青海省河湟谷地地质灾害易发性评价     

赵东亮  兰措卓玛  侯光良  许长军  李万志 《地质力学学报》2021,27(1):83-95

地处青藏高原东北缘的黄河与湟水谷地,由于剧烈的地质活动、 较大高差与强烈水力作用等,使得地质灾害非常频繁,为明确该区域的地灾易发性区划,选取地貌、坡度、坡高、植被、岩性、降雨量和距断层、距河流、距道路等因子构建评价指标体系,采用信息量模型计算崩塌、滑坡、泥石流及其综合地质灾害易发性指数,将研究区地质灾害易发性划分为极高...  相似文献   

甘肃河东春末夏初干旱的时空特征和预测研究     

王蕾  李栋梁  巴特尔  刘淑梅  高弟乐 《干旱气象》1999,(2)

利用甘肃５５ 个测站,１９６８ ～１９９７ 年５ 月中旬至６ 月中旬降水资料,采用 Ｅ Ｏ Ｆ、 Ｒ Ｅ Ｏ Ｆ、波谱分析,对春末夏初降水异常的空间结构及时间演变特征作了研究。结果表明,甘肃河东春末夏初降水异常在空间上主要表现为陇东、中部、陇东南、甘南４ 个主要类型。河东各主要气候区春末夏初降水的时间变化基本趋势是：８０ 年代春末夏初降水增加,而９０ 年代以来,降水均有不同程度减少,干旱加剧。甘肃河东春末夏初降水变化以短周期振荡为其主要特征。在１０ 年的年际变化中,陇东比各型均落后１ ～２ 年。从环流形势看,当春末夏初北半球５００ｈ Ｐａ 高度距平场结构呈现出明显的正 Ｐ Ｎ Ａ 型时,中国西北地区同期降水偏少  相似文献   

两广庞西垌-金山成矿带银金矿床分形性研究   总被引：10，自引：1，他引：9  

王祖伟  周永章  姚东良  张海华 《矿床地质》1999,18(2):183-188

庞西垌－金山银金成矿带侠于广东廉江县和广西博白县的交界,区内银金矿床以银为主,伴有金,铅锌等有益组分,属于蚀变破碎岩型银金矿床。研究表明,银金矿床具有明显的分形性,利用品位－频度的双对数坐标图求得的矿床银吕位的分维值Ｄ〈１,反映了在区域内银品位分布的差异较大,银品位的频率分布明显偏离正态分布。  相似文献   

非线性相互作用对高频方向谱估计的影响     

赵栋梁 《中国海洋大学学报(自然科学版)》1998,(4)

海浪组成波之间的三阶非线性相互作用产生的高次谐波,不仅改变了波面的外观形状,而且使得高频域不再满足通常的线性频散关系,当ｆ＞１．７ｆｐ时,频散关系应修改为ω２＝２ｇｋ。用最大似然法（ＭＬＭ）分析方向分布的结果表明：在二倍峰频附近,方向分布再次变窄,且能量在方向上的集中程度与海浪的成长状态有关,得到的高频方向分布跟Ｃａｕｄａｌ和Ｈａｕｓｅｒ（１９９６）的微波遥感结果定性一致。  相似文献   

玄参主要环烯醚萜苷热稳定性研究          下载免费PDF全文

龚友兰  刘东亮  邓长凤 《应用海洋学学报》2019,35(12):112-114

目的：研究玄参中各主要环烯醚萜苷在干燥过程和水浴加热过程中的稳定性。方法：将4等份玄参叶分别采用室温（20℃）干燥20d及40℃、60℃、80℃直接烘干,5等份玄参根冷浸液不同水浴温度（40℃、60℃、70℃、80℃、90℃）加热1h,HPLC法测定玄参中主要环烯醚萜苷桃叶珊瑚苷、哈帕苷、哈帕俄苷含量。结果：不同烘干温度下测得玄参叶中各环烯醚萜苷含量,以室温及40℃最低,60℃最高,但与80℃差异不明显;玄参根冷浸液不同水浴温度加热1h后,4种成分含量变化不显著。结论：玄参鲜药材干燥温度对其主要环烯醚萜苷含量影响很大,但提取过程中的温度对其影响不大。  相似文献   

