The Equatorial Pacific Carbon Model (EPCM)

Abstract

A computer simulated model representing carbon dynamics within the eastern equatorial Pacific was developed. The three compartment model incorporated the physical, biological and chemical processes most significant to the region of study representing both "normal" and highly disruptive conditions. The events which interrupt the normal carbon dynamics are known as El Niño events. The most profound effects that the El Niño has on the eastern equatorial Pacific are anomalously high sea-surface temperatures and a weakening in the typically intense upwelling motion. It is during these periods that the equatorial Pacific has been thought as being a sink for carbon dioxide. The EPCM incorporated these extreme changes, as typified by sea-surface temperature and upwelling, in order to determine the levels of sensitivity of the model parameters to these adversive conditions. The EPCM suggests that variations in upwelling rates have a much greater effect on model parameters than a change in sea-surface temperatures. As well, it has been suggested that cooler temperatures limit zooplankton and phytoplankton parameters much more than warmer conditions. Lastly, it has been demonstrated that, according to the EPCM, the equatorial Pacific is always a source of carbon dioxide to the atmosphere. Net movement towards the atmosphere persists even during periods when upwelling is at its weakest, as simulated by the EPCM.