本溪,中国枫叶之都

本溪市地处辽宁中东部山区,是“八山一水一分田”的山区城市,属北半球中温带半湿润大陆季风气候,雨量充沛,四季分明。自然条件过渡性强,气候生物旅游资源丰富多样,基本类型占全国全部类型的54%,是我国北方植被覆盖率高、动植物类型丰富的独特区域。     

河西走廊东部冬季沙尘暴的典型个例及气候特征分析

应用1971—2016年河西走廊东部代表站的地面观测资料、NCEP 2.5°×2.5°月均地面至300 hPa高空资料,2006—2016年民勤逐日07和19时每隔10 m加密高空资料,分析了近45年河西走廊东部冬季沙尘暴天气的年际变化特征。同时选取2016年11月两次沙尘暴天气过程从天气学成因、物理量场及近地面边界层特征等方面进行了诊断分析。结果表明:近45年河西走廊东部冬季沙尘暴日数呈减少趋势,产生大风沙尘天气的主要原因不仅与大型冷暖空气强度及环流形势有关,还与冷锋过境时间、日变化、近地层风速和干湿程度关系密切。夜间至早晨近地面逆温厚且强,大气层结稳定,削弱沙暴强度,而午后到傍晚,逆温薄而弱,大气层结不稳定性强,加强了动量下传和风速,增强沙暴强度。近地层越干,风速越大,沙暴越强。     

中国西北地区东部盛夏降水特征及对初春地表感热异常的响应

选用1961-2015年中国西北地区74个气象站逐月地表感热通量计算资料,及其东部155个常规气象站夏季的月降水资料以及NCEP/NCAR月平均再分析资料,通过经验正交函数分解(EOF)、线性回归分析、奇异值分解(SVD)等数理统计分析方法,分析了西北地区东部盛夏(7-8月)降水的时空异常演变特征及其与西北地区初春(3-4月)地表感热异常的联系及成因。结果表明:(1)中国西北地区东部盛夏降水由东南向西北递减,总体呈年代际减少趋势,减少最明显的区域为宁夏北部、内蒙古中南部。其空间异常型主要表现为全区一致的增多(减少)和西北-东南向"-+-"变化。(2)当西北地区初春(3-4月)地表感热通量整体异常偏强(弱)时,盛夏(7-8月),在贝加尔湖以南、中国北方的上空出现高度场异常偏高(低),中国西北地区水汽辐散(辐合)加强,西北地区东部宁夏平原降水出现异常偏少(偏多);而陕西南部有水汽的辐合(辐散)加强,有(不)利于该地区降水的产生。     

Organic Carbon Isotopic Evolution during the Ediacaran-Cambrian Transition Interval in Eastern Guizhou, South China： Paleoenvironmental and Stratigraphic Implications

Secular variations of carbon isotopic composition of organic carbon can be used in the study of global environmental variation, the carbon cycle, stratigraphic delimitation, and biological evolution, etc. Organic carbon isotopic analysis of the Nangao and Zhalagou sections in eastern Guizhou reveals a negative excursion near the Precambrian-Cambrian boundary that correlates with a distinct carbonate carbon isotopic negative excursion at this boundary globally. Our results also demonstrate that several alternating positive and negative shifts occur in the Meishucunian, and an obvious negative anomaly appears at the boundary between the Meishucunian and Qiongzhusian. The isotope values are stable in the middle and lower parts but became more positive in the upper part of the Qiongzhusian. Evolution of organic carbon isotopes from the two sections in the deepwater facies can be well correlated with that of the carbonate carbon isotopes from the section in the shallow water facies. Integrated with other stratigraphic tools, we can precisely establish a lower Cambrian stratigraphic framework from shallow shelf to deep basin of the Yangtze Platform.     

