bluuebunny/crossref_metadata_2025 huggingface dataset:
Advanced processing strategies regarding an improved GFZ GRACE/GRACE-FO RL07 time series
Authors: Hauk Markus , Dahle Christoph , Wilms Josefine , Michael Murböck , Panafidina Natalia , Flechtner Frank
Published: September 2022

GFZ, as part of the GRACE/GRACE-FO Science Data System, is one of the official Level-2 processing centers routinely providing monthly gravity models. These models are used by a wide variety of geoscientists to infer mass changes mainly at the Earth’s surface. While the current release 6 (RL06) is still operationally processed, plans and internal tests for a reprocessed GFZ RL07 time series are already in progress.

In this context, advanced processing strategies are developed within the Research Unit (RU) NEROGRAV (New Refined Observations of Climate Change from Spaceborne Gravity Missions) funded by the German Research Foundation DFG. The main focus is on an improved stochastic modeling regarding both instrument data (accelerometer and inter-satellite ranging observations) as well as background models (e.g. by the utilization of covariance information for these models). At the same time, the solved-for parameter space, in particular regarding empirical accelerations, has been revised. Finally, also the potential benefit by adding observations of the laser-ranging interferometer (LRI) onboard GRACE-FO has been investigated.

This poster provides an overview of the developed advanced processing strategies, and their individual and combined impact on GFZ’s Level-2 products compared to current GFZ RL06 solutions.
Forecasting Global Land Water Storage using GRACE data
Authors: Li Fupeng , Kusche Jürgen , Sneeuw Nico , Siebert Stefan , Gerdener Helena , Wang Zhengtao , Chao Nengfang , Chen Gang , Tian Kunjun
Published: September 2022

Existing approaches for seasonal forecasts of land water storage via land surface models use meteorological forecast products as forcing data. Yet, such meteorological forecast data contain large uncertainties, which inevitably map into highly uncertain land water storage predictions. As a result, current seasonal forecasting of land water storage contains extensive uncertainties. The Gravity Recovery and Climate Experiment (GRACE) satellite mission greatly contributed to monitoring historical land water storage change (TWSC). But many applications like seasonal forecasting of land water storage using GRACE data remains underexplored. Here we analyze the lag relationship between hydrometeorological variables - e.g., precipitation, sea surface temperature, or runoff - and GRACE-derived total water storage change (TWSC). We find that TWSC detected by GRACE lags behind all considered hydrometeorological variables by a few months after removing seasonal effects. By using this lag relationship we forecast the nonseasonal TWSC fields up to one year lead. The prediction approach developed here is based on mostly observational inputs and the validation by GRACE-FO observations suggests it can provide more reliable prediction of global land water storage as compared to model simulations.
Slow changes in terrestrial water storage underestimated by global hydrological models
Authors: Pfeffer Julia , Decharme Bertrand , Cazenave Anny , Munier Simon , Blazquez Alejandro , Barnoud Anne
Published: September 2022

The GRACE (Gravity Recovery And Climate Experiment) and GRACE Follow-On (FO) satellite gravity missions enable global monitoring of the mass transport within the Earth’s system, leading to unprecedented advances in our understanding of the global water cycle in a changing climate. This study focuses on the quantification of changes in terrestrial water storage based on an ensemble of GRACE and GRACE-FO solutions and two global hydrological models. Significant changes in terrestrial water storage are detected at pluriannual and decadal time-scales in GRACE and GRACE-FO satellite gravity data, that are considerably underestimated by global hydrological models. The largest differences (more than 20 cm in equivalent water height) are observed in South America (Amazon, Sao Francisco and Parana river basins) and tropical Africa (Congo, Zambezi and Okavango river basins). Significant differences (a few cm) are observed worldwide at similar time-scales, and are generally well correlated with precipitation. While the origin of such differences is unknown, part of it is likely to be climate-related and at least partially due to inaccurate predictions of hydrological models. Slow changes in the terrestrial water cycle may indeed be overlooked in global hydrological models due to inaccurate meteorological forcing (e.g., precipitation), unresolved groundwater processes, anthropogenic influences, changing vegetation cover and limited calibration/validation datasets. Significant differences between GRACE satellite measurements and hydrological model predictions have been identified, quantified and characterised in the present study. Efforts must be made to better understand the gap between both methods at pluriannual and decadal time-scales, which challenges the use of global hydrological models for the prediction of the evolution of water resources in changing climate conditions.
A 6-year cycle in the climate system
Authors: Pfeffer Julia , Cazenave Anny , Mandea Mioara , Dehant Veronique , de Viron Olivier , Saraswati Anita , Zhu Ping
Published: September 2022

The natural climate variability is responsible for large fluctuations in the climate system over a broad range of time and space scales. The characterization of such oscillations (accelerations, trends, seasonal signals) is critical to understand the causes of change in the climate system and improve future climate scenarios. In this study, we report an oscillation with a pseudo-periodicity around 6 years in many climate variables, including the surface mass anomalies retrieved from GRACE and GRACE Follow-On missions. Changes in terrestrial water storage are shown to exhibit a 6-year oscillation at tropical latitudes in the Southern hemisphere (North of South America, tropical Africa, North of Australia). Similar oscillations have been detected in the precipitation, but were found to be underestimated by global hydrological models such as ISBA-CTRIP or WGHM. These discoveries echo the recent detection of a 6-year cycle in the global mean sea level and the ice mass balance of the Greenland ice-sheet and continental glaciers, as well as in regional climate indices (Atlantic Multidecennal Oscillation, North Atlantic Oscillation, Pacific Decadal Oscillations) by Moreira et al., (2021). The causes for such short-term oscillations in the climate system are still unexplained but we note that a 6-year cycle has also been reported in the length of day (LOD) and robustly attributed to liquid core dynamics. While the 6-year cycle in LOD, geomagnetic field and core dynamics may be unrelated to the 6-year oscillation detected in several climate parameters, we briefly discuss potential mechanisms that could link deep Earth and surface processes.

