The role of mean state on changes in El Niño’s flavor

Recently, many studies have argued for the existence of two types of El Niño phenomena based on different spatial distributions: the conventional El Niño [or Eastern Pacific (EP) El Niño], and the Central Pacific (CP) El Niño. Here, we investigate the decadal modulation of CP El Niño occurrences using a long-term coupled general circulation model simulation, focusing, in particular, on the role of climate state in the regime change between more and fewer CP El Niño events. The higher occurrence regime of the CP El Niño coincides with the lower occurrence regime of EP El Niño, and vice versa. The climate states associated with these two opposite regimes resemble the leading principal component analysis (PCA) modes of tropical Pacific decadal variability, indicating that decadal change in climate state may lead to regime change in terms of two different types of El Niño. In particular, the higher occurrence regime of CP El Niño is associated with a strong zonal gradient of mean surface temperature in the equatorial Pacific, along with a strong equatorial Trade wind over the area east of the dateline. In addition, the oceanic variables—the mixed layer depth and the thermocline depth—show values indicating increased depth over the western-to-central Pacific. The aforementioned climate states obviously intensify zonal advective feedback, which promotes increased generation of the CP El Niño. Frequent CP El Niño occurrences are not fully described by oceanic subsurface dynamics, and dynamical or thermodynamical processes in the ocean mixed layer and air–sea interaction are important contributors to the generation of the CP El Niño. Furthermore, the atmospheric response with respect to the SSTA tends to move toward the west, which leads to a weak air–sea coupling over the eastern Pacific. These features could be regarded as evidence that the climate state can provide a selection mechanism of the El Niño type.     

GIS空间插值方法在内蒙古气温插值中的应用

文章对GIS软件中几种常见插值方法的原理进行了详述,剖析了插值过程中参数设置对插值结果产生的影响。以内蒙古多年平均气温插值为例,对比了各种插值方法的优劣,结果表明:普通克里金法的插值结果最能反映内蒙古多年平均气温的分布特征,均方根误差为1.138℃;反距离权重法可反映基本特征但等值线不够平滑、局部有"牛眼"现象,均方根误差为1.260℃;趋势面法不能反映基本特征,均方根误差为1.425℃;使用协同克里金法,将高程作为协同因子对普通克里金算法进行改善,未取得明显效果。     

Altered atmospheric responses to eastern Pacific and central Pacific El Niños over the North Atlantic region due to stratospheric interference

The two types of El Niño that have been identified, namely the eastern Pacific (EP) and central Pacific (CP) El Niños, are known to exert different climatic impacts on the North Atlantic region during winter. Here, we investigate the characteristics of the teleconnection of the two El Niño types with a focus on the stratosphere-troposphere coupling. During the EP El Niño, polar stratospheric warming and polar vortex weakening frequently occur with a strong tendency for downward propagation near the tropopause. Consequently, the atmospheric pattern within the troposphere over the North Atlantic sector during midwinter closely resembles the negative North Atlantic Oscillation pattern. In contrast, during CP El Niño events stratospheric warming events exhibit a much weaker downward propagation tendency. This difference in the stratospheric circulation response arises from the different seasonal evolution of the tropospheric wave response to the two El Niño types. For the EP El Niño, the Aleutian Low begins growing during December and is sustained throughout the entire winter (December to February), which provides favorable conditions for the continuous downward propagation of the stratospheric warming. We also discuss the origin of the difference in the teleconnections from the two types of El Niño associated with the distinct longitudinal position of the warm SST anomaly that determines troposphere-stratosphere coupling.     

内蒙古中部地区近50a土壤干旱化趋势及其原因

选取内蒙古中部地区为研究对象，在比较实测土壤湿度和NCEP土壤湿度资料的基础上，试用近50a(1950～1999年)的NCEP地表层(0～10cm)土壤湿度(Soil Water Content，简称SW)资料，分析这一地区表层土壤湿度的变化趋势和干旱化的可能原因。结果表明，这一地区的SW有明显的季节变化，即呈二波型。高SW出现在冬季12月一次年3月(冻土期)和8、9月(雨季)。最干期出现在5、6月，另一干期在晚秋。20世纪60年代中期进入北方干旱化时期，最严重的干旱出现在90年代。周期为20～30a的年代际变化是SW变异中最重要的成分。暖冬可能是表层土壤干旱化最重要的原因，特别是在70年代和90年代，而地表植被的人为破坏，则明显加剧了这种干旱化进程，夏季降雨可能是比较次要的因素。结果还说明，对于我国北方地区，SW是一种可用于描述干旱化大致趋势的物理量。     

