东海原甲藻赤潮的垂向发展过程:生物-物理耦合数值模拟

近年来,东海原甲藻赤潮在我国东海近岸海域频繁发生。本研究利用生物-物理耦合模型对发生于2005年的东海原甲藻赤潮进行后报模拟,并对控制其起始与发展的因素展开研究。该模型由东海原甲藻种群动力学模型与多层嵌套的水动力模型组合。通过对比模拟结果与室内实验结果,证实种群动力学模型能够很好地重现东海原甲藻在不同光照与磷营养限制条件下的生长过程,同时能够再现藻细胞内部磷含量及藻类对外部营养盐浓度的影响。耦合模型能够较好地再现模拟海域水动力（见Sun et al.,2016）与东海原甲藻赤潮的时空分布。模拟的赤潮发展过程与此前研究中的观测结果一致,且模拟结果表明模型能够捕捉到赤潮初期种群的次表层孕育现象。随后模拟结果被用于诊断决定赤潮垂直分布的决定性因素,结果表明磷酸盐是控制这一现象的关键因素。同时,表层风场在决定赤潮的分布中扮演着重要角色。模拟结果强调了营养盐限制在东海原甲藻次表层孕育及消散过程中的作用,本文所建立的耦合模型需要进一步优化并应用于其它条件下东海原甲藻赤潮的研究中。     

北京市门头沟区门头口村煤矿矿山环境治理

本文简述了门头沟区龙泉镇门头口村煤矿自然地理状况和区域地质环境条件,分析了矿区存在的主要矿山地质环境问题和次生地质灾害。根据现场实际条件,提出了治理工程设计。矿山环境治理工程与园林工程相结合,为矿山环境治理与人居环境改善相结合提供经验。     

基于EGM2008模型和多面函数的似大地水准面拟合综合研究

文中讨论用多面函数拟合似大地水准面中函数模型的改进、多面函数之核心点及光滑因子的选取问题,并结合工程实例进行验证.研究得出如下结论:在利用正双曲函数拟合时,加入截距后可提高拟合的精度;利用EGM2008模型,内插出覆盖测区的格网交点及GNSS/水准点的高程异常,绘制等值线图,能可视化地选取多面函数的核心点;利用搜索和绘制散点图等,可十分有效地选定使拟合精度最高的光滑因子.     

亚洲热带夏季风的首发地区和机理研究

文中分析了多年逐候平均 85 0hPa风场和黑体辐射温度等物理量的时空演变 ,结果表明 ,90°E以东的孟加拉湾、中南半岛和南海是亚洲热带夏季风首先爆发的地区 ,爆发时间在 2 7～ 2 8候 ,具有突发性和同时性。 90°E以西的印度半岛和阿拉伯海是热带夏季风爆发较晚的地区 ,季风首先在该区 10°N以南爆发 ,时间约在 30～ 31候 ,然后向北推进 ,6月末在全区建立 ,爆发过程具有渐进性。机制分析表明 ,由于 110～ 12 0°E的中高纬东亚大陆在春季和初夏地面感热通量、温度和气压的迅速变化 ,使热带低压带首先在该处冲破高压带 ,生成大陆低压 ,并引导西南气流在 90°E以东地区首先建立。在 90°E以西的印度半岛地区 ,地面感热通量在 4～ 5月间几乎没有明显变化 ,因而印度季风比南海季风晚爆发约 1个月。由此得出 ,90°E是东亚夏季风和南亚夏季风的分界线。此外 ,还着重探讨了南亚高压的季节变化与亚洲热带夏季风爆发的时间联系。发现南亚高压中心位置与亚洲热带夏季风爆发时间有较好的对应关系。南亚高压中心跳过 2 0°N时 ,南海夏季风爆发 ,跳过 2 5°N时 ,印度夏季风在其南部爆发。将用上述方法确定的爆发时间与用其他方法确定的爆发时间相比较 ,发现它们在南海地区有较好的一致性 ,在印度地区略有差异。     

北半球温室气体和土地利用/覆盖变化对地面气温日较差的影响

为了探究温室气体(greenhouse gas,GHG)和土地利用/覆盖变化(land use and land cover change,LULCC)对于地面气温日较差(diurnal temperature range,DTR)的影响及相对贡献作用,本文采用耦合地球系统模式(Community Earth System Model)进行了模拟研究。模拟结果表明:GHG浓度的增加导致北半球中高纬度地区年平均DTR显著降低,但GHG引起DTR变化存在显著的季节差异,在暖季和冷季,北美地区和西伯利亚地区呈现出相反的变化特征,GHG增加对于中高纬度地区年平均DTR的降低作用主要是由冷季贡献的。LULCC通过影响叶面积指数和地面反照率显著降低东亚、南亚、欧洲和北美东部地区的DTR。通过创建一种新的分析方式,本文研究了GHG和LULCC对DTR的相对贡献作用,在北半球高纬度地区,GHG在DTR的变化中扮演着主导作用,但在中纬度地区和南亚地区,无论是DTR变化数值的正负符号还是大小,LULCC都起着显著的影响作用。     

