共查询到19条相似文献,搜索用时 46 毫秒
1.
2.
3.
详细阐述了利用地球重力场模型位系数计算高程异常的数学模型。选取标准向前列递推法和跨阶次递推法作为缔合勒让德函数的计算方法,分析了两种算法的适用范围。以高精度的超高阶EIGEN-6C4重力场模型为例,选择全球范围内5°×5°的格网组成的2701个点和具有代表性的12个点计算高程异常,将计算结果和ICGEM网站计算结果比较验证了算法的可靠性,并绘制了全球范围内5m等高距的高程异常等值线图,实现了全球高程异常的可视化。 相似文献
4.
高程信息是时空位置的重要组成部分,实时获取高精度海拔高是测绘导航信息化的关键步骤之一。北斗导航终端能快速高效地测定大地高,结合高精度的数字高程基准模型,可实时获取精密海拔高程。在顾及1985国家高程基准与全球高程基准之间垂直偏差的基础上,基于GOCE+EGM08重力场模型构建了统一到CGCS 2000椭球的区域数字高程基准模型,该模型范围对应北斗区域导航的覆盖范围,即55°S~55°N,55°E~180°E,模型精度优于米级,满足北斗导航终端对海拔高的应用需求;利用实时SQLITE数据库技术,基于该数字高程基准模型构建了北斗导航终端的海拔实时获取系统,实现了任意测点精密海拔高程的实时获取。 相似文献
5.
6.
7.
8.
分析了重力卫星数据构建的地球重力场模型EIGEN-CHAMP03S(140)、ITG-Grace2010s(180)、GO_CONS(240)、GOCO02s(250)的内符合精度,还与综合性地球重力场模型(EGM2008)进行了比较。然后,选用我国范围内854个AB级GPS/水准点,检核各模型分阶次确定的高程异常与实测值之间的差异,以体现其外符合精度。结果表明:以重力卫星数据构建地球重力场模型能以较高精度来表征重力场的中长波部分,与EGM2008模型的精度相当。在我国范围内,计算似大地水准面都能够达到米级精度,其中GOCO02s(250)模型精度最好,能达到0.5m的精度。 相似文献
9.
研究了基于EGM2008大地水准面模型的高程传递原理,通过青岛地区已知控制点数据计算得到EGM2008大地水准面模型与我国大地水准面差距,利用EGM2008模型计算高程异常的方法,结合GNSS技术实现高程传递。利用青岛市C级GNSS控制网数据,基于EGM2008模型,采用3种不同的拟合方法,建立了区域高程异常残差场,反演高程异常值与已知控制点高程异常值进行比对。利用青岛市D级GNSS点的数据对构建的格网模型的精度进行检核。结果表明:EGM2008大地水准面模型与我国的大地水准面存在22 cm左右的偏差;基于EGM2008模型的高程传递精度可达厘米级,可用于近海高程传递,几种拟合方法精度相当。 相似文献
10.
11.
12.
13.
黄东海大气边界层高度季节变化特征及其成因 总被引:2,自引:0,他引:2
利用CFSR再分析资料,采用EOF的分析方法统计分析了黄东海边界层高度的季节变化特征,探讨了2个模态的分布型以及与之相联系的下垫面热通量和垂直环流,统计了ICOADS资料中近30a逐月低云发生频率和海雾发生频率,揭示了其与边界层高度分布特征的一致性。结果表明:盛行风的平流作用与下垫面特征相结合造成的低空稳定性的变化是黄东海边界层高度时间上夏季低、冬季高,空间上呈现东高西低、南高北低的重要因素。EOF分析中第一模态表现为整个黄东海区域具有一致性,主要是大尺度环流的影响;第二模态为春秋相反的2个分布型,与海洋锋、冷舌以及暖水团的季节变化有着密切关系。黄东海大气边界层高度的最大值出现时间以及其大小在空间上较为一致,而最小值以黄东海海洋锋为界,向北逐渐减小,以南差异性不大,出现时间上有较大的差异。,这主要由黄东海冷舌、暖水团以及海洋锋的季节变化所引起对边界层经向分布影响较大所引起的。春夏季节,南部(西部)低云发生频率高于北部(东部),海雾发生频率低于北部(东部);海雾高频区对应较低边界层高度,而低云高频区对应相对较高边界层高度。 相似文献
14.
