THE STRONG AND STABLE UPWELLING AND DOWNWELLING REGIONS IN THE ECMAN LAYER OF THE SOUTH CHINA SEA
On the basis of distribution of curl (τ/f) computed by the means monthly data of wind and relationship between the curl (τ/f) with the vertical velocity W [equation (5)], the regions of upwelling [Rot(τ/f) > 0, W < 0] and downwelling [Rot(τ/f) < 0, W > 0] in the Ecman layer of South China Sea were determined. The results indicates that the upwelling and downwelling phenomena are occurred almost everywhere in the sea, but the most strong (/W/ ≥ 10-3 cm/s) and stale ones in the following locations:
1. Very strong upwelling in he Southern Central Vietnam coastal and shelf waters during South West Monsoon (Fig. 2). The hydrological analysis indicate that in the centre of the upwelling, the /W/ can reach to 10-1 – 10-2 cm/s, the water temperature anomaly - to -3 ÷ -50C and salinity anomaly - to +1,2%o at the depths of 50 - 100 m.
2. The strong upwelling in the region North West and South West of Luzon island during North East Monsoon, when the water temperature anomaly can reach to -30C and salinity - to +1%o at the depths of 50 – 100 m (Fig. 1).
3. The strong downwelling in the Southern Central Vietnam coastal and shelf waters and in the region South West of Taiwan during North East Monsoon (Fig. 1).τ is the wind stress, f is the Coriolic parameter, W is the vertical velocity.