Rainfall effect on wind waves and the turbulence beneath air-sea interface

Rainfall effects on wind waves and turbulence are investigated through the laboratory experiments in a large wind-wave tank. It is found that the wind waves are damped as a whole at low wind speeds, but are enhanced at high wind speeds. This dual effect of rain on the wind waves increases with the increase of rain rate, while the influence of rainfall-area length is not observable. At the low wind speed, the corresponding turbulence in terms of the turbulent kinetic energy （TKE） dissipation rate is significantly enhanced by rain- fall as the waves are damped severely. At the high wind speed, the augment of the TKE dissipation rate is suppressed while the wind waves are enhanced simultaneously. In the field, however, rainfall usually hin- ders the development of waves. In order to explain this contradiction of rainfall effect on waves, a possibility about energy transfer from turbulence to waves in case of the spectral peak of waves overlapping the inertial subrange of turbulence is assumed. It can be applied to interpret the damping phenomenon of gas trans- fer velocity in the laboratory experiments, and the variation of the TKE dissipation rates near sea surface compared with the law of wall.     

WAVEWATCH和SWAN嵌套模拟台风浪场的结果分析

利用WAVEWATCH和SWAN嵌套模拟2007年8月墨西哥湾飓风迪安的波浪场.将QSCAT/NCEP混合风场与台风模型风场合成为背景风场.修改WAVEWATCH和SWAN嵌套接口以使WAVEWATCH和SWAN2种海浪预报模式能够有效地嵌套运行.利用WAVEWATCH和SWAN嵌套模拟飓风迪安的波浪场,采用浮标资料检验模拟结果,以验证WAVEWATCH和SWAN模拟的准确性及修改后嵌套接口的可用性.结果表明,修改嵌套接口之后模式运行平稳,2种模式的结果与浮标及高度计观测数据均基本吻合.嵌套模拟结果好于单纯使用WAVEWATCH模拟的结果,体现了利用2种模式嵌套模拟台风浪场的科学性.     

青藏高原东北部甘加盆地古梯田地层与年代初探

梯田是人类几千年来利用和改造自然能力的象征,在人类社会发展中发挥了重要的作用。甘加盆地位于青藏高原东北部甘肃省夏河县,盆地内的丘陵、山麓地带分布大面积的层状梯形景观,疑似弃耕的古代梯田。本文在实地考察的基础上,基于卫星遥感资料,通过GIS手段分析发现古梯田面积为42.2 km²（约63000亩）,主要分布在盆地内央曲河及其支流两侧海拔2936~3326 m间的山坡上。通过对3个古梯田剖面样品的磁化率、总有机碳/氮（TOC、TN）含量、孢粉、粒度等环境代用指标分析,同时对比具有准确年代控制的自然剖面磁化率与粒度。研究结果显示：梯田开垦于晚全新世（距今3000 a）古土壤,梯田剖面顶部25~35 cm不同于自然剖面而呈均一化的指标证实了耕作层的存在（距今约1000 a以下层位）;但耕作层之上TOC、TN含量的增多,以及梯田剖面与自然剖面整体一致的指标变化趋势说明了梯田被短期利用后长期废弃;结合历史文献资料推断夏河古梯田是在北宋“弓箭手屯田”制度（1074—1125年）下开垦的;气候重建资料显示该时段温度较高、降水增加,整体有益于农业生产。本文提供了过去人类社会适应气候变化的典型案例。     

多方向不规则波传播变形数值模拟

在推广的缓坡方程数学模型基础上建立了多方向不规则波数学模型,综合考虑了波浪折射、绕射、反射、底摩擦和风能输入等因素。基于线性波浪理论,将波浪方向谱在频率和方向上按等能量分割法离散后,分别计算各组成波的传播变形,再计算合成波要素。缓坡方程数学模型采用改进的ADI法求解,计算效率高,稳定性好。采用椭圆形浅滩不规则波模型试验结果和单突堤不规则波绕射理论解对数学模型进行了验证,数值模拟结果和试验值及理论解符合良好。利用该模型进行了某港港内波浪折射、绕射和反射的联合数值模拟,给出了合理的港内波高分布。     