Mineral Components, Texture, and Forming Conditions of Hydrothermal Chimney on the East Pacific Rise at 9°-10°N

To characterize the hydrothermal processes of East Pacific rise at 9o-10oN, sulfide mineral compositions, textural, and geochemical features of chimney ores were studied using ore microscope, scanning electron microscope, X-ray diffraction analysis, and electron microprobe techniques. Results show that there are three mineral assemblages for the hydrothermal chimney ores, namely: (i) anhydrite marcasite pyrite, (ii) pyrite sphalerite chalcopyrite, and (iii) chalcopyrite bornite digenite covellite. Mineral assemblages, zonational features, and geochemical characteristics of the ore minerals indicate that ore fluid temperature changed from low to high then to low with a maximum temperature up to 400 ℃. The chimney is a typical black smoker. The initial structure of the chimney was formed by the precipitation of anhydrites, and later the sulfides began to precipitate in the inner wall.     

Tectonic Landform of Quaternary Lakes and Its Implications for Deformation in the Northern Qinghai-Tibet Plateau

The Hohxil region in the northern Qinghai-Tibet Plateau is occupied by numerous plateau lakes,which have long been inferred as being tectonic products.However,so far little evidence has been found to support this tentative inference.Field survey and morphotectonic analysis of TM satellite images in the eastern segment of the Hohxil region revealed that Kusai Lake and Yelusu Lake are S- shaped pull-apart basins,which were dominated by left strike-slip master faults trending WNW-ESE. The pull-apart distanc...     

三度体梯度磁异常全方位正反淀方法

首创了磁法勘探学科中三度体任意方向梯度磁异常全方位正、反演方法。首先,在球坐标系中,导出了三度体任意方向梯度磁异常的两个球谐级数通用正演表达式,为实现全方位反演奠定了理论基础。然后,由第１个梯度磁异常球谐级数表达式出发,提出了三度体总磁化方向、磁矩模值反演方法;由第２个梯度磁异常球谐级数表达式出发,提出了三度体磁矩重心、近似形态与分布范围,以及有广泛实用价值的“均磁凸形体”边界点位置等全方位反演方     

黄金标准样品的X—射线荧光光谱定量分析

应用化学计量学-X-射线光谱分析软件包CMXRS V2.1,在基本参数法进行基体效应校正的基础上,选择合适的样条函数,并采用微孔面罩及石蜡衬底等实验技术,测定了29个黄金标准样品中的Au、Ag、Cu和Zn。结果证明,方法可行。Au含量在99％以上的样品,Au的分析误差不超过0.14％,Au含量小于99％的样品,Au的分析误差不超过0.25％。     

帕默尔旱度模式的进一步修正

为了正确评估干旱，根据帕默尔旱度模式的思路和1986年安顺清等人修正的帕默尔旱度模式，我们以济南、郑州和太原3站逐年逐月气温和降水等作为基本资料（1961～2000年），以哈尔滨、佳木斯、呼和浩特、沈阳、北京、固原、西安、汉中、青岛、德州、运城、长沙、武汉、南昌、杭州、福州、广州、昆明、南宁、成都和贵阳21个站的有关资料（1961～2000年）为权重因子修正资料，并且在计算可能蒸散时选用了FAO推荐的彭曼-蒙蒂斯公式。另外0～20 cm和20～100 cm土层的土壤田间有效持水量根据我国测定的资料和土壤特性确定，对帕默尔旱度模式进行了进一步修正。利用此模式计算了我国北方地区139个站点（1961年1月～2000年12月）的帕默尔指数值。将计算的帕默尔指数值与一些文献记载的实际旱涝灾情相对照进行验证，表明进一步修正的帕默尔旱度模式能较为准确地评估旱涝情况，适合应用于我国     

湘鄂西地区下寒武统牛蹄塘组页岩气储层特征

湘鄂西地区下寒武统发育一套有利的页岩气储层.选择不同沉积-构造单元内的典型页岩气井,通过有机地化测试、矿物X衍射、场发射扫描电镜及核磁共振等技术方法,对牛蹄塘组页岩气储层特征进行了对比分析.研究表明,页岩矿物组成受沉积相控制明显,浅水陆棚区页岩矿物组成表现出"低硅高钙"特征,盆地相区页岩矿物组成表现出"高硅低钙"特征;...