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Reyes Castañeda, Cristhian Henry - One of the best experts on this subject based on the ideXlab platform.
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“Estudio comparativo del mortero de adherencia convencional y el mortero embolsado para la elaboración de muros de albañilería, Lima-2018”
'Universidad Cesar Vallejo', 2018Co-Authors: Reyes Castañeda, Cristhian HenryAbstract:El presente trabajo de investigación es de enfoque cuantitativo, puesto que muestra los resultados de un análisis comparativo de las propiedades física-mecánicas en Pilas y Muretes de albañilería, utilizando Mortero de Adherencia Convencional (Cemento-Arena-Agua) con proporción de Cemento-Arena 1:4, Morteros Embolsados denominados (Mortero Fácil “UNICON” y Mortero Fácil “TOPEX”) y considerando un solo tipo de Ladrillo kk-18H marca “Pirámide”. Por lo que la presente tiene como objetivo elaborar muros de Albañilería Portantes para comparar Resistencias en Compresión Axial, Compresión Diagonal y en Adherencia entre Ladrillo y Mortero .Además de los resultados obtenidos en el Laboratorio se evidencio la superioridad del Mortero Embolsado sobre el Mortero Tradicional en todos los Ensayos sometidos. Por esta razón el uso del Mortero Embolsado (TOPEX Y UNICON) disminuye el precio de costo en la elaboración de un Murete por m2 por lo que se sugiere que se puede usar en remplazo del Mortero de Adherencia Convencional
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“Estudio comparativo del mortero de adherencia convencional y el mortero embolsado para la elaboración de muros de albañilería, Lima-2018”
'Universidad Cesar Vallejo', 2018Co-Authors: Reyes Castañeda, Cristhian HenryAbstract:TesisLima NorteEscuela Profesional de Ingeniería CivilDiseño Sísmico y EstructuralEl presente trabajo de investigación es de enfoque cuantitativo, puesto que muestra los resultados de un análisis comparativo de las propiedades física-mecánicas en Pilas y Muretes de albañilería, utilizando Mortero de Adherencia Convencional (Cemento-Arena-Agua) con proporción de Cemento-Arena 1:4, Morteros Embolsados denominados (Mortero Fácil “UNICON” y Mortero Fácil “TOPEX”) y considerando un solo tipo de Ladrillo kk-18H marca “Pirámide”. Por lo que la presente tiene como objetivo elaborar muros de Albañilería Portantes para comparar Resistencias en Compresión Axial, Compresión Diagonal y en Adherencia entre Ladrillo y Mortero .Además de los resultados obtenidos en el Laboratorio se evidencio la superioridad del Mortero Embolsado sobre el Mortero Tradicional en todos los Ensayos sometidos. Por esta razón el uso del Mortero Embolsado (TOPEX Y UNICON) disminuye el precio de costo en la elaboración de un Murete por m2 por lo que se sugiere que se puede usar en remplazo del Mortero de Adherencia Convencional
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Estudio comparativo del mortero de adherencia convencional y el mortero embolsado para la elaboración de muros de albañilería, Lima-2018
'Universidad Cesar Vallejo', 2018Co-Authors: Reyes Castañeda, Cristhian HenryAbstract:El presente trabajo de investigación es de enfoque cuantitativo, puesto que muestra los resultados de un análisis comparativo de las propiedades física-mecánicas en Pilas y Muretes de albañilería, utilizando Mortero de Adherencia Convencional (Cemento-Arena-Agua) con proporción de Cemento-Arena 1:4, Morteros Embolsados denominados (Mortero Fácil “UNICON” y Mortero Fácil “TOPEX”) y considerando un solo tipo de Ladrillo kk-18H marca “Pirámide”. Por lo que la presente tiene como objetivo elaborar muros de Albañilería Portantes para comparar Resistencias en Compresión Axial, Compresión Diagonal y en Adherencia entre Ladrillo y Mortero .Además de los resultados obtenidos en el Laboratorio se evidencio la superioridad del Mortero Embolsado sobre el Mortero Tradicional en todos los Ensayos sometidos. Por esta razón el uso del Mortero Embolsado (TOPEX Y UNICON) disminuye el precio de costo en la elaboración de un Murete por m2 por lo que se sugiere que se puede usar en remplazo del Mortero de Adherencia Convencional
Chester J Koblinsky - One of the best experts on this subject based on the ideXlab platform.
