云南境内陆态网络GNSS观测资料数据处理与初步结果

利用GAMIT/GLOBK软件对云南境内陆态网络GNSS观测资料,包括27个GNSS基准站自2011年至今的连续观测资料,以及170多个GNSS区域站2009、2011、2013年3期区域复测资料进行了处理,基线处理的重复性在水平方向优于1.79mm+1.1×10?9×S,在垂直方向优于5.99mm+1.46×10?9×S(S为基线长度,以mm为单位),计算得到了基线及点位时间序列和欧亚框架下的测站运动速度场。初步分析了坐标时间序列的变化规律,并利用刚体运动模型反演了云南地区各活动块体的现今地壳运动,初步结果表明云南地块运动方向逐渐由SSE向SSW变化,运动幅度由西向东、由北向南逐渐减弱,菱形块体外各个块体运动速度大幅衰减。该初步结果可为后期GNSS数据的进一步运用提供参考。     

Improving monthly streamflow prediction in alpine regions: integrating HBV model with Bayesian neural network

Statistical methods have been widely used to build different streamflow prediction models; however, lacking of physical mechanism prevents precise streamflow prediction in alpine regions dominated by rainfall, snow and glacier. To improve precision, a new hybrid model (HBNN) integrating HBV hydrological model, Bayesian neural network (BNN) and uncertainty analysis is proposed. In this approach, the HBV is mainly used to generate initial snow-melt and glacier-melt runoffs that are regarded as new inputs of BNN for precision improvement. To examine model reliability, a hybrid deterministic model called HLSSVM incorporating the HBV model and least-square support vector machine is also developed and compared with HBNN in a typical region, the Yarkant River basin in Central Asia. The findings suggest that the HBNN model is a robust streamflow prediction model for alpine regions and capable of combining strengths of both the BNN statistical model and the HBV hydrological model, providing not only more precise streamflow prediction but also more reasonable uncertainty intervals than competitors particularly at high flows. It can be used in predicting streamflow for similar regions worldwide.     

濮阳小震集中区地震丛集特征分析

利用濮阳小震集中区1970年1月—2019年12月地震目录,基于最邻近事件距离算法计算地震丛集率,分析该区地震丛集特征。结果发现:(1)在中强地震前,濮阳小震集中区地震丛集率存在高值现象,而后出现不同程度的低值,与强震前地震活动从增强到平静的过程相吻合,对地震危险区判定有一定指示意义;(2) 1997年以来,4级以上地震主要分布在聊城—兰考断裂西侧,且小震出现相对“稀疏”异常,应给予关注。     

Analyzing the Waveform of the Shunchang Earthquakes in Fujian Province

On March 13, 2007, two earthquakes with M4.7 and M4.6 occurred in Zhengfang Village, Shunchang, Fujian. The M4.7 earthquake is the most intensive one in the Fujian region since the establishment of the Fujian digital seismic networks. These two earthquakes provide us with valuable first-hand observation data for seismological research. This paper analyzes their waveforms and concludes that （ 1 ） the crustal thickness in the seismic region is estimated to be about 40km according to the observed head-wave critical distance; （2） there is a salient difference between the ratios of S-wave＇s maximum amplitudes of these two earthquakes; （3） the focal depth of the M4.7 earthquake is estimated to be 8.4km according to the clear depth phrase sPn in waveforms, which is the same with the result of other determination methods.     

COSI-Corr技术在风沙地貌研究中的初步应用及精度检验

沙丘移动与形态监测是风沙地貌研究的重要内容,传统的测量方法对大范围的风沙地貌进行动态监测存在很大的困难。光学影像配准与关联（Co-registration of Optically Sensed Images and Correlation,COSI-Corr）技术的出现为区域风沙地貌的动态演化与监测研究提供了良好契机。讨论了COSI-Corr技术在沙丘移动和形态监测中的优势和存在的主要问题,通过无人机野外地面实测结果检验了COSI-Corr的测量精度。结果表明：沙丘背风坡底缘COSI-Corr测量精度最高,月测量误差0.01～0.53 m,达到影像分辨率的1/30像元;在沙丘背风坡底缘,COSI-Corr测量精度与沙丘底面积呈线性关系,底面积越大,COSI-Corr测量误差越大;个别沙丘脊线部位出现极大异常点,与沙丘脊线部位的光噪影响有关。COSI-Corr技术在风沙地貌监测中尚属起步阶段,一些具体的问题还需要我们在实践中不断的去检验和改进,但它确实极大提高了野外风沙地貌动态监测的效率,为研究大尺度范围内风沙地貌的时空动态演化过程提供了可能,在未来的风沙地貌研究中将具有广阔的应用前景。     

