卫星云图资料估计湿度的适时回归方法及其影响诊断   总被引：1，自引：3，他引：1  

吴诚鸥  沈桐立  王顺凤 《南京气象学院学报》2001,24(2):162-164

提出适时回归方法，由卫星云图资料估计湿度场，数理统计中的回归诊断是查找野点的有力方法，本文成功地运用回归诊断于卫星云图资料估计湿度场，提高了精确度，得到良好效果。  相似文献   

用GMS—5气象卫星资料遥感监测白天雾的研究   总被引：16，自引：2，他引：16  

李亚春  孙涵  李湘阁  唐勇  徐萌 《南京气象学院学报》2001,24(3):343-349

用日本GMS－5静止气象卫星的可见光通道和长波红外通道的资料，采用多通道合成和图像增强技术生成云雾彩色图像，分析了云雾的纹理特征、运动规律和消散规律，探讨了白天雾和低层云的遥感监测和识别方法，对沪宁高速公路沿线大雾进行了实时监测。  相似文献   

气象卫星探测资料在数值天气预报中的应用   总被引：2，自引：0，他引：2  

郑祚芳  沈桐立  张秀丽 《气象》2001,27(9):3-8

卫星遥感技术和其他非常规观测技术的发展和成熟，提供了大量的非实时、非完全、准连续的观测资料。与其他非常规观测资料相比，卫星观测资料具有水平分辨率高，观测面广阔，测量误差易于掌握等优点。分析和总结了目前卫星观测资料在数值天气预报模式中的应用情况，并对其未来发展做了一些有益的探讨。  相似文献   

Glonass Laser Ranging Accuracy With Satellite Signature Effect   总被引：1，自引：0，他引：1  

Toshimichi Otsubo  Graham M. Appleby  Philip Gibbs 《Surveys in Geophysics》2001,22(5-6):509-516

GLONASS satellites have been tracked by the worldwide laser ranging networkas well as by the GLONASS-borne microwave-based technique. Owing to thelarge size of their corner cube reflector arrays, the amount of ranging data is enough to determine their orbits from laser ranging data alone. We found, however, that the large size of the array affected the accuracy of measurement to an extent that is dependent on the characteristics of the ranging systems. An azimuthal variation of the reflector array response was also detected in observations from single-photon laser ranging. Orbital analysis reveals that the effect makes the measured range on average 22 mm shorter than expected in the absence of the large array, which explains more than half of the offset of 39 mm previously discovered between microwave and laser orbits.  相似文献   

Slicer Laser Altimetry In The Eastern Caribbean     

P. Jansma  G. Mattioli  A. Matias 《Surveys in Geophysics》2001,22(5-6):561-579

Data acquired by the airborne Scanning Lidar Imager of Canopies by EchoRecovery (SLICER) laser altimeter provided high-resolution digital topographicdata over Puerto Rico, the Dominican Republic and several of the Lesser AntillesIslands. The instrument was developed by the NASA-Goddard Space Flight Center.It has the capability of multibeam resolution of ground elevations beneath densecanopy areas. Data, therefore, can be used to generate a more accurate representation of the ground surface by removing the vegetation cover. Although internal precision is high (10 cm to 1 m), absolute accuracy is difficult to evaluate and depends on several factors, including the post-processed kinematic GPS (KGPS) flight path for the aircraft platform and clear identification of ground returns in the SLICER waveform. We compared topographic profiles from USGS 30 m and 1:250K DEMs for Puerto Rico with those generated by SLICER and with spot elevations derived from static and continuous GPS surveys. SLICER and KGPS surveys cross at six points in western Puerto Rico. Agreement between both elevation data sets is excellent and well fit (r = 0.921) by a linear model with a final residual bias of -0.501 m for SLICER ground returns relative to KGPS elevations. The agreement between SLICER and USGS 30 m DEMs is also very good with the largest errors associated with steep slopes and high vegetation cover. Residuals between KGPS and USGS 30 m DEMs are +1 ± 25 m, assuming a fixed uniform offset of +43.23 m between WGS84 and mean sea level.  相似文献   

Contributions of Satellite Laser Ranging to Past and Future Radar Altimetry Missions     

P. Exertier  P. Bonnefond  J. Nicolas  F. Barlier 《Surveys in Geophysics》2001,22(5-6):491-507

Satellite laser ranging (SLR) has proven avery efficient method for contributingto the tracking of altimetric satellites anddetermining accurately their orbitalthough hampered by the non-worldwide coverageand the meteorologicalconditions. Indeed, in some cases it is the onlymethod available to determinethe satellite orbit (e.g., the orbits of the ERS-1and Geosat-Follow-On missions).Moreover, any operational and non-weather dependenttechniques, like GPS,DORIS, PRARE, can exhibit systematic errors inpositioning and orbitography. Acomparison with SLR results allows to evidence sucherrors and vice versa. Fordoing that, two different approaches for determiningprecise orbits can beconsidered: one based on global orbit determination,the other on a short-arctechnique used to locally improve a global orbitdetermined by another trackingtechniques, such as DORIS or GPS. We can thusvalidate a global orbit andachieve orbit quality control to a level of2 to 3 centimeters at present and expectto achieve a level of 1 to 2 centimeters inthe near future. Errors induced bystation coordinates or by the gravity field(geographically correlated errors, forexample) can be estimated from SLR tracking data.Colocation experiments withdifferent techniques in the same geodetic siteplay also a key role to ensure preciserelationships between the geodetic referenceframes linked to each technique. Inparticular, the role of the SLR technique is tostrengthen the vertical component(including velocity) of the positioning, whichis crucial for altimetry missions.The role of SLR data in the modelling of the firstterms of the gravity field has finally to be emphasized,which is of primary importance in orbitography,whatever the tracking technique used.Another application of SLR technology is thesatellite altimeter calibration. Examples of past calibrationand future experiments are given, including theaccuracy we can expect from the Jason-1 and EnviSatspace oceanography missions.  相似文献   

