Use of Dynamically Downscaled Climate Projections for the Lower Santa Cruz River Basin
Progress Report
January 19, 2018Dr. Hsin-I Chang
Hydrology and Atmospheric Sciences, University of [email protected]
Climate Simulation Downscaling Methodology
Regional Climate Products• North America• Statistical (LOCA)• Dynamical – (RCP 8.5 only)
provided by Univ. of Arizona, # of grid points: 1511 x 651, size per point 25 km x 25km
DownscalingStatistical vs Dynamical
Extract climate data for LSCRB study region
# of grid points: 124x124, Size per point: 25 km x 25 km
IPCC Emissions Scenarios• RCP 4.5 (Lower Risk)• RCP 8.5 (Higher Risk)
Global Climate Models• Size per point:
209 km x 209 km• Supply climate
projection information for regional climate model simulation
Dynamically Downscaled Climate Products used to date
• 3 IPCC global climate projections identified (High Risk Scenario)• GFDL (United States)• MPI-ECHAM6 (Germany)• HadGEM2 (United Kingdom)
• Regional climate model used: • WRF (Weather Research and Forecasting model)
Data Source: University of ArizonaNorth American Coordinated Regional Climate Downscaling Experiment (NA-CORDEX)
Current Status [WRF-MPI 25km]
• Precipitation climatology data processing: 1950 – 2070• Temperature climatology data processing: 1950 – 2070• Daily extreme precipitation analysis: 1950 – 2070 • Daily extreme temperature analysis: 1950 – 2070
Climate Analysis Metrics from Partner Input
• Extreme event: intensity and frequency• Daily precipitation• Daily temperature change
• Monsoon onset: timing • Five-day running average of daily precipitation
• Length of dry period before monsoon onset: timing
Best precipitation climatology: WRF-MPI Summer projection: 5-10% reductionWinter projection: 30-50% reduction
c
WRF-MPI(1971 -2000)
Tucson Airport 1971 – 2000
WRF-MPI(2001 - 2040)
Average Monthly Precipitation, WRF-MPI over LSCR Basin
Prec
ipita
tion,
mm
/mon
th
1 inch (25.4 mm)
WRF-MPI: Top 10% Daily Precipitation Events [Aug]
WRF-MPI1950 - 2010
WRF-MPI2011 - 2070
25.4 mm = 1 inch
25.4 mm = 1 inch
• Max. rainfall threshold reduced: 150 mm/day 90 mm/day• Extreme rainfall PDF shifted toward lower threshold
WRF-Reanalysis: top 10% Daily Precipitation Events [Aug, 1950-2010]
25.4 mm = 1 inch
# of
eve
nts
Precipitation, (mm/day)
WRF-MPI: Top 10% Daily Precipitation Events [Dec]
• Max. rainfall threshold increased: 23 mm/day 30 mm/day• Extreme rainfall PDF shifted toward lower threshold
25.4 mm = 1 inch
25.4 mm = 1 inch
WRF-MPI1950 - 2010
WRF-MPI2011 - 2070
WRF-MPI: Top 10% of average Daily Temperatures [Aug]
• More extreme temperature days over 100F• Extreme temperature PDF shifted toward
higher threshold
WRF-MPI1950 - 2010
WRF-MPI2011 - 2070
# of
eve
nts
• More high temperature extreme days
• Extreme temperature distribution peaking between 50-70F
WRF-MPI: Top 10% of average Daily Temperatures [Dec]
WRF-MPI: Change in number of extreme values by thresholds
More extreme warm days, a lot less days with high rainfall for both winter and summer
(F) 9 - 16 17 - 25 26 – 34 35 - 43 44 - 52 53 – 61 62 – 70 71 – 79 80 – 88 89 – 97 98 – 106 107 - 117
9 - 16 17 - 25 26 – 34 35 - 43 44 - 52 53 – 61 62 – 70 71 – 79 80 – 88 89 – 97 98 – 106 107 - 117
Summary: LSCR Basin Climate Analysis
• Proposed methodology approach demonstration using metric suggested by study partners – comments?
• Is there agreement on this methodology?
• The ‘best performing’ climate model (WRF-MPI) predicts more warm days, less high rainfall days by the end of 2070
• Ongoing Activities:• Same analysis for other NA-CORDEX simulations (GFDL, HadGEM2)• Compare with observations and LOCA data
