Rapid extreme meteorological events detected by daily regional GRACE solutions

2021 ◽  
Author(s):  
Guillaume Ramillien ◽  
Lucia Seoane ◽  
José Darrozes
Keyword(s):  
Water Mass ◽  
Heavy Precipitation ◽  
Mass Storage ◽  
Continental Hydrology ◽  
Daily Water ◽  
Range Rate ◽  
Along Track ◽  
Total Energy Conservation ◽  
Orbiter Mission

<p>We investigate the possibility to use the Low-Earth Orbiter mission well known as GRACE to detect sudden regional variations of water mass storage caused by heavy precipitation and flooding episodes caused by the passage of tropical hurricanes of categories 4-5 (from day to a week). For this purpose, daily water mass solutions are produced from along-track GRACE geopotential anomalies to catch the signatures of these intense meteorological events. These geopotential variations are derived from accurate inter-satellite K-Band Range Rate (KBRR) measurements made along the 5-second orbits by imposing the total energy conservation to the twin GRACE vehicles. The determination of these surface sources is made over a regional network of juxtaposed triangular tiles of quasi-constant areas, and they are refreshed by a Kalman filtering for integrating progressively daily geopotential observations. These latter data have been previously reduced from known gravitational effects of atmosphere and oceanic masses (including periodic tides) for isolating the continental hydrology contribution. Our estimates of regional hydrological impacts are also compared to the ones obtained by synthesis of daily degree-40 Stokes coefficients provided by ITSG, Graz.</p>

Fast determination of surface water mass changes using regional orthogonal functions

2020 ◽  
Author(s):  
Guillaume Ramillien ◽  
Lucia Seoane
Keyword(s):  
Surface Water ◽  
Water Mass ◽  
Mass Density ◽  
Extended Kalman Filtering ◽  
Orthogonal Functions ◽  
Continental Hydrology ◽  
The Matrix ◽  
Range Rate ◽  
Along Track

<p>Approaches based on Stokes coefficient filtering and « mass concentration » representations have been proposed for recovering changes of the surface water mass density from along-track accurate GRACE K-Band Range Rate (KBRR) measurements of geopotential change. The number of parameters, i.e. surface triangular tiles of water mass, to be determined remains large and the choice of the regularization strategy as the gravimetry inverse problem is non unique. In this study, we propose to use regional sets of orthogonal surface functions to image the structure of the surface water mass density variations. Since the number of coefficients of the development is largely smaller than the number of tiles, the computation of daily GRACE solutions for continental hydrology, e.g. obtained by Extended Kalman Filtering (EKF), is greatly fastened and eased by the matrix dimensions and conditioning. The proposed scheme of decomposition is applied to the African continent where it enables to very localized sources of (sub-)monthly water mass amplitudes.</p>

scholarly journals Recovery of Rapid Water Mass Changes (RWMC) by Kalman Filtering of GRACE Observations

2020 ◽  
Vol 12 (8) ◽  
pp. 1299
Author(s):  
Guillaume Ramillien ◽  
Lucía Seoane ◽  
Maike Schumacher ◽  
Ehsan Forootan ◽  
Frédéric Frappart ◽  
...  
Keyword(s):  
Kalman Filtering ◽  
Water Mass ◽  
Extreme Weather Events ◽  
Grace Data ◽  
Weather Events ◽  
Continental Hydrology ◽  
Realistic Description ◽  
Range Rate ◽  
Recovery Approach ◽  
Along Track

