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1.
Per Knudsen 《Journal of Geodesy》1994,68(1):7-18
The effects of residual ocean tide signals on altimetric mesoscale variability estimates are analyzed in the north east Atlantic region using one year of Geosat Exact Repeat Mission data. The variability is evaluated along collinear tracks and covariance functions are determined. Initial results show that the average variability is about 10 cm. Variability values of 15–20 cm are found between Iceland and the Faeroe Islands and values up to 1/2 m are found near the coast of the UK. Then a procedure for estimation of ocean tide signals combined with the collinear analyses was tested. A separation of the estimated tide residuals associated with M2, S2, and N2 resulted in a significant reduction of the variability. The average variability decreased to 5 cm and the temporal correlations vanished. A reduction of the large variability values from 15–50 cm to 5–10 cm demonstrates that significant residual ocean tide signals can be estimated and removed efficiently in a collinear analysis of the mesoscale ocean variability. 相似文献
2.
Procedures to calculate mean sea surface heights and gravity anomalies from altimeter-derived sea surface heights and along-track
sea surface slopes using the least-squares collocation procedure are derived. The slope data is used when repeat track averaging
is not possible to reduce ocean variability effects. Tests were carried out using Topex, Geosat, ERS-1 [35-day and 168-day
(2 cycle)] data. Calculations of gravity anomalies in the Gulf Stream region were made using the sea surface height and slope
data. Tests were also made correcting the sea surface heights for dynamic ocean topography calculated from a degree 360 expansion
of data from the POCM-4B global ocean circulation model. Comparisons of the anomaly predictions were carried out with ship
data using anomalies calculated for this paper as well as others.
Received: 19 August 1996 / Accepted: 14 April 1997 相似文献
3.
One year (November 1986 to October 1987) of Geosat altimeter data with improved orbits produced at The Ohio State University
has been used to define sea surface heights for 22 ERM and one year averaged Geosat track. All sea surface heights were referenced
to the single reference track through the application of geoid gradient corrections. The root mean square (RMS) gradient correction
was on the order of ±1 cm although it could reach 20 cm with data points in trench areas. 10 values used to form the mean
were considered.
Although this study was initially driven by a need for a good reference sea surface for geodetic applications the formation
of the reference track yields information on the variability of the ocean surface in the first year of the Geosat ERM. The
RMS point variability was ± 12.6 cm with only a very small number of values exceeding 50 cm when a depth editing criteria
was used. Global plots of the sea surface variability clearly reveal the major ocean currents and their variations in position
in the year. Examination of the 1° × 1° averaged sea surface height variations show average and maximum variability values
as follows: Gulf Stream (29 and 50 cm); Kurshio Current (24 and 49 cm); Agulhas Current (24 and 52 cm) and the Gulf of Mexico
(18 and 31 cm). These magnitudes may be dependent on the radial orbit correction procedure. To investigate this effect sea
slope variations were also computed. These results also showed clear current structures but also high frequency gravity field
information despite efforts to average out such information.
The data described in the paper is available from the authors for numerous other studies, some of which are suggested in the
paper. 相似文献
4.
5.
ARGO upper salinity measurements: perspectives for L-band radiometers calibration and retrieved sea surface salinity validation 总被引:1,自引:0,他引:1
With the view of preparing the strategy for the calibration/validation of future L-band satellite radiometers, we examine the salinity variability recorded by Array for Real-Time Geostrophic Oceanography (ARGO) floats in the upper 10-m layer of the surface ocean. Using one year of ARGO measurements,we show that the surface salinity variability at ten days and 200-km scales is above /spl plusmn/0.1 psu for 30% of the drifters and that this variability is larger than 0.2 psu in tropical regions affected by strong river discharges and by precipitations, and in frontal areas characterized by strong mesoscale activity. Vertical gradient observed between 5-10-m depth is much lower than the horizontal variability but leads to systematic biases in the tropics. The South Pacific Ocean appears to be the less variable both vertically and horizontally. 相似文献
6.
海洋涡旋数量大、分布广、含能高、裹挟强,是研究物质循环、能量级联和圈层耦合的理想载体。对涡旋的全生命周期追踪观测成为21世纪以来海洋遥感领域最重要的进展之一,并引发了新一轮涡旋研究的热潮。本文从涡旋的温度异常、物质示踪、旋转流场和闭合拓扑等特征出发,简述了红外辐射计、可见光扫描仪、微波高度计、合成孔径雷达等遥感技术在涡旋观测中的机理和方法,重点阐述了卫星高度计涡旋识别与追踪算法及其在涡旋形态学、运动学和动力学中的应用。基于虚拟星座下的多参数遥感,介绍了涡旋在海洋、大气、生态等交叉学科领域的前沿应用和最新进展。指出当前涡旋遥感发展面临的亚中尺度、垂直结构、跨学科研究等3大挑战,展望了新一代遥感技术在未来海洋科学特别是涡旋海洋学研究中的应用前景。 相似文献
7.