 

Moreira, L., Cazenave, A., & Palanisamy, H. (2021). Influence of interannual variability in estimating the rate and acceleration of present-day global mean sea level. Global and Planetary Change, 199, 103450.
Mass Change as a core element of NASA’s Earth System Observatory: update and progress on pre-formulation activities
Authors: Wiese David , Dunn Charley , Gross Michael , Webb Frank , Dahya Neil , Girerd Andre , Bettadpur Srinivas , Bienstock Bernard , Ware Brent , Boening Carmen , Chrone Jonathan , Loomis Bryant , Luthcke Scott , Rodell Matthew , Sauber Jeanne , Herrmann Nicole , Tsaoussi Lucia
Published: September 2022

The 2017-2027 US National Academy of Sciences Decadal Survey (DS) for Earth Science and Applications from Space classified mass change as one of five Designated Observables having the highest priority in terms of Earth observations required to better understand the Earth system over the next decade.  In response to this designation, NASA initiated multi-center studies with an overarching goal of defining observing system architectures for each Designated Observable.  The Mass Change Designated Observable study concluded in 2021, after identifying a small subset of high value observing system architectures for further study during Pre-Phase A formulation.  Mass Change is in the process of concluding Pre-Phase A activities and transitioning to Phase A, after successfully passing a Mission Concept Review in June 2022.  The baseline architecture is a partnership between NASA and DLR with an architecture design similar in nature to GRACE-FO.  This concept meets the primary goal of maintaining continuity in the mass change data record.  In parallel, ESA is continuing their Phase A studies focused on launching an inclined pair of satellites to complement this baseline architecture which would result in a demonstration of the Bender constellation and thus enhance the overall science and applications value of the observing system.  In this talk, an overview of Mass Change pre-formulation activities will be provided, as well as a status update on next steps and associated milestones.
Evapotranspiration frequently increases during droughts
Authors: Zhao Meng , Aa Geruo , Liu Yanlan , Konings Alexandra
Published: September 2022

Changes in evapotranspiration (ET) substantially affect water availability and ecosystem health. Higher evaporative demand during drought acts to increase ET, but droughts also reduce the moisture supply necessary for ET. These competing factors limit straightforward prediction of even the sign of ET anomalies during droughts.  Drought-driven increases in evapotranspiration (ET+) are of particular concern because they quickly deplete water resources, causing flash droughts and acute stress on ecosystems. Here, we used GRACE/GRACE-FO and a water balance approach to show that ET+ is globally widespread, occurring in 44.4% of drought months. The sign of ET’s drought response depends most on the magnitude of precipitation and of total water storage anomalies, rather than its location. CMIP6 Earth system models underestimate the ET+ probability by nearly half, and more so in drier regions, primarily due to missing representations of soil structure effects on soil evaporation, and incorrectly parametrized plant and soil traits. These processes should be prioritized to reduce model uncertainties in the water-energy-food nexus. 
Improved alternative GRACE-FO accelerometer transplant product computed at TU Graz
Authors: Mayer-Guerr Torsten , Oehlinger Felix , Kvas Andreas , Krauss Sandro , Suesser-Rechberger Barbara
Published: September 2022

The GRACE-FO satellites are equipped with three-axis accelerometers, measuring the non-gravitational forces. After one month in orbit, the GRACE-D accelerometer data degraded and its measurements were replaced by synthetic accelerometer data, the so-called transplant data, officially generated by the Jet Propulsion Laboratory (JPL). For the ITSG-Grace2018 GRACE-FO release, the gravity field recovery is based on an alternative in-house transplant product (Behzadpour et. al. 2021,  https://doi.org/10.1029/2020JB021297). This product is generated by a remove-restore method implementing non-gravitational force models.

In this work, we present a new improved version of TU Graz transplant product. The force modelling includes now a tuned satellite macro model, self-shadowing effects, and thermal radiation forces. For the transplant step, an additional estimate of the thermospheric density along the orbit was introduced to account for the different orientation of the satellites.
Kinematic orbits and their contribution to monitoring Earth's gravity field
Authors: Suesser- Rechberger Barbara , Mayer-Guerr Torsten , Krauss Sandro , Dumitraschkewitz Patrick , Oehlinger Felix , Kvas Andreas
Published: September 2022