We demonstrate a new approach to recover water mass changes from GRACE satellite data at a daily temporal resolution. Such a product can be beneficial in monitoring extreme weather events that last a few days and are missing by conventional monthly GRACE data. The determination of the distribution of these water mass sources over networks of juxtaposed triangular tiles was made using Kalman Filtering (KF) of daily GRACE geopotential difference observations that were reduced for isolating the continental hydrology contribution of the measured gravity field. Geopotential differences were obtained from the along-track K-Band Range Rate (KBRR) measurements according to the method of energy integral. The recovery approach was validated by inverting synthetic GRACE geopotential differences simulated using GLDAS/WGHM global hydrology model outputs. Series of daily regional and global KF solutions were estimated from real GRACE KBRR data for the period 2003–2012. They provide a realistic description of hydrological fluxes at monthly time scales, which are consistent with classical spherical harmonics and mascons solutions provided by the GRACE official centers but also give an intra-month/daily continuity of these variations.

scholarly journals Alignment determination of the Hayabusa2 laser altimeter (LIDAR)

2021 ◽  
Vol 73 (1) ◽  
Author(s):  
Hirotomo Noda ◽  
Hiroki Senshu ◽  
Koji Matsumoto ◽  
Noriyuki Namiki ◽  
Takahide Mizuno ◽  
...  
Keyword(s):  
Altimeter Data ◽  
Gravity Assist ◽  
Laser Altimeter ◽  
Trajectory Error ◽  
Flight Data ◽  
Camera Image ◽  
Operation Period ◽  
The Cross ◽  
Along Track

AbstractIn this study, we determined the alignment of the laser altimeter aboard Hayabusa2 with respect to the spacecraft using in-flight data. Since the laser altimeter data were used to estimate the trajectory of the Hayabusa2 spacecraft, the pointing direction of the altimeter needed to be accurately determined. The boresight direction of the receiving telescope was estimated by comparing elevations of the laser altimeter data and camera images, and was confirmed by identifying prominent terrains of other datasets. The estimated boresight direction obtained by the laser link experiment in the winter of 2015, during the Earth’s gravity assist operation period, differed from the direction estimated in this study, which fell on another part of the candidate direction; this was not selected in a previous study. Assuming that the uncertainty of alignment determination of the laser altimeter boresight was 4.6 pixels in the camera image, the trajectory error of the spacecraft in the cross- and/or along-track directions was determined to be 0.4, 2.1, or 8.6 m for altitudes of 1, 5, or 20 km, respectively.

Recoverability of Callisto gravity field influenced by orbiter mission characteristics

2021 ◽  
Author(s):  
William Desprats ◽  
Daniel Arnold ◽  
Michel Blanc ◽  
Adrian Jäggi ◽  
Mingtao Li ◽  
...  
Keyword(s):  
Gravity Field ◽  
Noise Model ◽  
Force Model ◽  
Tracking Data ◽  
Science Center ◽  
National Space ◽  
Beta Angle ◽  
Dynamical Parameters ◽  
Range Rate ◽  
Orbiter Mission

<p>The exploration of Callisto is part of the extensive interest in the icy moons characterization. Indeed, Callisto is the Galilean moon with the best-preserved records of the Jovian system formation. Led by the National Space Science Center (NSSC), Chinese Academy of Science (CAS), the planned Gan De mission aims to send an orbiter around Callisto in order to characterize its surface and interior. Potential orbit configurations are currently under study for the Gan De mission proposal.</p><p>As part of a global characterization of Callisto, its gravity field can be inferred using radio tracking data from an orbiter. Mission characteristics such as orbit type, Earth beta angle and solar elongation will have a direct influence on the recoverability of its gravity field parameters. In this study, we will analyse this influence from closed-loop simulations using the planetary extension of the Bernese GNSS Softwareai.</p><p>A number of reference orbits with different orbital characteristics will be selected for the Gan De mission and, using an extended force model, will be propagated from different starting dates and different initial Earth beta angles. Realistic Doppler tracking data (2-way X-band Doppler range rate) will be simulated as measurements from ground stations, with a dedicated noise model. These observations will then be used to reconstruct the orbit along with dynamical parameters. The focus of this presentation will be on the quality of the retrieved gravity field parameters and tidal Love number k2.</p>

