Future Gravity Mission Concepts for Sustained Observation of Mass Transport in the Earth System

Mapping Intimacies ◽

10.5194/egusphere-egu21-9447 ◽

2021 ◽

Author(s):

Roland Pail

Keyword(s):

Mass Transport ◽

Closed Loop ◽

Cold Atom ◽

Radial Component ◽

Transport Processes ◽

Single Pair ◽

Earth System ◽

Next Generation ◽

The Earth ◽

Gravity Mission

Next Generation Gravity Missions are expected to enhance our knowledge of mass transport processes in the Earth system, establishing their products applicable to new scientific fields and serving societal needs. Compared to the current situation (GRACE Follow-On), a significant step forward to increase spatial and temporal resolution can only be achieved by new mission concepts, complemented by improved instrumentation and tailored processing strategies.In extensive numerical closed-loop mission simulations studies, different mission concepts have been studied in detail, with emphasis on orbit design and resulting spatial-temporal ground track pattern, enhances processing and parameterization strategies, and improved post-processing/filtering strategies. Promising candidates for a next-generation gravity mission are double-pair and multi-pair constellations of GRACE/GRACE-FO-type satellites, as they are currently jointly studied by ESA and NASA. An alternative concept is high-precision ranging between high- and low-flying satellites. Since such a constellation observes mainly the radial component of gravity-induced orbit perturbations, the error structure is close to isotropic, which significantly reduces artefacts of along-track ranging formations. This high-low concept was proposed as ESA Earth Explorer 10 mission MOBILE and is currently further studies under the name MARVEL by the French space agency. Additionally, we evaluate the potential of a hybridization of electro-static and cold-atom accelerometers in order to improve the accelerometer performance in the low-frequency range.In this contribution, based on full-fledged numerical closed-loop simulations with realistic error assumptions regarding their key payload, different mission constellations (in-line single-pair, Bender double-pair, multi-pairs, precise high-low tracking) are assessed and compared. Their overall performance, dealiasing potential, and recovery performance of short-periodic gravity signals are analyzed, in view of their capabilities to retrieve gravity field information with short latencies to be used for societally relevant service applications, such as water management, groundwater monitoring, and forecasting of droughts and floods.

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Recovering climate-related mass transport signals by current and next-generation gravity missions

10.5194/egusphere-egu2020-3753 ◽

2020 ◽

Author(s):

Roland Pail ◽

Henryk Dobslaw ◽

Annette Eicker ◽

Laura Jensen

Keyword(s):

Climate Change ◽

Time Series ◽

Mass Transport ◽

Gravity Field ◽

Transport Processes ◽

Measuring System ◽

Climate Projections ◽

Earth System ◽

Next Generation ◽

The Earth

Gravity field missions are a unique geodetic measuring system to directly observe mass transport processes in the Earth system. Past and current gravity missions such as CHAMP, GRACE, GOCE and GRACE-Follow On have improved our understanding of large-scale mass changes, such as the global water cycle, melting of continental ice sheets and mountain glaciers, changes in ocean mass that are closely related to the mass-related component of sea level rise, which are subtle indicators of climate change, on global to regional scale. Therefore, mass transport observations are also very valuable for long-term climate applications. Next Generation Gravity Missions (NGGMs) expected to be launched in the midterm future have set high anticipations for an enhanced monitoring of mass transport in the Earth system with significantly improved spatial and temporal resolution and accuracy. This contribution will present results from numerical satellite mission performance simulations designed to evaluate the usefulness of gravity field missions operating over several decades for climate-related applications. The study is based on modelled of mass transport time series obtained from future climate projections until the year 2100 following the representative emission pathway RCP8.5 Numerical closed-loop simulations will assess the recoverability of mass variability signals by means of different NGGM concepts, e.g. GRACE-type in-line single-pair missions, Bender double-pair mission being composed of a polar and an inclined satellite pair, or high-precision high-low tracking missions following the MOBILE concept, assuming realistic noise levels for the key payload. In the evaluation and interpretation of the results, special emphasis shall be given to the identification of (natural or anthropogenic) climate change signals in dependence of the length of the measurement time series, and the quantification of robustness of derived trends and systematic changes.

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Mass variation observing system by high low inter-satellite links (MOBILE) – a new concept for sustained observation of mass transport from space

Journal of Geodetic Science ◽

10.1515/jogs-2019-0006 ◽

2019 ◽

Vol 9 (1) ◽

pp. 48-58 ◽

Cited By ~ 6

Author(s):

R. Pail ◽

J. Bamber ◽

R. Biancale ◽

R. Bingham ◽

C. Braitenberg ◽

...

