海水声速剖面基函数的重构性能分析

海水声速剖面通常使用经验正交函数（Empirical Orthogonal Function,EOF）进行稀疏表示,然而基函数会受到数据完备性和数据测量时间的制约,其代表性误差会导致声速剖面重构精度受限。为了提高声速剖面的重构精度,本文利用模糊C均值聚类对BOA_Argo历史数据集进行聚类分析,探讨不同聚类空间的训练集数据对实测声速剖面重构精度的影响。研究表明,声速剖面具有明显的时空聚集特性,聚类后的历史声速剖面集生成的基函数和平均声速剖面具有最优的重构性能。本文研究结果有助于为历史声速剖面训练集的选取提供实际指导意义,进而提高声速剖面重构精度乃至反演精度。     

The atmospheric circulation patterns influencing the frequency of spring sand-dust storms in the Tarim Basin

Using NCEP/NCAR reanalysis data and the sand-storm frequency data fi＇om 37 weather stations in the Tarim Basin for the period 1961-2009, the relationship between the frequency of spring sandstorms in the Tafim Basin and the associated atmospheric circu- lation pattems is analyzed in this study. We found significantly negative correlations between sandstorm frequency and the 500-hPa geopotential height over the Paris Basin and midwestem Mongolia, while there were positive correlations over the Ural River region. The rising of the 500-hPa geopotential height in midwestem Mongolia and its falling over the Ural region corre- spond to a weakening of the large-scale wave patterns in the Eurasian region, which directly causes the frequency of the sand-dust storms in the Tarim Basin to decline. Also, the abrupt decline in the spring sandstorm frequency in the Tarim Basin observed in the last half-century is associated with profound changes in the atmospheric circulation in these key regions. At the interannual scale, the strengthened cyclonic atmospheric circulation patterns in the western part of Mongolia and the anticyclonic patterns over the East European plains at 500-hPa geopotential height, are responsible for frequent sandstorm occurrences in the Tarim Basin.     

腾格里沙漠东南缘4种灌木的生物量预测模型

灌木生物量模型是预测灌木生物量最有效的方法。选择腾格里沙漠南缘荒漠生态系统中常见的4种灌木（驼绒藜(Ceratoides latens)、盐爪爪(Kalidium foliatum)、珍珠猪毛菜(Salsola passerina)、红砂(Reaumuria soongarica)）为研究对象,以株高（H）和冠幅（C）的复合因子灌木体积（V）为自变量,通过回归分析,分别构建了4种灌木和混合物种的叶、新生枝、老龄枝、地上部分、地下部分和整株生物量的预测模型。通过决定系数（R2）、估计值的标准误（SEE）和回归检验显著水平（p＜0.05）筛选出了最优的生物量估测模型。结果显示:4种灌木的生物量模型主要以幂函数W=aVb为最优模型,少数以三次函数W=a+bV+cV2+dV3为最优模型。灌木生物量与V之间呈极显著的相关关系（p＜0.001）,决定系数较高,分别为:叶片（0.775＜R2＜0.866）,新生枝（0.694＜R2＜0.840）,老龄枝（0.819＜R2＜0.916）,地上部（0.832＜R2＜0.917）,地下部分（0.74＜R2＜0.808）,全株（0.811＜R2＜0.912）,说明预测模型可以应用于此4种灌木的生物量估算。不同物种之间及不同器官之间的生物量模型存在差异,在实际使用中,要根据物种来选择相应的模型。生物量模型的建立有助于全面估算荒漠生态系统的生物量,并进一步评估生态系统不同碳库的碳存储量与碳循环。为有效提高荒漠草地碳储量、合理实施生态系统管理和人为干预提供科学依据。     

风沙流中沙粒起跳初速度分布的探讨

风沙流结构中起跃沙粒的初速度分布,是连接微观研究和宏观研究的桥梁。笔者分析了已有的实验数据,就沙质地表起跃沙粒的速度分布、角度分布进行了计算;并运用碰撞理论建立了一个二维碰撞模型。考虑边界条件的影响,运用概率论统计的思想计算了风沙流结构中起跃沙粒初速度的概率分布,并和实验值进行了对比,得到了较好的结果,对风沙流中起跃沙粒的速度分布有了一个定性的认识。     

福建永安石林地貌的现代生物喀斯特侵蚀营力

本文以永安石林为例，阐述分析了石林地貌的现代生物喀斯特侵蚀现象的类型及形态特征。结果表明，地表及地下的生物喀斯特侵蚀营力是石林现代侵蚀过程的主要因素，石林表面的大部分均有微生物覆盖并起侵蚀作用，形成明显的微观及超微溶蚀形态，石林表面的溶蚀作用性质不同于传统认识。对石林地貌发育提出了新的思考。     