High Precision 14C Analysis in Small Seawater Samples

Radiocarbon ◽  
2019 ◽  
Vol 62 (1) ◽  
pp. 13-24 ◽  
Author(s):  
Núria Casacuberta ◽  
Maxi Castrillejo ◽  
Anne-Marie Wefing ◽  
Silvia Bollhalder ◽  
Lukas Wacker
Keyword(s):  
Inorganic Carbon ◽  
Water Mass ◽  
High Spatial Resolution ◽  
Dissolved Inorganic Carbon ◽  
Ion Beam ◽  
Beam Physics ◽  
Automated Method ◽  
Labview Program ◽  
Seawater Samples

ABSTRACTA new method to extract CO2 in seawater samples for the determination of F14C has been developed in the Laboratory of Ion Beam Physics at ETH Zurich. The setup consists of an automated sampler designed to extract dissolved inorganic carbon (DIC) from 7 samples in a row, by flushing the seawater with He gas to extract CO2. The fully automated method is controlled via a LabVIEW program that runs through all consecutive steps: catalyst preconditioning, CO2 extraction, CO2 trapping, thermal CO2 release from the trap into the reactor and finally the graphitization reaction which is performed simultaneously in the 7 reactors. The method was optimized by introducing a Cu-Ag furnace that was placed between the water and zeolite traps, which resulted in a better and faster graphitization performance (<2 hr) compared to previously used techniques. The method showed to be reproducible with an unprecedented precision of 1.7‰ even though consuming only 50–60 mL of seawater. The high throughput of 21 samples per day allows for coverage of future oceanographic transects with high spatial resolution, thus fostering the use of radiocarbon (14C) as water mass tracer.

Along-track analysis of GRACE and GRACE Follow-On KBR and LRI data for new science applications

2020 ◽  
Author(s):  
Shin-Chan Han ◽  
Khosro Ghobadi Far ◽  
Jeanne Sauber ◽  
Christopher Mccullough ◽  
David Wiese ◽  
...  
Keyword(s):  
High Frequency ◽  
Reference Range ◽  
Numerical Differentiation ◽  
Line Of Sight ◽  
Short Term ◽  
Orbital State ◽  
New Science ◽  
Range Rate ◽  
Along Track ◽  
Track Analysis

&lt;p&gt;We present a method of analysing inter-satellite tracking data for detecting short-term (sub-monthly) gravitational changes from GRACE and GRACE Follow-On.&amp;#160; The method is based on the residual range-rate data with respect to the reference range-rate computed with dynamic orbital state vectors.&amp;#160; Then, we apply a numerical differentiation to compute range-acceleration residuals.&amp;#160; We found that the range-acceleration residuals are near-perfectly correlated with the line-of-sight gravity difference (LGD) between two spacecrafts and the transfer (admittance) function between them can be determined regardless of time and space (Ghobadi-Far et al., 2018, JGR-Solid Earth, https://doi.org/10.1029/2018JB016088).&amp;#160; The transfer function, to be applied directly to range-acceleration residuals, enables accurate LGD determination with the error of 0.15 nm/s^2 over the frequency band higher than 1 mHz (5 cycles-per-revolution), whereas the actual GRACE measurement error is several times larger.&lt;/p&gt;&lt;p&gt;In this presentation, we present two new geophysical applications to examine high-frequency gravitational changes at times scales of significantly less than one month; Gravitational observation of tsunamis triggered by the 2004 Sumatra, 2010 Maule, and 2011 Tohoku earthquakes and transient gravitational changes due to Earth&amp;#8217;s free oscillation excited by the 2004 earthquake. &amp;#160;Lastly, we present new results from GRACE Follow-On KBR and LRI inter-satellite ranging data.&amp;#160;&lt;/p&gt;

scholarly journals The ATS-F/NIMBUS-E Tracking Experiment

1972 ◽  
Vol 48 ◽  
pp. 112-120 ◽  
Author(s):  
F. O. von Bun
Keyword(s):  
Integration Time ◽  
Time Interval ◽  
Tracking Systems ◽  
Tracking Errors ◽  
Original Intent ◽  
Laser Tracking ◽  
Ground Station ◽  
Error Analyses ◽  
Range Rate