首先利用重力恢复与气候实验(gravity recovery and climate experiment,GRACE)卫星重力、卫星测高和海洋温盐数据分析了2003-2012年间南海海水质量的变化特征,进而结合海洋和气象资料探讨了厄尔尼诺和南方涛动(El Ni?o-Southern Oscillation,ENSO)、净淡水通量、海水体积输送和陆地径流在此期间对南中国海海水质量变化的影响。研究结果表明,南海海水质量变化主要受海面净淡水通量和海水体积输送的联合调制影响,周边陆地径流对其影响有限。南海海水质量季节性变化显著,且具有明显的长期增加趋势;ENSO通过改变降水和黑潮自吕宋海峡流入南海的水量影响南海海水质量,使得南海海水质量存在着显著的具有ENSO特征的年际变化。 相似文献
8.
Seasonal global mean sea level change from satellite altimeter, GRACE, and geophysical models 总被引:2,自引:1,他引:2
J. L. Chen C. R. Wilson B. D. Tapley J. S. Famiglietti Matt Rodell 《Journal of Geodesy》2005,79(9):532-539
We estimate seasonal global mean sea level changes using different data resources, including sea level anomalies from satellite
radar altimetry, ocean temperature and salinity from the World Ocean Atlas 2001, time-variable gravity observations from the
Gravity Recovery and Climate Experiment (GRACE) mission, and terrestrial water storage and atmospheric water vapor changes
from the NASA global land data assimilation system and National Centers for Environmental Prediction reanalysis atmospheric
model. The results from all estimates are consistent in amplitude and phase at the annual period, in some cases with remarkably
good agreement. The results provide a good measure of average annual variation of water stored within atmospheric, land, and
ocean reservoirs. We examine how varied treatments of degree-2 and degree-1 spherical harmonics from GRACE, laser ranging,
and Earth rotation variations affect GRACE mean sea level change estimates. We also show that correcting the standard equilibrium
ocean pole tide correction for mass conservation is needed when using satellite altimeter data in global mean sea level studies.
These encouraging results indicate that is reasonable to consider estimating longer-term time series of water storage in these
reservoirs, as a way of tracking climate change. 相似文献
9.
韩英 《武汉大学学报(信息科学版)》2008,33(2):208-211
利用小波多分辨分析方法对1992年10月至2002年8月南海区域海面高异常时间序列进行了分析处理,提取了该区域海面高线性升高信息.结果表明,南海区域在9.86 a的时间里海面高平均升高了94.1 mm;并获取了从2 a至45 d的5种波动传播的振幅和相位,分析了波动传播的概貌. 相似文献
10.
中国十分重视海洋遥感及其监测技术的发展,初步形成了具有优势互补的海洋遥感观测体系,并发挥了显著的经济和社会效益。其中,海洋一号(HY-1A/B)卫星已经广泛应用于中国海温预报业务系统、冬季海冰业务监测、夏季赤潮和绿潮监测、海岸带动态变化监测、近岸海水水质监测和渔业遥感监测等方面。海洋二号(HY-2A)卫星不仅填补了中国海洋动力环境卫星遥感的空白,也是目前国际上唯一在轨运行的集主被动微波遥感器于一身的综合型海洋动力环境卫星,具备同时获取风场、有效波高、海面高度和海面温度的能力。通过卫星获得的数据提高了中国海洋环境监测与灾害性海况预报的水平,为国民经济建设和国防建设、海洋科学研究、全球变化研究等提供了可靠的遥感数据,同时还在国际对地观测体系中发挥了重要作用,受到国内外用户的高度认可。海洋一号和海洋二号卫星系列为中国建立完善的海洋环境立体监测体系奠定了坚实基础。根据国家发展和"一带一路"建设的实施,在加快建设海洋强国、维护海洋权益和加快发展海洋经济的进程中对海洋遥感的发展也进一步提出了更高的要求和更紧迫的需求。为此,紧紧围绕国家海洋强国战略需求,在《国家民用空间基础设施中长期发展规划(2015年—2025年)》中专门规划了海洋观测卫星系列,服务于中国的海洋资源开发、环境保护、防灾减灾、权益维护、海域使用管理、海岛海岸带调查和极地大洋考察等方面,同时兼顾陆地和大气观测领域的需求。在充分继承已有HY-1A/B、HY-2A、高分三号(GF-3)和中法海洋卫星(CFOSAT)成功研制经验和应用成果的基础上,发展多种光学和微波遥感技术,建设新一代的海洋水色卫星和海洋动力环境卫星,具备卫星组网观测能力;发展海洋监视监测卫星,构建优势互补的海洋卫星综合观测体系。通过空间基础设施的建设,海洋遥感卫星必将在建设海洋强国的进程中发挥出重要作用。 相似文献
11.
