Evaluation of the third- and fourth-generation GOCE Earth gravity field models with Australian terrestrial gravity data in spherical harmonics

In March 2013 the fourth generation of ESA’s (European Space Agency) global gravity field models, DIR4 (Bruinsma et al, 2010b) and TIM4 (Pail et al, 2010), generated from the GOCE (Gravity field and steady-state Ocean Circulation Explorer) gravity observation satellite were released. We evaluate the models using an independent ground truth data set of gravity anomalies over Australia. Combined with GRACE (Gravity Recovery and Climate Experiment) satellite gravity, a new gravity model is obtained that is used to perform comparisons with GOCE models in spherical harmonics. Over Australia, the new gravity model proves to have significantly higher accuracy in the degrees below 120 as compared to EGM2008 and seems to be at least comparable to the accuracy of this model between degree 150 and degree 260. Comparisons in terms of residual quasi-geoid heights, gravity disturbances, and radial gravity gradients evaluated on the ellipsoid and at approximate GOCE mean satellite altitude (h=250 km) show both fourth generation models to improve significantly w.r.t. their predecessors.Relatively, we find a root-mean-square improvement of 39 % for the DIR4 and 23 % for TIM4 over the respective third release models at a spatial scale of 100 km (degree 200). In terms of absolute errors TIM4 is found to perform slightly better in the bands from degree 120 up to degree 160 and DIR4 is found to perform slightly better than TIM4 from degree 170 up to degree 250. Our analyses cannot confirm the DIR4 formal error of 1 cm geoid height (0.35 mGal in terms of gravity) at degree 200. The formal errors of TIM4, with 3.2 cm geoid height (0.9 mGal in terms of gravity) at degree 200, seem to be realistic. Due to combination with GRACE and SLR data, the DIR models, at satellite altitude, clearly show lower RMS values compared to TIM models in the long wavelength part of the spectrum (below degree and order 120). Our study shows different spectral sensitivity of different functionals at ground level and at GOCE satellite altitude and establishes the link among these findings and the Meissl scheme (Rummel and van Gelderen in Manuscripta Geodaetica 20:379–385, 1995)

The earth's gravitational field recovery based on an optimal combination of GRACE and GOCE satellite data

Modelling the global gravitational field of the Earth in terms of spherical harmonic coefficients has been performed by a stand-alone inversion of a 4-month set of the Gravity Field and Steady-State Ocean Circulation Explorer (GOCE) Satellite Gravity Gradiometry (SGG) data and a 9-month set of the GOCE kinematic orbits, as well as by a combined inversion of the aforementioned data sets and 1-year sets of the Gravity Recovery and Climate Experiment (GRACE) K-Band Ranging (KBR) data and its kinematic orbits. It is shown, in particular, that an incorporation of the GOCE data may lead to a dramatic improvement of the GRACE-based gravity field models. The added value of the GOCE data is primarily attributed to the diagonal components of the SGG gravitational tensor.Geoscience and Remote SensingCivil Engineering and Geoscience

Understanding data noise in gravity field recovery on the basis of inter-satellite ranging measurements acquired by the satellite gavimetry mission GRACE

Spectral analysis of data noise is performed in the context of gravity field recovery from inter-satellite ranging measurements acquired by the satellite gravimetry mission GRACE. The motivation of the study is two-fold: (i) to promote a further improvement of GRACE data processing techniques and (ii) to assist designing GRACE follow-on missions. The analyzed noise realizations are produced as the difference between the actual GRACE inter-satellite range measurements and the predictions based on state-of-the-art force models. The exploited functional model is based on the so-called “range combinations,” which can be understood as a finite-difference analog of inter-satellite accelerations projected onto the line-of-sight connecting the satellites. It is shown that low-frequency noise is caused by limited accuracy of the computed GRACE orbits. In the first instance, it leads to an inaccurate estimation of the radial component of the inter-satellite velocities. A large impact of this component stems from the fact that it is directly related to centrifugal accelerations, which have to be taken into account when the measured range-accelerations are linked with inter-satellite accelerations. Another effect of orbit inaccuracies is a miscalculation of forces acting on the satellites (particularly, the one described by the zero-degree term of the Earth’s gravitational field). The major contributors to the noise budget at high frequencies (above 9 mHz) are (i) ranging sensor errors and (ii) limited knowledge of the Earth’s static gravity field at high degrees. Importantly, we show that updating the model of the static field on the basis of the available data must be performed with a caution as the result may not be physical due to a non-unique recovery of high-degree coefficients. The source of noise in the range of intermediate frequencies (1–9 mHz), which is particularly critical for an accurate gravity field recovery, is not fully understood yet. We show, however, that it cannot be explained by inaccuracies in background models of time-varying gravity field. It is stressed that most of the obtained results can be treated as sufficiently general (i.e., applicable in the context of a statistically optimal estimation based on any functional model)

