Analysis of diurnal air temperature range change in the continental United States

Diurnal temperature range (DTR) is an important indicator for climate change. In this paper, diurnal air temperature range variations of the continental United States over the past one hundred years were investigated to discover the temporal trend and spatial patterns. While the annual mean DTR of the United States has steadily decreased during the past decades, it is found that the decreased amplitude has spatial and seasonal patterns. Seasonal and spatial variations of DTR were analyzed for the four regions, northeastern, northwestern, southeastern, and southwestern. Fall and summer witnessed a significant decrease in DTR in all regions. Spring and winter, on the other hand, have experienced much smaller decreases. Temporal trend and spatial patterns of daily maximum and minimum temperatures were also investigated to gain insight of DTR change.