2006～2007年北部湾海-气热通量变化特征

用2006年夏～2007年秋在北部湾获得的船测气象资料,由块体公式计算了海-气通量.结果表明:北部湾春、夏季节获得热通量,而秋、冬季节失去热通量.春季通过湍流交换造成的热通量对海面热平衡的贡献最小,其次是夏季、冬季和秋季.在年平均尺度上感热通量和潜热通量分别占净辐射通量的7.4%和77.4%,15.2%的净辐射热量通过海洋过程消耗掉.感热通量随海-气温差的加大而增大,而与风速之间呈现复杂的非线性关系.海-气温差增加1 ℃,感热通量增加6.7～12.7 W/m2;较大的感热通量(>30 W/m2)容易出现在5～10 m/s风速条件下.潜热通量与风速和相对湿度呈明显的相关关系:风速增加1 m/s,潜热通量增加约18 W/m2,而相对湿度下降1%会导致6 W/m2潜热通量的增加.     

MODIS产品估算复杂地形下的光合有效辐射

提出基于MODIS大气和地表产品反演高精度复杂地形下的光合有效辐射模型。该方法是对普通的大气传输模型进行简化, 在模型中分别考虑了削减光合有效辐射的5个主要因子: 瑞利散射、臭氧和水汽吸收、气溶胶散射以及地表和大气间的多次反射。从3个方面考虑了复杂地形对于光合有效辐射的影响: (1) 坡度和坡向; (2) 天空可视角; (3) 邻近地形的附加辐射。提取2006年晴空条件下的估算结果与中国生态网络山东禹城站和长白山站的实测值的比较, 得到相关系数分别为0.924和0.9, 表明模型反演结果能够较好地解译实际光合有效辐射的变化。通过比较考虑地形和不考虑地形2种情况得到的光合有效辐射, 定量地分析了地形对光合有效辐射的影响。     

Estimation of wave forces on large compliant platforms

Compliant offshore structures such as spars, tension leg platforms (TLPs) and semi-submersibles have been dramatically improved in recent years due to their capability for deep water operation. Waves are the most important environmental phenomenon affecting these offshore structures. Estimation of wave forces is vital in offshore structure design. For large compliant offshore plat-forms, Morrison's equation is not valid anymore and usually diffraction theory is used. In this research, by using the finite difference method, a detailed analysis of the first-order diffraction of monochromatic waves on a large cylinder as a structural element is per-formed to solve the radiation and diffraction potentials. The results showed that the developed model is a reliable tool to estimate the wave forces and hydrodynamic coefficients on large structure elements when wave diffraction and radiation are considered.     

两层流体中多个振荡水平圆柱潜体水动力特性

采用解析方法研究了无限水深两层流体中多个振荡水平圆柱潜体的水动力特性。在线性势流理论框架内,基于多极子方法建立了辐射势的解析表达式,在此基础上导出了附加质量和阻尼系数的计算公式,采用边界元方法对这种解析方法进行验证,同时研究了两种不同工况下多个振荡水平圆柱潜体水动力的特性,结果表明,两层流体的密度比、圆柱的淹没深度以及圆柱的排列方式和间距等参数的变化对水平圆柱群附加质量和阻尼系数有很大的影响。     

The vertical attenuation of irradiance as a function of turbidity: a case of the Huanghai(Yellow) Sea in spring

The planar photosynthetically available radiation (PAR), turbidity and concentration of chlorophyll a (chl a), were measured at 26 stations in the Huanghai (Yellow) Sea during a cruise of China SOLAS from 19 to 27 March 2005. Due to low chl a (<0.35 mg · m-3 ) in upper layers (above 5 m), suspended particulate matter became the major factor that influenced the turbidity in early spring. The calculated vertical diffuse attenuation coefficient of PAR, K PAR , varied with water depths with a maximum value in t...     

