Japan Geoscience Union Meeting 2019

Presentation information

[J] Oral

S (Solid Earth Sciences ) » S-GD Geodesy

[S-GD03] Geodesy General Contributions/Global Geodetic Observing System

Mon. May 27, 2019 3:30 PM - 5:00 PM 304 (3F)

convener:Koji Matsuo(Geospatial Information Authority of Japan), Yusuke Yokota(Institute of Industrial Science, The University of Tokyo), Takahiro Wakasugi(Geospatial Information Authority of Japan), Chairperson:Yuji Harada(Macau University of Science and Technology), Koji Matsuo

4:20 PM - 4:35 PM

[SGD03-09] Sea level evaluation in northern Australian coast

*Yuta Tokui1, Kosuke Heki1 (1.Hokkaido University)

Keywords:Altimeter, GRACE, Argo float, SSH, ENSO

Sea surface heights (SSH) are observed by satellite ocean altimetry, and it changes by
two major causes. They are barystatic changes e.g. inflow of melt water from land ice, and
thermal expansion of sea water, and they can be observed by GRACE and Argo floats,
respectively. The three quantities behave differently from region to region, and their mutual
link is important to understand regional characteristic of oceans. Here we study sea level
changes in northern Australian coast (consisting of the Arafura, Timor, and Solomon Seas
and the Gulf of Carpentaria). This region is characterized by large seasonal changes in
SSH and gravity, and influenced by multiple climate changes such as ENSO (El Nino and
Southern Oscillation) and IOD (Indian Ocean Dipole). First, we compare three changes
(altimetric, thermosteric and gravity) to evaluate sea level budget. We found that SSH
changes mainly come from steric changes excluding Gulf of Carpentaria where barystatic
changes prevail. Next, we use the Empirical Orthogonal Functions (EOF) approach to
identify the major modes of the seasonal and interannual variability. Seasonal changes in
SSH are strong in Gulf of Carpentaria. The 1 st EOF of gravity indicates that main seasonal
change occur in phase in the land and the sea. We also found that long-term precipitation
variability appears as the 2nd EOF. The EOF analysis further showed that non-seasonal
altimetric and gravity changes are driven mainly by climate changes, mainly ENSO in SSH
and PDO in gravity.