Shin-Ichi Ito Kazuyuki Uehara Takashi Miyao Hideo Miyake Ichiro Yasuda Tomowo Watanabe Yugo Shimizu 《Journal of Oceanography》2004,60(2):425-437
An observation line along the TOPEX/POSEIDON (T/P) ground track 060 was set to estimate the Oyashio transport. We call this
line the OICE (Oyashio Intensive observation line off-Cape Erimo) along which we have been conducting repeated hydrographic
observations and maintaining mooring systems. T/P derived sea surface height anomaly (SSHA) was compared with velocity and
transport on OICE. Although the decorrelation scale of SSHA was estimated at about 80–110 km in the Oyashio region, the SSHA
also contains horizontal, small-scale noise, which was eliminated using a Gaussian filter. In the comparison between the SSHA
difference across two selected points and the subsurface velocity measured by a moored Acoustic Doppler Current Profiler (ADCP),
the highest correlation (0.92) appeared when the smoothing scale was set at 30 km with the two points as near as possible.
For the transport in the Oyashio region, the geostrophic transport between 39°30′ N and 42°N was compared with the SSHA difference
across the same two points. In this case the highest correlations (0.79, 0.88 and 0.93) occurred when the smoothing scale
was set at 38, 6 and 9 km for reference levels of 1000, 2000 and 3000 db, respectively. The annual mean transport was estimated
as 9.46 Sv in the 3000 db reference case. The Oyashio transport time series was derived from the T/P SSHA data, and the transports
are smaller than that estimated from the Sverdrup balance in 1994–1996 and larger than that in 1997–2000. This difference
is consistent with baroclinic response to wind stress field.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
15.
16.
SARAL/AltiKa GDR-T are analyzed to assess the quality of the significant wave height (SWH) measurements. SARAL along-track SWH plots reveal cases of erroneous data, more or less isolated, not detected by the quality flags. The anomalies are often correlated with strong attenuation of the Ka-band backscatter coefficient, sensitive to clouds and rain. A quality test based on the 1 Hz standard deviation is proposed to detect such anomalies. From buoy comparison, it is shown that SARAL SWH is more accurate than Jason-2, particularly at low SWH, and globally does not require any correction. Results are better with open ocean than with coastal buoys. The scatter and the number of outliers are much larger for coastal buoys. SARAL is then compared with Jason-2 and Cryosat-2. The altimeter data are extracted from the global altimeter SWH Ifremer data base, including specific corrections to calibrate the various altimeters. The comparison confirms the high quality of SARAL SWH. The 1 Hz standard deviation is much less than for Jason-2 and Cryosat-2, particularly at low SWH. Furthermore, results show that the corrections applied to Jason-2 and to Cryosat-2, in the data base, are efficient, improving the global agreement between the three altimeters. 相似文献
17.
Interactions of Mesoscale Eddy and Western Boundary Current: A Reduced-Gravity Numerical Model Study
A reduced-gravity primitive equation eddy resolving model is used to study the interaction of a typhoon-induced eddy and a wind-driven general circulation. A typhoon-induced eddy is characterized by a core with a relative vorticity of the same order as the local Coriolis parameter. This eddy is neutrally stable relative to a disturbance induced by the westward advection of the eddy, due to the planetary β-effect. Hence, its evolution in the open ocean is similar to the classical frontal geostrophic eddy. Within the western boundary flow regime, the eddy is entrained northward by the mean circulation. This northward eddy advection and the mean-vorticity advection due to eddy flow induce another disturbance with a north-south asymmetry into the circular eddy. Together with the zonal asymmetric disturbance, associated with the planetary β-effect, the original circular eddy becomes unstable. The nonlinear eddy-flow interactions in the eastern flank of a western boundary current causes the eddy to deform quickly into an ellipse and lose its waters and energy into the mean circulation. 相似文献
18.
U. C. Mohanty Krishna K. Osuri A. Routray M. Mohapatra Sujata Pattanayak 《Marine Geodesy》2013,36(4):294-314
An attempt is made to delineate the relative performances and credentials of GFS, FNL, and NCMRWF global analyses/forecast products as initial and boundary conditions (IBCs) to the WRF-ARW model in the simulation of four Bay of Bengal tropical cyclones (TCs). The results suggest that FNL could simulate horizontal advection of vorticity maxima at 850 hPa; hence, the tracks are more realistic with least errors as compared to GFS and NCMRWF. The mean landfall errors for 24-, 48-, and 72-hour forecasts are 73, 41, and 72 km, respectively. The TC intensity is well captured by NCMRWF IBCs, as it could predict 850 hPa vorticity maxima. The 24-hour accumulated rainfall is well simulated with FNL, and equitable threat score is more than 0.2 up to 100 mm with minimum bias. 相似文献