Keyword(s):

Mass Transport ◽

Gravity Field ◽

Role Model ◽

Water Cycle ◽

European Space Agency ◽

Radial Component ◽

Transport Processes ◽

Next Generation ◽

New Instrument ◽

Satellite Missions

Abstract As changes in gravity are directly related to mass variability, satellite missions observing the Earth’s time varying gravity field are a unique tool for observing mass transport processes in the Earth system, such as the water cycle, rapid changes in the cryosphere, oceans, and solid Earth processes, on a global scale. The observation of Earth’s gravity field was successfully performed by the GRACE and GOCE satellite missions, and will be continued by the GRACE Follow-On mission. A comprehensive team of European scientists proposed the next-generation gravity field mission MOBILE in response to the European Space Agency (ESA) call for a Core Mission in the frame of Earth Explorer 10 (EE10). MOBILE is based on the innovative observational concept of a high-low tracking formation with micrometer ranging accuracy, complemented by new instrument concepts. Since a high-low tracking mission primarily observes the radial component of gravity-induced orbit perturbations, the error structure is close to isotropic. This geometry significantly reduces artefacts of previous along-track ranging low-low formations (GRACE, GRACE-Follow-On) such as the typical striping patterns. The minimum configuration consists of at least two medium-Earth orbiters (MEOs) at 10000 km altitude or higher, and one low-Earth orbiter (LEO) at 350-400 km. The main instrument is a laser-based distance or distance change measurement system, which is placed at the LEO. The MEOs are equipped either with passive reflectors or transponders. In a numerical closed-loop simulation, it was demonstrated that this minimum configuration is in agreement with the threshold science requirements of 5 mm equivalent water height (EWH) accuracy at 400 km wavelength, and 10 cm EWH at 200 km. MOBILE provides promising potential future perspectives by linking the concept to existing space infrastructure such as Galileo next-generation, as future element of the Copernicus/Sentinel programme, and holds the potential of miniaturization even up to swarm configurations. As such MOBILE can be considered as a precursor and role model for a sustained mass transport observing system from space.

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Applicability of NGGM near-real time simulations in flood detection

Journal of Geodetic Science ◽

10.1515/jogs-2019-0011 ◽

2019 ◽

Vol 9 (1) ◽

pp. 111-126

Author(s):

A. F. Purkhauser ◽

J. A. Koch ◽

R. Pail

Keyword(s):

European Space Agency ◽

Earth System ◽

The Earth ◽

Future Mission ◽

Space Agency ◽

Flood Detection ◽

The One ◽

Real Time Simulations ◽

Grace Mission ◽

Gravity Mission

Abstract The GRACE mission has demonstrated a tremendous potential for observing mass changes in the Earth system from space for climate research and the observation of climate change. Future mission should on the one hand extend the already existing time series and also provide higher spatial and temporal resolution that is required to fulfil all needs placed on a future mission. To analyse the applicability of such a Next Generation Gravity Mission (NGGM) concept regarding hydrological applications, two GRACE-FO-type pairs in Bender formation are analysed. The numerical closed loop simulations with a realistic noise assumption are based on the short arc approach and make use of the Wiese approach, enabling a self-de-aliasing of high-frequency atmospheric and oceanic signals, and a NRT approach for a short latency. Numerical simulations for future gravity mission concepts are based on geophysical models, representing the time-variable gravity field. First tests regarding the usability of the hydrology component contained in the Earth System Model (ESM) by the European Space Agency (ESA) for the analysis regarding a possible flood monitoring and detection showed a clear signal in a third of the analysed flood cases. Our analysis of selected cases found that detection of floods was clearly possible with the reconstructed AOHIS/HIS signal in 20% of the tested examples, while in 40% of the cases a peak was visible but not clearly recognisable.

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Evaluation of Pendulum NGGM Scenarios by Full Closed-Loop Simulation

10.5194/egusphere-egu21-12257 ◽

2021 ◽

Author(s):

Florian Wöske ◽

Benny Rievers

Keyword(s):

