Keen swimmers, surfers and divers would have noticed some marked changes in water temperature along our coast in the past few weeks. The cold water is a result of a process called upwelling where cold water is brought to the surface from deeper areas off the edge of the continental shelf (60 to 80km offshore). This is driven by two processes. The first one is the presence of strong and persistent north-east winds that push water offshore due to a process called Ekman transport.

Ekman transport is caused by the forces acting between layers of water and