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empirical orthogonal function analysis of global TOPEX poseidon altimeter data and implications for detection of global sea level rise
Journal of Geophysical Research, 1996Co-Authors: James R Hendricks, Robert R Leben, George H Born, Chester J KoblinskyAbstract:Two years of TOPEX/POSEIDON altimeter data are examined to determine the dominant spatial features and timescales of sea surface height variability in the global oceans and to estimate the rate of global sea level rise. Empirical orthogonal function (EOF) decomposition of 69 cycles of TOPEX altimeter data into the significant modes of variability reveals dominant annual and interannual timescales. The annual modes include the hemispheric-scale changes in steric height due to seasonal heating variations, changes in the strength of the major current systems in the equatorial Pacific, and the reversing monsoonal circulation in the Indian Ocean. The interannual modes capture oscillations in the tropical Pacific characteristic of recent El Nino events. A 2-year history of the change in mean sea level derived from TOPEX altimeter data reveals a rise of 5.2 mm/yr. By analyzing the contribution of each EOF mode to global mean sea level variations, we find that 82% of the rise in mean sea level is caused by a single interannual mode of variability. Altimeter data spanning only 2 years, however, are insufficient to resolve a complete El Nino-Southern Oscillation (ENSO) cycle which dominates the interannual EOF modes. Thus most of the rise in mean sea level derived from TOPEX altimetry is an artifact of incomplete temporal sampling of interannual variability. When a longer time series of TOPEX altimeter data is obtained and a complete ENSO cycle is observed, a significant reduction in the rate of global mean sea level rise estimated from TOPEX altimetry is expected. Most of the remaining rise in global mean sea level is explained by the annual EOF modes, suggesting a possible connection between sea level rise and changes in the steric component of sea surface height.
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the equator anomaly region as seen by the TOPEX poseidon satellite
Advances in Space Research, 1996Co-Authors: Dieter Bilitza, Chester J Koblinsky, S Zia, R Williamson, B BeckleyAbstract:Abstract Satellite altimeter observations of ice and sea surface heights are affected by the retardation/refraction of the altimeter signal in the ionospheric plasma. Altimeter data therefore need to be correct for the ionospheric influence using a ionospheric model like the International Reference Ionosphere. Another possibility is the use of a dual-frequency instrument like the TOPEX altimeter on the TOPEX/Poseidon satellite. By measuring the heights above the Earth surface at two frequencies the ionospheric electron content (IEC) between the ground and the satellite can be determined and thus the ionospheric correction (which is proportional to IEC) can be properly accounted for in the altimeter data analysis. Dual-frequency altimeter thus in effect provide a IEC measurement as a byproduct of the sea surface height observation. The ionospheric data base established by TOPEX/Poseidon since its launch in August 1992 provides a unique opportunity to study the distribution of IEC above the oceans with a 10-day repeat cycle, a region covered only by very few prior observations. The highly variable equator anomaly region is of particular interest since it is the region where globally the highest IEC values occur. We compare the TOPEX IEC with IEC values calculated from the IRI model for different satellite passes representing different conditions in terms of local time, latitude, longitude, and season. Our study points to the possible improvements of IRI that could be accomplished with the TOPEX ionospheric data base.
