Comparison of TOPEX/POSEIDON Altimeter Derived Wind Speed and Wave Parameters with Ocean Buoy Data in the North Indian Ocean   总被引：1，自引：0，他引：1  

Jignesh Kshatriya  Abhijit Sarkar  Raj Kumar 《Marine Geodesy》2001,24(3):131-138

Results of comparison exercises carried out between the state-of-the-art TOPEX/POSEIDON altimeter-derived ocean surface wind speed and ocean wave parameters (significant wave height and wave period) and those measured by a set of ocean data buoys in the North Indian Ocean are presented in this article. Altimeter-derived significant wave height values exhibited rms deviation as small as ±0.3 m, and surface wind speed of ±1.6 m/s. These results are found consistent with those found for the Pacific Ocean. For estimation of ocean wave period, the spectral moments-based semiempirical approach, earlier applied on GEOSAT data, was extended to TOPEX/POSEIDON. For this purpose, distributions of first four years of TOPEX/POSEIDON altimeter data and climatology over the North Indian Ocean were analyzed and a new set of coefficients generated for estimation of wave period. It is shown that wave periods thus estimated from TOPEX/POSEIDON data (for the subsequent two years), when compared with independent data set of ocean data buoys deployed in the North Indian Ocean, exhibit improved accuracy (rms ~ ±1.4 nos) over those determined earlier with GEOSAT data.  相似文献   

泥浆性能对定向钻进铺管孔壁稳定性的影响     

黄光明 《岩土钻凿工程》2008,(3):8-11

本文通过对泥浆性能的分析,特别是对泥浆流变参数的控制与调节在定向钻进非开挖铺管中的作用及其护壁原理的分析,简要阐述了泥浆性能对定向钻进铺管孔壁稳定性的影响,对非开挖定向钻进铺管施工有一定的指导意义。  相似文献   

用激光测距资料解地球定向参数的模型改进     

冯初刚  朱元兰 《测绘学报》2003,32(4):289-292

详细介绍了与SLR观测资料的高精度相适应的解EOP模型的改进，并且在复弧法中使用这个改进模型。当轨道参数为全局量，EOP参数为子弧量时，其中解极移运动Xp，Yp和日长变化率DUTIR的模型的更新，提高了解EOP的精度，特别提高了解DUTIR的精度；同时也提高了整个弧段的定轨精度。在EOP的改进模型中，以周日和半周日为周期的分量虽然对提高EOP本身的精度没有什么帮助，但是对整个弧段定轨精度的提高还是有益的。本文用1995—1999年LAGEOS-1的资料解得的EOP序列精度：Xp达0．43mas，Yp达0．41mas，DUTIR达0．022ms。90天弧长定轨残差好于2cm。  相似文献   

Under stress permeability determination of the Meuse/Haute-Marne mudstone     

S. Escoffier  F. Homand  N. Hoteit 《Engineering Geology》2005,81(3):329-340

In the underground waste isolation projects such as the ANDRA'one in the site of Bure, the transport properties of the surrounding rock mass is of fundamental importance. To measure very low permeability, we use the modified version of the pulse test proposed by Hsieh et al. [Hsieh, P.A., Tracy, J.V., Neuzil, C.E., Bredehoeft, J.D., Silliman, S.E., 1981. A transient laboratory method for determining the hydraulic properties of ‘tight’ rocks — I. Theory. Int. J. Rock Mech. Min. Sci. Geomech. Abstr. Vol. 18, pp. 245-252] which enables the intrinsic permeability, k, and the specific storage coefficient, S_s, of rocks such as mudstone to be characterized. In this paper, the special effort performed on the laboratory apparatus design, to ensure a good sensitivity of the rock response with respect to both parameters, k and S_s, is presented. In addition, two parameters identification procedures are proposed: the graphical method given by Hsieh et al. [Hsieh, P.A., Tracy, J.V., Neuzil, C.E., Bredehoeft, J.D., Silliman, S.E., 1981. A transient laboratory method for determining the hydraulic properties of ‘tight’ rocks — I. Theory. Int. J. Rock Mech. Min. Sci. Geomech. Abstr. Vol. 18, pp. 245-252] and a parameter identification based on the solution of an inverse problem. The efficiency of the apparatus design and the parameters identification procedures is then demonstrated though some pulse tests performed on the Meuse/Haute-Marne mudstone.  相似文献   