利用生态学和树轮年代学手段试析柴达木盆地东缘山地森林年龄结构与气候变化的关系

选取柴达木盆地东缘山地尔日格为研究剖面, 对坡面上的祁连圆柏(Sabina przewalskii Kom.)沿不同海拔高度进行采样。在利用交叉定年手段对所有样芯定年之后, 确定了样芯的起始年和结束年(死亡年龄), 然后利用树髓心年龄估算法和研究区域胸高年龄经验值最终确定了树木活体植株开始生长的年龄(长树年龄)。根据研究坡面上树木长树或死树年份随海拔和时间变化的变化规律, 探讨了它们与气候变化之间的可能关系, 从而用来作为树轮宽度重建的佐证手段之一。结果表明: 在森林上部和中部, 随海拔的升高, 树木的年龄呈递减趋势; 在森林下部, 随海拔的降低, 树木年龄趋于年轻化; 整个坡面长树峰值出现在公元1200年左右, 长树主要集中在森林中部的3900~4110m之间; 树木死亡的峰值出现在公元1600年之后的50年间, 死树主要集中在森中上部的4100~4210m之间。同时, 还发现在坡面树木死亡较集中的时期, 森林树木更新数目较低, 尤其是在森林上部; 而通过对不同海拔高度上最老树的生长年龄分析, 发现在坡面长树比较集中的时期, 森林下部有往更低海拔处长树的趋势。将研究坡面长树和死树随时间变化的分布情况与研究区附近利用树轮宽度重建的乌兰过去1000年上年9月到当年4月平均温度和德令哈过去1000年上年7月至当年6月降水量进行对比, 发现在40年尺度上, 高温对应着树木高生长数目, 低温并且降水量由多变寡则对应着树木低生长数目和高死亡数。表明: 温度的升高有利于研究坡面祁连圆柏更新的发生, 森林密度增大, 森林中部幼树更新存活数量最多, 森林下部有往更低海拔处长树的趋势, 森林上限随海拔的升高密度降低、树木趋于年轻化; 反之, 气候干冷, 树木更新条件变差, 受影响的区域主要集中在森林中部-森林林线中上部范围内, 死树相对比较集中。     

Multifractal detrended fluctuation analysis of the δ 18 O record of NGRIP ice core

The multifractal properties and scaling behaviors of the long-term and recent 2000-year δ ¹⁸ O records of NGRIP ice core are investigated by the multifractal detrended fluctuation analysis method. The generalized Hurst exponents, multifractal scaling exponents, and singularity spectrums of two δ ¹⁸ O records are derived to verify the multifractiality of two records. And the multifractal behaviors of two records are obviously different, which may reflect the climate change of the recent 2000-year time is quite different from one of the long-term time. In addition, the probability distribution analysis of two δ ¹⁸ O records is presented to manifest the different multifractality between two δ ¹⁸ O records of NGRIP ice core. Our results will be helpful to research the climate change.     

台风中降雨对中国高分3号合成孔径雷达观测信号的影响

Gaofen-3(GF-3), a Chinese civil synthetic aperture radar(SAR) at C-band, has operated since August 2016.Remarkably, several typhoons have been captured by GF-3 around the China Seas over its last two-year mission.In this study, six images acquired in Global Observation(GLO) and Wide ScanSAR(WSC) modes at verticalvertical(VV) polarization channel are discussed. This work focuses on investigating the observation of rainfall using GF-3 SAR. These images were collocated with winds from the European Centre for Medium-Range Weather Forecasts(ECMWF), significant wave height simulated from the WAVEWATCH-III(WW3) model, sea surface currents from climate forecast system version 2(CFSv2) of the National Centers for Environmental Prediction(NCEP) and rain rate data from the Tropical Rainfall Measuring Mission(TRMM) satellite. Sea surface roughness,was compared with the normalized radar cross section(NRCS) from SAR observations, and indicated a 0.8 correlation(COR). We analyzed the dependences of the difference between model-simulated NRCS and SARmeasured NRCS on the TRMM rain rate and WW3-simulated significant wave height. It was found that the effects of rain on SAR damps the radar signal at incidence angles ranging from 15° to 30°, while it enhances the radar signal at incidence angles ranging from 30° to 45° and incidence angles smaller than 10°. This behavior is consistent with previous studies and an algorithm for rain rate retrieval is anticipated for GF-3 SAR.     

中国对虾(Penaeus chinensis)的白点综合征病毒(WSSV)的提纯和核酸提取

作者从发生白点综合征的中国对虾中,提取了一株白点综合征病毒,用电镜对纯化的病毒进行了形态学观察,并对病毒纯化过程中蛋白酶抑制剂的使用及离心速度的选择进行了探讨。经蔗糖密度梯度离心,分取各带负染后电镜观察,病毒条带位于４０％～５０％蔗糖梯度之间,其完整毒粒长２２５～２７０ｎｍ,直径７５～８８ｎｍ,有的完整毒粒带有很长的尾,病毒衣壳长２５０～３２０ｎｍ,直径６０～８０ｎｍ。在匀浆使用的缓冲液中加入蛋白酶抑制剂ＰＭＳＦ,可得到完整的带包膜的病毒颗粒,比不使用ＰＭＳＦ的提纯效果要好。经３０００ｒ／ｍｉｎ离心５ｍｉｎ,５０００ｒ／ｍｉｎ离心２５ｍｉｎ,去除大部分的组织碎片,经１００００ｒ／ｍｉｎ离心１ｈ,可使大部分病毒沉淀。并采用传统的方法对病毒核酸进行了提取,其基因组经初步分析为ｄｓＤＮＡ。