Tidal characteristics analysis of main islands,reefs and shoals in South China Sea by NAO.99b data

A tide calculation model was built with the 8global grid-point tidal harmonic constants(M2,S2,N2,K2,K1,O1,P1 and Q1)of ocean tide model NAO.99 bto analyse the tidal characteristics of the islands,reefs and shoals in the South China Sea.The maximum tidal range,mean tidal range,mean high water interval and tidal characteristic coefficient at these islands,reefs and shoals were obtained from the calculated tide level every minute in 2010.The main conclusions are:Most of the islands,reefs and shoals are irregular diurnal tides,tidal characteristic coefficient is 2.98~4.34.There are 2high tides and 2low tides in continuous 6~7days half a month.The mean high water interval increases from northeast to southwest of the South China Sea.The mean high water interval at these islands,reefs and shoals is 8.32~11.63 hours,but it is 1.57 hours at Zengmu Shoal.The mean tidal range and maximum tidal range at these islands,reefs and shoals increase from northeast to southwest of the South China Sea,with the former being 65~92cm,the latter being 144~200cm.