Ice Sheet And Satellite Altimetry     

Frédérique Rémy  Benoît Legresy  Laurent Testut 《Surveys in Geophysics》2001,22(1):1-29

Since 1991, the altimeters of the ERS European Satellites allow the observation of 80% of the Antarctica ice sheet and the whole Greenland ice sheet: They thus offer for the first time a unique vision of polar ice caps. Indeed, surface topography is an essential data thanks to its capacity to highlight the physical processes which control the surface shape, or to test models. Moreover, the altimeter is also a radar which makes it possible to estimate the snow surface or subsurface characteristics, such as surface roughness induced by the strong katabatic wind or ice grain size. The polar ice caps may not be in a stationary state, they continue to respond to the climatic warming of the beginning of the Holocene, that is 18000 years ago, and possibly start to react to present climatic warming: the altimeter offers the unique means of estimating the variations of volume and thus the contribution of polar ice caps to present sea level change.  相似文献   

Geoid and Sea Surface Topography Derived from ERS-1 Altimeter Data by the Adjoint Method     

Blinken  Robert  Koch  Karl-Rudolf 《Studia Geophysica et Geodaetica》2001,45(3):235-250

A method for splitting sea surface height measurements from satellite altimetry into geoid undulations and sea surface topography is presented. The method is based on a combination of the information from altimeter data and a dynamic sea surface height model. The model consists of geoid undulations and a quasi-geostrophic model for expressing the sea surface topography. The goal is the estimation of those values of the parameters of the sea surface height model that provide a least-squares fit of the model to the data. The solution is accomplished by the adjoint method which makes use of the adjoint model for computing the gradient of the cost function of the least-squares adjustment and an optimization algorithm for obtaining improved parameters. The estimation is applied to the North Atlantic. ERS-1 altimeter data of the year 1993 are used. The resulting geoid agrees well with the geoid of the EGM96 gravity model.  相似文献   

High-resolution mean sea surface computed with altimeter data of Ers-1 (geodetic mission) and topex-poseidon   总被引：1，自引：0，他引：1  

A. Cazenave  P. Schaeffer  M. Berge  C. Brossier  K. Dominh  M. C. Gennero 《Geophysical Journal International》1996,125(3):696-704

The remote-sensing satellite ERS-1, launched in 1991 to study the Earth's environment, was placed on a geodetic (168-day repeat) orbit between 1994 April and 1995 March to map, through altimetric measurements, the gravity field over the whole oceanic domain with a resolution of 8 km at the equator in both along-track and cross-track directions. We have analysed the precise altimeter data of the geodetic mission, and, by also using one year of Topex-Poseidon altimeter data, we have computed a global high-resolution mean sea surface. The various steps involved in pre-processing the ERS-1 data consisted of correcting the data for environmental factors, editing, and reducing, through crossover analyses, the radial orbit error, which directly affects sea-surface height measurements. For this purpose, we adjusted sinusoids at 1 and 2 cycle rev⁻¹ along the ERS-1 profiles in order to minimize crossover differences between ERS-1 and yearly averaged Topex-Poseidon profiles. In effect, the orbit of Topex-Poseidon is very accurately determined (within 2–3 cm for the radial component), so Topex-Poseidon altimeter profiles can serve as a reference to reduce the ERS-1 radial orbit error. The ERS-1 residual orbit error was further reduced through a second crossover analysis between all ascending and descending profiles of the geodetic mission. The along-track ERS-1 and Topex-Poseidon data were then interpolated over the whole oceanic domain on a regular grid of 1/16°× 1/16° size. The mapping of the gridded sea-surface heights reveals the very fine structure of the marine geoid, up until now unknown at a global scale. This new data set will be most useful for marine geophysical and tectonic investigations.  相似文献   

Thermal omens before earthquakes   总被引：3，自引：0，他引：3  

刘德富  彭克银  刘维贺  黎令仪  侯建盛 《地震学报(英文版)》1999,12(6):710-715

IntroductionTopredictwherethedisastrousearthquakeoccursisoneofthegreatestproblemswhichconcernsthepublicmostandisdifficulttoresolvebythescienceandtechnologyoftoday.Inordertoresolvetheproblemandreducethelossofanearthquake,aseriesofobservationsystemshavebeeninstalledaroundtheworldtoattempttofindsomeomenbeforeaneanhquake.Butmostoftheearthquakepredictionsarefailedbecauseof"lookonewayandrowanother".Itshowsthatthecapabilityoftheobservationsystemofthestress-strainfieldandotherphysicparameterfields,whi…  相似文献