Upwelling can occur by a variety of mechanisms, but all require a circulation pattern that sets up a surface deficit.

The nature of the regional biological response will be dependent on many different environmental conditions, not just nutrients - but regardless upwelling always leads to increased relative biomass in the upwelling area.

Satellites are very useful for providing information on physical conditions and phytoplankton responses, but must be "truthed" to accurate ground conditions. Scientists are ever developing new sensors with modified algorithms to improve ability, sensitivity, and accuracy.