Focal Mechanism Solutions and Stress Field Inversion of Moderately Strong Earthquakes in the Northern Tianshan Area

Using the focal mechanism solutions of 24 moderately strong earthquakes in the northern Tianshan area, we carried out system cluster and stress field inversion analysis. The result indicates that, the focal mechanism solutions of moderately strong earthquakes are mainly dipslip reverse faulting in the northern Tianshan area. The principal rupture planes of earthquakes are NW-oriented. It is basically consistent with the strike of earthquake structure in its adjacent area. The direction of the principal compression stress P axis is nearly NS, and its inclination angle is small; while the inclination angle of the principal extensional stress T axis is large. It shows that the regional stress field is mainly controlled by the near-NS horizontal compressive stress. The direction of the maximum principal stress shows a gradation process of NNE-NS-NW from east to west.     

Effect of a thermokarst lake on soil physical properties and infiltration processes in the permafrost region of the Qinghai-Tibet Plateau,China

Changes in the hydrological processes in alpine soil constitute one of the several key problems encountered with studying watershed hydrology and ecosystem stability against the background of global warming. A typically developing thermokarst lake was chosen as a subject for a study using model simulation based on observations of soil physical properties, infiltration processes, and soil moisture. The results showed that the selected thermokarst lake imposed certain changes on the soil infiltration processes and, with the degree of impact intensifying, the initial infiltration rate decreased. The greatest reduction was achieved in the area of moderate impact. However, the stable infiltration rate and cumulative infiltration gradually increased in the surface layer at a depth of 10 and 20 cm, both decreasing initially and then increasing, which is correlated significantly with soil textures. Moreover, the cumulative infiltration changed in line with steady infiltration rate. Based on a comparative analysis, the Horton model helps better understand the effect on the soil infiltration processes of the cold alpine meadow close to the chosen thermokarst lake. In conclusion, the formation of the thermokarst lake reduced the water holding capacity of the alpine meadow soil and caused the hydraulic conductivity to increase, resulting in the reduction of runoff capacity in the area of the thermokarst lake.     

河北沿海海侵灾害初探

文中以包含海进、海岸侵蚀和海水入侵的广义“海侵”概念,论述河北沿海地区海侵现状及其危害,探讨海侵产生的自然原因和人为活动的影响,在此基础上,评估海侵发展趋势。     

社会满意度调查在城市体检与评估中的应用

回顾满意度的概念内涵,在城市研究中的应用进展基础上,总结了北京城市体检及住建部城市体检工作中满意度调查的实施方案和主要分析结论,梳理了社会满意度调查的特征。研究表明,主观满意度数据相比客观数据更为鲜活,能够准确反映不同群体对城市发展的价值判断与意愿,体现居民的关注点,在分析中与人群属性链接可以深挖不同人群的主要诉求,并且根据体检评估对象情况,灵活设置指标和确定优劣等级,易于发现水平差异和问题短板。未来城市体检中应建立常态化城市体检社会满意度调查工作机制,注重与客观数据、市民热线数据等多源数据的融合,主客观相互印证来指导城市规划及管理,从而提升城市建设精细化水平。     

赣南山地丘陵区城市人口增长与建成区扩张耦合关系

随着中国经济发展逐步进入转型期,新型城镇化的深入推进成为区域经济持续发展的强大引擎,但在城镇化进程中产生的耕地安全、空间冲突等问题日益突出。分析山地丘陵城市人地关系,有利于把握城市发展质量、为山地丘陵区深入推进新型城镇化战略提供认识基础。研究以赣南原中央苏区为例,在2001年、2012年城市人口与建成区面积数据基础上,通过修正集中度构建了基于山地丘陵地区人口增长-建成区扩张耦合指数模型,利用数理统计及空间分析方法对其进行深入分析。结果表明:2001—2012年,城市人口及建成区集中度呈现出典型的幂分布特征,空间分布上则形成核心-边缘结构。城市人口与建成区集中度间的关联性显著增强,空间布局均以东北-西南方向为主,但二者由不均衡逐步趋于拟合,城市人口增长-建成区扩张的空间格局、规模差异均较大;趋势线在东西方向上变化十分显著,南北方向上起伏度变化则进一步增大。2001—2012年,赣南苏区主导城市类型由人口增长型转变为人地协调型;而人口增长-建成区扩张耦合格局则以建成区扩张型城市为主,城市蔓延式扩张现象明显。研究立足各级城市人地发展现状,提出促进赣南苏区城市人地协调发展差别化建议及措施。