WHOI Study Offers Clues to Better Rainfall Predictions

WOODS HOLE – The saltiness of seawater depends largely on how much moisture is pulled into the air as evaporative winds sweep over the ocean.

But pinpointing where the moisture rains back down is a complicated question scientists have long contended with.

Now, scientists at the Woods Hole Oceanographic Institution have found a potential path to better seasonal rainfall predictions.

Their study, which is published in the May 6 issue of Science Advances, shows a clear link between higher sea surface salinity levels in the North Atlantic Ocean and increased rainfall on land in the area between the Sahara Desert and the savannah across Central Africa.

Each year, an estimated 100,000 cubic miles of water evaporates from ocean surface waters – enough to flood our entire lower 48 states to a depth of 60 yards.

About 90 percent of this moisture falls right back into the ocean as precipitation – a vast recycling of moisture that represents the bulk of the global water cycle.

But about 10 percent of the evaporated water gets carried over land where it falls out as rain.

Having successfully linked North Atlantic salinity with rainfall, the WHOI team has begun applying their techniques to other regions.

They recently correlated high springtime salinity in the northwestern portion of the North Atlantic with summer rainfall in the U.S. Midwest, and have a “whole list of other places” they want to investigate.