- document
-
Wakker, K.F. (author), Ambrosius, B.A.C. (author), Leenman, H. (author), Noomen, R. (author), Piersma, H.J.D. (author), van der Ploeg, T. (author), Schrama, E.J.O. (author)This report covers various aspects of the orbit computation requirements for the 24 satellites of the proposed ESA NAVSAT global navigation system. It starts with an overview of the general characteristics of the satellite orbits and the visibilities of the satellites from the 6 globally distributed uplink stations (Regional Centers). In...report 1984
- document
- Schrama, E.J.O. (author) report 1989
- document
- Schrama, E.J.O. (author) doctoral thesis 1989
- document
- Schrama, R.J.P. (author) journal article 1992
- document
- Schrama, R.J.P. (author) doctoral thesis 1992
- document
- Rummel, R. (author), van Gelderen, M. (author), Koop, R. (author), Schrama, E. (author), Sanso, F. (author), Brovelli, M. (author), Miggliaccio, F. (author), Sacerdote, F. (author) report 1993
- document
- Schrama, E. (author) master thesis 2002
- document
-
Kusche, J. (author), Schrama, E.J.O. (author)Monitoring hydrological redistributions through their integrated gravitational effect is the primary aim of the Gravity Recovery and Climate Experiment (GRACE) mission. Time?variable gravity data from GRACE can be uniquely inverted to hydrology, since mass transfers located at or near the Earth's surface are much larger on shorter timescales...journal article 2005
- document
-
Ditmar, P.G. (author), Kuznetsov, V. (author), Van Eck van der Sluis, A.A. (author), Schrama, E. (author), Klees, R. (author)Performance of a recently proposed technique for gravity field modeling has been assessed with data from the CHAMP satellite. The modeling technique is a variant of the acceleration approach. It makes use of the satellite accelerations that are derived from the kinematic orbit with the 3-point numerical differentiation scheme. A 322-day data set...journal article 2005
- document
- Schrama, I.J. (author) master thesis 2006
- document
- Schrama, I.J. (author) master thesis 2006
- document
- Twigt, D.J. (author), De Goede, E.D. (author), Schrama, E.J.O. (author), Gerritsen, H. (author) journal article 2007
- document
- Schrama, E.J.O. (author), Visser, P.N.A.M. (author) journal article 2007
- document
-
Signal and noise in Gravity Recovery and Climate Experiment (GRACE) observed surface mass variationsSchrama, E.J.O. (author), Wouters, B. (author), Lavallée, D.A. (author)The Gravity Recovery and Climate Experiment (GRACE) product used for this study consists of 43 monthly potential coefficient sets released by the GRACE science team which are used to generate surface mass thickness grids expressed as equivalent water heights (EQWHs). We optimized both the smoothing radius and the level of approximation by...journal article 2007
- document
-
Wouters, B. (author), Schrama, E.J.O. (author)One of the major problems one has to deal with when working with Gravity Recovery and Climate Experiment (GRACE) data is the increasing error spectrum at higher degrees in the provided Stokes coefficients, appearing as unphysical North?South striping patterns in the maps of equivalent water height (EWH). This phenomenon is commonly suppressed by...journal article 2007
- document
-
Wouters, B. (author), Chambers, D. (author), Schrama, E.J.O. (author)Using satellite gravity data between February 2003 and January 2008, we examine changes in Greenland's mass distribution on a regional scale. During this period, Greenland lost mass at a mean rate of 179 ± 25 Gt/yr, equivalent to a global mean sea level change of 0.5 ± 0.1 mm/yr. Rates increase over time, suggesting an acceleration of the mass...journal article 2008
- document
-
Bouman, J. (author), Rispens, S. (author), Gruber, T. (author), Koop, R. (author), Schrama, E. (author), Visser, P. (author), Tscherning, C.C. (author), Veicherts, M. (author)One of the products derived from the gravity field and steady-state ocean circulation explorer (GOCE) observations are the gravity gradients. These gravity gradients are provided in the gradiometer reference frame (GRF) and are calibrated in-flight using satellite shaking and star sensor data. To use these gravity gradients for application in...journal article 2008
- document
-
Visser, P.N.A.M. (author), Schrama, E.J.O. (author), Sneeuw, N. (author), Weigelt, M. (author)The so-called Colombo-Nyquist (Colombo, The global mapping of gravity with two satellites, 1984) rule in satellite geodesy has been revisited. This rule predicts that for a gravimetric satellite flying in a (near-)polar circular repeat orbit, the maximum resolvable geopotential spherical harmonic degree (lmax) is equal to half the number of...conference paper 2009
- document
-
Schrama, E.J.O. (author), Wouters, B. (author)In this paper we discuss a new method for determining mass time series for 16 hydrological basins representing the Greenland system (GS) whereby we rely on Gravity Recovery and Climate Experiment (GRACE) mission data. In the same analysis we also considered observed mass changes over Ellesmere Island, Baffin Island, Iceland, and Svalbard (EBIS)....journal article 2011
- document
-
Schrama, E.J.O. (author), Wouters, B. (author), Vermeersen, L.L.A. (author)This paper summarizes results obtained for Greenland’s mass balance observed with NASA’s GRACE mission. We estimate a Greenland ice sheet mass loss at ?201 ± 19 Gt/year including a discernible acceleration of ?8 ± 7 Gt/year2 between March 2003 and February 2010. The mass loss of glacier systems on the South East of Greenland has slowed down...journal article 2011