Print Email Facebook Twitter Statistically optimal estimation of Greenland Ice Sheet mass variations from GRACE monthly solutions using an improved mascon approach Title Statistically optimal estimation of Greenland Ice Sheet mass variations from GRACE monthly solutions using an improved mascon approach Author Ran, J. (TU Delft Physical and Space Geodesy) Ditmar, P.G. (TU Delft Physical and Space Geodesy) Klees, R. (TU Delft Physical and Space Geodesy) Farahani, H. (TU Delft Novel Aerospace Materials) Date 2017 Abstract 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 spectral content of the gravity anomalies is properly accounted for by applying a low-pass filter as part of the inversion procedure to make the functional model spectrally consistent with the data. The full error covariance matrices of the monthly GRACE solutions are properly propagated using the law of covariance propagation. Using numerical experiments, we demonstrate the importance of a proper data weighting and of the spectral consistency between functional model and data. The developed methodology is applied to process real GRACE level-2 data (CSR RL05). The obtained mass anomaly estimates are integrated over five drainage systems, as well as over entire Greenland. We find that the statistically optimal data weighting reduces random noise by 35–69%, depending on the drainage system. The obtained mass anomaly time-series are de-trended to eliminate the contribution of ice discharge and are compared with de-trended surface mass balance (SMB) time-series computed with the Regional Atmospheric Climate Model (RACMO 2.3). We show that when using a statistically optimal data weighting in GRACE data processing, the discrepancies between GRACE-based estimates of SMB and modelled SMB are reduced by 24–47%. Subject Data weightingGRACEGreenland Ice SheetMasconSurface mass balance To reference this document use: http://resolver.tudelft.nl/uuid:e955169d-c7e0-4f8e-8836-1eab8e296567 DOI https://doi.org/10.1007/s00190-017-1063-5 ISSN 0949-7714 Source Journal of Geodesy, 92 (2018) (3), 299–319 Part of collection Institutional Repository Document type journal article Rights © 2017 J. Ran, P.G. Ditmar, R. Klees, H. Farahani Files PDF 10.1007_s00190_017_1063_5.pdf 2.77 MB Close viewer /islandora/object/uuid:e955169d-c7e0-4f8e-8836-1eab8e296567/datastream/OBJ/view