For the observation of temporal mass variations on Earth, the determination of the Earth's gravity field is of great importance. Therefore, additional concepts are required to bridge possible gaps occurring within dedicated gravity field missions such as CHAMP, GRACE and GOCE or between consecutive gravity field missions i.e., GRACE and GRACE Follow-On. Gravity field solutions based on kinematic orbits of low earth orbiting (LEO) satellites are a common practice. Our working group use an in-house developed approach based on an iterative least-squares adjustment utilizing raw GNSS observations for the kinematic orbit determination. Since varying algorithms, models, and processing strategies applied by diﬀerent institutions can lead to inconsistencies, which aﬀects the performance we now use GNSS products which are consistently processed with our in-house software package GROOPS.  As a result, improved kinematic orbit and subsequently gravity field solutions could be achieved due to this consistency. Up to now, we reprocessed the kinematic orbits of 19 LEO satellite missions, including non-gravity missions like Sentinel 1A/B, Sentinel 3A/B, Swarm A/B/C, TerraSAR-X, TanDEM-X, MetOp A/B, and Jason 1/2/3. On our website we subsequently publish these kinematic orbit solutions together with further satellite orbit products like the reduced dynamic orbit, the attitude, and the accelerations due to non-conservative forces.  Based on these kinematic orbits a time series of individual monthly gravity field solutions has been determined. Additional to more precise orbits, enhanced non-gravitational force models based on satellite macro models contribute to more accurate gravity field solutions. The time series spans meanwhile 20 years without gaps, starting in January 2002. For this time span, we will show the mass variations for regions such as Greenland, the Amazon basin and other large river basins and compare the results derived from the kinematic orbits with those from COST-G Swarm and COST-G GRACE/GRACE-FO.
Analysis of the ITSG-Grace daily models in the determination of polar motion excitation function
Authors: Partyka Aleksander , Nastula Jolanta , Śliwińska Justyna , Kur Tomasz , Wińska Małgorzata
Published: September 2022

The polar motion (PM) changes comprehension is one of the major tasks in geodesy. In order to learn about the changes in PM caused by internal forces, it is necessary to perform detailed analyses of the so-called PM excitation functions of geophysical fluids layers - atmosphere, ocean and terrestrial hydrosphere with cryosphere. The impact of land hydrosphere is not well understood and the study of the Hydrological Angular Momentum (HAM) is still the main research topic in finding the agreement between observed geodetic changes in PM and geophysical ones. The study of different HAM excitations is possible through the use and analysis of temporal gravity models, which are constantly being developed by numerous research centres around the world.

The main aim of this study is to check the usefulness of ITSG daily gravity field models in determination of PM excitation at sub-seasonal time scales. To do so, we compare the equatorial components (χ1 and χ2) of the HAM calculated using the ITSG (The Institute of Geodesy at Graz University of Technology) daily gravity field models (ITSG-Grace2016, ITSG-Grace2018) with hydrological signal in the PM excitation (geodetic residuals) and HAM from LSDM (Hydrological Land Surface Discharge Model). Data from ITSG are the object of our work because they have a daily temporal resolution and allow us to determine oscillations with higher frequencies than the more commonly used monthly data. The period of our work was narrowed down to the years of the GRACE mission with the highest density of data, in order to avoid the impact of data gaps that can disrupt our short-term analyses. We limit our study to the period between 2004 and 2011 due to meaningful gaps in GRACE observations before and after this period.

The equatorial components of the PM excitation were calculated from the relationship between χ1, χ2 and the Stokes coefficients of degree-2, order-1 (∆C21, ∆S21) provided in the ITSG-Grace models. In this work, the HAM and SLAM (Sea-level Angular Momentum) series from the LSDM provided by GFZ (GeoForschungsZentrum in Potsdam) and the geodetic residuals, which are the differences between the geodetic angular momentum (GAM) and the sum of atmospheric and oceanic excitation, provided by Observatoire de Paris, were used for comparison with the PM excitation series determined from the ITSG-Grace models. In order to evaluate PM excitations obtained from ITSG-Grace models with series from other models, we determined short-period amplitude spectra and calculated correlation and root mean-square errors (RMSE). Our analyses confirm the existence of a sub-monthly signal in the HAM series determined from ITSG daily data. We observed a similar signal in LSDM-based HAM but with notably weaker amplitudes.

 

 
Ensemble Error Assessment for AOD1B RL07
Authors: Shihora Linus , Liu Zhijun , Balidakis Kyriakos , Dobslaw Henryk
Published: September 2022

The Atmosphere and Ocean non-tidal De-aliasing Level-1B (AOD1B) product is widely used in satellite gravimetry to correct for transient effects of atmosphere-ocean mass variability that would otherwise alias into monthly-mean global gravity fields. The most recent release is based on the global ERA5 reanalysis and ECMWF operational data together with simulations from the general ocean circulation model MPIOM consistently forced with fields of the same atmospheric data-set.

While the newly released AOD1B RL07 improves over its predecessors in several aspects, residual uncertainties in the modelled mass variations remain. Especially for the oceanic component the poorly developed ocean observing system for rapid wind-driven flow results in larger uncertainties compared to the atmospheric component. In addition, the last uncertainty assessment of AOD1B is based on data from RL05 which is now believed to be too pessimistic.
We present results from an MPIOM based ensemble study that varies the atmospheric forcing by using the ERA5, MERRA2 and JRA55 reanalyses, as well as the initial conditions of the simulation. This will allow for an assessment of the residual errors in the oceanic component of AOD1B RL07 and can be used in the computation of spatial error covariance matrices for the rigorous incorporation of stochastic information into the gravity field estimation process. 
Comparison of gap-filling temporal methods to improve GRACE and GRACE-FO time series
Authors: Lecomte Hugo , Rosat Severine , Mioara Mandea
Published: September 2022

The GRACE and GRACE Follow-On missions are separated by an 11-month gap between 2017 and 2018 and contain 22 more missing months. These gaps in the time series lead to a difficult recovery of gravity variation signals with pluri-annual temporal scales. In this context, various studies proposed machine learning approaches and decomposition techniques to predict the missing values.