豫西渑池地区中元古界兵马沟组沉积环境分析          下载免费PDF全文

左鹏飞  李雨  郑德顺  孙风波  杨东亮 《地质科技通报》2019,38(3):70-80

华北克拉通南缘中元古代早期发育陆源碎屑-碳酸盐岩沉积,豫西地区兵马沟组作为其早期陆源碎屑充填沉积,对于探讨中元古代早期华北克拉通南缘沉积环境演化有重要意义。在野外地质剖面实测基础上,结合岩性及粒度特征划分沉积相,探讨渑池地区兵马沟组沉积环境演化,为华北克拉通南缘中元古代早期沉积环境演化提供约束。豫西渑池地区兵马沟组剖面自下而上主要岩性为含砾砂岩-粉砂岩、泥岩-含砾砂岩,垂向上沉积物粒度特征具粗-细-粗的变化,概率累计曲线揭示其水动力条件先减小后变大,兵马沟组下段为河控三角洲的三角洲平原-三角洲前缘-前三角洲-三角洲前缘亚相,上段为滨海相的临滨-前滨亚相,其代表华北克拉通南缘构造活跃期-稳定盖层沉积期之间初期海进-海退旋回;中元古代早期,华北克拉通南缘表现为北东高南西低的古地形特征,兵马沟组是该时期熊耳群或华北克拉通古老基底遭受快速剥蚀的产物;对比不同地区的兵马沟组沉积特征,其在区域上的沉积差异可能是沉积时间及古地形差异性造成的。渑池地区兵马沟组在该时期仍受华北克拉通熊耳裂谷活动的影响,兵马沟组记录了裂谷盆地充填早期的演化过程,对研究华北克拉通南缘中元古代早期大地构造演化具有重要意义。  相似文献   

The Influence of Wind Speed and Sea States on Whitecap Coverage     

JIA Nan  ZHAO Dongliang 《中国海洋大学学报(英文版)》2019,(2):282-292

Callaghan and White(2009) put forward the automated whitecap extraction(AWE) technique to determine the whitecap coverage(W). An improved AWE was used to analyze images collected in the South China Sea during 2012 and 2013 and in western Pacific during 2015 to determine W. The influences of meteorological and oceanographic factors on whitecap coverage were investigated in this study. It is found that W increases with wind speed. Scale factor and exponent of parameterization for W(U10) vary greatly in different models. Overall, there is a larger scatter of W at low wind speed than at high wind speed. W decreases with the increasing of wave age. Compared with wind speed, the scatter of W is smaller with wave age, which means the impact of wave age on the whitecap coverage is more robust under various environmental conditions. There is no significant dependence on SST and whitecap coverage seems to weakly decrease with SST. W decreases with the atmospheric stability. Relationship between W and wind speed change when swells are dominant. Swell can suppress wave breaking and decrease W. The effect is independent of the deflection angle between wind wave and swell.  相似文献   

A Practical bi-parameter formula of gas transfer velocity depending on wave states   总被引：5，自引：0，他引：5  

Dongliang Zhao  Lian Xie 《Journal of Oceanography》2010,66(5):663-671

The parameter that describes the kinetics of the air-sea exchange of a poorly soluble gas is the gas transfer velocity which is often parameterized as a function of wind speed. Both theoretical and experimental studies suggest that wind waves and their breaking can significantly enhance the gas exchange at the air-sea interface. A relationship between gas transfer velocity and a turbulent Reynolds number related to wind waves and their breaking is proposed based on field observations and drag coefficient formulation. The proposed relationship can be further simplified as a function of the product of wind speed and significant wave height. It is shown that this bi-parameter formula agrees quantitatively with the wind speed based parameterizations under certain wave age conditions. The new gas transfer velocity attains its maximum under fully developed wave fields, in which it is roughly dependent on the square of wind speed. This study provides a practical approach to quantitatively determine the effect of waves on the estimation of air-sea gas fluxes with routine observational data.  相似文献   

Impacts of wave and current on drag coefficient and wind stress over the tropical and northern Pacific     

Zengan Deng  Dongliang Zhao  Kejian Wu  Ting Yu  Jian Shi 《中国海洋大学学报(英文版)》2008,7(4):373-378

By taking into consideration the effects of ocean surface wave-induced Stokes drift velocity U,w and current velocityU,c on the drag coefficient,the spatial distributions of drag coefficient and wind stress in 2004 are computed over the tropical andnorthern Pacific using an empirical drag coefficient parameterization formula based on wave steepness and wind speed.The globalocean current field is generated from the Hybrid Coordinate Ocean Model (HYCOM) and the wave data are generated from Wave-watch Ⅲ (WW3).The spatial variability of the drag coefficient and wind stress is analyzed.Preliminary results indicate that theocean surface Stokes drift velocity and current velocity exert an important influence on the wind stress.The results also show thatconsideration of the effects of the ocean surface Stokes drift velocity and current velocity on the wind stress can significantly im-prove the modeling of ocean circulation and air-sea interaction processes.  相似文献   

广西大范围暴雨气候异常对太平洋年代际涛动的响应     

覃卫坚  李栋梁  蔡悦幸 《热带气象学报》2022,38(2):161-170

使用1961—2016年广西79个地面气象观测站逐日降水资料、美国国家海洋和大气管理局(NOAA)逐月太平洋年代际振荡(PDO)指数资料、NCEP/NCAR再分析资料、国家气候中心西太平洋副热带高压指数资料,利用相关和合成分析等方法研究广西大范围暴雨气候异常对PDO的响应。结果表明：广西大范围暴雨日数存在显著增多的突变新特征,对PDO有反位相变化的响应。当PDO处于冷位相时,对应着5—8月贝加尔湖阻塞高压和澳大利亚高压显著性偏强;索马里越赤道气流明显增强,与西太平洋副热带高压西侧边沿的东南风容易形成季风槽;形成从新几内亚岛东北部沿海到华南地区的低空风场为“反气旋-气旋-反气旋-气旋”波列传播,使广西大范围暴雨日数偏多。当PDO处于暖位相时,大气环流异常特征相反,广西大范围暴雨日数偏少。  相似文献