When it rains, it pours. This may be one of the most common idiomatic expressions around the world, but it is what literally happens in Sumatra every day. In fact, the concern of communities around the world about rainfall and storms becoming stronger may be important, but what happens in the so called "Maritime Continent" may just be much worse. This group includes major islands like Java, Sumatra, Papua New Guinea, Borneo, along with other smaller islands. Not only do they experience rainfall, but they also have to deal with periodic monsoon rains. That much rainfall leads to unwanted flash flooding.
Giuseppe Torri, an atmospheric scientist from the University of Hawaii (UH), is the lead author of a new study at Manoa School of Ocean and Earth Science and Technology (SOEST). The team of researchers revealed in their study the connection between the daily rainfall in Sumatra and the global atmospheric phenomenon called the Madden-Julian Oscillation (MJO). They wanted to see how the MJO is affecting the amount of rainfall that the Maritime Continent is receiving.
The MJO is a phenomenon that circles around tropical countries and bring about changes in the weather patterns on a weekly or monthly time scales. It can alternately bring cloudy and rainy periods and dry warmer periods.
Torri along with the co-authors of the study found that the effect of MJO on the weather patterns in Sumatra is quite significant. When MJO was hovering actively near the Maritime Continent, there was a significant increase in the amount of water vapor present in the atmosphere. This creates a greater potential for rain to fall. More variations of the presence of water vapor in the atmosphere can be observed and all of them lead to the possibility of heavy rainfall every time. Also, the team has observed that the rain and the clouds seem to move faster at night when the MJO is more active.
The team collected their data from a network of GPS stations that were installed around Sumatra alongside all the other towns surrounding it. A team of scientists who are observing the tectonic activity on the West Coast of Sumatra had them installed. Sadly, the GPS technology is somehow distorted by the water vapor present in the atmosphere. Such distortion was seen by Steven Businger as an opportunity to better understand the state of the atmosphere and believed that there is more use for the data it collected.
With the extensive coverage of the GPS stations all over Sumatra, the team had a treasure box of highly detailed images of the atmospheric changes on the island on a daily basis. While the current study clearly shows the impact of the MJO phenomenon on the daily rainfall that Sumatra receives, the team hopes to team up with SOEST to investigate the impacts further.
