October 2004 – Update from the Climate Science Team

• Robert Balling
• Joseph Zehnder

Joe Zehnder and Robert Balling, of the DCDC Climate Science Team introduced the uncertainties of climatic conditions that impact our region's water supply. While the region's water supply is geographically influenced by the characteristics of the seven states in the Colorado River Basin, the climate for the area is influenced by global factors.

Knowing that the Palmer Hydrological Drought Index identifies central Arizona as anticipating severe drought is not enough information to forecast the trend. When including global patterns such as the Pacific Decadal Oscillation patterns, 80% of the variance in climate remains unexplained. As a result, data gathering efforts need to increase, with links to hydrology and human use. At a different scale, the urban heat island phenomenon is clearly impacting greater Phoenix.
Presentation (2 MB pdf)

Mesoscale meteorological modeling (MM5) is used to create an urban surface energy scheme that identifies climatic conditions in the region. In the past 30 years, daytime temperatures have experienced little change, while nighttime temperatures have increased by three degrees. Further, the spatial distribution of the increased heat has expanded with growth. Looking forward, using landcover projections created by Maricopa Association of Governments (MAG), the urbanized areas will experience increased temperatures at night. However, the geography encompassing the current metropolitan area will not get hotter. These results present possible research opportunities in understanding the radius of influence urban heat has on surrounding areas.
Presentation (3 MB pdf)