Hurricane researchers have compiled the longest-ever record of hurricane strikes in the Atlantic ocean that shows that the El Nino weather pattern acts plays a significant part in giving rise to furious hurricanes. The research studies all hurricanes that have occurred in the past 5000 years.
The core of the study was Laguna Playa Grande on the Puerto Rican Island of Vieques, which is very vulnerable to hurricane strikes. Two geologists from the Woods Hole Oceanographic Institute in Massachusetts, in 2003, began digging up sediment cores from the bottom of Laguna Playa Grande, which is usually protected and alienated from the ocean during storms, but in case of an intense hurricane strike, storm surges carry sand from the ocean beach over the dunes and also into the lake.
The study revealed that the sediments from the lake, the coarse-grained beach sand, as well as bits of shell, were quite different from the lake’s normal finer-grained silt. This was a clear indication that a hurricane struck the island at that point in the past.
The previous records were matched with present studies of hurricane history in New York and the Gulf Coast, which revealed that the variability in hurricane activity matched in all three places. The records also proved that the number of intense hurricanes increased during years when El Nino was weak.
El Nino, is a weather phenomenon characterized by warmer-than-normal waters off the Pacific coast of South America, can prevent development of intense hurricanes.
The processes that govern the formation, intensity and track of Atlantic hurricanes are still poorly understood. Based on this work, we now think that there may be some sort of basin-wide ‘on-off switch’ for intense hurricanes,
said Jeff Donnelly, one of the two scientists on the team.
Via: Livescience