94/220 GHz星载雷达双波长比对非球形冰晶云参数敏感性分析     

吴举秀  窦芳丽  安大伟  顾瑜  周青  刘伟 《气象学报》2019,77(3):529-540

利用不同形状冰晶的散射特性,获得了非球形冰晶云的94/220 GHz测云雷达双波长比,探讨了非球形冰晶云的双波长比与云内微物理参数的关系,分析了衰减前后的星载雷达反射率因子及双波长比的垂直廓线。结果表明:（1）双波长比可以反映小到0.1 mm中值尺度的冰粒子,对粒子总数、谱的形状参数不敏感,对粒子大小、形状、云衰减较敏感。（2）雷达灵敏度一定时,星载雷达可测云厚与雷达波长、冰含水量（IWC）的垂直分布、云厚及衰减有关;没有进行衰减订正时,双波长比和衰减有关,冰含水量越大,波长越短,衰减越大,双波长比最大值与可探测云厚有关。两部雷达可探测冰含水量为0.001—0.1 g/m3、厚2 km的冰云;当云厚5 km、冰含水量垂直分布在0.001—0.2 g/m3时,云厚的94%基本可以被220 GHz云雷达探测到。（3）如果两部雷达气象方程中用水的介电因子,测量回波强度应进行介电因子的订正后再计算双波长比。   相似文献   

电子地图印刷网点修正模型的建立以及网点修正参数的确定     

魏斌 《测绘学院学报》1998,(1)

文中从地图的自动化生产出发 ,针对印刷网点的扩大特征 ,结合地图设计与出版系统 ,提出了链形网点阶调压缩的公式和各色各阶调网点的修正模型 ,并求出了各色各阶调网点的修正参数。  相似文献   

Mkn501长期光变性质     

杨江河  樊军辉  刘怡  王永祥  杨如曙 《天文学报》2007,48(4):407-417

在R和I波段对Mkn 501进行了测光观测,并结合历史文献得到Mkn 501在近30年间的光学、红外和射电等多个波段的光变曲线;讨论了光变与色指数之间的关系,发现色指数(B—V)与(B—R)之间有强相关,相关系数r=0.73.利用DCF方法分析了多波段光变的相关性,发现B波段与4.8GHz和红外波段的光变存在一定的正相关,利用CLEANest方法对B波段的光变曲线进行频谱分析,结果表明Mkn 501的光变曲线存在2个可能的周期,即(10.06±0.04)年和(21.60±0.17)年.  相似文献   

表面粗糙度参数的计算机辅助测量     

张世亮 《广东海洋大学学报》1996,(1)

介绍了一种用９Ｊ型光切法显微镜、６Ｊ型干涉法显微镜及电动轮廓仪，对ＧＢ１０３１—８３定义的表面粗糙度参数（Ｒａ，Ｒｚ，Ｒｙ，Ｓ．Ｓｍ）进行计算机辅助测量的方法。给出了有关计算公式，程序框图与测量实例。  相似文献   

Macrozoobenthic biomass in the Bay of Seine (eastern English Channel)   总被引：1，自引：0，他引：1  

Jean-Claude Dauvin  Thierry Ruellet 《Journal of Sea Research》2008,59(4):320-326

The benthic biomass values of various trophic groups were studied for the first time at the scale of the entire Bay of Seine (50 × 100 km) in the eastern English Channel. Sampling was carried out before and after the winter of 1999. In both cruises the suspension feeders dominated (66% of the 12 gAFDW m^− 2 in 1998 and 56% of the 10 gAFDW m^− 2 in 1999).The common European ophiuroid Ophiothrix fragilis was the most important contributor to total biomass. The repartition of its patches (sometimes > 20 gAFDW m^− 2) cannot be explained by the environmental parameters recorded (viz., granulometry, organic matter and pigment content).  相似文献   

样本输入方式对极端学习机预报日长变化的影响     

雷雨  蔡宏兵  赵丹宁 《天文研究与技术》2015,(3)

针对极端学习机(Extreme Learning Machine,ELM)用于日长(Length-Of-Day,LOD)变化预报过程中,样本输入方式对预报结果的影响进行了研究。采用跨度、连续和迭代3种样本输入方式对日长变化进行预报。结果表明,不同的样本输入方式对预报结果有很大影响,样本按跨度输入的预报精度最低;样本采用连续输入方式在短期和中长期预报中预报精度较高,但计算速度较慢,较适合中长期预报;样本按迭代输入方式的短期预报精度稍优于连续输入方式,而中长期预报精度则不如连续输入方式,但具有较高的预报效率。这对于日长变化的实时快速预报有着较高的现实意义。  相似文献