海面风应力偏离风向的观测与分析

针对海气界面风应力方向与风向不一致的现象,2015年2月4日至3月12日在南海博贺观测平台开展了综合观测,利用涡动相关法计算了海气界面风应力,并在3类大气稳定度条件下分析了风应力矢量偏离风矢量的角度变化,进一步讨论了大气层结稳定时两者角度之差与风速的参数化关系。结果表明:在大气层结稳定条件下,风应力矢量偏向风矢量左侧,且偏离角度随逆波龄和风速增大而减小;当大气层结不稳定时,风应力矢量一般偏向风矢量右侧。海气界面风应力矢量受海表面风、波浪以及大气层结的共同调制。     

民勤沙区白刺果实性状的变异性研究

民勤沙区天然白刺果实的大小、形状、颜色、味道、果实出肉率、果汁含糖量等性状的种下变异非常丰富,且果实、果核的大小、形状等性状的株间变异较大,而株内的变异却很小,这为优良果实个体的选择奠定了一定基础。代表果实和果核大小的不同指标的发育有较高的相关性,但果形和核形的变异仍相对独立,且果形的变化对果实产量有较大影响。果实大的个体出肉率高,果形小（果实圆）的个体出肉率也高;果实越大果汁的含糖量越低,反之越高。     

Hit or miss: Glacial incisions of snowball Earth

Estimated at ~58 Ma in duration, the Sturtian snowball Earth (ca. 717–659 Ma) is one of the longest‐known glaciations in Earth history. Surprisingly few uncontroversial lines of evidence for glacial incisions associated with such a protracted event exist. We report here multiple lines of geological field evidence for deep but variable glacial erosion during the Sturtian glaciation. One incision, on the scale of several kilometres, represents the deepest incision documented for snowball Earth; another much more modest glacial valley, however, suggests an erosion rate similar to sluggish Quaternary glaciers. The heterogeneity in snowball glacial incisions reported here and elsewhere was likely influenced by actively extending horst‐and‐graben topography associated with the breakup of supercontinent Rodinia.     

500m深度拖曳系统的设计与试验

针对500 m波浪式拖曳系统的技术要求,介绍了拖体、流线型拖缆、电控绞车和总控程序4个关键部分的设计;根据海上的试验情况,分析了拖体的缆深比和定深拖曳等数据,表明本系统达到预期要求,可以为上层海洋学的调查与观测提供良好的平台。     

盘星藻烷烃生物标志物特征及其热演化试验的初步研究

本文以盘星藻作为典型样品，研究淡水水生单细胞藻类的烷烃生物标志特征及其热解生烃特征。实验结果表明，盘星藻生烃主要分成四大类：正烷烃、稀烃、无环类异戊二烯和二环萜类。ｎＣ１７在正烷烃组分中占５１．６％。检出一组Ｃ２０的二环萜类同分异构体，其含量相当于正浣烃含量的９７．１％。盘星藻热解生烃也以低碳数烃类为主，与高等植物来源的烃类相区别；甾烷Ｃ２９／（Ｃ２７＋Ｃ２８＋Ｃ２９）值为０．５左右，与海洋浮游生     

Soil moisture retrieving using hyperspectral data with the application of wavelet analysis

As a powerful tool, the wavelet transform method has been widely used in feature extraction for hyperspectral data, while few studies are focused on soil moisture retrieving. The objective of this study was to evaluate the effectiveness of discrete wavelet transform (DWT) for soil moisture retrieving. In this study, a total of 78 measurements of soil moisture and hyperspectral data were collected through soil sampling as well as laboratory quantitative control. There were 13 different mother wavelets capable of decomposing hyperspectral data that were recommended, along with six decomposition levels from 5 to 10. The performances of two feature extraction methods namely band selection and DWT were compared, using three indexes, i.e., R ², R _adj and root mean square error (RMSE) introduced to validate soil moisture retrieving results. The experimental results indicated that the wavelet transform method could significantly reduce the dimensionality of hyperspectral data, resulting in a much more effective performance. Among the 78 estimation models using the wavelet transform, there were 42 models superior to band selection, with 24 models yielding good correlations between the predicted soil moisture and the measured ones (R ² ≥ 0.7, RMSE ≤ 0.050, p ≤ 0.05). Furthermore, when the wavelet decomposition level was 9 and the mother wavelets were Daubechies 2, Daubechies 4, Reserve Biorthogonal 3.3 and Biorthogonal 6.8, the retrieving results were optimum. Additionally, the experimental results proved that the wavelet analysis technique was capable of preserving high- and low-frequency spectral information at different decomposition scales, and could correctly reflect the variation of soil moisture. Thus, it would be helpful in further environmental monitoring.     

