GRACETOOLS—GRACE Gravity Field Recovery Tools

This paper introduces GRACETOOLS, the first open source gravity field recovery tool using GRACE type satellite observations. Our aim is to initiate an open source GRACE data analysis platform, where the existing algorithms and codes for working with GRACE data are shared and improved. We describe the first release of GRACETOOLS that includes solving variational equations for gravity field recovery using GRACE range rate observations. All mathematical models are presented in a matrix format, with emphasis on state transition matrix, followed by details of the batch least squares algorithm. At the end, we demonstrate how GRACETOOLS works with simulated GRACE type observations. The first release of GRACETOOLS consist of all MATLAB M-files and is publicly available at Supplementary Materials.

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Multiresolution wavelet analysis applied to GRACE range rate residuals

10.5194/gi-2018-50 ◽

2019 ◽

Cited By ~ 1

Author(s):

Saniya Behzadpour ◽

Torsten Mayer-Gürr ◽

Jakob Flury ◽

Beate Klinger ◽

Sujata Goswami

Keyword(s):

Wavelet Analysis ◽

Gravity Field ◽

Recovery Process ◽

Ocean Tide ◽

Discrete Wavelet ◽

Error Sources ◽

Gravity Field Recovery ◽

Multi Resolution Analysis ◽

Range Rate ◽

Process Observation

Abstract. For further improvements of gravity field models based on Gravity Recovery and Climate Experiment (GRACE) observations, it is necessary to identify the error sources within the recovery process. Observation residuals obtained during the gravity field recovery contain most of the measurement and modeling errors and thus can be considered as a realization of actual errors. In this work, we investigate the ability of wavelets to help in identifying specific error sources in GRACE range rate residuals. The Multi-Resolution Analysis (MRA) using Discrete Wavelet Transform (DWT) is applied to decompose the residual signal into different scales with corresponding frequency bands. Temporal, spatial, and orbit-related features of each scale are then extracted for further investigations. The wavelet analysis has proved to be a practical tool to find the main error contributors. Beside the previously known sources such as K-Band Ranging (KBR) system noise and systematic attitude variations, this method clearly shows effects which the classic spectral analysis is hardly able or unable to represent. These effects include long-term signatures due to satellite eclipse crossings and dominant ocean tide errors.

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RL05 monthly and 10-day gravity field solutions from CNES/GRGS

10.5194/gstm2020-51 ◽

2020 ◽

Author(s):

Jean-Michel Lemoine ◽

Stéphane Bourgogne

Keyword(s):

Time Series ◽

Gravity Field ◽

Time Span ◽

Full Time ◽

Accelerometer Data ◽

Times Series ◽

Grace Data ◽

Range Rate ◽

Combined Time Series ◽

Recent Version

In February 2020 CNES/GRGS published its 5th reprocessing (called "RL05") of the GRACE data, from August 2002 to August 2016. The extension of this series covering the span of the GRACE-FO data, 2018-now, will be released in October. This new times series comes, as for the previous releases, in a monthly and a 10-day time resolution.&#160; The main differences of the new release with respect to the previous one are : - the use of the most recent version of the JPL KBR data (version 3), - the use of the IGS orbits and clocks in replacement of the GRGS ones, - a completely homogenous processing over the full time span, - the use of AOD1B-RL06 for the dealiasing data in replacement of the ERA-Interim+TUGO products. For the processing of the GRACE-FO data we have used the TUGRAZ transplant accelerometer data instead of the JPL one, resulting in a great stabilization of the accelerometer scale factors, now close to 1 over the full time span, in a reduction of the range-rate and GPS residuals and in an improvement of the gravity field solutions. This presentation will focus on the processing details and on the comparison of this new series with the Release 06 from JPL / GFZ / CSR, the ITSG-Grace2018 time series from TUGRAZ, and the combined time series from the new international combination service COST-G.

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Instrument Data Simulations for GRACE Follow-on: Observation and Noise Models

10.5194/essd-2017-45 ◽

2017 ◽

Author(s):

Neda Darbeheshti ◽

Henry Wegener ◽

Vitali Müller ◽

Majid Naeimi ◽

Gerhard Heinzel ◽

...

