Download or read book A Study of Time varying Geopotential Models for ICESat Precision Orbit Determination written by Shannon Anne Kolensky and published by . This book was released on 2012 with total page 114 pages. Available in PDF, EPUB and Kindle. Book excerpt: Precision orbit determination (POD) plays a vital role in the success of space-borne laser altimetry missions, such as ICESat (Ice, Cloud, and Land Elevation Satellite). Although current ICESat POD processing standards are achieving remarkable accuracy, new time-varying geopotential models derived from the GRACE (Gravity Recovery And Climate Experiment) mission were investigated as candidates to improve POD performance for the planned ICESat-2 mission. The objective of this research is to examine the effect of these time-varying geopotential models -- which include models of non-tidal atmospheric and ocean variability, seasonal variability caused by water mass motion, and secular variations caused by present-day ice-melt and glacial isostatic adjustment -- on ICESat POD. The quality of the POD solutions produced with the new geopotential models was quantified by examining the usual orbit quality tests -- DDHL (double-differenced high-low) and SLR (satellite laser ranging) observation residuals and orbit overlaps. Although the solutions produced in every test case indicated consistency and high accuracy of 1-2 cm, these metrics were rather insensitive to the small changes in the POD solutions induced by the new geopotential models, and were incapable of identifying any statistically significant improvements in the POD. However, examination of geographically correlated radial orbit perturbations showed that the radial orbit differences exhibited significant variability on the order of several millimeters, and were coherent with the temporal variability of the models implemented. Since radial orbit errors directly relate to the scientific quantities of interest in the ICESat mission -- the altimetry measurements and derived ice-sheet surface elevations -- this result is of obvious importance. The most notable effects included an annual radial orbit variation of up to 4 mm over the Amazon region induced by implementing the GRACE Annual model, and a secular variation of radial orbit differences over Greenland when the GRACE Trend model was applied. The effect of radial orbit error on ice-sheet altimetry was quantified by examining the mean geographically correlated radial orbit differences. Since the ice sheet elevation rates computed by ICESat scientists are on the order of tens of centimeters per year, it was concluded that, although the radial orbit perturbations are readily observable, with magnitudes on the order of a few millimeters they are too small to have a significant impact on the altimetry science. However, depending on the scientific objectives and radial orbit accuracy requirements set for ICESat-2, these effects may be important, and the use of time-varying geopotential models in ICESat-2 POD may be beneficial.
Download or read book Expected Improvements in Modeling Earth s Time variable Gravity Field Using Multiple GRACE like Satellite Constellations written by Maxon Vaughn Widner (IV) and published by . This book was released on 2018 with total page 274 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Gravity Recovery and Climate Experiment (GRACE) mission has been a principal contributor in the study and quantification of Earth's time-varying gravity field. With continuing missions like GRACE Follow-On and the Gravity Field and Steady-State Ocean Circulation Explorer (GOCE) capitalizing on improved technologies such as laser interferometry and drag-free flying systems, respectively, the temporal aliasing of high frequency geophysical processes is anticipated to be the primary source of errors for future missions. Micro-satellite technology has presented the feasibility of improving the architecture of future missions with the implementation of a constellation of satellites having similar characteristics as GRACE. Such a configuration is suggested and analyzed to help address these under-sampling errors. The initial series of simulations is designed to build off the current GRACE mission with a near polar orbit, 450 km altitude, but with each satellite spaced approximately 120 km apart. Because of atmospheric and residual ground interference the reliability of ranging data diminishes at greater distances and therefore scenarios involving distances between satellites greater than 1,100 km are not evaluated. A multi-satellite orbit determination package (MSODP) is used to simulate these configurations and the observations corresponding to their orbits. This data is then processed using the Center for Space Research's Advanced Equation Solver for Parallel Systems (AESoP) linear least squares estimator providing high degree and order gravity field map solutions for each case. A sensitivity analysis is performed by varying certain parameters including: satellite spacing, altitude, and technological improvements. The multiple case results are consolidated to help ascertain the most optimal configuration for error reduction. Another series of data is provided from simulations which represent a constellation of satellites in a similar orbit except for the orbital plane being inclined at 72° with the same methodology implemented. This data is then combined in various configurations with the original data set of measurements and compared with the data from the original polar orbit scenario to determine the impact of a second train of satellites and their mitigation of detrimental effects like longitudinal striping. An analysis is performed to quantify the improvements of these configurations and is then evaluated to find optimal parameters for single and multiplane constellations. These results are extrapolated to show their impact on assessing metrics that would most benefit the water market's interests.