The intermittent vertical heat flux over a spruce forest canopy

Vertical heat and momentum fluxes were measured by the eddy correlation method under near-neutral conditions during both day and night above a spruce forest canopy. Results show that 50% of the heat transported to the spruce canopy during night and away from the canopy during the day occurs in extreme magnitude events, the majority of less than one second duration. Extreme-magnitude events were more frequent and lasted longer during the day than during the night. The distributions of the duration of extreme events in the same direction as the net heat flux and the turbulence intensity for both day and night were similar.During the night, the mean horizontal windspeed was about 1 m s^-1 and the measured coincident transport of momentum and heat accounted for 36% of the total heat flux. The predominant mechanism of forced convection during the extreme nightime heat transport events was excess heat sweeps in which the duration of the event is usually less than 1 s. During the day, the mean horizontal windspeed was about 2 m s ^-1 and the measured coincident transport of momentum and heat accounted for only 16% of the total heat flux. Local free convection was suggested to account for 27% of the total heat flux. The predominant mechanism of mixed convection during the extreme daytime heat transport events is deficit heat inward interactions. During both night and day, about 10% of the total heat transport occurred in extreme events working against the thermal gradient.Now atPurdue University, West Lafayette, IN, U.S.A.     

Linkage of liquid conductivity of glacier ice with its alkalinity over the north Qinghai-Xizang (Tibet) Plateau

Liquid conductivity (EC) measurement was conducted for the samples collected from several snow pits and ice cores over the Qinghai-Xizang (Tibet) Plateau, with their time range covering seasonal, decadal and centennial scales. Unlike the previous attention mostly focused on the acidity (H⁺) responding to the solid conductance (ECM) of glacial ice, we introduce the alkalinity (OH⁻) of snow and ice to show how it responds to EC. Strong linear relationship was established between EC and OH⁻ for these snow pits and ice cores. Positive correlation is also established between EC and major cations (Ca²⁺, Mg²⁺, Na⁺ and K⁺). Since the cations are known as the proxies for the intensity of mineral dust influx onto glaciers of the northern Qinghai-Xizang Plateau, we believe that EC could be used as an indicator for the history of dust input in deep ice core study. In fact, records in Guliya ice core since the Little Ice Age (LIA) indicate that dust load in glacier may depend on the combination of temperature and humidity. “Cold-dry” combination favors the dust arising, and results in higher EC and OH⁻ values, while “warm-wet” combination prevents dust form and EC and OH⁻ values are lower. In the past century, with the atmospheric warming and precipitation increasing over the northern plateau, which means an atmospheric condition of dust decreasing, both EC and OH⁻ displayed rapid decline.     

流沙湾底栖贝类耐污值的研究

于2008年3月～2009年1月在流沙湾设7采样站,对底栖贝进行了6次采样调查。用Lenat耐污值估算方法对流沙湾底栖贝类耐污进行分析,建立16个分类单元(科)贝类的耐污值谱。结果表明,16个分类单元(科)的耐污值均在6.5以上,其中骨螺科、织纹螺科和汇螺科的耐污值为10.0;马蹄螺科、笔螺科和帘蛤科耐污值在9.0~9.9之间;蚶科、贻贝科、牡蛎科、樱蛤科、竹蛏科、绿螂科、牙螺科和钥孔虫戚科在8.0~8.9之间;蟹守螺科与滨螺科在6.0~7.0之间。流沙湾大多数贝类的耐污值集中于耐污值谱的高端(≥8.0),水体的环境梯度值处于较高值,说明流沙湾已处于中度到高度的污染水平。     

应力量值研究综述

地壳应力场在板块运动模拟、青藏高原隆升、地震孕育和发生等地球动力学研究中具有重要地位.而目前大多数地壳应力方面的研究侧重于方向的确定,对应力量值研究甚少.我们总结了地质、地球物理等方法确定应力量值的思路,在此基础上提出了根据大地震前后应力方向变化和地震破裂应力降张量估计地震震源附近应力量值.并辅以地震前后平均视应力方法等其他方法共同对应力量值进行进一步约束的思路.大地震前后的应力方向变化根据大量前震和余震的震源机制给出.地震破裂造成的应力降场可根据地震破裂详细分布计算,则已知大小和方向的地震应力降场与方向已知、大小未知的地震前后应力张量之间可以构建数学关系,从而得到应力量值.根据地震前震和余震的宽频带辐射能量和地震矩张量目录得到大地震前后的平均视应力,两者之差对应于地震应力降,根据这种关系得到震前应力量值的另一个估计.两种方法相结合,给出应力量值及误差估计,为地球动力学研究提供新的约束.