Options for Improving Climate Modeling to Assist Water Utility ...

Water Utility Climate Alliance White Paper
Options for Improving Climate Modeling to Assist Water Utility Planning for Climate Change
There is the potential for partnering between individual RCM development groups and
water utility planners.
Improvements to RCMs are often transferable to GCMs, as spatial resolution in GCMs
increase allowing them to simulate more regional details.
Evaluation of RCMs with 10–20-km grid spacing is expected to show improvements to
storm-total snowfall, timing of seasonal snowmelt, and high-rate rainfall. Additional
investment in microphysics and snow pack parameterizations may improve storm-total
snowfall and episodic and seasonal snowmelt. Additional investment in 2–10 km grid
spacing may show improvement in high-rate rainfall.
Cons
Investments solely in RCM design may redirect efforts away from ensemble approaches
or statistical downscaling, so that while RCM simulation of variables critical to water
utility planning may improve, the development of ensembles of local projections is not
ensured.
Current observational systems may be inadequate for detailed evaluation of new model
components.
RCM output will likely still not mimic actual station measurements and still will likely
require statistical processing, such as bias correction, in order to use it as input to
hydrological and decision system models.
Availability
Evaluations of some RCM component tests could begin within the year, with experiments
continuing for the next 10 years. Evaluations of some components, such as choice of grid
spacing and utility of multi-moment or binned microphysics parameterization, may be completed
by the next round of CMIP, which is scheduled for 2011.
Estimate of costs
An investment in research staff will be needed, similar to the level of funding from an
external grants program, such as the recent DOE Request for Proposal (RFP) for highrisk,
high-reward regional modeling that contained about $2 million per year:
$5 million/year for 5–10 years (five-year total of $25 million; 10-year total of
$50 million).
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