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an error covariance model for sea surface topography and velocity derived from TOPEX poseidon altimetry
Journal of Geophysical Research, 1994Co-Authors: Lucia S Tsaoussi, Chester J KoblinskyAbstract:In order to facilitate the use of satellite altimeter-derived sea surface topography and velocity in oceanographic models, a methodology is presented for deriving the total error covariance and its geographic distribution from TOPEX/POSEIDON measurements. The model is formulated using a parametric model fit to the altimeter range observations. The topography and velocity are modeled with spherical harmonic expansions whose coefficients are found through optimal adjustment to the altimeter range residuals using Bayesian statistics. All other parameters, including the orbit, geoid, surface models, and range corrections are provided as unadjusted parameters. The maximum likelihood estimates and errors are derived from the probability density function of the altimeter range residuals conditioned with a priori information. Estimates of model errors for the unadjusted parameters are obtained from the TOPEX/POSEIDON postlaunch verification results and the error covariances for the orbit and the geoid, except for the ocean tides. The error in the ocean tides is modeled, first, as the difference between two global tide models and, second, as the correction to the present tide model, the correction derived from TOPEX/POSEIDON data. A formal error covariance propagation scheme is used to derive the total error. Our global total error estimate for the TOPEX/POSEIDON topography relative to the geoid for one 10-day period is found to be 11 cm RMS. When the error in the geoid is removed, thereby providing an estimate of the time dependent error, the uncertainty in the topography is 3.5 cm RMS. This level of accuracy is consistent with direct comparisons of TOPEX/POSEIDON altimeter heights with tide gauge measurements at 28 stations. In addition, the error correlation length scales are derived globally in both east-west and north-south directions, which should prove useful for data assimilation. The largest error correlation length scales are found in the tropics. Errors in the velocity field are smallest in midlatitude regions; they are less than 2 cm/s over most of the Southern Ocean. For both variables the largest errors are caused by uncertainty in the geoid. More accurate representations of the geoid await a dedicated geopotential satellite mission. Substantial improvements in the accuracy of ocean tide models are expected in the very near future from research with TOPEX/POSEIDON data. Consequently, estimates of the time dependent sea surface topography from TOPEX/POSEIDON could achieve a total uncertainty of less than 3 cm RMS. This level of accuracy from a spaceborne sensor represents a remarkable engineering achievement and a major contribution to ocean science.
C. K. Shum - One of the best experts on this subject based on the ideXlab platform.
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laurentia crustal motion observed using TOPEX poseidon radar altimetry over land
Journal of Geodynamics, 2008Co-Authors: C. K. Shum, Yuchan Yi, Alexander BraunAbstract:Abstract A new method to estimate the vertical crustal motion from satellite altimetry over land was developed. The method was tested around Hudson Bay, where the observed vertical motion is largely caused by the incomplete glacial isostatic adjustment (GIA) as a result of the Laurentide ice sheet deglaciation since the last glacial maximum (LGM). Decadal (1992–2003) TOPEX/POSEIDON radar altimetry data over land surfaces were used. The results presented here are improved compared to a previous study (Lee, H., Shum, C.K., Kuo, C.Y., Yi, Y., Braun, A., 2008. Application of TOPEX altimetry for solid Earth deformation studies. Terr. Atmos. Ocean. Sci. 19, 37–46. doi:10.3319/TAO.2008.19.1-2.37(SA).) which estimated vertical motion only over relatively flat land surfaces (standard deviation of the height variation β = 0.4) whereas the combination of land altimetry solution with other measurements match best with the models RF3S20 ( β = 0.0) or RF3S20 ( β = 0.2) in terms of mean and standard deviation of the differences. It is anticipated that this innovative technique could potentially be used to provide additional constraints for GIA model improvement, and be applied to other geodynamics studies.
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hydrological and oceanic excitations to polar motion andlength of day variation
Geophysical Journal International, 2000Co-Authors: Jianli Chen, C. K. Shum, Ben F. Chao, Clark R. Wilson, Byron D TapleyAbstract:SUMMARY Water mass redistributions in the global hydrosphere, including continental water storage change and non-steric sea level change, introduce variations in the hydrological angular momentum (HAM) and the oceanic angular momentum (OAM). Under the conservation of angular momentum, HAM and OAM variations are signi¢cant excitation sources of the Earth rotational variations at a wide range of timescales. In this paper, we estimate HAM and OAM variations and their excitations to polar motion and length-of-day variation using soil moisture and snow estimates and non-steric sea level change determined by TOPEX/Poseidon satellite radar altimeter observations and a simpli¢ed steric sea level change model. The results are compared with the variations of polar motion and LOD that are not accounted for by the atmosphere. This study indicates that seasonal continental water storage change provides signi¢cant contributions to both polar motion and LOD variation, especially to polar motion X, and the non-steric sea level change is responsible for a major part of the remaining excitations at both seasonal scale and high frequencies, particularly in polar motion Y and LOD. The good correlation between OAM contributions and the remaining excitations shows that large-scale non-tidal mass variation exists in the oceans and can be detected by TOPEX/Poseidon altimeter observations.