Closed Loop ◽

Variational Equation ◽

Satellite Measurement ◽

Observation Data ◽

Near Surface ◽

The Earth ◽

Cross Track ◽

Along Track ◽

Grace Mission ◽

Gravity Mission

The GRACE mission (2002-2017) delivered temporal gravity field solutions of the Earth for 15 years. It's successor, GRACE follow-on (GRACE-FO) is continuing it's legacy since May 2018. The time series of monthly gravity fields revealed global mass redistribution in in the near surface layer of the Earth with unprecedented accuracy. This assessed a completely new observable in geoscience disciplines and has become a crucial data product for climate research. Despite the groundbreaking success and relevance of the GRACE mission(s) for Earth observation and climate science, no further successor gravity mission is planned, yet. Summarized by the name Next Generation Gravity Mission (NGGM) concepts for future gravimetry missions have been proposed and analyzed for a while. As an outcome of these studies the so called Bender-configuration (two GRACE-like satellite pairs, one in a polar orbit and a second in an inclined orbit around 60&#176; to 70&#176;) is the concept currently favored by the scientific community for a candidate of the next gravity mission to be realized. However, an other concept still remains interesting due to specific advantages that might contribute to future improvements of gravity missions. In order to emphasize this, we present results of a full closed loop-simulation for a different ll-SST approach, the so called pendulum. It offers a quite similar overall performance with just two satellites. For this configuration the satellites are following each other in orbits with slightly different longitudes of the ascending nodes, thus the inter-satellite measurement direction is varying between along-track and cross-track. This configuration makes an interferometric laser ranging (LRI) quite challenging on the technical level. Nevertheless, the LRI accuracy is not necessarily needed. The relevance of the pendulum configuration has also been shifted into the focus of the French MARVEL mission proposal. In this contribution we analyze in detail the performance of the pendulum formation with the main parameters being the angle between along-track and cross-track component of the ranging direction at the equator, and the mean distance between the satellites. We conduct the angle variation for different mean ranges and assumed ranging accuracies. As reference, the GRACE and Bender concepts are simulated, as well. The orbit simulations are performed using a derivative of the ZARM/DLR XHPS mission simulator including high precision implementations of non-gravitational accelerations. The different concepts and configurations include complete GRACE-FO like attitude control and realistic environment models. State-of-the-art instrument noise models based on GRACE/-FO are used to generate observation data for accelerometer (ACC), range dependent inter satellite ranging (KBR/LRI), kinematic orbit solution (KOS) and star camera (SCA). For the gravity recovery process we use the classical variational equation approach. As for real GRACE processing, ACC calibration parameter are estimated and KOS and KBR range-rate observations are weighted by VCE.

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Next generation framework for aquatic modeling of the Earth System

Geoscientific Model Development Discussions ◽

10.5194/gmdd-2-279-2009 ◽

2009 ◽

Vol 2 (1) ◽

pp. 279-307 ◽

Cited By ~ 1

Author(s):

B. M. Fekete ◽

W. M. Wollheim ◽

D. Wisser ◽

C. J. Vörösmarty

Keyword(s):

Model Development ◽

Learning Curves ◽

Earth System ◽

Next Generation ◽

Model Calculations ◽

System Models ◽

The Earth ◽

Wide Range ◽

Spatial Domains ◽

Earth System Models

Abstract. Earth System model development is becoming an increasingly complex task. As scientists attempt to represent the physical and bio-geochemical processes and various feedback mechanisms in unprecedented detail, the models themselves are becoming increasingly complex. At the same time, the complexity of the surrounding IT infrastructure is growing as well. Earth System models must manage a vast amount of data in heterogeneous computing environments. Numerous development efforts are on the way to ease that burden and offer model development platforms that reduce IT challenges and allow scientists to focus on their science. While these new modeling frameworks (e.g. FMS, ESMF, CCA, OpenMI) do provide solutions to many IT challenges (performing input/output, managing space and time, establishing model coupling, etc.), they are still considerably complex and often have steep learning curves. The Next generation Framework for Aquatic Modeling of the Earth System (NextFrAMES, a revised version of FrAMES) have numerous similarities to those developed by other teams, but represents a novel model development paradigm. NextFrAMES is built around a modeling XML that lets modelers to express the overall model structure and provides an API for dynamically linked plugins to represent the processes. The model XML is executed by the NextFrAMES run-time engine that parses the model definition, loads the module plugins, performs the model I/O and executes the model calculations. NextFrAMES has a minimalistic view representing spatial domains and treats every domain (regardless of its layout such as grid, network tree, individual points, polygons, etc.) as vector of objects. NextFrAMES performs computations on multiple domains and interactions between different spatial domains are carried out through couplers. NextFrAMES allows processes to operate at different frequencies by providing rudimentary aggregation and disaggregation facilities. NextFrAMES was designed primarily for hydrological modeling purposes, but many of its functionality should be applicable for a wide range of land surface models. In its present capabilities NextFrAMES is probably inadequate to implement fully coupled Earth System models, but future versions with the guidance from Earth System developers might someday eliminate its limitations. Our intent with NextFrAMES is to initiate a dialog about new ways of expressing models that is less tied to the actual implementation and allow scientist to develop models at a more abstract level.

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