水产品质量。一方面,在0.05°分辨率上,先以自动气象站观测降水数据为基准,采用概率密度函数（PDF）匹配法订正雷达和卫星估测降水产品的系统偏差,将雷达降水产品的偏差从-0.05 mm/h降至-0.008 mm/h;再采用贝叶斯模型平均（BMA）方法融合雷达和卫星降水产品,形成0.05°分辨率的中国区域覆盖完整且最优的联合降水背景场。此外,在0.01°分辨率上,以0.05°分辨率的卫星-雷达贝叶斯模型平均联合降水产品为背景,采用1 km雷达估测降水的空间结构信息进行降尺度,亦能有效提高0.01°分辨率背景场的质量。然后,分别以不同分辨率的卫星-雷达联合降水产品为背景,采用统计方法量化误差估计,再采用最优插值方法融入地面观测。通过2419个中国国家级气象台站的独立样本检验,评估了多种类型的降水资料及融合试验产品在中国地区的质量。结果表明,两种分辨率的三源融合试验产品的精度均优于任何单一来源的降水产品,特别是在站点稀疏地区,降水精度均较融合前有显著提高,达到了较好的融合效果,其中在0.05°分辨率上采用“概率密度函数+贝叶斯模型平均+最优插值”方法的三源融合降水产品整体质量最好,而0.01°分辨率上基于“概率密度函数+贝叶斯模型平均+降尺度+最优插值”方法的三源融合降水产品在强降水监测上更有优势。   相似文献   

近40年海南岛冷冬气候特征及其成因分析   总被引：1，自引：0，他引：1  

朱晶晶  赵小平  吴慧  党建涛  易灵伟 《气象》2018,44(10):1286-1294

利用海南岛17个市、县近40年气象观测站逐月气温观测资料,参照《暖冬等级》国家标准,对海南岛异常冷冬事件的时空分布规律进行了分析。在此基础上,利用国家气候中心提供的74项环流指数以及1977—2017年NCEP/NCAR全球再分析格点资料、NOAA ERSST全球海表温度格点资料以及Nino3. 4指数和AO指数,对海南岛冷冬事件形成机制进行了研究。结果表明:海南岛冬季平均气温存在明显的年代际变化特征,近40年海南岛冷冬频发,共出现12次冷冬年。南部市、县发生冷冬的频次大于中部及北部,北部市、县冷冬发生的强度强于南部。海南岛冷冬形成原因主要是对流层大气环流异常,西伯利亚高压增强,东亚冬季风显著偏强,对应副热带高压偏弱、位置偏东,影响海南岛的冷空气更加活跃,使得海南岛冬季气温偏低。另外,南海海温较常年偏低,ENSO冷位相叠加AO指数正位相,有利于进一步诱发大气环流异常,促使海南岛冬季气温偏低,出现异常冷冬事件。  相似文献   

0920号超强台风“卢碧”引起的强海上大气波导成因分析与数值模拟研究   总被引：2，自引：1，他引：1  

胡昊  费建芳  丁菊丽  王挺  黄小刚  程小平  袁炳 《气象学报》2018,76(4):620-634

基于中国台湾地区主持的侵台台风之飞机侦察及下投式探空仪观测实验（Dropwindsonde Observations for Typhoon Surveillance near the Taiwan Region,DOTSTAR）获得的高分辨率下投式探空仪探测资料,分析了2003年9月—2012年8月所有发生在中国台湾地区附近海域的台风型大气波导事件,遴选出一次由0920号超强台风“卢碧”引起的强台风型海上大气波导过程作为研究对象。利用欧洲中期数值预报中心（ECMWF）再分析资料（水平分辨率0.125°×0.125°）,对此次波导的生成原因进行了分析;基于WRF模式比较了不同初始化方法对台风强度、尺度和周围台风型大气波导的模拟能力。结果表明,此次强台风型大气波导发生在台风环流西北侧外围的弱下沉运动区,其形成与850 hPa高度附近北方强干空气平流导致湿度随高度锐减密切相关。在数值模拟中运用台风动力初始化方法,可以有效改进台风强度、路径和尺度的模拟效果,进而有利于改善台风型大气波导尤其是波导层所在高度的模拟效果。台风外围出现的大气波导通常以悬空波导为主,模拟效果与台风螺旋雨带和内核尺度的模拟关系密切,而与台风强度和眼墙结构关系不大。中尺度数值模式WRF具有模拟台风型大气波导的能力,是研究台风型大气波导的有力手段。   相似文献   

Simulating urban dynamics in China using a gradient cellular automata model based on S-shaped curve evolution characteristics   总被引：1，自引：0，他引：1  

Xiaoping Liu  Bin Ai  Xia Li  Guangjin Tian  Yimin Chen 《International journal of geographical information science》2018,32(1):73-101