Annual amphidromes: a common feature in the ocean? 总被引:1,自引:0,他引:1
The scientific term "amphidrome" is usually associated with tides in oceanography. The dozen tidal amphidromes observed in the ocean are critical points that determine the fundamental pattern of the global tidal system. Exploration of recently available satellite data with an unprecedented 1-2 decades duration suggests that an amphidrome is not a tide-only phenomenon in the ocean. Analysis of altimeter-derived sea level anomaly (SLA) data and radiometer-derived sea surface temperature (SST) data allows ten amphidromic points to be clearly identified in annual SLA and SST variations. These amphidromes are located in the tropical areas of the Pacific, Atlantic, and Indian oceans. Their existence implies that the annual cycle (in time) of the atmosphere-ocean system is translated into a rotary variation (in space) for many of the geophysical parameters. It can be concluded that annual amphidromes are common, the knowledge of which is of particular interest, given their annually "constant" nature, for the monitoring and understanding of oceanic, climatic, as well as biological variabilities at seasonal to decadal scales, which strongly affect many aspects of the natural and societal activities on the globe. 相似文献
12.
本文利用AVISO卫星高度计资料识别并追踪了北太平洋2007年—2012年的中尺度涡,并利用OSTIA的海表温度SST(Sea Surface Temperature)资料与MODIS的叶绿素a浓度(Chl-a)资料,研究了北太平洋2007年—2012年中尺度涡SST和Chl-a浓度的时空分布特征,并分析北太平洋典型中尺度涡SST与Chl-a浓度的变化特征,主要结论如下:本文共识别出992个中尺度涡,其中442个气旋涡,550个反气旋涡。中尺度涡SST时空分布特征为:气旋涡温度强度(ICE)月变化特征比反气旋涡温度强度(IAE)更强。ICE年际变化显著,IAE则不明显。温度强度较强的气旋涡和反气旋涡集中分布在黑潮延伸区。中尺度涡Chl-a浓度时空分布特征如下:气旋涡和反气旋涡Chl-a浓度月变化特征明显,且二者的变化趋势一致;年际变化则均不明显。Chl-a浓度值高的中尺度涡主要分布在高纬海域。中尺度涡SST与海洋动力参数(振幅、涡度和涡动能(EKE))的相互关系为:反气旋涡SST与振幅的相关性亦正亦负,且在空间上均匀分布。气旋涡SST与振幅的负相关系数主要分布在黑潮延伸区。正相关性强的反气旋涡多于气旋涡。反气旋涡SST与涡度的相关性亦正亦负,气旋涡SST与涡度呈负相关。反气旋涡SST与EKE的相关性亦正亦负;气旋涡的相关性为正。中尺度涡Chl-a浓度与海洋动力参数的相互关系为:反气旋涡Chl-a浓度与振幅的相关性为正,且在空间上均匀分布;气旋涡在黑潮延伸区与阿拉斯加湾呈正相关。反气旋涡和气旋涡Chl-a浓度与涡度均呈正相关。反气旋涡Chl-a浓度与EKE呈正相关;气旋涡Chl-a浓度与EKE相关性亦正亦负。 相似文献
13.
新一代卫星重力探测任务GRACE大大提高了地球重力场模型中长波分量的精度,使得联合卫星测高平均海面分离更精细稳态海洋动力地形成为可能。本文利用T/P(1994年~2003年)和JASON-1(2003年~2005年)卫星测高数据确定了全球30′×30′平均海面高;基于重力场模型WHU-GM-05,计算得到对应于海面高的GRACE海洋大地水准面格网值;利用“移去-恢复法”和高斯滤波求得全球稳态海面地形。与EGM96、R io05、ECCO和GGM02模型进行比较,检验结果表明GRACE任务有效的改善了海洋大地水准面的精度,使得稳态海洋动力地形能够呈现更多细部。 相似文献
14.
15.