Keyword(s):

Gravity Field ◽

Simulated Data ◽

Laser Interferometry ◽

Scientific Basis ◽

Satellite Mission ◽

Earth’S Gravity Field ◽

Gravity Field Recovery ◽

Grace Data ◽

Data Files ◽

Grace Mission

Abstract. The Gravity Recovery and Climate Experiment (GRACE) mission has yielded data on the Earth's gravity field to monitor temporal changes for more than fifteen years now. The GRACE twin satellites use microwave ranging with micrometer precision to measure distance variations between two satellites caused by the Earth's global gravitational field. GRACE Follow-on (GRACE-FO) will be the first satellite mission to use inter-satellite laser interferometry in space. The laser ranging instrument (LRI) will provide two additional measurements compared to the GRACE mission: interferometric inter-satellite ranging with nanometer precision and inter-satellite pointing information. We have designed a set of simulated GRACE-FO data, which include LRI measurements, apart from all other GRACE instrument data needed for the Earth's gravity field recovery. The simulated data files are publicly available via https://doi.org/10.22027/AMDC2 and can be used to derive gravity field solutions like from GRACE data. This paper describes the scientific basis and technical approaches used to simulate the GRACE-FO instrument data.

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Multiresolution wavelet analysis applied to GRACE range-rate residuals

Geoscientific Instrumentation Methods and Data Systems ◽

10.5194/gi-8-197-2019 ◽

2019 ◽

Vol 8 (2) ◽

pp. 197-207 ◽

Cited By ~ 1

Author(s):

Saniya Behzadpour ◽

Torsten Mayer-Gürr ◽

Jakob Flury ◽

Beate Klinger ◽

Sujata Goswami

Keyword(s):

Wavelet Analysis ◽

Gravity Field ◽

Recovery Process ◽

Ocean Tide ◽

Discrete Wavelet ◽

Error Sources ◽

Gravity Field Recovery ◽

Range Rate ◽

Process Observation ◽

Gravity Recovery

Abstract. For further improvements of gravity field models based on Gravity Recovery and Climate Experiment (GRACE) observations, it is necessary to identify the error sources within the recovery process. Observation residuals obtained during the gravity field recovery contain most of the measurement and modeling errors and thus can be considered a realization of actual errors. In this work, we investigate the ability of wavelets to help in identifying specific error sources in GRACE range-rate residuals. The multiresolution analysis (MRA) using discrete wavelet transform (DWT) is applied to decompose the residual signal into different scales with corresponding frequency bands. Temporal, spatial, and orbit-related features of each scale are then extracted for further investigations. The wavelet analysis has proven to be a practical tool to find the main error contributors. Besides the previously known sources such as K-band ranging (KBR) system noise and systematic attitude variations, this method clearly shows effects which the classic spectral analysis is hardly able or unable to represent. These effects include long-term signatures due to satellite eclipse crossings and dominant ocean tide errors.

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V04 Level-1 data processing status for GRACE and GRACE Follow-On

10.5194/egusphere-egu2020-10626 ◽

2020 ◽

Author(s):

Tamara Bandikova ◽

Hui Ying Wen ◽

Meegyeong Paik ◽

William Bertiger ◽

Mark Miller ◽

...

Keyword(s):

Data Processing ◽

Gravity Field ◽

Attitude Determination ◽

Precise Orbit Determination ◽

Sensor Data ◽

Satellite Mission ◽

Gravity Field Recovery ◽

Grace Data ◽

Level 1 ◽

Gravity Recovery

On May 22, 2020, the Gravity Recovery and Climate Experiment Follow-On (GRACE-FO), will celebrate two years of successful in-orbit operation. The primary goal of this satellite mission is to provide information about time variations of the Earth&#8217;s gravity field. This is possible due to precise orbit determination and inter-satellite ranging by determining the relative clock alignment of the USOs, precise attitude determination and accelerometry. High quality satellite observations are one of the fundamental requirements for successful gravity field recovery. NASA/Caltech Jet Propulsion Laboratory is the official Level-1 data processing and analysis center. The GRACE-FO Level-1 data are currently being processed with software version V04. This software will be used also for final reprocessing of the GRACE (2002-2017) Level-1 data. Here we present the analysis of two years of GRACE-FO sensor data as well as a preview of the reprocessed GRACE data, and discuss the measurement performance.

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Instrument data simulations for GRACE Follow-on: observation and noise models

Earth System Science Data ◽

10.5194/essd-9-833-2017 ◽

2017 ◽

Vol 9 (2) ◽

pp. 833-848 ◽

Cited By ~ 5

Author(s):

Neda Darbeheshti ◽

Henry Wegener ◽

Vitali Müller ◽

Majid Naeimi ◽

Gerhard Heinzel ◽

...

