LADCP配置文件和数据质量控制的参数设定

为在海洋调查中更好的使用LADCP获取现场观测资料和从观测资料中获取更真实的流速信息.详细阐述 了LADCP投放前配置文件和后期资料处理中数据质量控制的有关问题.给出了相关参数设置的依据,阐述了各个参数设置的不同影响,为今后外海调查提供参考.     

Surface sediment diatoms from the western Pacific marginal seas and their correlation to environmental variables

Diatom data of 192 surface sediment samples from the marginal seas in the western Pacific together with modern summer and winter sea surface temperature and salinity data were analyzed.The results of canonical correspondence analysis show that summer sea-surface salinity(SSS) is highly positively correlated with winter SSS and so is summer sea-surface temperature(SST) with winter SST.The correlations between SSSs and SSTs are less positively correlated,which may be due to interactions of regional current pa...     

Deriving Changjiang coastal zone wind from C-band SAR and its application to salinity simulation

Wind plays an important role in hydrodynamic processes such as the expansion of Changjiang （Yangtze） River Diluted Water （CDW）, and shelf circulation in the Changjiang estuary. Thus, it is essential to include wind in the numerical simulation of these phenomena. Synthetic aperture radar （SAR） with high resolution and wide spatial coverage is valuable for measuring spatially inhomogeneous ocean surface wind fields. We have collected 87 ERS-2 SAR images with wind-induced streaks that cover the Cbangjiang coastal area, to verify and improve the validity of wind direction retrieval using the 2D fast Fourier transform method. We then used these wind directions as inputs to derive SAR wind speeds using the C-band model. To demonstrate the applicability of the algorithms, we validated the SAR-retrieved wind fields using QuikSCAT measurements and the atmospheric Weather Research Forecasting model. In general, we found good agreement between the datasets, indicating the reliability and applicability of SAR- retrieved algorithms under different atmospheric conditions. We investigated the main error sources of this process, and conducted sensitivity analyses to estimate the wind speed errors caused by the effect of speckle, uncertainties in wind direction, and inaccuracies in the normalized radar cross section. Finally, we used the SAR-retrieved wind fields to simulate the salinity distribution off the Changjiang estuary. The findings of this study will be valuable for wind resource assessment and the development of future numerical ocean models based on SAR images.     

Environmental anomalies in the northeastern East China Sea during the last 3 000 years:implications for El Nio activity in the Holocene

To reconstruct the productivity changes for the last 10 500 a in the northeastern East China Sea (ECS),biogenic compounds (such as carbonate,organic carbon and opal),marine micropaleontological fossils (planktonic foraminifera,benthic foraminifera,radiolarian and silicoflagellate) and the compositional characters of benthic foraminifera fauna analyses were carried out on a sediment core DOC082 obtained from the western slope of Okinawa Trough (29°13.93'N,128°08.53'E;1 128 m water depth).The long-term changes of biogenic and micropaleontological proxies display some similarities through the last 10 500 a,which show three different phases:lower values are recorded during the early and middle Holocene (before about 4 000 a BP),followed by an abrupt and remarkable increase at about 4 000 a BP,the late Holocene (after about 3 000 a BP) is characterized by continuously high values.The multi-proxy data of paleoproductivity and percents of benthic foraminifera genera (Uvigerina and Bulimina) show that during the early and middle Holocene (10 500-4 000 a BP) productivity was relatively low with a sudden and distinct increase at about 4 000 a BP,and the late Holocene (3 400-0 a BP) is marked by significantly higher productivity.Also,the radiolarian-based sea surface temperature (SST) records reveal a distinct decline in SST in the late Holocene after 3 200 a BP,very different from the early and middle Holocene.For the last 3 000 a,the enhanced biological productivity and distinctly lower SST indicate a major change of oceanographic conditions in the northeastern ECS.These marine environmental anomalies are consistent with other paleoclimatic records for the late Holocene in the Chinese continent and its surrounding regions.After analyzing the mechanisms of modern productivity and SST changes in the northeastern ECS,and based on the climatic anomalies in the Chinese continent and variations in the Kuroshio Current during modern El Nio periods,we suggest that the anomalous environmental conditions in the northeastern ECS may imply intensified El Nio activity during the late Holocene.     