Cellular automata (CA) have been efficiently used to express the complexity and dynamics of cities at different scales. However, those large-scale simulation models typically use only binary values to represent urbanization states without considering mixed types within a cell. They also ignore differences among the cells in terms of their temporal evolution characteristics at different urbanization stages. This study establishes a gradient CA for solving such problems while considering development differences among the cells. The impervious surface area data was used to detect the urbanization states and temporal evolution trends of the grid cells. Transition rules were determined with the incorporation of urban development theory expressed as an S-shaped curve. China was selected as the case study area to validate the performance of the gradient CA for a national simulation. A comparison was also made to a traditional binary logistic-CA. The results demonstrated that the gradient CA achieved higher accuracies in terms of both spatial patterns and quantitative assessment indices. The simulation pattern derived from the gradient CA can better reflect the local disparity and temporal characteristics of urban dynamics. A national urban expansion for 2050 was also simulated, and is expected to provide important data for ecological assessments.  相似文献   

Spatiotemporal characteristics of urban air quality in China and geographic detection of their determinants   总被引：4，自引：2，他引：2  

Xiaoping Zhang  Zezhou Gong 《地理学报(英文版)》2018,28(5):563-578

Ambient air pollution brought by the rapid economic development and industrial production in China has exerted a significant influence on socio-economic activities and public health, especially in the densely populated urban areas. Therefore, scientific examination of regional variation of urban air quality and its dominant factors is of great importance to regional environmental management. Based on daily air quality index (AQI) datasets spanning from 2014 to 2016, this study analysed the spatiotemporal characteristics of air quality across different regions throughout China and ascertained the determinants of urban air quality in disparate regions. The main findings are as follows: (1) The annual average value of the urban AQI in China decreased from 2014 to 2016, indicating a desirable trend in air quality at the national scale. (2) The attainment rate of the urban AQI exhibited an apparent spatially stratified heterogeneity, wherein North China retained a high AQI value. The increase of Moran’s I Index reported an apparent spillover effect among adjacent regions. (3) Both at the national and regional scales, the seasonal tendency of air quality in each year is similar, wherein good in summer and relatively poor in winter. (4) Results drawn from the Geographic Detector analysis show that dominant factors influencing AQI vary significantly across urban agglomerations. Topographical and meteorological variations in urban areas may lead to complex spatiotemporal variations in pollutant concentration. Whereas given the same natural conditions, the human-dominated factors, such as industrial structure and urban form, exert significant impacts on urban air quality.The spatial spillover effects and regional heterogeneity of urban air quality illustrated in this study suggest the governments and institutions should set priority to the importance of regional cooperation and collaboration in light of environment regulation and pollution prevention.  相似文献   

蛭石精矿的有机改性试验     

李雪梅  廖立兵  谷勤  李瑞  王春燕 《岩矿测试》2008,27(1):63-66

采用十六烷基三甲基溴化铵(HDTMAB)对蛭石精矿进行了有机改性,利用X射线衍射法(XRD)、红外光谱(IR)、差示扫描量热法(DSC)和热失重分析(TG)对蛭石精矿和有机改性蛭石进行了表征。实验结果表明,当反应液中蛭石与水的质量比为1∶10、反应温度在60~70℃时,HDTMAB的阳离子HDTMA进入绝大部分蛭石晶粒的晶层,将蛭石的晶层间距撑大,蛭石的(001)晶面间距d001从1.45986 nm增大到3.70134 nm。HDTMA进入了单晶颗粒之间,将蛭石颗粒分散成单晶颗粒。  相似文献   

中天山白石头泉岩体年代学、岩石成因及构造意义   总被引：2，自引：2，他引：0  

刘四海  吴昌志  顾连兴  张遵忠  唐俊华  黎广荣  雷如雄  汪传胜 《岩石学报》2008,24(12):2720-2730

白石头泉岩体位于中天山北缘边界断裂(沙泉子断裂)南侧。该岩体从下至上可分为五个连续过渡的岩相带,即淡色花岗岩(a带),含天河石花岗岩(b带),天河石花岗岩(c带),含黄玉天河石花岗岩(d带)以及黄玉钠长花岗岩(e带),其中,b、c、d和e带均为a带分异的产物。白石头泉岩体的LA-ICP-MS锆石U-Pb定年结果表明,该岩体侵位于早二叠世早期(295.6±1.3Ma),并于印支期(~214Ma)经历了一次热事件的改造。淡色花岗岩在主量元素上富硅(SiO₂= 74.93%~76.18%)、富碱(K₂O + Na₂O=8.07%~8.80%)、富钠(K₂O / Na₂O=0.82~0.89),贫钙、镁,而在微量元素上富Rb、F和Ga(Al/Ga比值为2217~3134),贫Ba、Sr和Eu并具强烈的铕负异常(δEu=0.0020~0.0091),反映出其源区为富含白云母的片岩(或片麻岩),成岩压力较低,温度大于860℃。结合区域地质特征,作者等认为白石头泉岩体形成于相对拉张的构造背景,是中-上地壳源岩经历高温贫水熔融的产物,其形成与幔源岩浆内侵作用有关。  相似文献