Keyword(s):

Gravity Field ◽

Simulated Data ◽

Laser Interferometry ◽

Scientific Basis ◽

Satellite Mission ◽

Earth’S Gravity Field ◽

Gravity Field Recovery ◽

Grace Data ◽

Data Files ◽

Grace Mission

Abstract. The Gravity Recovery and Climate Experiment (GRACE) mission has yielded data on the Earth's gravity field to monitor temporal changes for more than 15 years. The GRACE twin satellites use microwave ranging with micrometre precision to measure the distance variations between two satellites caused by the Earth's global gravitational field. GRACE Follow-on (GRACE-FO) will be the first satellite mission to use inter-satellite laser interferometry in space. The laser ranging instrument (LRI) will provide two additional measurements compared to the GRACE mission: interferometric inter-satellite ranging with nanometre precision and inter-satellite pointing information. We have designed a set of simulated GRACE-FO data, which include LRI measurements, apart from all other GRACE instrument data needed for the Earth's gravity field recovery. The simulated data files are publicly available via https://doi.org/10.22027/AMDC2 and can be used to derive gravity field solutions like from GRACE data. This paper describes the scientific basis and technical approaches used to simulate the GRACE-FO instrument data.

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Electromagnetic characterization of strong-coupled Omega-type bianisotropic metamaterials using the state transition matrix method

Waves in Random and Complex Media ◽

10.1080/17455030.2021.1950946 ◽

2021 ◽

pp. 1-19

Author(s):

Ugur Cem Hasar ◽

Gokhan Ozturk ◽

Mehmet Ertugul ◽

Joaquim José Barroso ◽

Omar M. Ramahi

Keyword(s):

Matrix Method ◽

Transition Matrix ◽

State Transition ◽

The State ◽

State Transition Matrix

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Earth’s Time-Variable Gravity from GRACE Follow-On K-Band Range-Rates and Pseudo-Observed Orbits

Remote Sensing ◽

10.3390/rs13091766 ◽

2021 ◽

Vol 13 (9) ◽

pp. 1766

Author(s):

Igor Koch ◽

Mathias Duwe ◽

Jakob Flury ◽

Akbar Shabanloui

Keyword(s):

Gravity Field ◽

Time Variable ◽

Time Variable Gravity ◽

Gravity Field Recovery ◽

Variable Gravity ◽

Earth’S System ◽

Grace Mission ◽

Insight Into ◽

K Band

During its science phase from 2002–2017, the low-low satellite-to-satellite tracking mission Gravity Field Recovery And Climate Experiment (GRACE) provided an insight into Earth’s time-variable gravity (TVG). The unprecedented quality of gravity field solutions from GRACE sensor data improved the understanding of mass changes in Earth’s system considerably. Monthly gravity field solutions as the main products of the GRACE mission, published by several analysis centers (ACs) from Europe, USA and China, became indispensable products for quantifying terrestrial water storage, ice sheet mass balance and sea level change. The successor mission GRACE Follow-On (GRACE-FO) was launched in May 2018 and proceeds observing Earth’s TVG. The Institute of Geodesy (IfE) at Leibniz University Hannover (LUH) is one of the most recent ACs. The purpose of this article is to give a detailed insight into the gravity field recovery processing strategy applied at LUH; to compare the obtained gravity field results to the gravity field solutions of other established ACs; and to compare the GRACE-FO performance to that of the preceding GRACE mission in terms of post-fit residuals. We use the in-house-developed MATLAB-based GRACE-SIGMA software to compute unconstrained solutions based on the generalized orbit determination of 3 h arcs. K-band range-rates (KBRR) and kinematic orbits are used as (pseudo)-observations. A comparison of the obtained solutions to the results of the GRACE-FO Science Data System (SDS) and Combination Service for Time-variable Gravity Fields (COST-G) ACs, reveals a competitive quality of our solutions. While the spectral and spatial noise levels slightly differ, the signal content of the solutions is similar among all ACs. The carried out comparison of GRACE and GRACE-FO KBRR post-fit residuals highlights an improvement of the GRACE-FO K-band ranging system performance. The overall amplitude of GRACE-FO post-fit residuals is about three times smaller, compared to GRACE. GRACE-FO post-fit residuals show less systematics, compared to GRACE. Nevertheless, the power spectral density of GRACE-FO and GRACE post-fit residuals is dominated by similar spikes located at multiples of the orbital and daily frequencies. To our knowledge, the detailed origin of these spikes and their influence on the gravity field recovery quality were not addressed in any study so far and therefore deserve further attention in the future. Presented results are based on 29 monthly gravity field solutions from June 2018 until December 2020. The regularly updated LUH-GRACE-FO-2020 time series of monthly gravity field solutions can be found on the website of the International Centre for Global Earth Models (ICGEM) and in LUH’s research data repository. These operationally published products complement the time series of the already established ACs and allow for a continuous and independent assessment of mass changes in Earth’s system.

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