In this paper the objective of the ATS-F/NIMBUS-E Tracking Experiment, the first of such kind, is presented. Specifically, this experiment has a two-fold purpose: First, to gain experience in the practical use of satellite-to-satellite range and range rate data for very accurate orbit determination (this was its original intent); and second, to evaluate the real usefulness of such a technique for geodetic studies despite the fact that the 1000 km NIMBUS orbit is not ideally suited for such a purpose.The accuracies of the tracking systems of the satellite-to-satellite and satellite-to-ground link (ATS-F to the Rosman, N.C. ground station) will be ~ 0.035 cm/s in range rate and ~ 1 m in range – utilizing a 10 s integration time. With these values one obtains, based upon performed error analyses, orbit height errors in the order of 0.1 to 0.3 m for the near earth orbiting NIMBUS spacecraft. This experiment will therefore hopefully prove to be a significant first step for future Earth applications spacecraft carrying altimeters systems for measuring ocean height variations.In addition, laser corner reflectors placed on board the ATS-F will make a total independent position determination of this spacecraft to approximately 15 m to 30 m possible, assuming that the location errors of four laser tracking stations used to determine the orbit are about 3 m or 5 m in each component respectively, with laser ranging system noise errors of 1.2 m and bias errors of 0.15 m. A small position error of the ATS-F, the ‘orbiting tracking station’ is essential in order to make full usage of the small satellite-to-satellite tracking errors mentioned.For purpose of geodetic studies, one of the final goals, range rate variations of 0.1 cm/s or less corresponding to surface gravity anomaly of 20 mgal or less (over a half-width of 100 km on the Earth surface), will have to be measured during a time interval of approximately, say, 30–60 s. These values are within the range of the planned tracking systems accuracies for ATS-F and NIMBUS-E.

Neural model of relative mass flows of water and sugar in an installation for crystallizing and centrifuging A massecuite

2010 ◽  
pp. 506-514 ◽  
Author(s):  
Jan Iciek ◽  
Arkadiusz Jezierski
Keyword(s):  
Water Mass ◽  
Calculated Data ◽  
Reference Value ◽  
Neural Model ◽  
Balance Model ◽  
Relative Mass ◽  
Practical Application ◽  
Relative Water ◽  
Mass Flows

Three models of relative mass flows of water and sugar concerning crystallizing and centrifuging of A massecuite are presented. The input data for the calculation of particular flow volumes were the dry substance content wDS and sucrose content wS values measured in them during the sugarbeet campaign in one Polish beet sugar factory. These values, along with authors’ own knowledge and technological charts, provided the authors with the basis for the development of a mathematical model making possible the determination of appropriate, relative mass flows (sugar mass flow was accepted as the reference value) in a station for crystallizing and centrifuging of A massecuite. Then, an external balance model was developed to check the accuracy of the measured and of the calculated data. This model was provided with reliable data to develop a neural model. The developed and trained artificial neural network allowed for the simulation of relative water and sugar mass flows in an installation for crystallizing and centrifuging A massecuite. The results were satisfactory and the neural model developed was found to have a practical application in the simulation of the influence of particular sugar and water mass flows on the work of this installation.

GRACE-derived surface water mass anomalies by energy integral approach: application to continental hydrology

2011 ◽  
Vol 85 (6) ◽  
pp. 313-328 ◽  
Author(s):  
Guillaume Ramillien ◽  
R. Biancale ◽  
S. Gratton ◽  
X. Vasseur ◽  
S. Bourgogne
Keyword(s):  
Surface Water ◽  
Water Mass ◽  
Integral Approach ◽  
Energy Integral ◽  
Continental Hydrology
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