part to the south, while part finds its way through the passes between 

 the islands. North equatorial water from the open sea can find its 

 way into the Sulu Sea by way of Leyte Gulf and the Mindanao Sea to 

 the east, and to a somewhat lesser extent from the north through San 

 Bernardino Straits and Guimaras Strait. 



Currents : North-east Monsoon 



At the Surface (Chart 2). — The dynamic height anomalies of the 

 surface relative to the 800-decibar surface for the first survey are shown 

 in Chart 2. The circulation at that season of the year consisted of a 

 complex set of eddies. Two large eddies dominated the pattern — a 

 cyclonic eddy to the south, which hereafter will be referred to as the 

 "South Central Eddy", and an anticyclonic eddy toward the north- 

 east part of the sea, which hereafter will be referred to. as the " North 

 Central Edd3^" A number of minor eddies also occurred, an anticy- 

 clonic eddy to the north-west, and one south-east of the South Central 

 Eddy ; a cyclonic eddy in the extreme north and another to the west. 



No strong flow of water to or from the Sulu Sea is indicated. The 

 flow from the Mindanao Sea is limited to the southern part of the area 

 between Negros and Mindanao. This flow turns south. The southern 

 part of this current lies close to the Zamboanga Peninsula and probably 

 eventually enters the Celebes Sea either near Basilan Island or continues 

 along the Sulu Archipelago to enter the Celebes Sea by way of Sibutu 

 Passage east of Borneo. The main stream of water entering from the 

 Mindanao Sea turns northward through the central part of the Sulu Sea 

 and then turns west. In the western part of the Sulu Sea the stations 

 were too shallow for dynamic computations, so the fate of this water 

 beyond longitude 119° east is not shown. • It may continue out through 

 Balabac Strait to the China Sea, but at least part of it probably swings 

 south as part of the South Central Eddy, while another part probably 

 turns to the north as part of the North Central Eddy. 



Although the two halves of the Sulu Sea were surveyed two months 

 apart during the north-east monsoon there is no difficulty encountered 

 in drawing the dynamic topography for the sea as a whole, so that the 

 pattern presented in Chart 2 probably represents conditions generally 

 characteristic of the beginning of the north-east monsoon. 



At 100 Metres (Chart 3). — The dynamic height anomalies of the 

 100-decibar surface relative to the 800-decibar surface for the north- 

 east monsoon shows a pattern of flow essentially the same as at the 

 surface although the indicated velocities are less. The North Central 

 Eddy and the South Central Eddy are well defined, the circuitous route 

 of the west-flowing current remains as do the two northern eddies. 



A t 200 Metres (Chart 4) . — At a depth of 200 metres the currents are 

 very weak and the pattern of flow is somewhat different from that at 

 higher levels. Thel-e is still some evidence of the North Central Eddy. 

 The South Central Eddy has disappeared and is replaced with an extension 

 of the eddy to the north. The small eddy found off the Zamboanga 

 Peninsula at the 100-metre level persists at 200 metres. The 200-decibar 

 surface does not show the westerly current found at higher levels. This 

 may be related to the fact that there is no outlet to the China Sea at 

 this level. Water from the southern side of Mindanao Sea may still 

 flow southward into the Celebes Sea at this level. 



234 



