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Gravitational Signal of Mass Redistribution Due to Interannual Meteorological Oscillations in Atmosphere and OceanInterannual meteorological oscillations (ENSO, QBO, NAO, etc.) have demonstrable influences on Earth's rotation. Here we study their effects on global gravitational field, whose temporal variations are being studied using SLR (satellite laser ranging) data and in anticipation of the new space mission GRACE. The meteorological oscillation modes are identified using the EOF (empirical orthogonal function)/PC (principal component) decomposition of surface fields (in which we take care of issues associated with the area-weighting and non-zero mean). We examine two fields, one for the global surface pressure field for the atmosphere obtained from the NCEP reanalysis (for the past 40 years), one for the surface topography field for the ocean from the Topex/Poseidon (T/P) data (for the past 8 years). We use monthly maps, and remove the mean-monthly ("climatology") values from each grid point, hence focusing only on non-seasonal signals. The T/P data were first subject to a steric correction where the steric contribution to the ocean surface topography was removed according to output of the numerical POCM model. The respective atmospheric and oceanic contributions to the gravitational variation, in terms of harmonic Stokes coefficients, are then combined mode-by-mode. Since the T/P data already contain the oceanic response to overlying atmospheric pressure, no regards to the inverted-barometer behavior for the ocean need be considered. Results for the lowest-degree Stokes coefficients can then be compared with space geodetic observations including the Earth's rotation and the SLR data mentioned above, to identify the importance of each meteorological oscillations in gravitational variation signals.
Document ID
20020039792
Acquisition Source
Goddard Space Flight Center
Document Type
Conference Paper
Authors
Chao, B. F.
(NASA Goddard Space Flight Center Greenbelt, MD United States)
Au, A. Y.
(NASA Goddard Space Flight Center Greenbelt, MD United States)
Johnson, T.
(Naval Observatory Washington, DC United States)
Smith, David E.
Date Acquired
August 20, 2013
Publication Date
January 1, 2001
Subject Category
Meteorology And Climatology
Meeting Information
Meeting: 26th European Geophysical Society Meeting
Location: Nice
Country: France
Start Date: March 25, 2001
End Date: March 30, 2001
Sponsors: European Geophysical Society
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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