 

This study summarizes the different approaches that we have implemented and compares their results. We consider both grid and spherical harmonics at global scales. Some gap-filling solutions use an extrapolation of the GRACE products and some others propose to use Swarm gravity field products to reduce the missing data. We tested several methods in terms of their capacity to predict signals on monthly or annual periods, randomly chosen between 2005 and 2010. The Root-Mean Square Error between the predictions and the original solution gives an estimation of the uncertainty associated with each method.

 

We show that simple methods like « Constant, Trend, Annual and Semi-annual fit » do not deliver the complexity of the original signal. We finally conclude that the Singular Spectrum Analysis (SSA) and Multivariate SSA produce the best results at large spatial scales.
SLR sliding window solutions with daily sampling for replacing GRACE/GRACE-FO C20 and C30
Authors: Kang Zhigui , Ries John , Tamisiea Mark , Bettadpur Srinivas , Save Himanshu
Published: September 2022

The recovery of Earth’s time variable gravity field from satellite data relied on Satellite Laser Ranging (SLR) before missions like the Gravity Recovery and Climate Experiment (GRACE) and GRACE Follow-On (FO). Currently, the monthly gravity solutions from GRACE/GRACE-FO provide amazing information about the temporal variations of gravity field.  However, coefficients C20 and C30 derived from GRACE/GRACE-FO are unreliable. The coefficients, on the other hand, can be reasonably well determined using SLR data and can be used to replace the unreliable values from GRACE/GRACE-FO. In the future, GRACE-FO will provide 28-day sliding widow gravity solutions with weekly sampling. The corresponding SLR solutions should be also provided. Based on this motivation, we study the SLR 30-day sliding window solutions with daily sampling. The new SLR products can be used to replace unreliable coefficients C20 and C30 of both GRACE-FO monthly and sliding window products. This study presents the strategies of gravity recovery from SLR data and discusses the results.
Analysis of GRACE and GRACE-FO post-fit range-rate residuals
Authors: Fletling Nina , Flury Jakob , Duwe Mathias , Koch Igor
Published: September 2022

The monthly gravity field models at LUH are computed with a generalized dynamic orbit determination approach utilizing precise range-rate measurements derived from the K-band ranging system as main observations. A by-product of the gravity field computations are time series of range-rate residuals which represent a complex superposition of different effects, for example of instrumental, environmental and geophysical nature. An analysis of the residuals helps to gain knowledge of the different systematics that can be used to improve the computation strategy and thus the accuracy of the gravity field models.

Since a similar processing strategy was applied to the analyzed GRACE and GRACE-FO residuals, the smaller and more homogenous GRACE-FO residuals mainly reflect improvements in hardware and software.

Some noticeable abnormalities recur at certain positions and orientations of the satellites relative to the Earth and Sun. The transitions between sunlight and the Earth’s shadow are recognizable as well as the blinding of the star cameras by the Sun in specific angles. Moreover, the simultaneous blinding of both star cameras at GRACE by Sun and Moon can cause peaks in the residuals due to the transient outage of precise attitude determination.

Other amplitudes can be related, for instance, to temporary mode changes of the AOCS during maneuvers or to specific combinations of the received frequency and the temperature at the K-band ranging assembly. Besides the systematic errors, the residuals also contain geophysical signals. This applies mainly for regions with strong annual variations as well as where the models of high-frequency signals are prone to errors.
The forgotten second dimension of GRACE-like systems
Authors: Weigelt Matthias
Published: September 2022

Intersatellite ranging systems as implemented in the GRACE and GRACE-FO mission are considered one-dimensional observation systems. Range or range-rate are observed in the direction of the line-of-sight and connected in the modelling process to the relative position and velocity projected on the line-of-sight, respectively. However, the observed range is also proportional to the relative velocity vector projected on the change of the line-of-sight vector which is by definition perpendicular to the line-of-sight vector. This vector is nearly in radial direction of a GRACE-like system thus implying that the range observation also contains information about the radial direction of the gravity field. This contribution will show the mathematical derivations and investigates the feasibility of the using the additional direction in the gravity field recovery process.
The GRACE Plotter, a useful tool for intercomparison
Authors: Bourgogne Stéphane , Lemoine Jean-Michel
Published: September 2022

A quick reminder of the GRACE Plotter comparing capabilities, and a presentation of its brand new functionalities. Try it yourself at https://thegraceplotter.com.
Toward near-real time analysis of gravity change with the examples of flood and flash drought events
Authors: Han Shin-Chan , Tregoning Paul , McCullough Christopher
Published: September 2022

