HR: 10:25h
AN: G21E-01    [PDF]
TI: Global atmospheric datasets for excitations of Earth rotation and gravity
AU: * Salstein, D
EM: salstein@aer.com
AF: Atmospheric and Environmental Research, Inc., 131 Hartwell Ave., Lexington, MA 02421
AB: Atmospheric reanalyses are routinely used in geodetic applications because of their general reliability and consistency. Those from the US National Centers for Environmental Prediction-National Center for Atmospheric Research span over 55 years, including the whole era during which satellite-based data were available for ingestion into data assimilation systems. From this reanalysis system, fields of winds and surface pressures are used to compute excitations for Earth rotation and polar motion and related values of the torques that transfer angular momentum between the atmosphere, ocean, and solid Earth. Additionally, the surface pressure field closely reflects the atmospheric mass distribution, important for studies of terrestrial gravity. The reanalyses of the European Centre for Medium Range Weather Forecasts, first over 15 years, and scheduled soon for 40+ years, provides an alternate, and higher resolution, set of such data. These supplement the operational series that provide the state-of-the-art results at any particular time. To investigate periods outside those spanned by reanalyses, or to study how the atmosphere dynamically interacts with the solid Earth, we turn to atmospheric models driven by appropriate boundary conditions. For example, monthly mean results from 19 different general circulation models from the second phase of the Atmospheric Model Intercomparison Project, for the period 1979-95, are used to study the relationship of the atmosphere to length of day and polar motions. We note the seasonal and interannual variability of such excitation terms, including the spread among models, which may be considerable. We seek to determine the most effective set of physical modeling techniques that yield the observed (three-dimensional) fields of angular momentum and the related Earth rotational parameters of interest. When such models are run for extended periods of time, they may used to estimate the angular momentum over century-long periods; an example of such a model is that of the U.K. Hadley Centre. Lastly, coupled atmosphere-ocean models are necessary to understand the fluids' angular momentum and mass balance and geodetic implications. Future global warming scenarios have been simulated with these models and organized in the Coupled Model Intercomparison Project.
DE: 1223 Ocean/Earth/atmosphere interactions (3339)
DE: 1227 Planetary geodesy and gravity (5420, 5714, 6019)
DE: 1239 Rotational variations
SC: Geodesy [G]
MN: 2003 Fall Meeting