Download or read book Effect of GPS Orbit Errors on ICESat Precision Orbit Determination written by Hyung-Jin Rim and published by . This book was released on 2000 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Evaluation of Earth Gravity Field Models Used for Precise Satellite Orbit Determination Through Applications of Satellite Laser Ranging Data written by Mihloti Christina Botai and published by . This book was released on 2013 with total page 310 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book International Laser Ranging Services ILRS 2001 Annual Report written by and published by . This book was released on 2002 with total page 206 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Theory and Application of Extremely Precise Frequency Standards on Low Earth Orbit to the Determination of Geopotential Time variability written by Simone Giuliani and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Earth’s gravity plays a major role in molding our world. Monitoring the geopotential and its time variability reveals the mass redistribution occurring across our planet, thus informing us on matters like climate change and availability of water resources. The gravity features we are most interested in are characterized by spatial and temporal scales that can only be accessed via a mission in space. Among the most important gravity missions are GRACE/GRACE-FO and GOCE, which sense gravity through the derivatives of the Earth’s gravity field. We propose to apply chronometric geodesy, whose task is to measure gravity with clocks, in space through frequency comparison between orbiting clocks by means of the Doppler-canceling technique. The novelty of this approach consists in estimating Earth’s gravity via measurements of the geopotential itself, rather than its derivatives. The behavior of clocks in a gravitational field is governed by Einstein’s general relativity, which provides the best available description of gravitation. On the other hand, the frequency stability of clocks is now reaching 1019, becoming precise enough for geodesy applications. After describing the proposed gravity mission architecture, we provide a mathematical derivation of the Doppler-canceled frequency shift measurement. Then, we outline the estimation method and its numerical implementation, followed by a presentation of results. Our findings indicate the measurement can retrieve the geopotential coefficients with an accuracy potentially better than currently available gravity models employing clocks with a frequency stability of 1019. This result represents a proof of concept for the measurement, with gravity field solutions obtained from a mission simulation being shown here for the first time. However, once we introduce the orbit error, the kinematical approach utilized to solve the estimation problem presents severe limitations. The remedy is to adopt a dynamical approach, which would let us directly address the orbit error and other issues, e.g., frequency drift in clocks. In the conclusions, we discuss how to improve on our analysis and the necessary steps to follow in preparation for a future gravity mission, whose realization will be possible only when clock technology reaches the required performance (high frequency stability in a short integration time)
Download or read book International Aerospace Abstracts written by and published by . This book was released on 1999 with total page 1042 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Gravity and Geoid written by Hans Sünkel and published by Springer. This book was released on 1995-06-28 with total page 676 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume discusses recent advances and future prospects in the exploration of the gravity field. Both theoretical and practical aspects, ranging from gravity instrumentation, space and airborne gradiometry, satellite altimetry, the presentation of international measurement campaigns and projects, networks and gravity field-related data bases and software, to geophysical inversion techniques and recent undertakings such as the determination of the geoid in Europe, are dealt with.
Download or read book Coastal Altimetry written by Stefano Vignudelli and published by Elsevier. This book was released on 2023-06-27 with total page 248 pages. Available in PDF, EPUB and Kindle. Book excerpt: Coastal Altimetry: Selected Case Studies from Asian Shelf Seas provides information on developments over the past decade in the processing of remotely sensed altimetry in coastal areas, with an overview of expected errors and where they stem from, along with remaining gaps in processing. Challenges covered include the retracking of the altimetric signal to account for land contamination, tropospheric water corrections, and tidal model improvements, along with the pros and cons of widely available products. Additional chapters provide recent research in the regional seas of Asia and cover variability, dynamics, predictability and prediction, impacts of extreme events, effects to ecosystems, and more. This book offers readers a dataset that can illuminate our understanding of the propagation of planetary boundary waves that have a significant sea level signal in near coastal regions. As such, researchers and students who have a foundation in satellite altimetry and want to know the latest development of open ocean and coastal satellite altimetry, especially in Asian coastal regions, will benefit from this book. - Presents the advancement of coastal altimetry technologies from various dedicated experts - Includes case studies throughout to give real-life examples that can be implemented globally - Provides chapters that include summaries of key points and an outlook to the future
Download or read book Spring Meeting written by American Geophysical Union. Meeting and published by . This book was released on 2000 with total page 544 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Precise Geodetic Infrastructure written by National Research Council and published by National Academies Press. This book was released on 2010-10-25 with total page 157 pages. Available in PDF, EPUB and Kindle. Book excerpt: Geodesy is the science of accurately measuring and understanding three fundamental properties of Earth: its geometric shape, its orientation in space, and its gravity field, as well as the changes of these properties with time. Over the past half century, the United States, in cooperation with international partners, has led the development of geodetic techniques and instrumentation. Geodetic observing systems provide a significant benefit to society in a wide array of military, research, civil, and commercial areas, including sea level change monitoring, autonomous navigation, tighter low flying routes for strategic aircraft, precision agriculture, civil surveying, earthquake monitoring, forest structural mapping and biomass estimation, and improved floodplain mapping. Recognizing the growing reliance of a wide range of scientific and societal endeavors on infrastructure for precise geodesy, and recognizing geodetic infrastructure as a shared national resource, this book provides an independent assessment of the benefits provided by geodetic observations and networks, as well as a plan for the future development and support of the infrastructure needed to meet the demand for increasingly greater precision. Precise Geodetic Infrastructure makes a series of focused recommendations for upgrading and improving specific elements of the infrastructure, for enhancing the role of the United States in international geodetic services, for evaluating the requirements for a geodetic workforce for the coming decades, and for providing national coordination and advocacy for the various agencies and organizations that contribute to the geodetic infrastructure.