We discuss a methodology of scientifically utilizing high-precision laser ranging measurements (in addition to K-band microwave) for higher temporal sampling of surface mass changes.  The standard spatial analysis (i.e., global gravity field recovery) over a month period such as L2 and L3 data processing would produce a biased estimate when characteristic time scales of mass change processes are shorter than a month.  Our proposed time-domain (along-track) analysis will lead to better quantification of such processes.  Furthermore, we exploit the low-latency (within 1–3 days) Quick-Look (QL) L1B data to examine the feasibility of immediate assessment of extreme events such as flood and flash drought.  Such QL data processing can promote timely assessment of severe weather events and natural hazards as important applications of the GRACE-FO mission.  As examples, we present the data processing results for the 2019 South East US flash drought, the 2020 (unusually large) monsoonal flood in Bangladesh, and the 2021 Eastern Australia flood.  A new streamlined along-track data processing chain is proposed to facilitate utilization of superb laser ranging measurements for advanced quantification of rapid Earth system changes we experience recent years.
Impact of tone errors on gravity field solutions in NGGM concepts
Authors: Pfaffenzeller Nikolas , Pail Roland , Gruber Thomas , Usbeck Thomas , Gerardi Domenico
Published: September 2022

In order to meet the upcoming challenges of climate change, it is necessary to understand the different Earth system processes in more detail and to monitor them. With satellite gravity missions it is possible to continuously measure and observe mass transport processes on Earth globally.  For the current study on Next Generation Gravity Missions (NGGMs) which is called Mass Change and Geosciences International Constellation study (MAGIC) various parameters are subject of the investigation. One aspect is the instrument behavior and its impact on gravity field performance. Besides stochastic noise sources, deterministic errors are present in the instrument measurements, mainly caused by environmental variations on the satellites. These disturbances are generated by temperature variations that occur when passing through sun illuminated and shadow areas, as well as magnetic field variations. As a consequence, periodic errors occur at integer multiples of the orbital frequency.           
In this contribution we want to analyze the impact of the errors on gravity field solutions and provide the findings generated within the MAGIC study. In detail we want to present the results for GRACE-like and Bender-type constellation for scenarios considering an instrument only-case and a full-noise case including temporal gravity field. Depending on the amplitude of the tone errors, they can affect the complete spherical harmonic spectrum of the solutions. To mitigate the effect of tone errors, it is possible to encounter them in data processing e.g. by applying notch filters on the integer multiple of the orbital frequency. As a result of this approach, tone errors affect only the very low harmonic coefficients, but the remaining coefficients can be estimated with good quality.
Current status of CNES RL05 time series of solutions from GRACE and GRACE-FO data
Authors: Lemoine Jean-Michel , Bourgogne Stéphane , Blazquez Alejandro
Published: September 2022

The status of current work at CNES on GRACE/GRACE-FO data processing will be presented

Some details of the processing will be discussed, in particular:

- The negative impact of the unprecedented high altitude of GRACE-FO on the number of stable-resolved gravity field coefficients 

- An analysis of the range and range-rate residuals anomalies during entering and exiting eclipses

- The inclusion of the current LEGOS ensemble-solution of water-mass change in the set of evaluated solutions enables to analyze hydrology and ocean mass changes
Long-term wetting and drying conditions predicted by global climate models are (often) confirmed by satellite gravimetry
Authors: Eicker Annette , Schawohl Lennart , Jensen Laura , Bagge Meike , Dobslaw Henryk
Published: September 2022

Global coupled climate models are important for predicting future climate conditions. Due to sometimes large and often systematic model uncertainties, it is crucial to evaluate the outcome of model experiments against independent observations. Changes in the distribution and availability of terrestrial water storage (TWS), which can be measured by the satellite gravimetry missions GRACE and GRACE-FO, represent an important part of the climate system. However, the use of satellite gravity data for the evaluation of coupled climate models has only very recently become feasible. Challenges arise from large model differences with respect to land water storage-related variables, from conceptual discrepancies between modeled and observed TWS, from the still rather short time series of satellite data, and from a limited spatial resolution and sensitivity of the observations.

This presentation will highlight the latest results achieved from our ongoing research on climate model evaluation based on the analysis of an ensemble of models taking part in the Coupled Model Intercomparison Project Phase 6 (CMIP6). We will focus on long-term wetting and drying conditions in TWS, by deriving hot spot regions of common trends in GRACE/-FO observations and regions of large model consensus. In the discussion of the agreement/disagreement between observed and modeled trends we will consider uncertainties arising from dominant inter-annual variations in the short GRACE/-FO observation time span and from the necessary separation of the integral gravity signal (e.g.by subtraction of a GIA model)
Combining space gravimetry and other satellite observations to reduce spatial uncertainties
Authors: Blazquez Alejandro , Meyssignac Benoit , Berthier Etienne , Longuevergne Laurent , Cretaux Jean François
Published: September 2022