A Three-Dimensional Nearshore Hydrodynamic Model with Depth-Dependent Radiation Stresses

For the simulation of the three-dimensional (3D) nearshore circulation,a 3D hydrodynamic model is developed by taking into account the depth-dependent radiation stresses.Expressions for depth-depeedent radiation stresses in the Cartsian coordinates are introduced on the basis of the linear wave theory,and then vertical variations of depth-dependent radiation stresses are discussed.The 3D hydrodynamic model of EICIRC (Eulerian-Lagrangian CIRCulation) is extended by adding the terms of the depth-dependent or depth-averaged radiation stresses in the momentum equations.The wave set-up,set-down and undertow are simulated by the extended ELCIRC model based on the wave fields provided by the experiment or the REF/DIF wave model.The simulated results with the depth-dependent and depth-averaged radiation stresses both show good agreement with the experimental data for wave set-up and set-down.The undertow profiles predicted by the model with the depth-dependent radiation stresses are also consistent with the experimental results,while the model with the depth-averaged radiation stresses can not reflect the vertical distribution of undertow.     

阳光紫外辐射对羊栖菜人工幼苗生长和光合电子传递速率的影响

为探讨经济褐藻羊栖菜人工幼苗对阳光紫外辐射变化的响应,在全波段阳光辐射省(PAB,280～700nm)、去除UV-B辐射(PA,320～700nm)和光合有效辐射PAR(P,400～700nm)三种辐射处理及不同辐射水平下培养羊栖菜幼苗,并测定了其生长与光合作用的变化。结果表明,无论在紫外辐射(UVR)存在情况下(PA,PAB)还是滤除UVR(PAR)时,高辐射水平条件下(55%),羊栖菜幼苗都具有较高的生长速率,而低辐射水平下羊栖菜的生长速率较低。在不同辐射处理之间,随着辐射水平的增高,UVR的抑制效应逐渐突显。UVR降低羊栖菜幼苗的光合电子传递速率。     

榍石的高压结构研究

利用同步辐射和金刚石压腔(DAC)技术对天然矿物榍石进行原位高压能散模式X射线实验研究,结果表明榍石在3.9 GPa和10.9 GPa分别发生P 21/a→A 2/a和A 2/a→A 1结构相变,并首次确定10.9 GPa→25.1 GPa榍石结构很可能稳定保持A 1相。基于此认为榍石能在地球较深部位稳定存在,此外,本研究对探索地球深部T i和S i元素的地球化学行为也有一定帮助作用。     

太阳辐射模拟的DEM尺度影响因素分析

利用DEM分析方法为起伏地形下太阳辐射模拟提供了条件。然而DEM的尺度效应对太阳辐射模拟产生很大的影响。本文以黄土丘陵和秦岭高山为实验样区,以一系列不同分辨率的DEM,模拟日、月及年总天文辐射,比较其误差大小及地形分析的差异。实验结果显示,随着DEM栅格分辨率的降低,天文辐射逐渐增大;当栅格分辨率大于地面相对高差时,模拟的天文辐射基本稳定,坡向、坡度等地形因子对辐射的再分配作用已不显著。黄土丘陵区,当DEM分辨率接近1000m时,天文辐射年总量的相对误差为22%,超过该区域一个冬季的天文辐射量。秦岭山区地表起伏大,误差较黄土丘陵地区小,最大相对误差为17.8%。总之,地表起伏越小,DEM栅格分辨率对太阳辐射模拟的影响越大。     

岩石破裂电磁辐射(EMR)现象实验研究

岩石破裂电磁辐射现象是客观存在的物理现象.随着电磁辐射观测技术在地震研究、冲击矿压预测等领域的应用,极大地推动了岩石破裂电磁辐射的实验研究.本文对岩石破裂电磁辐射的影响因素以及相伴生的现象,以及有关的物理解释进行了概括介绍.由于不同研究者使用实验设计、实验参数、实验条件的不同,使得观测和研究结果同样难以统一认识.不同的研究者根据各自的试验提出了不同的物理机制.同时对已发现现象的重复性、证实性研究岩石试验缺乏.严重匮乏利用数值模拟以及建立模型定量研究岩石破裂的电磁辐射.此外,岩样实验系统不同于实际的地震系统,进行模拟震源环境的实验研究,发展大尺度的标本和原岩现场实验的基础上,如何建立室内室外岩石实验与地震观测事实之间的联系是问题的关键.