Local Climate Effects of a Large Urban Lake on Tempe, AZ.

Water features are becoming increasingly popular in residential and commercial development, particularly in the Southwest deserts. Housing developments, golf courses, local public parks and business/industrial parks are constructing urban lakes for their aesthetic, recreation, psychological, and economic benefits. The climate effects of these lakes are not well documented, but are often perceived by the public to be similar to the effects of larger water bodies. The City of Tempe, AZ constructed a 224-acre lake in the dry Salt River channel to boost local recreation and economic development, specifically the tourism market. The public perception was that the lake would increase humidity, and generate a warm season climate "like back east".

A complete permanent meteorological station was set-up on the west end of the lake. A large number of temperature-moisture sensors were deployed around the lake and outward from the lake throughout the city of Tempe. The sensors recorded 5-minute and 15-minute data. The most pronounced differences between sensors seen so far are not related to the distance from the lake, but are microclimate effects of the sensor locations. Sensors placed in open locations adjacent to large vegetated areas detect lower temperatures and higher dew points than sensors closer to the lake, but located between buildings. The dominant wind regime, parallel to the main axis of the lake, carries the water vapor up and down the river channel rather than into the city. The effects of the lake on temperatures perpendicular to the river channel are limited to within a few hundred feet of the water's edge, depending on local topography and land cover.