GRACE and GRACE-FO missions have provided gravity fields water mass changes within the Earth's surface since 2002.  This gravity fields are post-processed to infer water mass changes between Ocean and land storage compartments. Unfortunately, most storage compartments (lakes, groundwater, glaciers…) are too small to be resolved given the current spatial resolution of gravimetry missions, resulting in Leakage and Gibbs effects.This effects generates spurious signals that makes gravimetry-based Land water storage (LWS) changes estimates difficult to attribute and to interpret at individual basin and regional scales.
Here, we combine gravimetry-based water mass change data with independent satellite observations to derive refined estimates of the water mass changes. The combination consists in including observations from  satellite altimetry and high resolution visible imagery of glacier (Hugonnet et al., 2021) and lake (Cretaux et al., 2016) mass changes in the conversion process from gravity L2 data to water mass changes. The combination is done for all regions of the world on a monthly basis.
This approach allows to reduce the uncertainty in LWS changes at interannual to decadal time scales, and to derive glacier-free estimates of TWS in the endorheic basins and the exorheic basins.
We find that for the period from 2002 to 2021, the total LWS trend of 0.30±0.26 mm SLE/yr is mainly due to a mass loss in endorheic basins LWS of 0.24±0.13 mm SLE/yr. Over the same period, exorheic basins control interannual variability (2-5 years) but present a non-significative trend of 0.06±0.14 mm SLE/yr.
Detecting Preseismic Signals in GRACE Gravity Solutions: application to the 2011 Tohoku earthquake
Authors: Panet Isabelle , Narteau Clément , Lemoine Jean-Michel , Bouih Marie , Bonvalot Sylvain , Remy Dominique
Published: September 2022

Retrieving short-term preseismic signals before the occurrence of great subduction earthquakes is a major goal for seismic hazard mitigation. It requires a continuous monitoring of seismic and aseimic deformations within the entire subduction system, which cannot be obtained from space geodetic measurements of ground deformations and seismology only. With its unique sensitivity to mass redistributions at all depths along and around the descending slab, satellite gravity can bring key information to overcome this observational gap.

 

Taking the example of the 2011 Tohoku earthquake, we develop here a global and systematic analysis of time series of GRACE-reconstructed gravity gradients, to test whether the deep gravity signals preceeding the earthquake (Panet et al., 2018 ; Bouih et al. 2022) can be detected before the occurrence of the event, as a specific feature originating from solid Earth. Our approach is based on a refined detection of short-term gravity variations aligned with the subduction direction, and consistency tests between signals shared by different GRACE geoid models, allowing us to evaluate the signals robustness with respect to errors and oceanic corrections in the GRACE gravity solutions. Considering the GRGS and the CSR solutions, the results of these tests underline the unique character of the deep pre-Tohoku gravity variations compared to the usual variability of gravity, confirming its interpretation as pre-seismic signal.

 

We compare the preseismic gravity signals of the 2011 Tohoku and 2010 Maule earthquakes, and conclude that our approach can be applied to the systematic monitoring of the Pacific subduction belt.
Optomechanical accelerometers for geodesy
Authors: Guzman Felipe
Published: September 2022

Gravitational acceleration provides unique measurement opportunities to identify natural and man-made phenomena at global scales with signatures that are extremely difficult to mask due to their nature. Such gravitational observations are currently conducted with commercial gravimeters and gravity gradiometers that consist of complex mechanical structures operating large, inertially sensitive test masses and cumbersome displacement readout systems.

We are currently developing highly compact, portable, and cost-effective optomechanical inertial sensors of high sensitivity, building upon recent advances in the area of optomechanics. These technologies consist of low loss and highly stable monolithic mechanical oscillators that we combine with miniaturized laser interferometric displacement sensors, enabling us to achieve extremely high performances in acceleration sensing in small form factors.

To this end, it is necessary to develop various subsystems that are building blocks, each contributing to the implementation of these kinds of instruments. We will discuss our work on the fabrication of low-loss mechanical resonators, and the development of compact monolithic laser interferometer heads, fiber-based multi-color fiber interferometers, and new measurement concepts targeting smaller footprints and higher integration into photonic platforms. We will primarily report on the progress of our novel low-frequency optomechanical accelerometers for geodesy.
Predicting Sub-Monthly Total Water Storage Variations Using a New 5-Day Mascon Product and Deep Learning
Authors: Sun Alex , Rateb Ashraf , Save Himanshu , Scanlon Bridget , Hasan Emad
Published: September 2022

GRACE and GRACE Follow-On (GRACE-FO) missions provide unique information on the wetness state of a river basin with regard to its flood generation potential. However, the long latency of the standard monthly GRACE products has limited their direct applications in operational flood early warning.  The Center for Space Research (CSR) at The University of Texas is developing a new 5-day mascon product (CSR.5d) using GRACE measurements only. The 5-day solution represents the latest global mass changes and may thus be useful for detecting and predicting hydroclimate events (e.g., flooding) at the sub-monthly scale. In this work, we assessed the predictability of GRACE-like, short-term total water storage anomalies (TWSA) by using the experimental CSR.5d product as training samples. Specifically, a probabilistic deep learning model was used to learn the state-transition model underlying the CSR.5d TWSA, by using the antecedent TWSA and hydroclimatic variables (e.g., precipitation and air temperature) as predictors. By design, our method generates both predicted mean and uncertainty intervals at the same time. Performance metrics, obtained at the grid- and basin scales, suggest that the inherent dynamics of the TWSA variations can be learned well using the machine learning method, thus providing important insights on the operational use of the 5-day mascon product.
Changes of water storage in Germany since 2002 observed with GRACE/GRACE-FO
Authors: Güntner Andreas , Gerdener Helena , Boergens Eva , Kusche Jürgen , Kollet Stefan , Dobslaw Henryk , Hartick Carl , Sharifi Ehsan , Flechtner Frank
Published: September 2022

