Characterization of diurnal cycles in ZTD from a decade of global GPS observations   总被引：1，自引：0，他引：1  

Shuanggen Jin  O. F. Luo  S. Gleason 《Journal of Geodesy》2009,83(6):537-545

The diurnal cycle of the tropospheric zenith total delay (ZTD) is one of the most obvious signals for the various physical processes relating to climate change on a short time scale. However, the observation of such ZTD oscillations on a global scale with traditional techniques (e.g. radiosondes) is restricted due to limitations in spatial and temporal resolution. Nowadays, the International GNSS Service (IGS) provides an important data source for investigating the diurnal and semidiurnal cycles of ZTD and related climatic signals. In this paper, 10 years of ZTD data from 1997 to 2007 with a 2-hour temporal resolution are derived from global positioning system (GPS) observations taken at 151 globally distributed IGS reference stations. These time series are used to investigate diurnal and semidiurnal oscillations. Significant diurnal and semidiurnal oscillations of ZTD are found for all GPS stations used in this study. The diurnal cycles (24 hours period) have amplitudes between 0.2 and 10.9 mm with an uncertainty of about 0.5 mm and the semidiurnal cycles (12 h period) have amplitudes between 0.1 and 4.3 mm with an uncertainty of about 0.2 mm. The larger amplitudes of the diurnal and semidiurnal ZTD cycles are observed in the low-latitude equatorial areas. The peak times of the diurnal cycles spread over the whole day, while the peak value of the semidiurnal cycles occurs typically about local noon. These GPS-derived diurnal and semidiurnal ZTD signals are similar with the surface pressure tides derived from surface synoptic pressure observations, indicating that atmospheric tides are the main driver of the diurnal and semidiurnal ZTD variations.  相似文献   

基于能量守恒的星间距离变率与地球重力场频谱关系的建立与分析(英文)   总被引：1，自引：0，他引：1  

宁津生  钟波  罗志才  罗佳 《地球空间信息科学学报》2009,12(2):79-84

The spectral relationship between range-rate measurements and the gravity potential for low-low satellite-to-satellite tracking mission was established based on the energy conservation theory. Then the performances of satellite separation, the orbital altitude, and the accuracy of range-rate measurements in recovering the earth’s gravity field were simulated and analyzed by this method. Finally, the cumulative geoid errors of the reference mode were obtained by using the configuration parameters of the GRAC...  相似文献   

Paleoenvironmental implications of the guano phosphatic cementation on Dongdao Island in the South China Sea     

Xiao-Dong Liu  Li-Guang Sun  Zhong-Qi Cheng  San-Ping Zhao  Ke-Xin Liu  Xiao-Hong Wu  Zhou-Qing Xie  Xue-Bin Yin  Hong-Hao Luo  Xing-Fang Ding  Dong-Bo Fu  Yu-Hong Wang 《Marine Geology》2008,247(1-2):1-16

The phosphatic cement in the bioclastic sediment sequence on the northeastern shore of Dongdao Island in the South China Sea was studied and its paleoenvironmental implications discussed. Petrological characteristics and major, trace, REE element data unequivocally supported the notion that phosphatization was closely associated with avian guano decomposition and leaching, whereas carbon and oxygen isotope results further revealed that meteoric water were involved in these processes. AMS ¹⁴C dates on the brown phosphate cements indicate that they were formed around 5700, 5000–5100 and 2900 yr BP, respectively. The multi-episodes of phosphatization very likely correspond to intermittent seabird occupation on this island — possibly reflecting Holocene sea-level oscillation and/or long term climate changes in the South China Sea that have controlled seabird habitat. The phosphate cementation, which occurs widely in tropical islands, may be another useful monitor for sea-level and/or paleoclimate changes.  相似文献   

验后平差方法在Geosat/GM卫星测高数据处理中的应用   总被引：1，自引：0，他引：1       下载免费PDF全文

刘传勇  暴景阳  黄谟涛  欧阳永忠  陆秀平  李春菊  张献 《海洋测绘》2008,28(1):5-8

为了消除多代卫星测高数据之间的不协调性,利用两步处理法对Geosat/GM正常点海面高数据进行自交叉点平差及与T/P卫星测高数据联合平差,发现误差模型的系数计算出现异常,通过分析误差模型及正常点海面高数据的分布特征,找出了出现异常的原因,对计算方法进行改进后,大大提高了计算结果的稳定性和可靠性。  相似文献   

Effects of diet and body size on phosphorus utilization of Liza haematocheila T. ＆ S.   总被引：1，自引：0，他引：1  

