Climate adaptation in the southwest US: The SWPar4.5 parameter set for stochastic weather generators

Area of Science:

• Environmental science
• Climate science
• Hydrology

Background:

• Southwestern US climate assessment is challenging due to spatial gradients and intense, short rainfall events.
• Existing gridded climate data (e.g., ~4km daily) often fail to capture fine-scale precipitation dynamics.
• Point-scale data is essential for site-specific environmental models (point-, plot-, field-, and hillslope-scale).

Purpose of the Study:

• To develop a framework (Southwest Parameter Set 4.5 or SWPar4.5) for generating high-resolution (~800m) historical and future point-scale climate time series.
• To improve climate assessment accuracy in regions with extreme spatial gradients and intense precipitation.

Main Methods:

• SWPar4.5 uses monthly climate benchmarks to parameterize a stochastic weather generator.
• A data fusion approach combined two gridded climate projections (RCP4.5) with different spatiotemporal resolutions.
• The method generates daily time series with sub-daily precipitation patterns.

Main Results:

• SWPar4.5 provides point-scale climate time series at ~800m resolution.
• Generated data includes sub-daily precipitation patterns, revealing increases in local precipitation intensity.
• The framework facilitates targeted climate assessment for environmental modeling.

Conclusions:

• SWPar4.5 offers a valuable tool for detailed climate assessment in the southwestern US.
• Increased local precipitation intensity has significant implications for soil erosion, runoff, and other environmental indicators.
• High-resolution, point-scale climate data is critical for accurate environmental impact studies.