This video gives an overview of the causes and consequences of El Nino. This aperiodic fluctuation in atmosphere and ocean circulation in the equatorial Pacific impacts weather around the world. The phenomenon is associated with a cessation of the normal east-to-west trade winds in the east Pacific and the subsequent eastward propagation of the west Pacific warm pool across the basin. Because the marine food web depends upon phytoplankton blooms fertilized by nutrients upwelled from depth, their reduction during an El Nino event causes starvation up the marine food web in the east equatorial Pacific. Additionally, weather in other places has been linked to El Nino: with a greater chance of rain from California to Florida but drought in southeast Asia during an El Nino winter. Although our ability to detect the onset of an El Nino event has greatly improved over the past 20 years with increased monitoring by satellites and ocean buoys, scientists cannot predict it more than a few months in advance.
Ocean circulation color-coded by sea surface temperatures: boundary currents on the western side of ocean basins carries warm tropical water toward the cooler North and South Poles; upwelling of deep water on the eastern side and along the equator - especially in the east Pacific - brings cooler, nutrient-rich water up toward the sunlit surface.
Sea surface chlorophyll, the pigment in phytoplankton, is green in areas where sunlight and nutrients lead to blooms. The normally productive east equatorial Pacific is less productive during El Nino, especially evident with the strong event forming in 2015.
Sea surface temperature anomalies show the west Pacific warm pool moving east during an El Nino, resulting in a large warm anomaly in the east Pacific during 2015 - more than 3 degrees F warmer than normal, the warmest anomaly on record there.