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accuracy assessment of recent ocean tide models
Journal of Geophysical Research, 1997Co-Authors: C. K. Shum, Le C Provost, Philip L Woodworth, Olivier Francis, C King, S M Klosko, Jm Molines, Michael E ParkeAbstract:Over 20 global ocean tide models have been developed since 1994, primarily as a consequence of analysis of the precise altimetric measurements from TOPEX/POSEIDON and as a result of parallel developments in numerical tidal modeling and data assimilation. This paper provides an accuracy assessment of 10 such tide models and discusses their benefits in many fields including geodesy, oceanography, and geophysics. A variety of tests indicate that all these tide models agree within 2-3 cm in the deep ocean, and they represent a significant improvement over the classical Schwiderski 1980 model by approximately 5 cm rms. As a result, two tide models were selected for the reprocessing of TOPEX/POSEIDON Geophysical Data Records in late 1995. Current ocean tide models allow an improved observation of deep ocean surface dynamic topography using satellite altimetry. Other significant contributions include theft applications in an improved orbit computation for TOPEX/POSEIDON and other geodetic satellites, to yield accurate predictions of Earth rotation excitations and improved estimates of ocean loading corrections for geodetic observatories, and to allow better separation of astronomical tides from phenomena with meteorological and geophysical origins. The largest differences between these tide models occur in shallow waters, indicating that the current models are still problematic in these areas. Future improvement of global tide models is anticipated with additional high-quality altimeter data and with advances in numerical techniques to assimilate data into high-resolution hydrodynamic models.
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precision orbit determination for TOPEX poseidon
Journal of Geophysical Research, 1994Co-Authors: Byron D Tapley, C. K. Shum, John C Ries, G W Davis, R J Eanes, Bob E Schutz, M M Watkins, J A Marshall, R S Nerem, B H PutneyAbstract:The TOPEX/POSEIDON mission objective requires that the radial position of the spacecraft be determined with an accuracy better than 13 cm RMS (root mean square). This stringent requirement is an order of magnitude below the accuracy achieved for any altimeter mission prior to the definition of the TOPEX/POSEIDON mission. To satisfy this objective, the TOPEX Precision Orbit Determination (POD) Team was established as a joint effort between the NASA Goddard Space Flight Center and the University of Texas at Austin, with collaboration from the University of Colorado and the Jet Propulsion Laboratory. During the prelaunch development and the postlaunch verification phases, the POD team improved, calibrated, and validated the precision orbit determination computer software systems. The accomplishments include (1) increased accuracy of the gravity and surface force models and (2) improved performance of both the laser ranging and Doppler tracking systems. The result of these efforts led to orbit accuracies for TOPEX/POSEIDON which are significantly better than the original mission requirement. Tests based on data fits, covariance analysis, and orbit comparisons indicate that the radial component of the TOPEX/POSEIDON spacecraft is determined, relative to the Earth's mass center, with an RMS error in the range of 3 to 4 cm RMS. This orbit accuracy, together with the near continuous dual-frequency altimetry from this mission, provides the means to determine the ocean's dynamic topography with an unprecedented accuracy.
Anny Cazenave - One of the best experts on this subject based on the ideXlab platform.
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present day sea level change observations and causes
Reviews of Geophysics, 2004Co-Authors: Anny Cazenave, R. Steven NeremAbstract:We investigate climate-related processes causing variations of the global mean sea level on interannual to decadal time scale. Wc focus on thermal expansion of the oceans and continental water mass balance. We show that during the 1990s where global mean sea level change has been measured by TOPEX/Poseidon satellite altimetry. thermal expansion is the dominant contribution to the observed 2.5 mm/yr sea level rise. For the past decades, exchange of water between continental reservoirs and oceans had a small, but not totally negligible contribution (about 0.2 mm/yr) to sea level rise. For the last four decades, thermal contribution is estimated to about 0.5 mm/yr, with a possible accelerated rale of thermosteric rise during the 1990s. TOPEX/Posei don shows an increase in mean sea level of 2.5 mm/yr over the last decade, a value about two times larger than reported by historical tide gauges. This would suggest that there has been significant acceleration of sea level rise in the recent past, possibly related to ocean warming.
