TY - JOUR
T1 - Global surface and subsurface geostrophic currents from multi-mission satellite altimetry and hydrographic data, 1996-2011
AU - Chang, Chi Hung
AU - Kuo, Chung Yen
AU - Shum, C. K.
AU - Yi, Yuchan
AU - Rateb, Ashraf
N1 - Funding Information:
We acknowledge the constructive comments from the Editor and the anonymous reviewers, which have improved this paper. Chi-Hung Chang and Chung-Yen Kuo were partially supported by the Headquarters of University Advancement at the National Cheng Kung University. The research is also partially supported by NASA's Physical Oceanography Program (No. NNX09AF42G), NSF's Belmont Forum/IGFA Grant (No. ICER-1342644), and by Institute of Geodesy and Geophysics, CAS (Grant No. Y309473047). We acknowledge NASA, CNES and ESA for providing satellite altimetry data including TOPEX/POSEIDON, ERS-2, Jason-1 and Jason-2, making this study possible. We thank Remko Scharro for making RADS available to compute along-track multiple altimetry derived SSH anomalies, and ICGEM for the GOCE geoid model. We thank Masayoshi Ishii for providing the objectively analyzed global gridded composite hydrographic data, and to CDG of NCAR/UCAR for the NAO index. We acknowledge the TAO Project Office at NOAA/PMEL, http://www.pmel.noaa.gov/tao/index.shtml, and WHOI's KESS, http://uskess.whoi.edu, and Line-W, http://www.whoi.edu/science/PO/linew projects for providing in situ observations used in this study. The figures in this paper were prepared using the GMT graphics package (Wessel and Smith, 1991).
Publisher Copyright:
© 2016, National Taiwan Ocean University. All rights reserved.
PY - 2016
Y1 - 2016
N2 - Climate indices have been shown to be correlated with changes of absolute ocean current velocities. Yet there has been a lack of available estimates of accurate surface and subsurface current velocities with adequate data span to afford a detailed study. Here, we combined multiple mission satellite altimetry along-track sea surface heights (SSHs), the Gravity field and steady-state Ocean Circulation Explorer (GOCE) time-wise solution generated geoid model, and in situ hydrographic data, to estimate global surface and subsurface absolute geostrophic currents, 1996-2011. We used the profile approach to process satellite altimetry data, mitigating the negative impact of omission errors resulting from the spatial resolution discrepancies between the truncated GOCE geoid model and SSHs, on the estimation of the absolute dynamic topography (ADT), which was then combined with the relative dynamic topography derived from in situ hydrographic profiles to estimate near global mesoscale geostrophic current velocities at different depth layers. Results were validated by in situ moored current meter observations from the Tropical Atmosphere Ocean/TRIangle Trans-Ocean buoy Network (TAO/TRITON) and the Prediction and Research Moored Array in the Atlantic (PIRATA), showing the outperformance of profile approach over the conventional pointwise approach in determination of geostrophic currents. After validating the subsurface geostrophic currents with in situ observations from the Kuroshio Extension System Study (KESS) and Line-W projects, statistically significant correlation, between the multi-layer geostrophic current changes for Atlantic Meridional Overturning Circulation (AMOC) branches and the North Atlantic Oscillation (NAO) index, was found, which is in general agreement with other published studies.
AB - Climate indices have been shown to be correlated with changes of absolute ocean current velocities. Yet there has been a lack of available estimates of accurate surface and subsurface current velocities with adequate data span to afford a detailed study. Here, we combined multiple mission satellite altimetry along-track sea surface heights (SSHs), the Gravity field and steady-state Ocean Circulation Explorer (GOCE) time-wise solution generated geoid model, and in situ hydrographic data, to estimate global surface and subsurface absolute geostrophic currents, 1996-2011. We used the profile approach to process satellite altimetry data, mitigating the negative impact of omission errors resulting from the spatial resolution discrepancies between the truncated GOCE geoid model and SSHs, on the estimation of the absolute dynamic topography (ADT), which was then combined with the relative dynamic topography derived from in situ hydrographic profiles to estimate near global mesoscale geostrophic current velocities at different depth layers. Results were validated by in situ moored current meter observations from the Tropical Atmosphere Ocean/TRIangle Trans-Ocean buoy Network (TAO/TRITON) and the Prediction and Research Moored Array in the Atlantic (PIRATA), showing the outperformance of profile approach over the conventional pointwise approach in determination of geostrophic currents. After validating the subsurface geostrophic currents with in situ observations from the Kuroshio Extension System Study (KESS) and Line-W projects, statistically significant correlation, between the multi-layer geostrophic current changes for Atlantic Meridional Overturning Circulation (AMOC) branches and the North Atlantic Oscillation (NAO) index, was found, which is in general agreement with other published studies.
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U2 - 10.6119/JMST-016-1026-7
DO - 10.6119/JMST-016-1026-7
M3 - Article
AN - SCOPUS:85013683511
VL - 24
SP - 1181
EP - 1193
JO - Journal of Marine Science and Technology
JF - Journal of Marine Science and Technology
SN - 1023-2796
IS - 6
ER -