中国南海东部海域气候特征及风浪流极值参数的研究——LAGFD数值模式群的应用

本文采用先进的ＬＡＧＦＤ风、浪数值模式和ＰＯＭ（ＰｒｉｎｃｅｔｏｎＯｃｅａｎＭｏｄｅｌ）三维海流模式对自１９４５～１９９５年间发生并影响南海东部海域的２９９个历史最强热带气旋过程进行数值后报,给出了南海东部部分海域（１９°～２３°Ｎ,１１３°～１１８°Ｅ）中１０００ｍ等深线内６０个点的多年一遇风、浪、流和水位极值,并简要分析了南海东部（１５°～２７°Ｎ,１０８°～１２２°Ｅ）的气候特征,为该海域区域性海洋环境研究与工程开发提供了基础参考数据。     

不规则波远破波对直墙的作用

基于物模试验、理论推理、因次分析和工程实例验证等综合分析方法,就不规则波远破波对直墙作用力的计算方法进行了研究,用推荐的方法得到的结果与工程实例符合较好.     

乳山湾邻近海域波浪特征要素规律研究

基于高分辨率MASNUM第三代海浪模式并根据Yuan等(2009)提出的波浪破碎统计物理模型,对乳山湾外海2008年各个季节波浪特征要素(有效波高和跨零周期等)与波浪破碎参数(白冠覆盖率、卷入深度和破碎能量损耗率)进行了数值模拟。利用Janson-1卫星高度计观测资料对有效波高模拟结果进行了检验,平均误差在0.17m左右。模拟结果显示,该海域波浪参数具有明显的季节变化特征,在2008-08乳山湾邻近海域受大风天气过程影响期间,有效波高在1.0~1.8m,破碎参数变化显著,白冠覆盖率最大达4.5%,卷入深度在1.5m以上,相应的破碎能量损耗率量值在6~11kg/s3。结果表明,波浪破碎过程对该区域海洋动力环境有着重要影响,是造成乳山湾口表层高溶解氧的可能机制之一。     

厚碳酸盐覆盖区RVSP三维地震勘探应用效果分析

该文以中国南方一厚碳酸盐岩覆盖区的RVSP三维地震勘探实例,对RVSP三维地震勘探观测系统和数据采集参数的确定、地面等效处理和波场分离等关键处理技术及地质效果进行了阐述和分析,说明了RVSP在克服表浅层复杂地质条件及环境条件对资料的影响及提高地震资料的分辨率有其特定的优势,同时也提出了RVSP三维地震在采集和处理过程中的难点。     

Transition Periods Between Sea Ice Concentration and Sea Surface Air Temperature in the Arctic Revealed by an Abnormal Running Correlation

This study used the synthetic running correlation coefficient calculation method to calculate the running correlation coefficients between the daily sea ice concentration(SIC) and sea surface air temperature(SSAT) in the Beaufort-Chukchi-East Siberian-Laptev Sea(BCEL Sea), Kara Sea and southern Chukchi Sea, with an aim to understand and measure the seasonally occurring changes in the Arctic climate system. The similarities and differences among these three regions were also discussed. There are periods in spring and autumn when the changes in SIC and SSAT are not synchronized, which is a result of the seasonally occurring variation in the climate system. These periods are referred to as transition periods. Spring transition periods can be found in all three regions, and the start and end dates of these periods have advancing trends. The multiyear average duration of the spring transition periods in the BCEL Sea, Kara Sea and southern Chukchi Sea is 74 days, 57 days and 34 days, respectively. In autumn, transition periods exist in only the southern Chukchi Sea, with a multiyear average duration of only 16 days. Moreover, in the Kara Sea, positive correlation events can be found in some years, which are caused by weather time scale processes.     

Dynamic Analysis of a Single-Column Platform (II)

This paper describes the study of a single-column structure used as well-head platform. In order to check the reliability of computation theory and programme, model tests have been carried out. The paper introduces the conclusion of tests and the dynamic properties of single-column platform are obtained.