An increase in big storms has elevated tropical rainfall totals, according to a recent study.

Researchers at the University of New South Wales found that an increase in large thunderstorms is the primary reason for increasing rainfall in certain parts of the tropics. This phenomenon has long been seen as a projection of climate change.

"The observations showed the increase in rainfall is directly caused by the change in the character of thunderstorms in the tropics rather than a change in the total number of thunderstorms," Dr. Jackson Tan, lead author of the study, said in a statement."What we are seeing is more big and organized storms and fewer small and disorganized storms."

Thunderstorms play an important role in rainfall in the tropics. Despite organized deep convective storms only occurring 5 percent of the time in the world's equatorial regions, they deliver almost 50 percent of all its rainfall.

The research has also contributed to answering the important question whether the increase in rainfall observed in the tropics was simply caused by the fact of a warmer atmosphere or whether the underlying circulation in that region had changed.

The changes to the deep convection discovered in the study suggested a dynamic change in the climate system was responsible for the change in rainfall.

"If this rainfall change was caused simply by a warmer atmosphere holding more moisture, we would have expected an increase in the average rainfall when each system, organized or disorganized, occurs," Tan said. "Instead, the number of organized storms, which is largely controlled by the dynamics of the atmosphere, have increased in frequency, suggesting that the increase in rainfall is related to more than a simple warming of the atmosphere."

Climate model results have long suggested that we would see increased precipitation in the tropics as a result of climate change. However, the exact nature of this change remained unclear.