The crossover adjustment plays a central role in the processing of satellite altimeter measurements. The usual procedure
is to form sea surface height differences at crossover points, solve for the radial orbit error (with due attention to the
singular nature of the estimation problem) and then to construct altimetric sea-level maps using the mean sea surface heights
at the crossover points. Our approach is very different, to make direct use of measurements at crossover points without differencing
and to estimate simultaneously orbit parameters, mean sea surface height and sea surface height variability in a single, unified
adjustment. The technique is suited for repeat data over an area small enough that adjoining passes may be considered to be
parallel and to permit the solution of a set of linear equations of dimension equal to the number of crossover points. The
size of the numerical problem is almost independent of the number of repeat cycles of the altimeter mission. Explicit recognition
is given to the rank defect of the least-squares estimation problem; we show that, for an orbit model with r parameters, the rank defect of the local crossover problem is exactly r
2. The defect may be overcome by choosing an appropriate set of constraints – either giving a best fit of mean sea surface
heights to a reference surface, or minimising orbit parameters, or a minimum norm solution in which both mean sea surface
heights and orbit parameters are minimised. There is no need to choose a reference pass, all passes are treated equally and
data gaps are easily accommodated. Numerical results are presented for the south-western Indian Ocean, based on the first
2 years of altimeter data from the Geosat Exact Repeat Mission.
Received: 31 May 1996 / Accepted: 19 April 1997 相似文献
16.
针对海洋中尺度涡现象,提出一种基于海平面高度异常数据(SLA)的中尺度涡泛克里金提取算法。该算法运用变差函数工具计算SLA变差场,定义为广义振幅场,再利用泛克里金插值消除数据虚警和噪声,借助广义振幅场与实际振幅的关系通过少数几条特征等值线实现涡旋及其属性的提取。选取北太平洋作为实验区,采用2012年4月的4期SLA进行了中尺度涡的定量提取、分析,共提取出841个中尺度涡(含3个多核涡),包含450个气旋涡和391个反气旋涡;与其他遥感提取方法的对比显示北太平洋中尺度涡的成功检测率接近90%,过度检测率小于20%。结果表明:(1)算法具有省时高效性,通过对SLA场的重构创建广义振幅场,避免了等值线筛选过程,相对于海面高度闭合等值线等其他遥感方法具有判据简单及提取速度快的特性;(2)可靠性好,能够通过推导得出的特征等值线确保稳定的提取准确度;算法建立在发展成熟的等值线提取方法之上,并且有变差函数与泛克里金法的理论支撑;(3)自适应性强,可以对任意海区进行实时的涡旋检测和提取,并且除振幅值统计资料及必要基础数据外无需依赖其他辅助性数据。 相似文献
17.
18.
Mean sea surface heights and residual radial orbit errors are estimated simultaneously in a single global crossover adjustment
of multiple cycles of satellite altimetry data. The rank defect inherent in the estimation problem is explicitly identified
and treated in various ways to give solutions that minimise (in norm) either orbit errors or mean sea surface heights. The
rank defect gives rise to geographically correlated orbit error, consisting of those components of the orbit error or those
components of the map of sea surface heights which fall within the nullspace of the estimation problem and which cannot be
distinguished as orbit error or ocean signal. We show that, in the case of Topex/Poseidon data, the geographically correlated error consists largely of long-wavelength and long-period sea surface fluctuations, which
in the past has often been assigned as orbit error.
Received 11 September 1995; Accepted 2 September 1996 相似文献
19.
以北极为研究区,使用CryoSat-2数据,利用现有海冰厚度卫星测高研究中4种主流算法(Laxon03算法、Kurtz09算法、Yi11算法和Laxon13算法)分别对北冰洋海冰厚度进行估算,并将估算结果与研究区IceBridge机载激光测高冰厚数据进行了比较,探索各算法海冰厚度估算的差异,寻找最优的估算算法,为估算长时序海冰厚度提供基础和参考。结果表明,4种算法估算的海冰厚度空间分布较为一致,但不同算法估算的结果差异较大,可达0.476 m;4种算法估算结果大小依次为Laxon03算法、Yi11算法、Laxon13算法、Kurtz09算法;4种算法估算的平均海冰厚度差异,在北极波弗特海海域最大,其次是北极中心海域、格陵兰和挪威海;Laxon13算法估算结果相对于IceBridge观测结果与其他算法相比,具有最小的平均偏差和均方根误差,是卫星测高估算海冰厚度的最优算法。 相似文献
20.
利用TOPEX/Poseidon卫星测高资料监测全球海平面变化 总被引:17,自引:1,他引:17
本文利用1993年1月至1999年5月的TOPEX/Poseidon卫星测高数据计算了全球海平变化。海平面模型误差和不恰当的加权方法都会影响全球海平面序列的周年变化,潮汐模型误差对于季节性变化有明显的影响。利用两个高度计算的海平面变化存在周年变化存在明显的差异,利用TOPEX高度计和Poseidon高度计得到的该时段全球平均海平面的变化率分别为2.0mm/a和-0.5mm/a。与南方涛动指数的比较 相似文献