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THE STRONG AND STABLE UPWELLING AND DOWNWELLING REGIONS IN THE ECMAN LAYER OF THE SOUTH CHINA SEA

Vo Van Lanh, Tong Phuoc Hoang Son, Nguyen Van Tuan

Abstract


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.

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DOI: https://doi.org/10.15625/1859-3097/7/2/6336 Display counter: Abstract : 16 views. PDF : 0 views.

Journal of Marine Science and Technology ISSN: 1859 3097

Published by Vietnam Academy of Science and Technology