Results from GOCE++ Dynamical Coastal Topography and tide gauge unification using altimetry and GOCE. Ole B. Andersen, P Knudsen, K. Nielsen, C. Hughes, P. L. Woodworth, R. Bingham, G. Woppelmann, M. Gravelle, L. Fenoglio-Marc, M. Kern
ESA (ITT) Goce + Height System Unification Roadmap (2011-2014): 2015: ESA issued an ITT (GOCE ++) To focus on individual elements Project still ongoing until late 2017 Courtesy: Gruber et al., 2014) 2 DTU Space, Technical University of Denmark
Objectives and scope. Propose and develop an approach to estimate a consistent DT at tide gauges, coastal areas, and open ocean Determine a consistent MDT using GOCE with consistent error covariance fields. Connect measurements of a global set of tide gauges and investigate trends Develop and outlook how the approach could be further improved using improved coastal altimetry. Validate the approach in well-surveyed areas where DT can be determined at tide gauges 3 DTU Space, Technical University of Denmark
Test Regions. 4 DTU Space, Technical University of Denmark
Evaluating Ocean MDT vs TG MDT (= MSS-N) MDT Geoid 5 DTU Space, Technical University of Denmark
6 DTU Space, Technical University of Denmark
Australia Getting MSS closer to the coast 7 DTU Space, Technical University of Denmark
Coastal Altimetry Updating the Coastal MSS GOT 4.10 vs FES2012. 8 DTU Space, Technical University of Denmark
Software Architecture for creating coastal MDT GOCE++DYCOT Coastal MDT Software Toolbox. • Written in R. • Command line interface. • Allow filtering combining different MSS + GOCE geoids • Allos integration of MDT with TG, • Error estimation. 9 DTU Space, Technical University of Denmark
Creation a consistent MDT in coastal region and the coast using GOCE+Altimetry+TG. Here test- region with ” well known ” MDT 10 DTU Space, Technical University of Denmark
Bridging the Coastal Gap for Geodetic MDT. Here: Raw unfiltered MDT = DTU13MSS – EIGEN-6C4 GEODETIC MDT DOES FREQUENTY NOT SATISFY COASTAL DYNAMICS 11 DTU Space, Technical University of Denmark
Gaussian Filtering 0.6 dg. Each Contour line represent 1 cm MDT 12 DTU Space, Technical University of Denmark
GOCE++ Approach Iterative box-car filtering with resetting of land values at each iteration. Here: R = 0.15deg, 15 iterations. Land values set to 5 cm. Better contours at coast. But 13 DTU Space, Technical University of Denmark
Integrating with Drifters enhances sw signal (DTU17MDT+Drifter) 14 DTU Space, Technical University of Denmark
ROMS MDT (courtesy of John Wilkin@Rudgers) Contour interval = 1 cm 15 DTU Space, Technical University of Denmark
MDT Error estimate A new bootstrap approach is used The selected region is divided into blocks Sample with replacement between the different blocks count the number of repetitions per block Use the iterative average filter function 16 DTU Space, Technical University of Denmark
Integration with Tide gauges • Setteled for a fixed period (2003-2007) where ocean/altim MDT and TG are processed consistenly. GOCE++ SW • IB correction must me accounted for. accounts for this • Tide System convertion must me accounted for. • System is sensitive to the value on land 17 DTU Space, Technical University of Denmark
Integration with SONEL GPS Measured Tide Gauges (Ellipsoidal height) 18 DTU Space, Technical University of Denmark
Summary • GOCE ++ DYCOT results are appearing on gocedt.eu and paper is in preparation. • MDT evaluation with Tide Gauges is promising for ” geodetic approach”, and in general agreement on the 5 -10 cm is found. • GOCE++DYCOT has developed an approach to estimate a consistent DT at tide gauges, coastal areas, and open ocean • An approach to determine error estimates on MDT is being tested Connect measurements of a global set of SONEL tide gauges performed and trends are now available. • More to follow. Develop and outlook how the approach could be further improved using improved coastal altimetry. 19 DTU Space, Technical University of Denmark
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