Suchergebnisse

The seasonal sea level variations observed from tide gauges over 1900-2013 and gridded satellite altimeter product AVISO over 1993-2013 in the northwest Pacific have been explored. The seasonal cycle is able to explain 60-90% of monthly sea level variance in the marginal seas, while it explains less than 20% of variance in the eddy-rich regions. The maximum annual and semiannual sea level cycles (30 and 6 cm) are observed in the north of the East China Sea and the west of the South China Sea, respectively. AVISO was found to underestimate the annual amplitude by 25% compared to tide gauge estimates along the coasts of China and Russia. The forcing for the seasonal sea level cycle was identified. The atmospheric pressure and the steric height produce 8-12 cm of the annual cycle in the middle continental shelf and in the Kuroshio Current regions separately. The removal of the two attributors from total sea level permits to identify the sea level residuals that still show significant seasonality in the marginal seas. Both nearby wind stress and surface currents can explain well the long-term variability of the seasonal sea level cycle in the marginal seas and the tropics because of their influence on the sea level residuals. Interestingly, the surface currents are a better descriptor in the areas where the ocean currents are known to be strong. Here, they explain 50-90% of interannual variability due to the strong links between the steric height and the large-scale ocean currents. ; This research is funded by Lloyd's Register Foundation, which supports the advancement of engineering-related education, and funds research and development that enhances safety of life at sea, on land and in the air. This work is also funded by the UK Natural Environment Research Council, which supports the work of X. Feng (in part), M. N. Tsimplis, F. M. Calafat and P. Cipollini at the National Oceanography Centre. X. Feng and J. Zheng appreciate the National Science Fund for Distinguished Young Scholars (grant 51425901). G. Jorda and M. Marcos acknowledge two Ramon y Cajal contracts funded by the Spanish Ministry of Economy and the Regional Government of the Balearic Islands ; Peer Reviewed