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ice cover variability in the caspian and aral seas from active and passive microwave satellite data
Polar Research, 2003Co-Authors: A. Kouraev, Anny Cazenave, Fabrice Papa, P I Buharizin, Jeanfrancois Cretaux, Julia Dozortseva, Frederique RemyAbstract:The paper discusses time and space variations of ice extent in the Caspian and Aral seas during the last decade (1992–2002). It uses synergy of data from active (radar altimeter) and passive (radiometer) microwave nadirlooking instruments onboard the TOPEX/Poseidon satellite. The proposed approach is substantiated and validated using both in situ and satellite imagery data for the Caspian Sea. The results indicate significant spatial and temporal variability of ice conditions, with a significant decrease of both the duration of ice season and ice extent during the last four winters (1998–2002). The TOPEX/Poseidon-derived time series of sea ice extent are very valuable in view of the fragmentary and mostly unpublished data on ice conditions on the Caspian and Aral seas since the mid-1980s.
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recent sea level change in the mediterranean sea revealed by TOPEX poseidon satellite altimetry
Geophysical Research Letters, 2001Co-Authors: Anny Cazenave, Cecile Cabanes, K Dominh, Sylvain MangiarottiAbstract:Using altimetry data of the TOPEX/Poseidon satellite available since early 1993, we show that the eastern Mediterranean sea level has been continuously rising during 1993–1999, at a rate up to 20 mm/yr southeast of Crete. Sea level rise is also observed in the Algerian-Provencal basin as well as in the Tyrrhenian and Adriatic seas. The north Ionian sea, on the other hand, shows an opposite trend, i.e., a sea level drop during the past seven years. Sea surface temperature trends are strongly correlated to sea level trends, indicating that at least part of the observed sea level change has a thermal origin. The recent Mediterranean sea level rise observed by TOPEX/Poseidon may be related to the warming trends reported from hydrographic cruises in the intermediate and deep waters of the eastern basin since the early 1990s, and of the western basin since the 1960s.
Byron D Tapley - One of the best experts on this subject based on the ideXlab platform.
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hydrological and oceanic excitations to polar motion andlength of day variation
Geophysical Journal International, 2000Co-Authors: Jianli Chen, C. K. Shum, Ben F. Chao, Clark R. Wilson, Byron D TapleyAbstract:SUMMARY Water mass redistributions in the global hydrosphere, including continental water storage change and non-steric sea level change, introduce variations in the hydrological angular momentum (HAM) and the oceanic angular momentum (OAM). Under the conservation of angular momentum, HAM and OAM variations are signi¢cant excitation sources of the Earth rotational variations at a wide range of timescales. In this paper, we estimate HAM and OAM variations and their excitations to polar motion and length-of-day variation using soil moisture and snow estimates and non-steric sea level change determined by TOPEX/Poseidon satellite radar altimeter observations and a simpli¢ed steric sea level change model. The results are compared with the variations of polar motion and LOD that are not accounted for by the atmosphere. This study indicates that seasonal continental water storage change provides signi¢cant contributions to both polar motion and LOD variation, especially to polar motion X, and the non-steric sea level change is responsible for a major part of the remaining excitations at both seasonal scale and high frequencies, particularly in polar motion Y and LOD. The good correlation between OAM contributions and the remaining excitations shows that large-scale non-tidal mass variation exists in the oceans and can be detected by TOPEX/Poseidon altimeter observations.
