Coastal seafloor observatory at Xiaoqushan in the East China Sea

Abstract

The seafloor observation system is becoming an important infrastructure for marine research because it is transforming oceanic research from temporal investigation to long term observation. The East China Sea coastal seafloor observatory, located between 30°31′44″N, 122°15′12″E and 30°31′34″N, 122°14′40″E, is constructed near the Xiaoqushan Island outside the Hangzhou Bay on the inner continental shelf of the East China Sea. The observatory is connected by a submarine optical fiber composite power cable that is more than one kilometer long and consists of a special junction box that transmits power and communication signals to different instruments. The special junction box has a variety of waterproof plugs and connects to three different instruments installed in a trawl preventer. The submarine optical fiber composite power cable is landed on the platform by The East China Sea Branch, State Oceanic Administration and the power is continuously supplied by the solar panels and solar battery on the top of the platform. The real time data are directly sent through the cable to the platform and are transmitted by CDMA wireless to the receiver at the State Key Laboratory of Marine Geology of Tongji University. Measurements at the observatory have been taken since April 20, 2009 after installation and the results have been interpreted. The characteristics of the near bottom boundary are constrained by a sediment suspension model using portion of the observed data. In particular, discussion is provided on the sea surface height anomaly at Xiaoqushan Island influenced by the tsunami driven by the 2010 Earthquake in Chile. The successful establishment of the coastal seafloor observatory is the first step toward future development of seafloor observation systems in China. It not only accumulates experiences in technology and engineering, but also paves the way for performing important oceanic research using the long term continuous observation platform.