康斌  线薇薇  武云飞 《中国海洋湖沼学报》2008,26(2):157-161

A 21-d laboratory experiment was conducted to study, the phosphorus （P） utilization of two different diets by redlip mullet Liza haematocheila T. ＆ S. Sand-filtered water in salinity 30 and temperatare 25℃ was used. Twenty-nine fish individuals were divided into three groups： 11 to group 1 （G1） fed on diet 1, 11 to group 2 （G2） fed on diet 2, and 7 to contrast group. Diet 1 was a commercial feed, more valuable in nutrition than diet 2 that similar to natural detritus. The results show the intake phosphorus （IP） of G1 was significantly higher than that of G2, and both increased linearly with body size at a certain amount of diet. The retention phosphorus （RP） in fish of G1 was lower than G2. The relationship between retention phosphorus and body size was positive and stronger in G2. Significant difference in faecal phosphorus （FP） was found between G1 and G2. Body size significantly impacted the excretion phosphorus （EP） in G1 but G2. The loss of intake phosphorus in G1 was 10.83-20.27 mg per g fish weight gain, higher than that in G2 for 6.63-9.56. Of the phosphorus, about 10% was allocated into growth, 50% in faeces, and the rest lost in excretion. The main part of phosphorus was lost in faeces but excretion. The phosphorus budget of the fish could be described as 100IP = 7.40RP ＋ 47.39FP ＋ 36.63EP （Diet 1） or 100IP = 11.93RP ＋ 56.64FP ＋ 21.76EP （Diet 2）.  相似文献   

我国地震预报的战略建议与思考     

骆鸣津  池顺良 《大地测量与地球动力学》2000,20(1):89-94

讨论了我国地震预报面对的问题和困难。认为只有加强以形变为主的前兆观测 ,才能作出地震的短临预报。目前前兆观测的主要问题在于可信度差 ,应把重点放在仪器探头上 ,只有探头提供的信息“源”可靠了 ,后续的采集、传输、预报的“流”才会有坚实的基础。我国现在建立以形变为主的前兆台网的技术条件已经成熟 ,建议建立全国高精度的高、中、低频衔接的前兆物理信息观测网络。  相似文献   

Wavenumber and depth properties of temperature finestructure in the region around the Ryukyu Islands     

鲍献文  吴克俭  罗义勇 《中国海洋湖沼学报》1999,17(3):258-264

INTRODUCTIONTheoceanicfinestructureintheEastChinaSea (ECS)Kuroshioregionhadbeenstudiedbyvariousresearchers.Fangetal.(1 988)studiedthefeaturesofthefinestructureinthesouthernshelfareaandtheKuroshioareaintheECSbyusingCTDdata .Baoetal.(1 996)analyzedsomefeaturesofthermohalinefinestructureandrevealeditsrelationwiththewatermassesandcurrentssysteminthenorthernECS .ButoceanicfinestructureintheeasternregionoftheKuroshiohassel dombeenstudied .Inthispaper,basedon 4 2CTDprofilesgatheredinsum…  相似文献   

尖吻鲈苗种工厂化培育模式的初步研究     

冯晓宇  罗儒端  孙启前  刘青利 《广东海洋大学学报》1999,(1)

采用室内水泥池及活饵培育配套技术进行尖吻鲈苗种阶段工厂化育苗。投放刚孵化出膜的仔鱼１６０万尾,经室内池８ｄ的培育,成活率为９０％;经１３ｄ的培育其规格超过１ｃｍ,成活率为５６．９％;经２４ｄ的培育平均规格达２ｃｍ左右,平均成活率为５０％,共育出８０万尾。苗种生长快,体质健壮,成活率高。关键技术是：基础设施配套;采用不同活饵,做到适口、及时转化、足量;定期过筛分级培育;水质控制良好;注意防病。２ｃｍ以上鱼种阶段采用多种方式培育,经１５～２０ｄ的饲养,规格达３～４ｃｍ,平均成活率为６５％～７５％。  相似文献   

裂纹深度和形状对构件断裂韧度的影响     

陈贤 《广东海洋大学学报》1999,(4)

在弯曲疲劳试验机上对几组包含有不同 a/ w值的贯穿裂纹和不同 a、c值的半椭圆裂纹的构件进行弯曲疲劳实验。结果表明 ,对于 60 Si2 Mn A钢来说 ,无论是表面裂纹还是贯穿裂纹 ,在浅裂纹情况下 ,其断裂韧度值比深裂纹高出 2 5%左右。当 a/ w值大于 0 .1时 ,无论 a/ w如何变化 ,KIC值基本保持不变。裂纹形状对断裂韧度的影响也不明显。  相似文献   

高精度GPS观测及其在福建东南沿海地壳形变研究中的应用   总被引：1，自引：1，他引：0  

邵占英  刘经南  姜卫平  徐菊生  罗佳  刘序俨  林继华 《大地测量与地球动力学》1999,19(4):1

对福建东南沿海ＧＰＳ地壳形变监测网的两期观测资料的处理方法及其精度进行了深入讨论,并根据复测资料的对比,对该地区现今地壳运动的基本特征进行了初步的分析。结果表明两期ＧＰＳ观测资料经严密处理后其基线重复性精度优于１０－ ８,高程分量的精度固定误差小于７ｍ ｍ ,比例误差优于１０－ ８,满足了研究该地区现今地壳运动的基本需要。利用统一处理后的两期ＧＰＳ观测结果获得了该地区现今地壳运动的基本图象,表明该地区相对于全球ＩＴＲＦ框架整体呈南东东向运动,台湾和福建沿海大陆相对运动是北西向压缩。这个结果和本地区北西向主压应力的构造应力场状态一致。ＧＰＳ测区范围内测点的相对运动表明测网所跨越的北东、北东东向断裂呈右旋走滑趋势,其活动量为毫米。  相似文献