A recent sequence of years with below-average precipitation and above-average air temperatures in large parts of Europe, going along with decreasing lake and groundwater levels, low flow conditions in rivers, damage to forest ecosystems and reduced or failing crop yields in agriculture, raised the public debate on the current and future availability of water resources. In Germany, the public debate has been boosted by reports on drastically decreasing Terrestrial Water Storage (TWS) based on satellite gravimetry, with the JPL Mascon data indicating a TWS decrease of indicating a TWS loss of -2.4 Gt / year for the area of Germany from 11/2002 to 10/2021. To provide additional scientific evidence to this debate, we analyzed the GRACE and GRACE-FO data products of COST-G, GFZ and ITSG Graz / University of Bonn, resulting in German-wide TWS trends of -0.7 to -1.3 Gt / year for this period. Signal leakage of Alpine glacier mass loss leads to spuriously more negative TWS trends for Germany. Furthermore, we stress that given extreme positive TWS anomalies in 2002 and very negative anomalies in 2018 and 2019, the resulting trend values are very sensitive to the selected time period. A longer TWS time series for Germany simulated with a hydrological model indicates that the trend values for the period of satellite gravimetry are not representative of the long-term dynamics. Thus, they are not suited for extrapolating to future TWS trends.  
Mapa de publicaciones científicas y análisis bibliométrico de la Revista Folia Amazónica en Loreto, Perú
Authors: Zárate-Gómez Ricardo , Palacios-Vega Juan José , Jarama-Vilcarromero Anita Rocio , Fachín-Malaverri Lizardo Manuel , Rondona-Vásquez Indira , Mendez-Torres Elmer Alfredo , Jung Nina Ines , Ramos-Rodríguez María Claudia , Mozombite-Pinto Linder Felipe
Published: September 2022

Objetivo. Elaborar un mapa de publicaciones donde se visualicen las investigaciones científicas espacializadas a través de puntos de coordenadas geográficas en el departamento de Loreto, de forma preliminar con publicaciones de la revista Folia Amazónica.Método. Se aplicaron técnicas cartográficas y bibliométricas para analizar 255 artículos científicos publicados entre los años 1988 y 2016 en la revista Folia Amazónica.Resultados. Las publicaciones estuvieron centralizadas en el área de influencia de la carretera Iquitos – Nauta, Jenaro Herrera, cuenca baja y media del río Nanay y sector izquierdo de la cuenca del río Marañón. La red científica generada a través de la revista Folia Amazónica evidenció una figura “no conexa”. Las afiliaciones institucionales correspondieron a 71 entidades, 12 países y 386 autores, donde Perú y Francia tuvieron mayor producción científica, en tanto Estados Unidos tuvo mayor cantidad de instituciones afiliadas a la revista Folia Amazónica después del Perú.Conclusiones. El mapa de publicaciones representa una gran herramienta de investigación con proyección de desarrollo y gestión científica. La integración con otras revistas permitirá orientar proyectos que coadyuven al desarrollo del departamento de Loreto y en un futuro en el ámbito amazónicos.
O bibliotecário gestor na implicação da preservação digital pela análise das políticas dos repositórios das universidades públicas
Authors: Nascimento de Farias Ronnie Anderson , França de Lima Izabel
Published: September 2022

Objetivo.As instituições interessadas na preservação digital precisam planejar, investir e organizar-se, adotando diretrizes e uma infraestrutura tecnológica para esse processo. Tem como objetivo apresentar uma análise sobre o papel do profissional bibliotecário na preservação digital por meio das políticas de Informação dos Repositórios Institucionais das universidades públicas nacionais.Metodo. Foi utilizado o método de Bardin para analise do conteúdo das políticas informacionais, sendo a pesquisa caracterizada como descritiva e explicativa. A abordagem da pesquisa foi quanti-qualitativa e o método de pesquisa empregado para fundamentação teórica foi o bibliográfico e documental. O universo da pesquisa foi as políticas de informação dos Repositórios Institucionais nos sites das universidades presentes no registro do Cadastro Nacional de Cursos e Instituições de Educação Superior (Cadastro e-MEC) - base de dados oficial dos cursos e Instituições de Educação Superior- IES, comtemplando as universidades públicas municipais, federais e estaduais, segundo a categoria administrativa do Cadastro e-MEC.Resultados. Foram feitas analise das políticas no período de março a agosto de 2020 comtemplando 51 repositórios institucionais. As universidades publicas que não possuíam política documentada foram 21, com prevalência na região Sudeste. O cenário evidencia a inexpressividade das implicações do bibliotecário gestor na preparação de diretrizes e mecanismos para garantir o controle e a preservação digital da produção nacional e intelectual gerada pela instituição.Conclusões. Ainda não é documentada a política de preservação digital pela grande maioria dos repositórios institucionais públicos nacionais, por isso é fundamental a atuação do bibliotecário na equipe de preservação do repositório institucional atendento as diretrizes fundamentais para preservação a longo prazo.
Saudabilidade Gastronômica: análise bibliométrica
Authors: Divino Dias Frederico , De Aguiar Filho Armando Sérgio , Pinheiro Marta Macedo Kerr
Published: September 2022

