Satellites reveal El Niño's impact
Datafrom NASA satellites is being used to help scientists analyze how ElNiño– a natural, regularly-occurring event that sees large volumes ofwarm water move through the Pacific Ocean – is affecting apopulation of tiny ocean plants. A decline in the number of these plantscan cause big disruptions to coastal fishing industries.
DuringEl Niño years, large volumes of warm water – roughly equivilent tohalf the volume of the Mediterranean Sea – move across the Pacific,altering everything from storm systems in the atmosphere to thetiniest plants residing below the ocean waves.
Thatwarm water has a particular effect on tiny organisms, stopping coldwaters from rising and cutting off nutrientscarried by the currents. The disruption of that process, known asupwelling, essentially starves a population of small plants calledphytoplankton, which form the base of the food chain. Whenphytoplankton numbers drop, it can have a knock-on effect on coastalfishing industries, with the fish themselves finding themselveswithout a key food source.
Now,researchers have been using satellite data, gathered by instrumentssuch as the Moderate Resolution Imaging Spectrometer on NASA's Aqua probe, to look at the color of the ocean. That information is thenprocessed by ocean color software called SeaDAS to map exactly wherephytoplankton are more or less abundant. The color of the waterallows scientists to determine how much green chlorophyll is present,which directly translates to the amount of phytoplankton in thatarea.
Generatedfrom months of satellite data, the color maps provide a visualiationof El Niño's impact on phytoplankton, showing a drop in populationsat the height of the current event in December 2015. As El Niñosubsides, the researchers are continuing to watch the populations,studying when and where the phytoplankton reappear.
Theteam has also worked to compared the current event to the 1997-98occurrence, finding that the drop in chlorophyll, and therefore theeffect on coastal phytoplankton population, was much less severe thistime around. This is attributed to the events being centered indifferent geographical locations, with the warm water influxaffecting coastal areas more during the older event.
Theuse of satellite data isn't the only ongoing effort to betterunderstand El Niño events. One other NASA team is looking to use supercomputersto analyze the ebbs and flows of nutrients, which in turn could allowmanagers of fisheries to estimate how much fish will be caught in anygiven year.
Lookingforward, the researchers hope to make more complex assertions, usingsatellite data to describe, based on the flow of nutrients, whereindividual species of phytoplankton will bloom or recede, providingeven more in-depth information as to the health of the wider oceanecosystem.