Strong winds off the Mexican coast when the El Salvadorean fisherman set off drove him, and the virtual tracers, quickly off shore. Some of the tracers drifted into currents that led them to overshoot the Marshall Islands, where Alvarenga washed up. Others have not yet reached the islands.
"Overall, however, the 16 tracers show a remarkably narrow path over this long period of time," the researchers wrote. The tracers passed by Ebon atoll within only two degrees latitude, or about 190km.
"Alvarenga's claim that he had been adrift for 13 months and that he came from Mexico, therefore, falls well within the model's limits and is consistent with the prevailing pattern of wind and ocean currents during his ordeal," they concluded.
And medical experts have also said that his tale of living off the turtles, fish and seabirds he managed to catch is possible - albeit rare.
"Most experts would say it's surprising, but theoretically possible," said Surgeon Commander Dennis Freshwater, a survival specialist from the Royal Navy.
Alvarenga is now in El Salvador. Angel Fredi Sermeno, a psychiatrist, said the fisherman was now terrified of the sea, adding that he was suffering from mental exhaustion that often made him burst into tears.
Alvarenga's boat remains on Ebon atoll, where it is being used to ferry people between islands.