Understanding data noise in gravity field recovery on the basis of inter-satellite ranging measurements acquired by the satellite gavimetry mission GRACE

Spectral analysis of data noise is performed in the context of gravity field recovery from inter-satellite ranging measurements acquired by the satellite gravimetry mission GRACE. The motivation of the study is two-fold: (i) to promote a further improvement of GRACE data processing techniques and (ii) to assist designing GRACE follow-on missions. The analyzed noise realizations are produced as the difference between the actual GRACE inter-satellite range measurements and the predictions based on state-of-the-art force models. The exploited functional model is based on the so-called “range combinations,” which can be understood as a finite-difference analog of inter-satellite accelerations projected onto the line-of-sight connecting the satellites. It is shown that low-frequency noise is caused by limited accuracy of the computed GRACE orbits. In the first instance, it leads to an inaccurate estimation of the radial component of the inter-satellite velocities. A large impact of this component stems from the fact that it is directly related to centrifugal accelerations, which have to be taken into account when the measured range-accelerations are linked with inter-satellite accelerations. Another effect of orbit inaccuracies is a miscalculation of forces acting on the satellites (particularly, the one described by the zero-degree term of the Earth’s gravitational field). The major contributors to the noise budget at high frequencies (above 9 mHz) are (i) ranging sensor errors and (ii) limited knowledge of the Earth’s static gravity field at high degrees. Importantly, we show that updating the model of the static field on the basis of the available data must be performed with a caution as the result may not be physical due to a non-unique recovery of high-degree coefficients. The source of noise in the range of intermediate frequencies (1–9 mHz), which is particularly critical for an accurate gravity field recovery, is not fully understood yet. We show, however, that it cannot be explained by inaccuracies in background models of time-varying gravity field. It is stressed that most of the obtained results can be treated as sufficiently general (i.e., applicable in the context of a statistically optimal estimation based on any functional model).Physical Space GeodesyAstrodynamics & Space Mission

Health-related quality of life of breast cancer patients in the Eastern Mediterranean region: a systematic review and meta-analysis

Purpose: Breast cancer is the most common type of cancer in women around the world, and this applies to the Middle East as well. The goal of all medical care and treatment is to improve the quality of life (QoL) of patients. Accordingly, the present study aimed at evaluating the QoL of patients with breast cancer in the Middle East region. Methods: In this meta-analysis, three electronic databases (PubMed, Web of Science, and Scopus) were searched from inception until August 2018. The hoy et tool was used to evaluate the quality of the articles included in the meta-analysis. The search, screening, quality evaluation, and data extraction were carried out by two of the researchers. Results: Thirty-six studies conducted on 8347 Middle Eastern women with breast cancer entered the final stage. QoL was assessed by the European Organization for the Research and Treatment of Cancer Quality of Life Questionnaire in 20 studies, with 6034 patients. The mean of the reported QoL was between 31.1 and 75.6. Based on the results of the random effect method, the overall mean of the QoL was 60.5 (95 confidence interval 56.0, 65.0; I2 = 99.0). In six studies performed on 1053 individuals, QoL was classified as good, moderate, or poor. Less than one-third of patients (21) had a good QoL. Conclusions: Since less than one-third of patients had a good QoL, it seems necessary to design and implement an integrated and multidimensional educational program to improve QoL of patients with breast cancer. © 2019, Springer Science+Business Media, LLC, part of Springer Nature

Health-related quality of life of breast cancer patients in the Eastern Mediterranean region: a systematic review and meta-analysis

Purpose: Breast cancer is the most common type of cancer in women around the world, and this applies to the Middle East as well. The goal of all medical care and treatment is to improve the quality of life (QoL) of patients. Accordingly, the present study aimed at evaluating the QoL of patients with breast cancer in the Middle East region. Methods: In this meta-analysis, three electronic databases (PubMed, Web of Science, and Scopus) were searched from inception until August 2018. The hoy et tool was used to evaluate the quality of the articles included in the meta-analysis. The search, screening, quality evaluation, and data extraction were carried out by two of the researchers. Results: Thirty-six studies conducted on 8347 Middle Eastern women with breast cancer entered the final stage. QoL was assessed by the European Organization for the Research and Treatment of Cancer Quality of Life Questionnaire in 20 studies, with 6034 patients. The mean of the reported QoL was between 31.1 and 75.6. Based on the results of the random effect method, the overall mean of the QoL was 60.5 (95 confidence interval 56.0, 65.0; I2 = 99.0). In six studies performed on 1053 individuals, QoL was classified as good, moderate, or poor. Less than one-third of patients (21) had a good QoL. Conclusions: Since less than one-third of patients had a good QoL, it seems necessary to design and implement an integrated and multidimensional educational program to improve QoL of patients with breast cancer. © 2019, Springer Science+Business Media, LLC, part of Springer Nature