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Page 20
OF EXCELLENCE
IN INTERNATIONAL
MEETINGS
YEARS
Journal of EnvironmentalWaste Management and Recycling | Volume 2 Earth Science 2019
May 22-23, 2019 | Rome, Italy
EARTH SCIENCE,
RECYCLING & SPACE TECHNOLOGY
7th International Conference on
DECADAL VARIATIONS IN THE EARTH’S SHAPE FROM SLR AND GRACE
Minkang Cheng
University of Texas at Austin, USA
For over three decades, Satellite laser ranging (SLR) has recorded the global nature of the long-term and
long-wavelength climate induced hydrological mass redistribution within the Earth system, which results in
significant variations in the Earth’s shape and gravity field. The Earth’s shape (geoid) can be approximately rep-
resented by a triaxial ellipsoid defined by six parameters, including the polar (or the dynamic oblateness) and
equatorial flattering (or equatorial ellipticity, b) and the orientation (e) of the equatorial principal axis. Those
fundamental parameters can be determined by the degree-2 Stokes coefficients C20, C22 and S22. Study the
variations in the gravity coefficients can improve our understanding of the long and short-term climate forcing
on the Earth system. Analysis of satellite Laser ranging and data over four decades has shown that significant
quadratic variation and decadal variations in the Earth’s dynamic oblateness (characterized by geo-potential
zonal coefficients, C20) are well correlates with the short and decadal tropical variability characterized by the El
Niño-Southern Oscillation Index. The quadratic variation is combination of a GIA-induced linear decrease and
a slowly increasing rate due to global mass redistribution associated with the melting of the glaciers and ice
sheets. Earth’s equator is flattering with a rate of 0.014 mm/year and a significant drift of the equatorial prin-
cipal axis shifted from westward to eastward during ~2000 based on the 35 year SLR and 15 year GRACE data.
Those variations are results of both the on-going global isostatic adjustment (GIA) following the last ice age
and climate-induced mass transport as well as the changes in the dynamic pressure loading on the core-man-
tle boundary (CMB). Detail analysis will be presented.
Minkang Cheng, J Environ Waste Management and Recycling 2019, Volume 2
Minkang Cheng did his PhD in Aerospace Engineering, University of Texas at Austin, USA in August 1988. He has Research experi-
ence in satellite dynamics and geodesy for gravity and earth rotation. He published his papers recently entitled as“Decadal variation
in Earth’s oblateness (J2) from satellite laser ranging data” in Geophysical Journal International; “The unexpected signal in GRACE
estimates of C20” in Journal of Geodesy and “Deceleration in the Earth’s oblateness” in Journal of Geophysical Research.
BIOGRAPHY