Q: How is the saltiness of the ocean connected to El Niño?
A: Research published recently in Geophysical Research Letters revealed that certain ocean salinity conditions can affect the intensity of El Niño events. Evaporation, rainfall, and other factors can cause variability in ocean salinity depending on location, and then “ocean currents can transport these salty or fresh waters around and redistribute the ocean salinity,” explains study coauthor Shineng Hu of Duke University. But the influence of ocean salinity has not traditionally been considered in El Niño research. In the new study, researchers studied 65 years of ocean data and found a correlation between certain salinity patterns and El Niño occurrences. They then used model simulations to determine that a robust boreal spring salinity pattern in the western Pacific can increase the intensity of El Niño by about 20% and make an extreme El Niño twice as likely. According to the study’s authors, the springtime pattern in the western Pacific causes a combination of fresher water near the equator and saltier water farther away to encourage eastward ocean currents, which in turn drives warm surface waters eastward and generates downwelling equatorial Kelvin waves, both of which favor the development of El Niño. Supercharged El Niño events can lead to severe weather like flooding and droughts, and the researchers believe the study could be used to improve the accuracy of the prediction of such incidents. “The findings indicate that salinity is another factor that should be considered in future models forecasting El Niño,” says lead author Shizuo Liu, also of Duke. The research is particularly relevant now, as many scientists are anticipating the formation of a strong El Niño later this year. [SOURCE: Duke University]
