Synoptic-statistical approaches to regional

downscaling of IPCC 21st century climate

projections: A Hawaiian Islands study

Oliver Timm,

International Pacific Research Center, SOEST, University of

Hawai'i at Manoa

Henry Diaz, NOAA/ESRL/CIRES, Boulder, Colorado

Thomas Giambelluca Dept. Geography, University of Hawai'i at

Manoa

IPCC's Fourth Assessment Report, 2007:

(more than 20 climate models took part)

precipitation change: likely to decrease

but for Hawaii, no robust signalsModels show a drier

climate

Models results inconsistentMost models: drier climateMost models: wetter

climate

No significant changeModels show a wetter

climate

Introduction:

H

H

Synoptic (=weather-related) studies:

Months with high/low precipitation in Hilo site of Big Island

[sea level pressure, wet season (Nov-Apr) between 1970-2000]

High Preciptation Low Preciptation

Rainfall controlled by large-scale circulation

Trade Wind RegimeKona Wind Regime

Model #1 Model #28 Model #30

Model #38 Model #40 Model #53

IPPC 21st century diagnostics: Changes in the mean

sea level pressure, wet season 2061-2099

Projected rainfall changes

Dry season May-October 2030-2060

Rainfall change

in percent of

present rainfall amount

Projected rainfall changes

Wet season November-April 2030-2060

Rainfall change

in percent of

present rainfall amount

Projected rainfall changes

Dry season May-October 2060-2100

Rainfall change

in percent of

present rainfall amount

Projected rainfall changes

Wet season November-April 2060-2100

Rainfall change

in percent of

present rainfall amount