Spectral Analysis on Sub-Tidal Variability of Salinity in Modaomen Waterway of Pearl River Estuary, China

Salinity and tidal range time series observed in Modaomen waterway was analyzed in power spectrum method, and both showed the period of half month (14.22d). Moreover, the salinity and tidal range time series were coherent at that period through cross spectrum analysis. Besides, the phase analysis at the period of 14.22d showed that, within the estuary, the salinity time series upstream lagged that of the downstream, and the response time of salinity time series to the tidal range time series was about 9-10d, increasing upstream. But the phase of salinity time series and response time to the tidal range at the estuary mouth did not correspond with the laws within the estuary. The response time of salinity to the tidal range was about 12d there.