Chronology and Geochemistry of Volcanic Rocks in the Cretaceous Suifenhe Formation in Eastern Heilongjiang, China

Zircon U-Pb ages and geochemical data of volcanic rocks in the Suifenhe Formation in eastern Heilongjiang Province are reported, and their petrogenesis is discussed in this paper. The Suifenhe Formation mainly consists of basalt, andesite, and dacite. Zircon from andesite and dacite are euhedral in shape and show typical oscillatory zoning with high Th/U ratios (0.18-0.57), implying its magmatic origin. Zircon U-Pb dating results by laser ablation inductively coupled plasma mass spectrometer (LA-ICP-MS) indicate that the 206Pb/238U ages of zircons from andesite range within 105-106 Ma, yielding a weighted mean age of 105.5±0.8 Ma (n=14), and that 206Pb/238U ages of zircons from dacite are between 90-96 Ma, yielding a weighted mean age of 93.2±1.3 Ma (n =13). The volcanic rocks from the Suifenhe Formation are subalkaline series and show a calc-alkaline evolutionary trend with SiO2 content of 47.69%-65.47%, MgO contents of 1.42%-6.80% (Mg#= 45-53), and Na2O/K2O ratios of 1.83-3.63. They are characterized by enrichment in large ion lithophile elements (LILE) and light-rare-earth elements (LREE), depletion in heavy rare earth elements (HREE) and high field strength elements (HFSE) (e.g., Nb, Ta, Ti), and low initial 87Sr/86Sr ratios (0.7041-0.7057) and positiveεNd(t) values (039-4.08), implying that they could be derived from a depleted magma source. Taken together, these results suggest that the primary magma of the volcanic rocks might originate from partial melting of the mantle wedge metasomatized by fluids derived from subducted slab under a tectonic setting of active continental margin.     

西北区东部一次大暴雨过程的湿位涡诊断与数值模拟

利用绝热、无摩擦大气湿位涡守衡理论和NCEP(1°×1°)再分析资料,对我国西北区东部2005年7月1~2日大暴雨过程进行了分析。结果表明:700 hPa上副热带高压西侧强西南气流北上,在西北区东部与东移南压的西北冷空气形成强辐合,是造成西北区东部这次强降水的主要影响系统。在700 hPa等压面上湿位涡与辐合区域相对应的是,在西北区东部存在一个湿位涡正压项MPV1的正值区和湿位涡斜压项MPV2的负值区域,它们准确地指示了辐合区的范围及变化,暴雨出现在辐合区中或MPV1和MPV2的等值线密集区边缘上;对流层高低层正值MPV1可以指示对流稳定的冷空气的变化,而对流稳定度小的暖湿气流表现为小的正值(高层)或负值(低层),等值线密集带指示了降水的后界。用模式输出的高时空分辨率资料诊断暴雨发生期间各个暴雨中心的等熵面结构,表明用湿位涡理论可以很好地解释这次暴雨发生的局地特征。     

我国东部极端降水时空分布及其概率特征

利用我国105°E以东地区210个测站近50年(1953—2002年)逐日降水资料,在REOF客观分区的基础上,确定各分区的极端降水最佳采样期为1~2日。进而研究了日极端降水量的气候特征。采用具有优良特性的L-矩参数估计方法对我国东部极端降水拟合Gumbel分布。结果表明,L-矩参数估计方法的拟合优度比其它方法有进一步提高,近50年来,极端降水趋势虽无明显变化,但其时空差异较大。符合Gumbel分布的极端降水重现期的地理空间分布,大致特征是,东南大、西北小,两湖盆地、黄海海湾及辽东半岛也有高值区。     

晚第四纪-全新世期间库拉泥火山的时空演化

泥质角砾相／流是识别泥火山的一个主要特征：角砾沉积的时间意味着泥火山的喷发历史,而角砾出现的规模表示了泥火山的强度。库拉泥火山位于地中海东部阿那克西曼德海山北缘水深1750m处,圆丘状。多波束及深拖旁侧声纳系统调查显示,库拉泥火山北向及峰顶具有比周围区域高的背向散射强度。     

地中海东部泥火山结构中烃类气体的来源迁移以及在水体中的行为

在被动大陆边缘的陆地和海底环境,常常可以发现泥火山结构的存在。泥火山的喷发主要由于沉积物深部形成的高压所诱发,而这种高压主要是由过度的气体和水体压力的积聚引起。这种情况下,气体、水体和沉积物被活化,沿着沉积物（通常是断裂）向上迁移,形成泥穹丘。     

世界各国（地区）围海造地发展现状及其对我国的借鉴意义

围海造地是人类开发利用海洋的重要方式,也是人类拓展生存空间及生产空间的重要手段.世界上大部分沿海国家或地区都有围海造地的历史,也因此积累了比较丰富的成功经验及失败教训.我国海岸线长、海湾多,改革开放以来,东部沿海地区一直是我国经济增长最活跃、工业化和城市化进程最快的区域.