闽北地区中侏罗世火山岩的发现及其地质意义

中侏罗世火山岩在东南沿海分布极少,但对区域中生代构造-岩浆活动过程及大地构造演化的研究具有重要意义。在闽北地区大面积白垩纪火山岩区调查中,在政和铁山地区发现中侏罗世火山岩,用LA-ICP-MS同位素测试技术测得的锆石U-Pb年龄为173.63±0.80Ma。火山岩属钙碱性系列流纹质熔结凝灰岩,显示过铝质、富钾、富集大离子亲石元素,亏损高场强元素等地球化学特征,推断其形成于陆缘弧环境,与古太平洋板块早期俯冲作用有关。     

Corporate social responsibility,green credit,and corporate performance: an empirical analysis based on the mining,power, and steel industries of China

Natural Hazards - From the perspective of corporate social responsibility and environmental risk management, green credit will have an important impact on corporate performance. The influence of...     

饱和度-压力曲线法预测柴油在毛细带中形成的透镜体厚度

轻非水相液体（LNAPL）进入到地下环境中,首先在非饱和带进行垂向迁移,到达毛细带后在地下水面以上形成饱和透镜体。准确预测LNAPL渗漏在毛细带形成的透镜体厚度,对于LNAPL的去除及污染含水层的修复具有重要的指导意义。通过模拟实验测定了水-油两相吸湿及脱湿曲线,采用水-油饱和度-压力曲线拟合出了吸湿及脱湿进入压力。根据透镜体达到稳定状态时脱湿、吸湿压力水头之间的关系,建立了透镜体厚度的预测计算方法,并以中砂和粗砂为例,预测出实验条件下柴油在毛细带形成透镜体稳定时的厚度分别为4.61 cm和1.29 cm。通过室内模拟槽实验,测得柴油在中砂和粗砂中迁移时形成的透镜体厚度分别为5.30 cm和1.50 cm。预测与实验结果的相对误差分别为13.0%和14.0%。误差产生的主要原因为脱湿与吸湿曲线是在非干燥情况下测得,从而导致预测的透镜体厚度偏小。     

海原-六盘山断裂带现今地震危险性的数值模拟分析

基于正交各向异性理论表征断层的变形行为,将平行断层面的剪切模量和周围介质剪切模量的比值作为反演参数,以海原-六盘山断裂附近现今GPS观测地壳水平运动速度场作为约束,通过构建三维有限元模型,采用遗传算法,反演了海原-六盘山断裂平行断层面的剪切模量分布.结果显示:六盘山断裂中南段平行断层面剪切模量与周围介质接近,且沿断层面...     

高效优化非分裂PML边界二阶标量波方程数值模拟方法

卷积完全匹配层（convolution perfectly matched layer,CPML）吸收边界是一种高效处理波动方程数值模拟中人工边界反射波的方法。本文基于传统的一阶系统CPML吸收边界条件推广并推导了新的二阶系统CPML边界条件（NCPML）。与常规二阶系统CPML边界条件不同,新边界条件推导的核心思想是在复数-频率域中忽略部分衰减因子空间变化特性,避免其在时间域产生复杂卷积算子,然后反变换至时间域得到基于CPML吸收条件的二阶标量波方程,并应用于二阶标量波方程数值模拟。均匀介质模型测试验证了NCPML吸收条件在内存使用上相对于常规二阶系统CPML与SPML（split PML）吸收条件更少。在对人工边界反射的吸收效果上,NCPML稍逊色于常规二阶系统CPML,但二者均相对于SPML优势明显。最后通过层状模型和Marmousi模型测试验证了NCPML的稳定性及其在效率上的优势。     

贵州省梵净山区域旅游经济与气候适宜度关系研究

根据特吉旺气候舒适度指数划分标准和贵州省旅游气象舒适度标准,利用梵净山区域2013—2017年气象资料及旅游统计资料,通过相关性分析、回归分析等统计方法,分析了梵净山区域经济与气候舒适度指数的相关性。结果表明：“SD气候舒适度指数”标准比“特吉旺气候舒适度指数”更适合研究梵净山区域气候舒适度指数;4—10月是梵净山旅游较适宜期,与旅游收入和客流量月平均数据均有较好的吻合度;气候舒适度指数对梵净山区域旅游经济呈显著的正相关关系,梵净山站为梵净山区域旅游经济气候舒适度指数分析的关键指标站。     

