HR: 1340h
AN: G43B-0806    [Abstracts]
TI: Oceanic Excitations On Polar Motion: A Cross Comparison Among Models
AU: * zhou, y
EM: yhzhou@shao.ac.cn
AF: Shanghai Astronomical Observatory, Chinese Academy of Sciences, 80 Nandan Road, Shanghai, 200030 China
AU: * zhou, y
EM: yhzhou@shao.ac.cn
AF: United Center for Astrogeodynamical Research, Chinese Academy of Sciences, 80 Nandan Road, Shanghai, 200030 China
AU: chen, j
EM: chen@csr.utexas.edu
AF: Center for Space Research, University of Texas at Austin, 3925 West Braker Lane, Suite 200, Austin, TX 78712 United States
AU: liao, x
EM: xhliao@shao.ac.cn
AF: Shanghai Astronomical Observatory, Chinese Academy of Sciences, 80 Nandan Road, Shanghai, 200030 China
AU: liao, x
EM: xhliao@shao.ac.cn
AF: United Center for Astrogeodynamical Research, Chinese Academy of Sciences, 80 Nandan Road, Shanghai, 200030 China
AU: wilson, c R
EM: clarkw@maestro.geo.utexas.edu
AF: Center for Space Research, University of Texas at Austin, 3925 West Braker Lane, Suite 200, Austin, TX 78712 United States
AU: wilson, c R
EM: clarkw@maestro.geo.utexas.edu
AF: Department of Geological Sciences, University of Texas at Austin, 26th St and Guadalupe St , Austin, TX 78712 United States
AB: Recent studies based on various oceanic general circulation models (OGCMs) demonstrated that the oceans are a major contributor to polar motion excitations. In this paper, we analyze and compare observed non-atmospheric polar motion excitations with oceanic angular momentum (OAM) variations determined from four OGCMs, which include the parallel ocean climate model (POCM), a barotropic ocean model (BOM), the Estimating the Circulation and Climate of the Ocean (ECCO) non-data-assimilating model (ECCO-NDA), and the ECCO data-assimilating model (ECCO-DA). The data to be analyzed span a 5-year­_s overlapped period from 1993 to 1997. At annual time scale, these four OAM estimates do not agree well with each other, while POCM shows relatively larger discrepancies than other three models. At intraseasonal time scales, ECCO-DA yields the best agreement with observations, and reduces the variance of non-atmospheric excitations by about 60%, 10-20% more than those explained by other three models. However, at the very short periods of 4-20 days, the BOM estimates could explain about half of the observed variance, twice as much as that by ECCO-NDA, and also shows considerably better correlation with observations. Due to different modeling schemes and methods, significant discrepancies could arise with respect to the quantity of modeling large-scale oceanic mass redistribution and current variation. A clear understanding of global oceanic contributions to polar motion excitation still remains a challenge.
DE: 1223 Ocean/Earth/atmosphere interactions (3339)
DE: 1239 Rotational variations
SC: Geodesy [G]
MN: 2004 AGU Fall Meeting