Searched for:
(1 - 20 of 48)

Pages

document
James, Rebecca K. (author), Pietrzak, J.D. (author), Candy, A.S. (author), Katsman, C.A. (author), van der Boog, C.G. (author), Riva, R.E.M. (author), Slobbe, D.C. (author), Klees, R. (author), More Authors (author)
Tropical beaches provide coastal flood protection, income from tourism, and habitat for flagship species. They urgently need protection from erosion, which is being exacerbated by changing climate and coastal development. Traditional coastal engineering solutions are expensive, provide unstable temporary solutions, and often disrupt natural...
journal article 2019
document
James, Rebecca K. (author), van Katwijk, Marieke M. (author), Pietrzak, J.D. (author), Candy, A.S. (author), Klees, R. (author), Riva, R.E.M. (author), Slobbe, D.C. (author), Katsman, C.A. (author), Herman, P.M.J. (author), More Authors (author)
Global oceanic pH is lowering, which is causing great concern for the natural functioning of marine ecosystems. Current pH predictions are based on open ocean models; however, coastal zones are dynamic systems with seawater pH fluctuating temporally and spatially. To understand how coastal ecosystems will respond in the future, we first need...
journal article 2019
document
Wouters, B. (author), Ditmar, P.G. (author), Ran, J. (author), Klees, R. (author), Schrama, Ernst (author), More Authors (author)
Satellite gravimetry data acquired by the Gravity Recovery and Climate Experiment (GRACE) allows to derive the temporal evolution in ice mass for both the Antarctic Ice Sheet (AIS) and the Greenland Ice Sheet (GIS). Various algorithms have been used in a wide range of studies to generate Gravimetric Mass Balance (GMB) products. Results from...
journal article 2019
document
Slobbe, D.C. (author), Klees, R. (author), Farahani, H. (author), Huisman, L. (author), Alberts, Bas (author), Voet, Pierre (author), Doncker, Filip De (author)
We present a local quasi-geoid (QG) model which combines a satellite-only global gravity model with local data sets using weighted least squares. The QG is computed for an area comprising the Netherlands, Belgium, and the southern North Sea. It uses a two-scale spherical radial basis function model complemented by bias parameters to account...
journal article 2019
document
Klees, R. (author), Slobbe, D.C. (author)
In this study, we quantified systematic errors in surface gravity anomalies, which were caused by systematic errors in gravity and heights of the gravity stations, and computed their impact on the quasi-geoid model of the Netherlands and Belgium. We found that 70% of the gravity datasets have statistically significant biases ranging from −2 mGal...
book chapter 2018
document
Ran, J. (author), Ditmar, P.G. (author), Klees, R. (author)
The mascon approach is a well-known technique to estimate mass anomalies in Greenland using GRACE satellite gravity data. It partitions the area of interest into laterally-homogeneous patches (mascons). An important aspect of the mascon approach is the chosen geometry of mascons. So far, its impact has not been fully understood. In this study,...
journal article 2018
document
Ditmar, P.G. (author), Tangdamrongsub, N. (author), Ran, J. (author), Klees, R. (author)
We propose a technique to regularize a GRACE-based mass-anomaly time-series in order to (i) quantify the Standard Deviation (SD) of random noise in the data, and (ii) reduce the level of that noise. The proposed regularization functional minimizes the Month-to-month Year-to-year Double Differences (MYDD) of mass anomalies. As such, it does...
journal article 2018
document
Klees, R. (author), Slobbe, D.C. (author), Farahani, H. (author)
The posed question arises for instance in regional gravity field modelling using weighted least-squares techniques if the gravity field functionals are synthesised from the spherical harmonic coefficients of a satellite-only global gravity model (GGM), and are used as one of the noisy datasets. The associated noise covariance matrix, appeared...
journal article 2018
document
Slobbe, D.C. (author), Klees, R. (author), Verlaan, M. (author), Zijl, F. (author), Alberts, BA (author), Farahani, H. (author)
We present an efficient and flexible alternative method to connect islands and offshore tide gauges with the height system on land. The method uses a regional, high-resolution hydrodynamic model that provides total water levels. From the model, we obtain the differences in mean water level (MWL) between tide gauges at the mainland and at the...
journal article 2018
document
van Westen, René M. (author), Dijkstra, Henk A. (author), Klees, R. (author), Riva, R.E.M. (author), Slobbe, D.C. (author), van der Boog, C.G. (author), Katsman, C.A. (author), Candy, A.S. (author), Pietrzak, J.D. (author), Zijlema, M. (author), James, Rebecca K. (author), Bouma, Tjeerd J. (author)