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measuring heat storage changes in the equatorial pacific a comparison between TOPEX altimetry and tropical atmosphere ocean buoys
Journal of Geophysical Research, 1998Co-Authors: Don P Chambers, Byron D Tapley, R H StewartAbstract:Heat storage variations in the equatorial Pacific have been studied from December 1992 through February 1997, using sea level data from the TOPEX altimeter and temperatures measured by 42 tethered buoys that are part of the Tropical Ocean-Atmosphere (TAO) array. The TOPEX measurements are converted to heat storage anomalies using a coefficient determined from mean climatological values. For 30-day averages the two measurements agree well over most of the region, except for the southwestern quadrant of the warm pool and a small region of the north-central equatorial Pacific. In the southwestern quadrant the TOPEX measurements indicate a smaller long-term heating rate than the TAO measurements, differing by as much as 30%. After examining conductivity-temperature-depth data in this region, it appears that the difference is due to a change in ocean salinity which is reflected in the TOPEX sea level measurements but not in the TAO heat measurements. The signal in the north-central region is predominately at an annual period, but there is not enough external measurements to determine what the source of the difference is. In the remainder of the equatorial Pacific, the agreement between the data suggests that the TOPEX measurements can be used to measure heat storage variations in the upper layer with reasonable accuracy. Thus TOPEX altimeter data can provide information about the heat budget of the equatorial Pacific in regions where there are few or no direct measurements.
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long period ocean heat storage rates and basin scale heat fluxes from TOPEX
Journal of Geophysical Research, 1997Co-Authors: Don P Chambers, Byron D Tapley, R H StewartAbstract:Over 3 years of TOPEX altimeter data have been used to estimate annual heat storage and long-period heat storage rates in 1° grids over the global oceans (65°S to 65°N). The mean annual heat storage rates computed from the TOPEX data agree with those computed from monthly-mean temperatures to within 30 W m2. The accuracy of long-term heat storage rates is estimated to be less than 10 W m2 over mid and low latitudes. Regional heat storage rates are larger than this error in many regions, most notably in the tropical Pacific and Indian Oceans and in the northern Atlantic Ocean. The heat storage changes associated with the 1991–1993 El Nino event are evident and agree with values computed from in situ measurements collected by the Tropical Ocean-Global Atmosphere program Tropical Atmosphere Ocean array moorings. The heat storage rates inferred from TOPEX data are also shown to qualitatively agree with sea surface temperature rates computed over the same time period. Finally, heat storage rates are integrated over ocean gyres to estimate atmosphere-ocean heat fluxes. Results suggest that from 1993 to 1995 the North Atlantic and the southern hemisphere gained heat from the atmosphere at a rate of between 1.5 and 2 W m2, while the North Pacific either lost heat or maintained zero net flux. However, the estimated error on this measurement is of the order of 1.5 W m2 indicating the true flux could be from 0 to 3 W m2. Both the TOPEX and temperature measurements suggest that the North Atlantic gained more heat per unit area than the North Pacific between 1992 and 1995.
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precision orbit determination for TOPEX poseidon
Journal of Geophysical Research, 1994Co-Authors: Byron D Tapley, C. K. Shum, John C Ries, G W Davis, R J Eanes, Bob E Schutz, M M Watkins, J A Marshall, R S Nerem, B H PutneyAbstract:The TOPEX/POSEIDON mission objective requires that the radial position of the spacecraft be determined with an accuracy better than 13 cm RMS (root mean square). This stringent requirement is an order of magnitude below the accuracy achieved for any altimeter mission prior to the definition of the TOPEX/POSEIDON mission. To satisfy this objective, the TOPEX Precision Orbit Determination (POD) Team was established as a joint effort between the NASA Goddard Space Flight Center and the University of Texas at Austin, with collaboration from the University of Colorado and the Jet Propulsion Laboratory. During the prelaunch development and the postlaunch verification phases, the POD team improved, calibrated, and validated the precision orbit determination computer software systems. The accomplishments include (1) increased accuracy of the gravity and surface force models and (2) improved performance of both the laser ranging and Doppler tracking systems. The result of these efforts led to orbit accuracies for TOPEX/POSEIDON which are significantly better than the original mission requirement. Tests based on data fits, covariance analysis, and orbit comparisons indicate that the radial component of the TOPEX/POSEIDON spacecraft is determined, relative to the Earth's mass center, with an RMS error in the range of 3 to 4 cm RMS. This orbit accuracy, together with the near continuous dual-frequency altimetry from this mission, provides the means to determine the ocean's dynamic topography with an unprecedented accuracy.
