Spatial Variation in Climate across the Phoenix, AZ Metropolitan Area at Various Time Scales

As urban LTER researchers select sites for long-term sampling, they need climate data on several scales to understand changes in deposition, vegetation, erosion, run-off, biomass, arthropod populations, etc. The use of a single meteorological station is not appropriate where the topography and land use are not homogeneous. A perfect example is the Phoenix metropolitan area. This study examines the variation in climate across Phoenix through the use of several networks of weather stations at multiple temporal and spatial scales. The differences are not simply explained by distance to the urban center or elevation. Air temperature is the most uniform, although it varies in response to land cover and elevation. Dew point temperature fluctuates widely in response to both local and regional influences at short (5-minute) and long (day to week) time scales. Although a general mountain/valley breeze regime dominates, wind directions vary significantly across the valley due to both complex terrain and roughness associated with land use and land cover. The bimodal precipitation pattern (winter frontal systems and summertime convection) results in widely varying rainfall amounts across the valley, at all time scales from single storms through annual totals. Researchers need data through a range of temporal and spatial scales to understand the changes in the long-term ecology of their permanent sites. They must use both the established networks and their own micromet stations to reveal the climate impacts at their field sites.