The Yucatan Channel connects the Caribbean Sea with the Gulf of Mexico and is the main outflow region of the Caribbean Sea. Moorings in the Yucatan Channel show high-frequent variability in kinetic energy (50–100 days) and transport (20–40 days), but the physical mechanisms controlling this variability are poorly understood. In this study, we...
journal article 2018
document
Sun, Y. (author), Riva, R.E.M. (author), Ditmar, P.G. (author), Klees, R. (author)
With the launch of the Gravity Recovery and Climate Experiment (GRACE) satellite mission in 2002 (http://www.csr.utexas.edu/grace), Satellite Gravimetry has become a unique tool to estimate hydrological water balance and mass balance of ice sheets, as well as to monitor mass re-distribution in the oceans and the solid Earth. However, satellite...
poster 2018
document
Klees, R. (author), Slobbe, D.C. (author), Farahani, H. (author)
The paper is about a methodology to combine a noisy satellite-only global gravity field model (GGM) with other noisy datasets to estimate a local quasi-geoid model using weighted least-squares techniques. In this way, we attempt to improve the quality of the estimated quasi-geoid model and to complement it with a full noise covariance matrix...
journal article 2018
document
Ran, J. (author), Vizcaino, M. (author), Ditmar, P.G. (author), van den Broeke, Michiel R. (author), Moon, Twila (author), Steger, Christian (author), Enderlin, Ellyn (author), Wouters, Bert (author), Noël, Brice (author), Reijmer, Catharina (author), Klees, R. (author), Zhong, Min (author)
The Greenland Ice Sheet (GrIS) is currently losing ice mass as the result of changes in the complex ice-climate interactions that have been driven by global climate change. In order to accurately predict future sea level rise, the mechanisms driving the observed mass loss must be better understood. Here, we combine data from the satellite...
journal article 2018
document
Ditmar, P.G. (author), Didova, O. (author), Klees, R. (author)
other 2018
document
Didova, O. (author), Gunter, B.C. (author), Riva, R.E.M. (author), Klees, R. (author)
To fully exploit data from the Gravity Recovery and Climate Experiment (GRACE), we separate geophysical signals observed by GRACE in Antarctica by deriving high-spatial resolution maps for present-day glacial isostatic adjustment (GIA) and ice-mass changes with the least possible noise level. For this, we simultaneously (i) improve the...
journal article 2018
document
Slobbe, D.C. (author), Sumihar, JH (author), Frederikse, T. (author), Verlaan, M. (author), Klees, R. (author), Zijl, F (author), Hashemi Farahani, H. (author), Broekman, R (author)
In this paper, we present a novel Kalman filter approach to combine a hydrodynamic model-derived lowest astronomical tide (LAT) surface with tide gauge record-derived LAT values. In the approach, tidal water levels are assimilated into the model. As such, the combination is guided by the model physics. When validating the obtained “Kalman...
journal article 2017
document
Farahani, H. (author), Klees, R. (author), Slobbe, D.C. (author)
We assess the surface gravity data requirements for a 5-mm quasi-geoid model for the Netherlands mainland and continental shelf in terms of omission and commission errors. The omission error critically depends on the roughness of the topography and bathymetry. For the Netherlands continental shelf, Central and Northern Netherlands, the...
journal article 2017
document
Guo, X. (author), Ditmar, P.G. (author), Zhao, Q (author), Klees, R. (author), Farahani, H. (author)
GPS data collected by satellite gravity missions can be used for extracting the long-wavelength part of the Earth’s gravity field. We propose a new data processing method which makes use of the ‘average acceleration’ approach to gravity field modelling. In this method, satellite accelerations are directly derived from GPS carrier phase...
journal article 2017
document
Hashemi Farahani, H. (author), Ditmar, P.G. (author), Miragaia Gomes Inacio, P. (author), Didova, O. (author), Gunter, B.C. (author), Klees, R. (author), Guo, X. (author), Guo, Jing (author), Sun, Y. (author), Liu, Xianglin (author), Zhao, Qile (author), Riva, R.E.M. (author)
We present a high resolution model of the linear trend in the Earth’s mass variations based on DMT-2 (Delft Mass Transport model, release 2). DMT-2 was produced primarily from K-Band Ranging (KBR) data of the Gravity Recovery And Climate Experiment (GRACE). It comprises a time series of monthly solutions complete to spherical harmonic degree 120...
journal article 2017
document
Ran, J. (author), Ditmar, P.G. (author), Klees, R. (author), Farahani, H. (author)
We present an improved mascon approach to transform monthly spherical harmonic solutions based on GRACE satellite data into mass anomaly estimates in Greenland. The GRACE-based spherical harmonic coefficients are used to synthesize gravity anomalies at satellite altitude, which are then inverted into mass anomalies per mascon. The limited...
journal article 2017
Searched for:
(1 - 20 of 48)

Pages