Objetivo. O presente estudo apresenta uma pesquisa bibliométrica que objetivou levantar o estado da arte da Gastronomia no cenário internacional. Como se trata de uma área nova que apresenta poucas publicações científicas, viu-se a necessidade de buscar dados mais claros acerca das discussões que vem sendo realizadas dentro da academia científica nesta área da ciência.Método. Por meio de uma pesquisa documental exploratória de cunho qualitativo, estudou-se um total de cem artigos científicos de forma estatística simples, sendo que 27 deles foram apreciados a partir da análise de conteúdo. A análise quantitativa trouxe à tona dados gerais ligados às informações tais como: nomes dos autores, filiação, áreas de publicação, nomes dos periódicos e palavras-chave. No que tange às análises qualitativas foram selecionados manuscritos específicos publicados em um periódico que se destacou no cenário da análise.Resultados. Notou-se ao longo do estudo que o maior quantitativo de publicações está baseado em um periódico em específico, sendo que grande parte dos autores são filiados à instituições superiores da Espanha. Neste contexto foi notória a associação da Gastronomia à área da Nutrição em eixos específicos.Conclusões. Conclui-se que a Gastronomia vem sendo deixada em um segundo plano nas discussões científicas próprias da área e evidenciou-se ser de grande valia estimular novos estudos que a envolvam enquanto campo da ciência. O trabalho evidenciou que o campo de estudo realmente possui, nos critérios estipulados, uma baixa de materiais publicados, o que pode comprometer os estudos pertinentes e demandar necessariamente a associação a outras áreas da ciência..
Tópicos de mudanças da RDA: percepção dos catalogadores da Universidade Federal de Minas Gerais
Authors: Holanda Paulo Marcelo Carvalho , Lourenço Cíntia de Azevedo
Published: September 2022

Objetivo. Apresentar as prinicpais percepções dos catalogadores das bibliotecas da UFMG referente a essas mudaças de regras e apontar os pontos forte e fracos destas percepções.Método. Caracteriza como aplicada, de investigação de abordagem científica no processo de descoberta indutiva, de objetivos exploratórios e descritivos e aspectos de métodos mistos, que combina ou associa as formas qualitativas e quantitativas. Utilizou-se como instrumento para coleta de dados a entrevista semiestruturada e para a análise de dados a abordadgem de análise de conteúdo.Resultados.  Apontam para a pouca familiaridade dos catalogadores referentes as mudanças da RDA sobre a percepção dos tópicos de elementos essenciais para descrição, transcrição RDA verus AACR2, terminologias e abreviações, subistituição de campos MARC 260 pelo campo 264, desiganadores de relacionamento e subistiuição da DGM.Conclusões. Os catalogadores das bibliotecas do sistema de bibliotecas da UFMG sobre a norma RDA, efetivamente, demonstronstraram que ainda não estão percebendo bem essas mudanças de regras da RDA, sendo necessário o conhecimento das regras e as mudanças propostas por elas, além de apontarem para a necessidade de aprendizagem e estudo continuado da norma, e pela demonstração prática do seu funcionamento.
Judô paralímpico: atuação profissional de professores das américas e europa
Authors: Antonio Baião Junior Arlindo , Júlio Gavião de Almeida José , Duarte Edison
Published: September 2022

O judô faz parte dos Jogos Paralímpicos para pessoas com deficiência visual. O objetivo desta pesquisa foi mapear as estratégias de ensino adotadas no processo de iniciação esportiva. Esta pesquisa quantitativa utilizou do método survey com escala likert de 5 pontos. A amostra foi formada por 20 professores de 11 países. Como resultado, constatou-se que todos os professores mesclam em sua atuação profissional aspectos tradicionais e inovadores, porém com maior ênfase nos inovadores (p<0.05). Os materiais mais utilizados citados foram: cordas (25%) bolas (23,3%) e panos (11,6%). Esperamos que esta pesquisa possa contribuir com futuros professores de judô paralímpico possibilitando novas perspectivas e reflexões.
Pengembangan Sistem Monitoring Filesystem Server Database Dengan Alert Menggunkanan Bot Telegram
Authors: Wali Azhary , Sulistyanto Agus , Defisa Tomi
Published: September 2022

Database adalah aspek yang sangat penting dari sebuah sistem, terutama di sebuah perusahaan yang aktifitas-aktifitasnya bergantung pada sistem tersebut. Oleh karena itu, ketersediaan database sangatlah penting. Salah satu hal yang penting dalam menjaga sebuah sistem dengan database adalah file backup database. Backup file ini disimpan di dalam sebuah filesystem, yang mana hal ini membuat filesystem perlu untuk dimonitoring. Pada sebuah perusahaan yang memiliki banyak server, sangatlah sulit untuk memonitor satu persatu server-server tersebut, sehingga diperlukan fleksibilitas. Telegram merupakan sistem berkirim pesan antar platform yang gratis dan memiliki API BOT. Di era dimana semua orang menggunakan telepon genggam, memonitor sebuah server secara remote menjadi mungkin. Yaitu dengan mengintegrasikan database server dengan telegram  untuk mengirimkan informasi server ke perangkat telepon genggam dari administrator menggunakan BOT telegram.