Statistical Downscaling of Rainfall for the Hawaiian Islands using CMIP5 Model Scenarios
The results presented show the estimated rainfall changes during the mid 21st century (model years 2041-2071) and late 21st century (model years 2071-2099) in percent of the present-day climatological seasonal rainfall amount (1978-2007) at each station. Two different representative concentration pathways (RCPs) were downscaled: RCP4.5 a medium range warming scenario and RCP8.5, the high emissions and strong warming scenario (see IPCC AR5 report for details on the RCPs). We provide the wet season (November-April) and dry season (May-September) results. The shown values represent the median of the multi-model ensemble results.
Besides the seasonal mean rainfall changes, we provide interpolated maps of the cross-validation (correlations coefficients between downscaled and observed historical rainfall anomalies). Further, derived statistics are provided that give insight into the expected changes in frequency of five seasonal rainfall anomaly classes from very dry to very wet seasons.
The statistical downscaling works with observational data from a network of rain gauge stations. The downscaled results are thus obtained at irregularly distributed rain gauge locations. Here, we extended the spatial representation of the station estimates into geographical maps by applying Ordinary Kriging for the four Island regions. The resulting maps have are provided in different resolutions (0.5 minute, 3km, and 250m). We used interpolation routines from the software package geoR in R for the first interpolation from irregular station points to 0.5 minute resolution (and 3km resolution maps). The high-resolution climatology maps served here as 'Paired rainfall maps' at 250m were produced with GIS software from the 3km resolution data.
“Scenario Maps” contain the statistically downscaled seasonal rainfall anomalies for the future climate change scenarios.
“Anomaly Classes” contain derived products from the multi-model ensemble downscaling results. They measure relative frequency of future rainfall anomalies within five different rainfall anomaly categories (very dry, dry, neutral, wet, very wet).
“Cross Validation” contains data sets with the Monte-Carlo generated cross-validation results (spatially interpolated Pearson correlation coefficients) measuring the correlation between observed seasonal rainfall anomalies and downscaled anomalies.
Elison Timm, O., T. W. Giambelluca, and H. F. Diaz (2015), Statistical downscaling of rainfall changes in Hawai‘i based on the CMIP5 global model projections, J. Geophys. Res. Atmos., 120, 92–112, doi: 10.1002/2014JD022059.
Additional information on the statistical downscaling approach can be found in:
Timm, O. and H. F. Diaz (2009), Synoptic-Statistical Approach to Regional Downscaling of IPCC 21st Century Climate Projections: Seasonal Rainfall over the Hawaiian Islands, J. Climate, 22, 4261–4280, doi: 10.1175/2009JCLI2833.1.
Scenario Maps: Precipitation anomaly [%], Krige error variance [%2]
Anomaly Classes: frequency
Cross Validation: correlation coefficient
|Zonal||Scenario Maps: Various Hawaiian Islands by 1/120 deg (0.5min), [climatology] 1/414 deg (250m), 1/34 deg (3km)
Anomaly Classes: Various Hawaiian Islands by 1/34 deg (3km)
Cross Validation: Various Hawaiian Islands by 1/414 deg (250m), 1/34 deg (3km), 1/120 deg (0.5min)
|Meridional||Scenario Maps: Various Hawaiian Islands by 1/120 deg (0.5min), [climatology] 1/414 deg (250m), 1/34 deg (3km)
Anomaly Classes: Various Hawaiian Islands by 1/37 deg (3km)
Cross Validation: Various Hawaiian Islands by 1/445 deg (250m), 1/37 deg (3km), 1/120 deg (0.5min)
|Temporal||Scenario Maps: [climatology] 1978-2007 (3km, 250m), [rcp45]: 2041-2071 mean (0.5min) and 2071-2099 mean (0.5min), [rcp85]: 2041-2071 mean (0.5min) and 2071-2099 mean (0.5min)
Anomaly Classes: [historial]: 1880-1991 MJJASO/NDJFMA, 1910-1940 MJJASO/NDJFMA, 1940-1970 MJJASO/NDJFMA, 1970-2000 MJJASO/NDJFMA, 1975-2005 MJJASO/NDJFMA, [rcp45/rcp85]: 2011-2014 MJJASO/NDJFMA, 2031-2061 MJJASO/NDJFMA, 2041-2071 MJJASO/NDJFMA, 2071-2099 MJJASO/NDJFMA
Cross Validation: N/A
|Acquired||Aug 1, 2014 (Updated Jul 2016)|
|Supplements||CMIP5 model scenarios (more information)|