Improving weather prediction in the Pacific

Sunday June 16, 2013 Written by Published in Technology

A climate scientist from the New Zealand Institute of Water and Atmospheric Research (NIWA) presented information on how weather is predicted in the Pacific on Friday.

The presentation by Dr Andrew Lorrey, which took place at the University of the South Pacific (USP), focused on what is called the ‘Island Climate Update’ (ICU) – a multi-national project involving a monthly summary of the climate in the South Pacific islands that gives an outlook for the coming months.

“This is really a one-of-a-kind process. It’s like the United Nations of weather forecasting. No Pacific Island is going it alone – we come together and agree on what we want to say to everyone,” said Lorrey.

“It tells us of any situations that are developing, such as where there’s going to be above or below-average rainfall We’re trying to draw as much information as possible, to make an informed decision. It’s the difference between having a jury decide on someone’s fate and having a judge.”

One focus of the work is the South Pacific Convergence Zone (SPCZ) – a transient cloud band that, when monitored over a period of time, exhibits patterns that give NIWA staff information about what to expect, such as how much rainfall there will be. NIWA averages the position of the SPCZ cloud band, and looks at its position relative to where it usually is.

The position of the SPCZ can indicate whether the Cook Islands can expect more tropical cyclones than usual, as well as how much rainfall there is likely to be.

“Conditions can change quite quickly. The Cook Islands are highly sensitive to the risks associated with SPCZ changes,” said Lorrey.

Lorrey hopes the forecasts will be able to inform people’s long-term decisions. Rather than only conserving water when rainfall has been low for some time, for example, the forecast could let people know that although there is currently plenty of water in their water tank, they should use it wisely because rainfall is likely to be low in the future.

“From decade to decade and year to year, you can get some very strong changes in rainfall.”

Lorrey said tropical cyclones are a major contributor to poverty, and the earlier people know one is likely, the better they can prepare.

“Tropical cyclones mean damaging winds, damaging rainfall damage to agriculture and damage to infrastructure. It can have a significant impact on people’s lives.”

NIWA is in the process of making the predictions more accessible, including being active on social media and looking into translating reports.

“It’s highly technical. We’re trying to get it to a stage where people without that technical knowledge can take it up and use it to make decisions.

“Getting the information out there is the most important thing. Staying informed is really important.”

Lorrey said looking at weather patterns over a long period of time helps NIWA to better predict the future.

“It’s really helping us to understand. It has effects that are far-reaching. Without the data we’re collecting, we wouldn’t have as rich an understanding as we do.”

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