Weekend/weekday diurnal temperature range in central Arizona

Many researchers have compared the diurnal temperature range (DTR) – the difference between the daytime maximum and the early morning minimum temperature – at a large number of selected weather stations in the continental United States, and elsewhere (Forster and Solomon, 2003). The difference between the weekday DTR (Tu-Th) and the weekend DTR (F-Su) was found to be as large as 0.5°K. It was hypothesized that the “weekday-weekend effect” is most likely tied to human activity and furthermore that aerosol-cloud interactions are most likely responsible. This present study examines the “weekday-weekend effect” at five Phoenix, Arizona urban weather stations (AZMET stations collecting data from1987-2003) and two rural AZMET stations located well out of urban Phoenix airshed approximately 80 kms outside of the city. Previous research on visibility and solar attenuation in Phoenix, Arizona has shown how systematic variations among days of the week and hours of the day were influenced by both pollutant source strength characteristics and meteorological phenomena (Idso and Cooley, 1980: and Idso and Kangieser, 1987). Thus it is plausible that the DTR patterns ought to reveal significant differences on the weekly timescale. Results thus far of the weekday-weekend effect between Phoenix urban and rural sites appear to be in close agreement with the Forster (2003) findings.