A coastal acoustic tomography experiment in the Qiongzhou Strait

An experiment for synchronous mapping of current velocity (V
_CAT
) and temperature (T
_CAT
) distributions was successfully carried out using four coastal acoustic tomography (CAT) systems, from March 17 to April 1, 2013, in the Qiongzhou Strait, China. During the CAT observation period, shipboard acoustic Doppler current profiler (ADCP) surveys were also performed to observe the current velocity (V
_ADCP
) and temperature (T
_ADCP
) for the purpose of comparison with the CAT data. Position offsets, including a long-time averaged offset and a short-period fluctuation offset, were corrected for temperature estimation. The horizontal distribution of V
_CAT
and T
_CAT
was reconstructed by an inverse technique using the CAT data. V
_CAT
was nearly parallel to the strait while T
_CAT
was higher in the southern area than in the northern area. During the whole observation period, T
_CAT
gradually increased by approximately 2°C, indicating seasonal warming. V
_CAT
was in good agreement with V
_ADCP
, while the root-mean-square differences (RMSDs) between V
_CAT
and V
_ADCP
for eastward and northward velocities were 0.10 m/s and 0.08 m/s, respectively. T
_CAT
was in approximate agreement with T
_ADCP
, with an RMSD of 0.30°C.