利用卫星进行双向时间传递

介绍了利用卫星进行双向时间传递方法的原理（TWSTT），包括了电离层延时误差、卫星转发时延、接收机和发射机时延和相对论效应修正误差。作者使用昆明站和临潼站的观测数据进行处理。得到高精度的时间比对。     

恒星类太阳和类长周期变星脉动激发机制的理论探讨

利用一种非局部和非定常的恒星对流理论,计算了0.6～3.0 M☉恒星演化模型的线性非绝热脉动.结果表明,赫罗图上脉动不稳定带右方的脉动不稳定的低温恒星可以分成2大类(群).一类由主序矮星、亚巨星和中低光度红巨星组成的类太阳振荡恒星,它们的中高阶(径向阶nr≥12)p模是脉动不稳定的,而低阶(nr≤ 5)模是脉动稳定的;另一类是由亮的红巨星和渐近巨星支星(AGB)组成的类长周期变星,它们的低阶模(nr≤5)是脉动不稳定的,而高阶模(nr≥12)却是脉动稳定的.能利用对流与脉动的耦合统一解释造父变星脉动不稳定带红边界、类太阳和类长周期变星脉动.对赫罗图右方的低温恒星的中低阶p模振荡,对流与脉动的耦合是主要的脉动激发和阻尼机制,而湍流的随机激发机制仅对类太阳振荡高阶p模重要.     

基于深度学习的太阳F_10.7辐射通量的短期预报研究

F_10.7太阳辐射通量作为输入参数被广泛运用于大气经验模型、电离层模型等空间环境模型,其预报精度直接影响航天器轨道预报精度.采用时间序列法统计了太阳辐射通量F10.7指数和太阳黑子数(SSN)的关系,给出了两者之间的线性关系,在此基础上提出了一种基于长短时记忆神经网络(Long and Short Term Memory,LSTM)的预报方法,方法结合了54 d太阳辐射通量指数和SSN历史数据来对F_10.7进行未来7 d短期预报,并与其他预报方法的预报结果进行了比较,结果表明:(1)所建短期预报7 d方法模型的性能优于美国空间天气预报中心(Space Weather Prediction Center, SWPC)的方法,预测值和观测值的相关系数(CC)达到0.96,同时其均方根误差约为11.62个太阳辐射通量单位(sfu),预报结果的均方根误差(RMSE)低于SWPC,下降约11%;(2)对预测的23、24周太阳活动年结果统计表明,太阳活动高年的第7 d F10.7指数预报平均绝对百分比误差(MAPE)最优可达12.9%以内,低年最优可达2...     

基于历史TLE的空间目标轨道预报误差演化规律研究

北美防空司令部(North American Aerospace Defense Command, NORAD)发布的双行根数(Two Line Element, TLE)是广大航天工作者最常用的轨道根数,与其对应的轨道模型是SGP4/SDP4 (Simplified General Perturbation Version 4/Simplified Deep-space Perturbation Version 4)解析模型.由于TLE中并没有包含相应的轨道精度信息,编目轨道的应用范围受到很大的限制.基于Space-Track网站发布的历史TLE数据和配套的SGP4/SDP4动力学模型,采用定轨标预报的方法统计并生成了大量目标轨道的预报误差,通过对预报轨道的时间区间划分给出了每个目标的预报误差随预报时间变化的拟合系数,并进一步对不同类型轨道预报误差的演化规律和特征进行了分类讨论,给出了4种轨道类型目标的轨道预报误差随时间演化的平均解析模型,为拓展双行根数的应用提供有价值的参考.     

冬季北极涛动与行星波活动的关系

为了进一步认识北极涛动与行星波之间的关系,利用NCEP/NCAR再分析资料并借助谐波分析、相关分析等方法讨论了北极涛动异常下行星波的活动情况。结果表明:在北极涛动指数强(弱)值年,纬向平均风场在中纬度明显减小(增大),在中高纬度明显增大(减小);行星波1波振幅在低纬度对流层中层和中纬度平流层明显增大(减小),在高纬度平流层明显减小(增大);2波振幅在中纬度对流层明显减小(增大),在高纬度平流层有所增大(减小)。E-P通量反映出在北极涛动强(弱)值年,行星波1波在中高纬度从地面向上传播显著增强(减弱),低纬度波导显著增强(减弱),极地波导显著减弱(增强);2波在中高纬度从地面向上传播显著减弱(增强),低纬度波导和极地波导变化不明显。     

福建永安雷暴气候特征分析

通过统计福建省永安市1958—2007年逐日雷暴观测资料,找出雷暴发生时空分布、年际、月际和日变化特征。结果表明：永安市雷暴日50年平均68．12日,年际变化呈波动减少趋势,3—9月是雷暴发生的高发期,占全年雷暴的95．3％,月际雷暴发生次数呈单峰型特征,峰值出现在8月,16—17时是一天中发生雷暴的最高期,西南方向发生的雷暴略多于其它方向。