Download or read book Satellites written by Michel Capderou and published by Springer Science & Business Media. This book was released on 2005-12-31 with total page 558 pages. Available in PDF, EPUB and Kindle. Book excerpt: This useful resource deals with satellite orbits, showing how the wide range of available orbits can be used in communications, positioning, remote-sensing, meteorology, and astronomy.
Download or read book Satellite Altimetry Over Oceans and Land Surfaces written by Detlef Stammer and published by CRC Press. This book was released on 2017-10-31 with total page 617 pages. Available in PDF, EPUB and Kindle. Book excerpt: Satellite remote sensing, in particular by radar altimetry, is a crucial technique for observations of the ocean surface and of many aspects of land surfaces, and of paramount importance for climate and environmental studies. This book provides a state-of-the-art overview of the satellite altimetry techniques and related missions, and reviews the most-up-to date applications to ocean dynamics and sea level. It also discusses related space-based observations of the ocean surface and of the marine geoid, as well as applications of satellite altimetry to the cryosphere and land surface waters; operational oceanography and its applications to navigation, fishing and defense.
Download or read book Global Geodetic Observing System written by Hans-Peter Plag and published by Springer Science & Business Media. This book was released on 2009-07-25 with total page 367 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Global Geodetic Observing System (GGOS) has been established by the Int- national Association of Geodesy (IAG) in order to integrate the three fundamental areas of geodesy, so as to monitor geodetic parameters and their temporal varia- ?9 tions, in a global reference frame with a target relative accuracy of 10 or b- ter. These areas, often called ‘pillars’, deal with the determination and evolution of (a) the Earth’s geometry (topography, bathymetry, ice surface, sea level), (b) the Earth’s rotation and orientation (polar motion, rotation rate, nutation, etc. ), and (c) the Earth’s gravity eld (gravity, geoid). Therefore, Earth Observation on a global scale is at the heart of GGOS’s activities, which contributes to Global Change - search through the monitoring, as well as the modeling, of dynamic Earth processes such as, for example, mass and angular momentum exchanges, mass transport and ocean circulation, and changes in sea, land and ice surfaces. To achieve such an - bitious goal, GGOS relies on an integrated network of current and future terrestrial, airborne and satellite systems and technologies. These include: various positioning, navigation, remote sensing and dedicated gravity and altimetry satellite missions; global ground networks of VLBI, SLR, DORIS, GNSS and absolute and relative gravity stations; and airborne gravity, mapping and remote sensing systems.
Download or read book EOS Science Plan written by and published by . This book was released on 1999 with total page 406 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Remote Sensing of the Cryosphere written by Marco Tedesco and published by John Wiley & Sons. This book was released on 2015-01-27 with total page 430 pages. Available in PDF, EPUB and Kindle. Book excerpt: The cryosphere, that region of the world where water is temporarily or permanently frozen, plays a crucial role on our planet. Recent developments in remote sensing techniques, and the acquisition of new data sets, have resulted in significant advances in our understanding of all components of the cryosphere and its processes. This book, based on contributions from 40 leading experts, offers a comprehensive and authoritative overview of the methods, techniques and recent advances in applications of remote sensing of the cryosphere. Examples of the topics covered include: • snow extent, depth, grain-size and impurities • surface and subsurface melting • glaciers • accumulation over the Greenland and Antarctica ice sheets • ice thickness and velocities • gravimetric measurements from space • sea, lake and river ice • frozen ground and permafrost • fieldwork activities • recent and future cryosphere-oriented missions and experiments All figures are in color and provide an excellent visual accompaniment to the technical and scientific aspect of the book. Readership: Senior undergraduates, Masters and PhD Students, PostDocs and Researchers in cryosphere science and remote sensing. Remote Sensing of the Cryosphere is the significant first volume in the new Cryosphere Science Series. This new series comprises volumes that are at the cutting edge of new research, or provide focussed interdisciplinary reviews of key aspects of the science.
Download or read book Next Generation Earth System Prediction written by National Academies of Sciences, Engineering, and Medicine and published by National Academies Press. This book was released on 2016-08-22 with total page 351 pages. Available in PDF, EPUB and Kindle. Book excerpt: As the nation's economic activities, security concerns, and stewardship of natural resources become increasingly complex and globally interrelated, they become ever more sensitive to adverse impacts from weather, climate, and other natural phenomena. For several decades, forecasts with lead times of a few days for weather and other environmental phenomena have yielded valuable information to improve decision-making across all sectors of society. Developing the capability to forecast environmental conditions and disruptive events several weeks and months in advance could dramatically increase the value and benefit of environmental predictions, saving lives, protecting property, increasing economic vitality, protecting the environment, and informing policy choices. Over the past decade, the ability to forecast weather and climate conditions on subseasonal to seasonal (S2S) timescales, i.e., two to fifty-two weeks in advance, has improved substantially. Although significant progress has been made, much work remains to make S2S predictions skillful enough, as well as optimally tailored and communicated, to enable widespread use. Next Generation Earth System Predictions presents a ten-year U.S. research agenda that increases the nation's S2S research and modeling capability, advances S2S forecasting, and aids in decision making at medium and extended lead times.
