IEG 환경지질연구정보센터

10월 27일(목)․지구물리학│물리탐사

116

Global and Arctic mean sea level variations from GRACE using a new ocean averaging kernel

Ki-Weon Seo

․Clark R. Wilson

․Jianli Chen

․No-Wook Park

․Choon-Ki Lee

1

Korea Polar Research Institute, [email protected]

2

Department of Geological Sciences, Jackson School of Geosciences, University of Texas at Austin

3

Center for Space Research, University of Texas at Austin

4

Department of Geoinformatic Engineering, Inha University

The two distinct causes of Mean Sea Level (MSL) variations, ocean mass and ocean density (steric) changes can in principle be separated by observing both changes in ocean mass and in sea surface height (SSH). Satellite altimetry has provided several decades of SSH ob- servations, but GRACE, launched in 2002, has been recognized as a pivotal mission because it directly measures ocean mass variations. Given its finite spatial resolution, an ocean averag- ing kernel for GRACE MSL estimates should minimize contamination due to terrestrial variations leaking from land into adjacent ocean regions. Here we develop an optimum ocean kernel using estimates of terrestrial leakage and ocean signals in synthetic GRACE data derived from geophysical models. Kernel design considers terrestrial water storage, ocean bottom pressure, glacier melting, and alias error in GRACE spherical harmonics. This optimum kernel provides superior estimates of seasonal and secular MSL variations relative to other ocean kernels in the published literature. When used with GRACE Release 04 (RL04) data from JPL, the trend and annual amplitude of global MSL variations during 2004-2009 are 2.37 mm/yr and 8.63 mm, respectively, closer than CSR and GFZ datato independentestimates using altimeter and other data. Arctic MSL variations and error sources are also estimated. Errors in the Arctic Ocean are relatively large, due both to leakage from surrounding land and from aliasing of ocean tide model errors.

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