The Influence of Vegetation Cover on Summer Precipitation in China： a Statistical Analysis of NDVI and Climate Data

This study provides new evidence for the feedback effects of vegetation cover on summer precipitation in different regions of China by calculating immediate (same season), and one-and two-season lagged correlations between the normalized difference vegetation index (NDVI) and summer precipitation. The results show that the correlation coefficients between NDVI in spring and the previous winter and precipitation in summer are positive in most regions of China, and they show significant difference between regions. The stronger one-and two-season lagged correlations occur in the eastern arid/semi-arid region, Central China,and Southwest China out of the eight climatic regions of China, and this implies that vegetation cover change has more sensitive feedback effects on summer precipitation in the three regions. The three regions are defined as sensitive regions. Spatial analyses of correlations between spring NDVI averaged over each sensitive region and summer precipitation of 160 stations suggest that the vegetation cover strongly affects summer precipitation not only over the sensitive region itself but also over other regions, especially the downstream region.     

NCEP-FNL与T213L31同化资料对比分析中的地形差异影响

分析了2005年5月11日至6月10日的NCEP-FNL与T213L31分析资料在位势高度、温度和风场上的整体差异,揭示了低层差异最小,差异极值主要分布在3个关键区的特征。进一步通过地形高度差异与位势高度差异的相关性分析,认为青藏高原附近的地形高度差异的极值是引起两种资料位势高度差异的主要原因,并计算分析了这种差异对高原周围中低层大气环流的动力和热力影响。结果显示,在NCEP-FNL中的西南涡强度和热源作用较强,中层风速切变较弱。     

2008年奥运会期间北京地区大气O3浓度模拟分析

利用空气质量模式系统RAMS-CMAQ模拟分析了2008年8月北京及周边地区近地面O3浓度的时空变化。分析结果表明,模式系统可以较好地模拟污染物以及气象要素的变化特征和区域分布情况;奥运会期间的污染控制对O3浓度的降低有明显的作用,但是在一些有利的气象条件下,O3易达到较高浓度:8月2日、24日14时(北京时间)左右O3浓度都在0.22mg.m-3以上,其中2日北京地区处于辐合的弱风场中,风速为1.5～2.5m.s-1,24日则是处于自南向北的有输送作用的风场中,风速为3.5～6.5m.s-1;污染控制对北京周边地区的效果要好于北京市区。     

Impact of land use changes on surface warming in China

Land use changes such as urbanization, agriculture, pasturing, deforestation, desertification and irrigation can change the land surface heat flux directly, and also change the atmospheric circulation indirectly, and therefore affect the local temperature. But it is difficult to separate their effects from climate trends such as greenhouse-gas effects. Comparing the decadal trends of the observation station data with those of the NCEP/NCAR Reanalysis (NNR) data provides a good method to separate the effects because the NNR is insensitive to land surface changes. The effects of urbanization and other land use changes over China are estimated by using the difference between the station and the NNR surface temperature trends. Our results show that urbanization and other land use changes may contribute to the observed 0.12℃ (10 yr)- 1 increase for daily mean surface temperature, and the 0.20℃ (10 yr)- 1 and 0.03℃ (10 yr)-1 increases for the daily minimum and maximum surface temperatures, respectively. The urban heat island effect and the effects of other land-use changes mayalso play an important role in the diurnal temperature range change. The spatial pattern of the differences in trends shows a marked heterogeneity.The land surface degradation such as deforestation and desertification due to human activities over northern China, and rapidly-developed urbanization over southern China, may have mostly contributed to the increases at stations north of about 38°N and in Southeast China, respectively. Furthermore, the vegetation cover increase due to irrigation and fertilization may have contributed to the decreasing trend of surface temperature over the lower Yellow River Basin. The study illustrates the possible impacts of land use changes on surface temperature over China.