Submesoscale activity over the shelf of the northern South China Sea in summer: simulation with an embedded model

We applied a primitive equation ocean model to simulate submesoscale activities and processes over the shelf of the northern South China Sea (NSCS) with a one-way nesting technology for downscaling. The temperature and density fields showed that submesoscale activities were ubiquitous in the NSCS shelf. The vertical velocity was considerably enhanced in submesoscale processes and could reach an average of 58 m per day in the subsurface. At this point, the mixed layer depth also was deepened along the front, and the surface kinetic energy also increased with the intense vertical movement induced by submesoscale activity. Thus, submesoscale stirring/mixing is important for tracers, such as temperature, salinity, nutrients, dissolved organic, and inorganic carbon. This result may have implication for climate and biogeochemical investigations.     

北京露天废弃矿山地质环境治理模式探讨

北京地区许多废弃的无主老矿山未实施矿山环境治理和土地资源恢复工程,矿区内地质环境和生态条件恶劣。本文对废弃矿山及其治理工程特点进行了分析,运用灰色关联度分析法,阐述了矿山废弃地土地资源破坏效应的四个因素——地表景观效应、土体污染效应、次生灾害效应、生态环境之间的联系。以房山区石窝大理石矿山废弃地治理工程为例,提出了矿山废弃地治理以矿山环境、灾害治理为主,以园林景观绿化为辅相结合的二维治理模式,在地形整治、挡土墙、绿化等措施的基础上进行园林景观的设计,结合周边居民生活需求,利用矿区内的正负地形渣堆和采石坑,进行景观的再生和组合,将采石坑设计成下沉式休闲公园和健身广场,希望通过园林景观绿化工程的实施,改善矿区及周边地表景观和生态环境。     

Dynamical downscaling of regional climate: A review of methods and limitations

The traditional dynamical downscaling (TDD) method employs continuous integration of regional climate models (RCM) with the general circulation model (GCM) providing the initial and lateral boundary conditions. Dynamical downscaling simulations are constrained by physical principles and can generate a full set of climate information, providing one of the important approaches to projecting fine spatial-scale future climate information. However, the systematic biases of climate models often degrade the TDD simulations and hinder the application of dynamical downscaling in the climate-change related studies. New methods developed over past decades improve the performance of dynamical downscaling simulations. These methods can be divided into four groups: the TDD method, the pseudo global warming method, dynamical downscaling with GCM bias corrections, and dynamical downscaling with both GCM and RCM bias corrections. These dynamical downscaling methods are reviewed and compared in this paper. The merits and limitations of each dynamical downscaling method are also discussed. In addition, the challenges and potential directions in progressing dynamical downscaling methods are stated.     

地球物理技术在识别海(咸)水入侵界线中的应用——以莱州湾冲洪积扇区为例

海(咸)水入侵是我国沿海地区的主要地质灾害之一,在一定程度上制约了沿海经济发展和生态文明建设,因此,识别海(咸)水入侵前缘界线对查明灾害发育现状和防治对策的制定具有重要意义。地球物理方法因施工方便、获取数据连续等优点成为海(咸)水入侵界线识别的重要技术手段。阐述了高密度电阻率法和EH-4法2种地球物理探测技术识别海(咸)水入侵界线的原理、依据,并以莱州湾南岸冲洪积扇区为实例进行了探讨。结果表明:这2种方法能够有效的识别海(咸)水入侵界线,并较好地与水质检测结果相吻合;高密度三维探测试验证明地球物理技术可以识别海(咸)水入侵界面的空间分布。     

A new modulation transfer function for ocean wave spectra retrieval from X-band marine radar imagery

When imaging ocean surface waves by X-band marine radar,the radar backscatter from the sea surface is modulated by the long surface gravity waves. The modulation transfer function(MTF) comprises tilt,hydrodynamic,and shadowing modulations. A conventional linear MTF was derived using HH-polarized radar observations under conditions of deep water. In this study,we propose a new quadratic polynomial MTF based on VV-polarized radar measurements taken from heterogeneous nearshore wave fields. This new MTF is obtained using a radar-observed image spectrum and in situ buoy-measured wave frequency spectrum. We validate the MTF by comparing peak and mean wave periods retrieved from X-band marine radar image sequences with those measured by the buoy. It is shown that the retrieval accuracies of peak and mean wave periods of the new MTF are better than the conventional MTF. The results also show that the bias and root mean square errors of the peak and mean wave periods of the new MTF are 0.05 and 0.88 s,and 0.32 and 0.53 s,respectively,while those of the conventional MTF are 0.61 and 0.98 s,and 1.39 and 1.48 s,respectively. Moreover,it is also shown that the retrieval results are insensitive to the coefficients in the proposed MTF.