Tuesday, April 30, 2013

Another study predicts a drier future for Hawai`i

Rainfall in the Islands has gradually dropped over the past three decades, and we seem to be facing an even more parched future.

University of Hawai`I and University of Colorado researchers, writing in the Journal of Geophysical Research, note that rainfall has slowly been declining since the late 1970s, and that the decline could continue through 2100.

The short version: Winters are drier than they used to be, and they will continue to be drier.

Hawai`i gets most of its rain in the winter, and the research they have done suggests the winter storms have been reducing in frequency.  The authors of the article are Oliver Elison Timm, Mami Takahashi, Thomas W. Giambelluca and Henry F. Diaz.

“For water resource and ecosystem management, and for other societal needs, we need to know whether this drying trend will continue this century,” said lead investigator Oliver Elison Timm at the International Pacific Research Center at UH Mānoa.

The team studied the large-scale weather patterns associated with heavy rain events.

“The patterns we saw did not surprise us,” said Oliver Elison Timm of the University of Hawai`i’s International Pacific Research Center. “For example, we found that the typical winter Kona storms with moist air-flow from the South often produce torrential rains in the islands.”

The large circulation patterns that create those downpours have been shifting, and reducing the number of rain events during the rainy season.

“We can’t predict individual rain events with our method,” said Thomas W. Giambelluca, Professor in the Department of Geography at UH Mānoa, but he said they can predict that drier winters and fewer winter downpours will be a pattern for most of the next century.

Another recent article doesn’t directly address the Hawaiian situation, but suggests in that in the tropics (We’re in the sub-tropics, so the data is not directly applicable.), areas that are already very wet will get wetter still. And areas that have significant ocean warming will also get wetter.

The article suggests more rain will occur with increasing warming in areas close to the equator. The authors of the piece are Ping Huang, Shang-Ping Xie,  Kaiming Hu, Gang Huang and Ronghui Huang, Shang-Ping Zie is with the University of Hawai`I’s International Pacific Research Center.

© Jan TenBruggencate 2013

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