HR: 16:00h
AN: G34A-01 INVITED     [Abstracts]
TI: Validation of ocean tide models around Antarctica using onshore GPS and gravity data
AU: * King, M A
EM: m.a.king@ncl.ac.uk
AF: University of Newcastle upon Tyne, School of Civil Engineering and Geosciences, Cassie Building, Newcastle upon Tyne, NE1 7RU United Kingdom
AU: Penna, N T
EM: nigel.penna@ncl.ac.uk
AF: University of Newcastle upon Tyne, School of Civil Engineering and Geosciences, Cassie Building, Newcastle upon Tyne, NE1 7RU United Kingdom
AU: Clarke, P J
EM: peter.clarke@ncl.ac.uk
AF: University of Newcastle upon Tyne, School of Civil Engineering and Geosciences, Cassie Building, Newcastle upon Tyne, NE1 7RU United Kingdom
AU: Thomas, I
EM: ian.thomas@ncl.ac.uk
AF: University of Newcastle upon Tyne, School of Civil Engineering and Geosciences, Cassie Building, Newcastle upon Tyne, NE1 7RU United Kingdom
AB: Ocean tide modeling errors, along with subsequent ocean tide loading (OTL) displacement modeling errors, alias into altimetry and time variable gravity (e.g., GRACE) time series. Present ocean tide models around Antarctica are shown to disagree by up to several decimeters per constituent, especially in the large ice shelf regions, and are presently only sparsely tested against independent data. In terms of modeled OTL displacements, the inter-model disagreements are of the order of a few millimeters or less per constituent and hence high quality geodetic measurements are able to rank relative model accuracy. To achieve this for the circum-Antarctic seas, GPS data from fifteen sites have been used to derive three-dimensional displacement estimates at eight diurnal and semidiurnal tidal frequencies. These are then compared with OTL displacement estimates derived from global and regional ocean tide models. Modeled tidal gravity variations are also compared with gravity measurements at the South Pole. In East Antarctica, where the tides are well-defined, sub-millimeter differences are demonstrated in each coordinate component with the lunar N2 and Q1 constituents in closest agreement. In West Antarctica, where sites are nearer the largest ice shelves, agreement with the older models (CSR3 and TPXO.2) and NAO.99b is poor for all constituents. Overall the GPS and gravity data agree best with newer tide models, such as TPXO.6.2, but further data are required to validate the models at the most remote locations.
DE: 1222 Ocean monitoring with geodetic techniques (1225, 1641, 3010, 4532, 4556, 4560, 6959)
DE: 1223 Ocean/Earth/atmosphere/hydrosphere/cryosphere interactions (0762, 1218, 3319, 4550)
DE: 4207 Arctic and Antarctic oceanography (9310, 9315)
DE: 4560 Surface waves and tides (1222)
SC: Geodesy [G]
MN: Fall Meeting 2005